Journal of Medical Economics
ISSN: 1369-6998 (Print) 1941-837X (Online) Journal homepage: http://www.tandfonline.com/loi/ijme20
Healthcare costs associated with skeletal-related events in breast cancer patients with bone metastases May Hagiwara, Thomas E. Delea & Karen Chung To cite this article: May Hagiwara, Thomas E. Delea & Karen Chung (2014) Healthcare costs associated with skeletal-related events in breast cancer patients with bone metastases, Journal of Medical Economics, 17:3, 223-230 To link to this article: http://dx.doi.org/10.3111/13696998.2014.890937
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Date: 05 November 2015, At: 13:09
Journal of Medical Economics 1369-6998 doi:10.3111/13696998.2014.890937
Vol. 17, No. 3, 2014, 223–230
Article 0143.R1/890937 All rights reserved: reproduction in whole or part not permitted
py Un t rig au fo t ht di hor r S sp ize a la d le © y, u s 20 vi e o ew p r 14 r C o an h d p ibi om In rin ted m fo rm t a . Au e si th rc aU ng or i le is al K co ed D py us is Lim fo ers tr ite rp c i b a er n d so d ut na ow io l u nl n se oa d,
May Hagiwara Thomas E. Delea
Policy Analysis Inc., Brookline, MA, USA
Karen Chung
Amgen Global Health Economics, Thousand Oaks, CA, USA Address for correspondence: May Hagiwara, PhD, Policy Analysis Inc. (PAI), Four Davis Court, Brookline, MA 02445, USA. Tel: +1-617-232-4400; Fax: +1-617-232-1155; [email protected] Keywords: Skeletal-related events – Breast neoplasms – Metastases – Healthcare costs
Accepted: 31 January 2014; published online: 18 February 2014 Citation: J Med Econ 2014; 17:223–30
No
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Original article Healthcare costs associated with skeletal-related events in breast cancer patients with bone metastases Abstract
Background: Patients with bone metastases secondary to breast cancer are pre-disposed to skeletal-related events (SREs), including spinal cord compression (SCC), pathologic fracture (PF), surgery to bone (SB), and radiotherapy to bone (RT). Objective: To document current patterns of healthcare utilization and costs of SREs in patients with breast cancer and bone metastases. Methods: This was a retrospective, observational study using the Thomson MedStat MarketScan Commercial Claims and Encounters database from 9/2002 to 6/2011. Study subjects included all persons with claims for breast cancer and for bone metastases, and 1 claims for an SRE. Unique SRE episodes were identified based on a gap of at least 90 days without an SRE claim, and classified by treatment setting (inpatient or outpatient) and SRE type (SCC, PF, SB, or RT). Results: Of 17,266 patients with breast cancer and bone metastases, 9142 (53%) had one or more SRE episodes. Among 5809 patients who met all other criteria, there were 7617 SRE episodes over mean (SD) follow-up of 17.2 (15.2) months. The percentage of episodes that required inpatient treatment ranged from 11% (RT) to 76% (SB). On average, inpatient SCC episodes (n ¼ 83 episodes) were most costly; while outpatient PF episodes (n ¼ 552 episodes) were least costly. Of the total SRE costs (mean [SE] $21,072 [$36,462]/ episode), 36% were attributable to outpatient RT (n ¼ 5265 episodes) and 31% to inpatient PF (n ¼ 838 episodes). Limitations: The administrative claims data used in this study may lack sensitivity and specificity for identification of clinical events and may not be generalizable to other populations. Also, for some SRE episode categories, the number of events was small and cost estimates may lack precision. Conclusion: In patients with breast cancer and bone metastases, SREs are associated with high costs and hospitalizations.
Introduction Breast cancer is one of the most common cancers in the US, with an estimated 226,870 new cases and 39,510 deaths in 2012, and it is the second leading cause ! 2014 Informa UK Ltd www.informahealthcare.com/jme
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of cancer death in women behind lung cancer1. The skeleton is the most common site of metastasis in women with advanced breast cancer2,3. Median survival in women with breast cancer and a diagnosis of bone metastases is 20–24 months2,4. Patients with bone metastases of breast cancer are at risk of a variety of skeletal-related events (SREs), such as pathological fractures, bone instability requiring surgery to the bone, radiation to the bone to control local tumor burden and manage pain, and spinal cord compression. These events can be associated with considerable morbidity, impaired health-related quality-of-life, reduced survival, and increased healthcare costs5. Numerous studies have examined the impact of SREs on costs in patients with bone metastases secondary to solid tumors among US as well as European populations6–16. In an analysis of US patients with breast cancer, Delea et al.8 estimated the expected costs of care directly attributable to SREs to be $13,940 per patient. After matching on baseline characteristics, expected total medical-care costs were $48,173 greater in patients with SREs vs those without8. Barlev et al.6 recently examined the costs of hospitalizations for SREs in US patients with bone metastasis secondary to prostate or breast cancer or with multiple myeloma. These authors reported that, among patients with breast cancer, the mean health plan payment per hospital admission was $59,854 for spinal cord compression, $26,936 for pathologic fracture, and $32,742 for surgery to the bone. Dura´n et al.15 and Hechmati et al.16 analyzed cost of SREs among patients in Germany, Italy, Spain, and the UK with bone metastasis secondary to solid tumor or multiple myeloma. The reported costs range from E5000–E12,000 for spinal cord compression and E3000–E9000 for surgery to bone. While these studies provide useful information on the costs of SREs in patients with bone metastases of solid tumors, they have some limitations. Although Barlev et al.6 examined the costs of SREs treated in the inpatient setting, little is known regarding the relative magnitude of the costs of SREs treated on both an inpatient and an outpatient basis. Also, none of these studies have examined the costs of episodes of care (EOC) for SREs. As defined in the literature, an EOC represents the period initiated by patient presentation with a diagnosis of a clinical condition and concluded when the condition is resolved17. EOC-based analyses have been used extensively to assess the costs of treatment of diseases such as diabetic foot ulcers18, abdominal pain19, and low back pain20. As many patients experience more than one SRE, EOC-based cost analysis can be useful in understanding the economic impact of different types of SREs, and in informing estimates of the potential cost savings that might accrue as a result of interventions that may prevent them. This study was conducted to document current patterns of healthcare utilization and costs of SREs in patients 224
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with breast cancer and bone metastases using EOC-based analyses.
Patients and methods Study design and data source A retrospective observational longitudinal cohort design was employed. Data for this study were from the Thomson MedStat MarketScan Commercial Claims and Encounters database. This database contains information on the US health insurance claims of employees of large, self-insured corporations and their dependents, along with a few commercial health plans. The database is fully de-identified and compliant with the Health Insurance Portability and Accountability Act of 1996 (HIPAA). Accordingly, IRB approval was not necessary. Data used in this study span the period from September 1, 2002–June 30, 2011 (‘study period’).
Patient selection Patients were included in the analysis if they met all of the following criteria: confirmed diagnosis of bone metastases (International Classification of Disease, 9th edition, Clinical Modification [ICD-9-CM] diagnosis codes 170.XX or 198.5X); confirmed diagnosis of breast cancer (174.XX) prior to bone metastases diagnosis; and one or more SRE episodes (detailed algorithm is found in section below, titled as Identification of SREs). For the purpose of this study, a patient was considered to have a ‘confirmed’ diagnosis if the patient had one or more inpatient facility claims with the diagnosis code or codes of interest listed as the primary diagnosis on the claim, or two or more medical claims on different days and no more than 6 months apart, with the same diagnosis code or codes of interest listed in any diagnosis field on the claims. This approach of identifying confirmed diagnoses was employed to improve the specificity of diagnoses based on ICD-9-CM diagnosis codes on health insurance claims. These codes may lack specificity if listed on claims for services provided to rule out certain diseases or as working diagnoses while clinical diagnoses are confirmed by pathological or other means. The ‘index date’ was defined as the date with the first confirmed diagnosis of bone metastases. The 6-month period prior to the index date was designated the ‘preindex period’; the period from the index date to the end of continuous enrollment was designated the ‘follow-up period’. Patients less than 18 years of age on the index date, with gender specified as male, less than 6 months of continuous enrollment prior to the index date, a diagnosis of primary cancer other than breast cancer prior to the index date, or with zero, missing, or negative cost data were excluded. Because diagnosis codes for primary cancer www.informahealthcare.com/jme ! 2014 Informa UK Ltd
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may sometimes be used for metastatic disease, patients were assumed to have other primary cancer only if they did not also have a corresponding claim for metastasis to the same site. For example, patients with claims with a diagnosis of primary liver neoplasm (ICD-9-CM 155.xx) as well as claims with diagnosis of metastasis to the liver (197.0x, 197.1x, 197.2x, and 197.3x) were not considered to have ‘other primary cancer’. Conversely, those with claims with diagnoses of primary liver neoplasm but without a claim for metastasis to the liver were assumed to have ‘other primary cancer’. Codes for identification of primary and secondary malignancies by site are listed in Supplementary Appendix A.
Patient characteristics For each patient, baseline demographic characteristics and comorbidities were assessed as of the index date, including calendar year, age, region, plan type, and Deyo’s version of the Charlson Comorbidity Index21. Pre-index healthcare utilization and costs also were measured including: the number of outpatient pharmacy claims or procedures for chemotherapy, systemic corticosteroids, and intravenous bisphosphonates; the number of outpatient pharmacy claims (i.e. prescriptions) for opioids, and oral bisphosphonates; and the number of claims for inpatient hospitalizations, emergency department visits, home healthcare visits, hospice care, skilled nursing facility care, physician office visits, hospital outpatient visits, laboratory tests, and other care. In counting these services, multiple claims occurring on the same day were counted once, except for outpatient prescriptions. Also tallied were the costs of inpatient hospitalizations, emergency department visits, home healthcare visits, hospice care, skilled nursing facility care, physician office visits, hospital outpatient visits, laboratory tests, and other healthcare services. Costs were approximated based on paid amounts (total gross payment after applying pricing guidelines such as fee schedules and discounts, but before applying deductibles, co-insurance, co-payments, and co-ordination of benefit).
Identification of SREs For each patient, the follow-up period was scanned to identify all medical claims indicative of an SRE (i.e. spinal cord compression, pathological fracture, surgery to bone, or radiotherapy). Diagnosis and procedure codes used to identify SREs are listed in Supplementary Appendix B. The codes used to identify SREs were based on coding algorithms used in prior studies7–9,13, supplemented with discussion with clinical and coding experts. When there was uncertainty with respect to the inclusion of codes for the identification of SREs, the coding algorithm was designed to be as specific as possible to avoid the inclusion of events ! 2014 Informa UK Ltd www.informahealthcare.com/jme
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that were not actually SREs. Regarding the identification of pathological fractures, there are two different sets of ICD-9-CM codes for fractures. Pathological or spontaneous fractures are classified in the musculoskeletal and connective tissue chapter of ICD-9-CM (i.e. ICD-9-CM 733.1x), whereas traumatic fractures are classified in the injury and poisonings chapter of ICD-9-CM (ICD-9-CM 800-824). Because pathological or spontaneous fractures may be associated with trivial trauma such as a minor fall, many such fractures may be incorrectly coded as traumatic fractures. For the purpose of this study, pathological fractures were, therefore, identified based on confirmed diagnoses of pathological fracture (i.e. ICD-9-CM 733.1x) or a confirmed diagnosis of traumatic fracture (ICD-9-CM 800-824) (see Patient Selection section for the definition of confirmed diagnosis). Claims with codes for traumatic fracture (ICD-9-CM 800-824) were only included, however, if there were no concurrent claims with codes suggesting accident (excluding accident codes for ‘falls on the same level’) or trauma. ‘Concurrent claims’ were defined as claims occurring during the 2-week period ending with the claim for the fracture. When identifying a confirmed diagnosis of fracture, all diagnosis codes for fractures to the same site were considered as confirmatory. When identifying surgery to bone, claims with concurrent claims suggesting accident (excluding falls on the same level) or significant trauma also were excluded. Because there are no body site modifiers for procedure codes for radiotherapy, claims for radiotherapy procedures were considered only if there was a concurrent claim with a diagnosis code for bone metastasis, spinal cord compression, bone pain (ICD-9-CM 733.90), or pathological fracture. For each patient with at least one SRE claim during the follow-up period, SRE episodes were identified using a gap of 90 days or more without an outpatient claim or an inpatient admission for an SRE. Gaps were defined based on the number of days without SRE claims starting with the last SRE claim (Figure 1). The choice of the 90-day gap was based on the observation that the mean daily cost of SRE-related care by time since the first SRE claim declined rapidly between 1 and 3 months after the first SRE claim and leveled off shortly thereafter. Each SRE episode was then classified into mutually exclusive categories. SREs include both diagnoses (spinal cord compression and pathological fracture) as well as procedures (surgery to bone and radiotherapy). These procedures may be used in the treatment of the diagnosed condition(s) (e.g. surgery to bone may be used for a pathological fracture). Spinal cord compression can present as an oncologic emergency, potentially leading to severe and permanent neurological damage including paresis or paralysis, loss of control of bladder and/or bowel function, loss of independence, reduced quality-of-life, and reduced survival22–25. Accordingly, in defining mutually exclusive SRE costs in breast cancer with bone metastases Hagiwara et al.
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Figure 1. Example for identifying SRE episodes with 90-day gap. Gaps were defined based on the number of days without SRE claims starting with the last SRE claim. PF, Pathological fracture; RT, Radiotherapy; SB, Surgery to bone; SCC, Spinal cord compression.
categories, we implemented a hierarchy in which the diagnoses of spinal cord compression and pathological fracture were at the top and surgery to bone and radiotherapy were at the bottom. This yielded the following hierarchy in order to identify mutually exclusive categories of SRE episodes based on evidence of confirmed diagnoses or procedures: spinal cord compression; pathological fracture without spinal cord compression; surgery to bone without spinal cord compression and without pathological fracture; and radiotherapy without any other types of SRE claims. Episodes were further classified as ‘inpatient’ or ‘outpatient’ based on the presence during the episode of one or more inpatient hospital claims with any SRE.
Table 1. Selection of study subjects. Criteria Confirmed diagnosis of bone metastases, confirmed diagnosis of breast cancer prior to bone metastases diagnosis, and one or more SRE claims during the follow-up period Exclusions (not mutually exclusive) Less than 6 months of continuous enrollment prior to index date More than one type of primary cancer prior to index date Male patients Total excluded Remaining
n
%
9142
100.0
2788
30.5
609
6.7
31 3333 5809
0.3 36.5 63.5
SRE, Skeletal-related event.
Outcome measures and analyses For each SRE episode, all the claims during the episode were scanned and classified as SRE-related or nonSRE-related according to ICD-9-CM diagnosis codes and procedure codes listed in Supplementary Appendix B. For each SRE episode, all the SRE-related costs (payments) were tallied and adjusted to calendar year 2010 US dollars26. The number and percentages of SRE episodes by type of SRE, treatment setting, and SRE claims identified during the episode, and the mean (standard error [SE]) SRE-related cost per episode by type of SRE and treatment setting were calculated. All analyses were conducted using SAS Proprietary Software, Release 9.2.3*.
Results Of 17,266 patients with bone metastases and breast cancer identified in the dataset, 9142 patients (53%) had at least one SRE. Of these, 5809 patients met all other criteria (Table 1). Mean (SD) age was 52.9 (8.0) years, 44% of patients resided in the South, followed by North Central (25%), West (17%), and Northeast (12%), and the majority had *SAS Proprietary Software, Release 9.2.3 is a registered trade name of SAS Institute Inc., Cary, NC.
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preferred provider organization (PPO) (62%), followed by health maintenance organization (HMO) (15%) plan types (Table 2). The mean (SD) Charlson index during the pre-index period was 4.7 (3.2), consistent with that in prior studies of patients with advanced breast cancer8. The mean (SD) duration of follow-up was 17.2 (15.2) months. There were 7617 SRE episodes identified among 5809 patients. Among spinal cord compression episodes (n ¼ 113), 78% of the episodes included claims for radiotherapy, while 41% included claims for pathological fracture (Table 3). Among pathological fracture episodes (n ¼ 1390), 58% of the episodes included claims for radiotherapy, while 42% included claims for surgery to bone and 28% included pathological fracture claims alone. Among surgery to bone episodes (n ¼ 191), 53% included claims for radiotherapy. Almost all episodes with claims for radiotherapy (86%) were classified as radiotherapy episodes. Twenty-three per cent of all SREs required inpatient treatment. Only 11% of radiotherapy episodes required inpatient treatment, whereas 76% of surgery to bone episodes and 73% of spinal cord compression episodes required inpatient treatment. The mean (SE) cost of SRE-related services per episode was $55,229 ($1438) for inpatient episodes and $11,080 ($200) for outpatient episodes. On average, inpatient www.informahealthcare.com/jme ! 2014 Informa UK Ltd
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Table 2. Patient characteristics at baseline (n ¼ 5809).
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Characteristic
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Table 2. Continued.
n (%) or Mean (SD)
Index year, n (%) 2003 2004 2005 2006 2007 2008 2009 2010 2011 Age, years, Mean (SD) Males, n (%)
330 (5.7) 513 (8.8) 587 (10.1) 687 (11.8) 827 (14.2) 876 (15.1) 1055 (18.2) 721 (12.4) 213 (3.7) 52.9 (8.0) 0 (0.0)
Region, n (%) South North Central West Northeast Unknown
2568 (44.2) 1442 (24.8) 975 (16.8) 699 (12.0) 125 (2.2)
Plan type, n (%) PPO Comprehensive HMO Other Charlson index, Mean (SD)a
3586 (61.7) 385 (6.6) 871 (15.0) 967 (16.6) 4.7 (3.2)
Healthcare utilization, n (%)a Chemotherapy Systemic corticosteroid IV Bisphosphonate Opioid Oral Bisphosphonate Cardiovascular medication Diabetes medication Hospitalization Emergency department visit Homehealth Hospice Skilled nursing facility Physician office visit Hospital outpatient visit Lab visits Other encounters
388 (6.7) 1510 (26.0) 61 (1.1) 3018 (52.0) 261 (4.5) 2259 (38.9) 409 (7.0) 967 (16.6) 1346 (23.2) 1069 (18.4) 12 (0.2) 29 (0.5) 5612 (96.6) 5258 (90.5) 2272 (39.1) 1114 (19.2)
Number of healthcare claims, Mean (SD)a,b Chemotherapy Systemic corticosteroid IV Bisphosphonate Opioid Oral Bisphosphonate Diabetes medication Hospitalization Emergency department visit Hospice Skilled nursing facility Physician office visit Hospital outpatient visit Lab visits Other encounters
0.22 (1.11) 0.49 (1.09) 0.03 (0.30) 1.98 (3.45) 0.12 (0.65) 0.35 (1.63) 0.23 (0.61) 0.44 (1.37) 0.02 (0.72) 0.02 (0.41) 13.5 (11.2) 7.0 (8.2) 1.38 (2.75) 0.51 (2.19)
Characteristic Healthcare costs, $, Mean (SD)a Hospitalization Emergency department visit Homehealth Hospice Skilled nursing facility Physician office visit Hospital outpatient visit Lab visits Other encounters Duration of follow-up, months, Mean (SD)
n (%) or Mean (SD)
4073 (15,333) 373 (2895) 260 (1357) 11 (339) 50 (1468) 10,115 (18,798) 13,131 (27,216) 197 (659) 292 (2722) 17.2 (15.2)
a
(continued )
spinal cord compression episodes were most costly with mean (SE) cost per episode of $102,205 ($11,733), followed by inpatient surgery to bone episodes with mean (SE) cost per episode of $77,235 ($7070) (Figure 2). ! 2014 Informa UK Ltd www.informahealthcare.com/jme
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Calculated over 6 months prior to index date. Values are numbers of claims. Except for medications, claims on the same day are counted once. Costs are in 2010 US dollars. HMO, Health maintenance organization; IV, intravenous; PPO, Preferred provider organization; SD, Standard deviation.
b
Outpatient episodes with pathological fracture were least costly, with mean (SE) cost per episode of $10,700 ($816).
Discussion This was a retrospective, observational study using health insurance claims data to document costs associated with SRE episodes in patients with breast cancer and bone metastases. Results of this analysis suggest that, in patients with breast cancer and bone metastases, SREs episodes are associated with high costs and hospitalizations. This study differs from prior studies of the costs of SREs in that an EOC approach was employed for estimating the costs of SREs. EOC analysis is appropriate for analyzing the economic burden of clinical events when their treatments involve a series of separate but related healthcare services. By using an EOC approach, a more complete picture of the costs of events can be obtained. Future health insurance claims-based studies on the costs of SREs, as well as potential other events such as adverse events of treatment of disease progression in cancer patients, should explore the use of EOC analysis. Use of an EOC approach, however, requires a rule for defining each episode. Our decision to use a 90-day gap to define SRE episodes was based on the observation that the mean daily costs of SRE-related care declined rapidly from 30 to 90 days post-SRE, and leveled off shortly thereafter. It is instructive to compare results of this study with those reported by Barlev et al.6, which also used the MedStat MarketScan databases to evaluate the costs of inpatient SRE episodes in patients with bone metastasis secondary to prostate or breast cancer. The mean costs per inpatient episode for spinal cord compression, pathological fracture, and surgery to bone reported by SRE costs in breast cancer with bone metastases Hagiwara et al.
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Table 3. Number of SRE episodes by types of SRE claims identified within each episode among patients with breast cancer and bone metastases. SRE classification
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Spinal cord compression (SCC) SCC only SCC and PF SCC and SB SCC and RT SCC and PF and SB SCC and PF and RT SCC and SB and RT SCC and PF and SB and RT Total Pathological fracture (PF) PF only PF and SB PF and RT PF and SB and RT Total Surgery to bone (SB) SB only SB and RT Total Radiotherapy (RT) Total
Inpatient, n (%)
Outpatient, n (%)
All episodes, n (%)
6 (7.2) 3 (3.6) 1 (1.2) 26 (31.3) 3 (3.6) 14 (16.9) 5 (6.0) 25 (30.1) 83 (100.0)
12 (40.0) 0 (0.0) 0 (0.0) 16 (53.3) 0 (0.0) 1 (3.3) 1 (3.3) 0 (0.0) 30 (100.0)
18 (15.9) 3 (2.7) 1 (0.9) 42 (37.2) 3 (2.7) 15 (13.3) 6 (5.3) 25 (22.1) 113 (100.0)
105 (12.5) 173 (20.6) 214 (25.5) 346 (41.3) 838 (100.0)
277 (50.2) 31 (5.6) 213 (38.6) 31 (5.6) 552 (100.0)
382 (27.5) 204 (14.7) 427 (30.7) 377 (27.1) 1390 (100.0)
66 (45.5) 79 (54.5) 145 (100.0) 658 (100.0) 1724 (100.0)
23 (50.0) 23 (50.0) 46 (100.0) 5265 (100.0) 5893 (100.0)
89 (46.6) 102 (53.4) 191 (100.0) 5923 (100.0) 7617 (100.0)
SRE, Skeletal-related event. Percentages were calculated for each episode type: inpatient, outpatient, and all episodes.
Figure 2. Mean (95% CI) cost of inpatient and outpatient SRE episodes among patients with breast cancer and bone metastases by type of SRE (number of patients ¼ 5809): (A) Inpatient SRE episodes; and (B) Outpatient SRE episodes.
Barlev et al. are $59,854, $26,936, and 32,742, respectively, which are considerably lower than the mean costs per inpatient episode reported here ($102,205, $58,416, and $77,235, respectively). This difference may be a consequence of a number of factors. First, EOC approach was used to define SRE episodes in this study and inpatient 228
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episodes reported include follow-up outpatient care. Barlev et al. considered only the cost of hospitalization. Second, this study used wider sets of codes to identify pathological fracture and surgery to bone. Third, Barlev et al. used data from both commercial plans and Medicare. This study focused on commercial plans only because of www.informahealthcare.com/jme ! 2014 Informa UK Ltd
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the possibility that some care received by Medicare patients may not be captured in the MedStat database. Limitations of this study should be noted. This study used administrative claims data that may be subject to data coding limitations and data entry error. Also, diagnostic and procedure codes on claims may have limited sensitivity and specificity for clinical diagnoses. This may have affected the distribution of SREs if some diagnosis codes are more sensitive or specific than others. As noted above, this study used data from the MedStat commercial database, and the estimates reported herein may not be generalizable to Medicare or other elderly patients. Further, the MarketScan commercial database is geographically diverse but not entirely representative of the US population, and patients from the database may not be representative of all commercially-insured patients in the US or other settings. Approximately 15% of patients in the study sample were in HMO plans. As a consequence of capitation arrangements, the payment field for office visits for these patients may result in potential under-estimation of outpatient SRE costs. The extent of this bias is likely to be small, however, as cancer patients are likely to receive treatment from oncologists rather than primary care physicians, and the former are less likely to be in capitated payment arrangements than the latter. In calculating costs, we included only the costs of services that were considered to be related to the treatment of SREs based on diagnosis and/or procedure codes. Thus, while the cost of some routine care services unrelated to treatment of SREs may have been included, these costs are likely to be small. On the other hand, our estimates may be conservative as they do not include the costs of services that were incurred as a consequence of SREs but that could not be attributed to SREs based on diagnosis or procedure codes. Lastly, for some SRE episode categories (e.g., inpatient and outpatient surgery to bone), the number of events was small and our estimates may lack precision.
Conclusion Results of this study suggest that SREs are associated with high costs among patients with breast cancer and bone metastases, and that these costs may be greater than estimated previously for some events. This study also demonstrates the utility of EOC-based analyses for evaluating the costs of clinical events in retrospective studies using health insurance claims data.
Transparency Declaration of funding The manuscript was funded by Amgen.
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Declaration of financial/other relationships May Hagiwara, PhD and Thomas E. Delea, MSIA are employees of Policy Analysis Inc. and have received funding for the research from Amgen. At the time this research was conducted, Karen Chung, PharmD, MS was an employee of Amgen and owned stock options in Amgen, Inc. JME Peer Reviewers on this manuscript have no relevant financial or other relationships to disclose. Acknowledgments The abstract and poster were presented at American Society of Clinical Oncology, Breast Cancer Symposium in San Francisco on September 15, 2012.
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from a prospective multinational observational study. J Med Econ 2013;16:691-700 Hornbrook MC, Hurtado AV, Johnson RE. Health care episodes: definition, measurement and use. Med Care Rev 1985;42:163-218 Mehta SS, Suzuki S, Glick HA, et al. Determining an episode of care using claims data. Diabetic foot ulcer. Diabetes Care 1999;22:1110-5 Klinkman MS. Episodes of care for abdominal pain in a primary care practice. Arch Fam Med 1996;5:279-85 Shekelle PG, Markovich M, Louie R. Comparing the costs between provider types of episodes of back pain care. Spine (Phila Pa 1976) 1995;20:221-6; discussion 227 Deyo RA, Cherkin DC, Ciol MA. Adapting a clinical comorbidity index for use with ICD-9-CM administrative databases. J Clin Epidemiol 1992;45:613-9 Abrahm JL, Banffy MB, Harris MB. Spinal cord compression in patients with advanced metastatic cancer: ‘‘all I care about is walking and living my life’’. JAMA 2008;299:937-46
23. Conway R, Graham J, Kidd J, et al. What happens to people after malignant cord compression? Survival, function, quality of life, emotional well-being and place of care 1 month after diagnosis. Clin Oncol (R Coll Radiol) 2007;19:56-62 24. Loblaw DA, Perry J, Chambers A, et al. Systematic review of the diagnosis and management of malignant extradural spinal cord compression: the Cancer Care Ontario Practice Guidelines Initiative’s Neuro-Oncology Disease Site Group. J Clin Oncol 2005;23:2028-37 25. Loblaw DA, Laperriere NJ. Emergency treatment of malignant extradural spinal cord compression: an evidence-based guideline. J Clin Oncol 1998;16:1613-24 26. U.S. Bureau of Labor Statistics. Consumer Price Index. Medical Care, US City Average. Series ID: CUUR0000SAM, CUUS0000SAM, 2008. Washington, D.C. http://www.bls.gov/cpi/home.htm. Accessed May 30, 2012
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ISSN: 1369-6998 (Print) 1941-837X (Online) Journal homepage: http://www.tandfonline.com/loi/ijme20
Healthcare costs associated with skeletal-related events in breast cancer patients with bone metastases May Hagiwara, Thomas E. Delea & Karen Chung To cite this article: May Hagiwara, Thomas E. Delea & Karen Chung (2014) Healthcare costs associated with skeletal-related events in breast cancer patients with bone metastases, Journal of Medical Economics, 17:3, 223-230 To link to this article: http://dx.doi.org/10.3111/13696998.2014.890937
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Journal of Medical Economics 1369-6998 doi:10.3111/13696998.2014.890937
Vol. 17, No. 3, 2014, 223–230
Article 0143.R1/890937 All rights reserved: reproduction in whole or part not permitted
py Un t rig au fo t ht di hor r S sp ize a la d le © y, u s 20 vi e o ew p r 14 r C o an h d p ibi om In rin ted m fo rm t a . Au e si th rc aU ng or i le is al K co ed D py us is Lim fo ers tr ite rp c i b a er n d so d ut na ow io l u nl n se oa d,
May Hagiwara Thomas E. Delea
Policy Analysis Inc., Brookline, MA, USA
Karen Chung
Amgen Global Health Economics, Thousand Oaks, CA, USA Address for correspondence: May Hagiwara, PhD, Policy Analysis Inc. (PAI), Four Davis Court, Brookline, MA 02445, USA. Tel: +1-617-232-4400; Fax: +1-617-232-1155; [email protected] Keywords: Skeletal-related events – Breast neoplasms – Metastases – Healthcare costs
Accepted: 31 January 2014; published online: 18 February 2014 Citation: J Med Econ 2014; 17:223–30
No
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Original article Healthcare costs associated with skeletal-related events in breast cancer patients with bone metastases Abstract
Background: Patients with bone metastases secondary to breast cancer are pre-disposed to skeletal-related events (SREs), including spinal cord compression (SCC), pathologic fracture (PF), surgery to bone (SB), and radiotherapy to bone (RT). Objective: To document current patterns of healthcare utilization and costs of SREs in patients with breast cancer and bone metastases. Methods: This was a retrospective, observational study using the Thomson MedStat MarketScan Commercial Claims and Encounters database from 9/2002 to 6/2011. Study subjects included all persons with claims for breast cancer and for bone metastases, and 1 claims for an SRE. Unique SRE episodes were identified based on a gap of at least 90 days without an SRE claim, and classified by treatment setting (inpatient or outpatient) and SRE type (SCC, PF, SB, or RT). Results: Of 17,266 patients with breast cancer and bone metastases, 9142 (53%) had one or more SRE episodes. Among 5809 patients who met all other criteria, there were 7617 SRE episodes over mean (SD) follow-up of 17.2 (15.2) months. The percentage of episodes that required inpatient treatment ranged from 11% (RT) to 76% (SB). On average, inpatient SCC episodes (n ¼ 83 episodes) were most costly; while outpatient PF episodes (n ¼ 552 episodes) were least costly. Of the total SRE costs (mean [SE] $21,072 [$36,462]/ episode), 36% were attributable to outpatient RT (n ¼ 5265 episodes) and 31% to inpatient PF (n ¼ 838 episodes). Limitations: The administrative claims data used in this study may lack sensitivity and specificity for identification of clinical events and may not be generalizable to other populations. Also, for some SRE episode categories, the number of events was small and cost estimates may lack precision. Conclusion: In patients with breast cancer and bone metastases, SREs are associated with high costs and hospitalizations.
Introduction Breast cancer is one of the most common cancers in the US, with an estimated 226,870 new cases and 39,510 deaths in 2012, and it is the second leading cause ! 2014 Informa UK Ltd www.informahealthcare.com/jme
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of cancer death in women behind lung cancer1. The skeleton is the most common site of metastasis in women with advanced breast cancer2,3. Median survival in women with breast cancer and a diagnosis of bone metastases is 20–24 months2,4. Patients with bone metastases of breast cancer are at risk of a variety of skeletal-related events (SREs), such as pathological fractures, bone instability requiring surgery to the bone, radiation to the bone to control local tumor burden and manage pain, and spinal cord compression. These events can be associated with considerable morbidity, impaired health-related quality-of-life, reduced survival, and increased healthcare costs5. Numerous studies have examined the impact of SREs on costs in patients with bone metastases secondary to solid tumors among US as well as European populations6–16. In an analysis of US patients with breast cancer, Delea et al.8 estimated the expected costs of care directly attributable to SREs to be $13,940 per patient. After matching on baseline characteristics, expected total medical-care costs were $48,173 greater in patients with SREs vs those without8. Barlev et al.6 recently examined the costs of hospitalizations for SREs in US patients with bone metastasis secondary to prostate or breast cancer or with multiple myeloma. These authors reported that, among patients with breast cancer, the mean health plan payment per hospital admission was $59,854 for spinal cord compression, $26,936 for pathologic fracture, and $32,742 for surgery to the bone. Dura´n et al.15 and Hechmati et al.16 analyzed cost of SREs among patients in Germany, Italy, Spain, and the UK with bone metastasis secondary to solid tumor or multiple myeloma. The reported costs range from E5000–E12,000 for spinal cord compression and E3000–E9000 for surgery to bone. While these studies provide useful information on the costs of SREs in patients with bone metastases of solid tumors, they have some limitations. Although Barlev et al.6 examined the costs of SREs treated in the inpatient setting, little is known regarding the relative magnitude of the costs of SREs treated on both an inpatient and an outpatient basis. Also, none of these studies have examined the costs of episodes of care (EOC) for SREs. As defined in the literature, an EOC represents the period initiated by patient presentation with a diagnosis of a clinical condition and concluded when the condition is resolved17. EOC-based analyses have been used extensively to assess the costs of treatment of diseases such as diabetic foot ulcers18, abdominal pain19, and low back pain20. As many patients experience more than one SRE, EOC-based cost analysis can be useful in understanding the economic impact of different types of SREs, and in informing estimates of the potential cost savings that might accrue as a result of interventions that may prevent them. This study was conducted to document current patterns of healthcare utilization and costs of SREs in patients 224
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with breast cancer and bone metastases using EOC-based analyses.
Patients and methods Study design and data source A retrospective observational longitudinal cohort design was employed. Data for this study were from the Thomson MedStat MarketScan Commercial Claims and Encounters database. This database contains information on the US health insurance claims of employees of large, self-insured corporations and their dependents, along with a few commercial health plans. The database is fully de-identified and compliant with the Health Insurance Portability and Accountability Act of 1996 (HIPAA). Accordingly, IRB approval was not necessary. Data used in this study span the period from September 1, 2002–June 30, 2011 (‘study period’).
Patient selection Patients were included in the analysis if they met all of the following criteria: confirmed diagnosis of bone metastases (International Classification of Disease, 9th edition, Clinical Modification [ICD-9-CM] diagnosis codes 170.XX or 198.5X); confirmed diagnosis of breast cancer (174.XX) prior to bone metastases diagnosis; and one or more SRE episodes (detailed algorithm is found in section below, titled as Identification of SREs). For the purpose of this study, a patient was considered to have a ‘confirmed’ diagnosis if the patient had one or more inpatient facility claims with the diagnosis code or codes of interest listed as the primary diagnosis on the claim, or two or more medical claims on different days and no more than 6 months apart, with the same diagnosis code or codes of interest listed in any diagnosis field on the claims. This approach of identifying confirmed diagnoses was employed to improve the specificity of diagnoses based on ICD-9-CM diagnosis codes on health insurance claims. These codes may lack specificity if listed on claims for services provided to rule out certain diseases or as working diagnoses while clinical diagnoses are confirmed by pathological or other means. The ‘index date’ was defined as the date with the first confirmed diagnosis of bone metastases. The 6-month period prior to the index date was designated the ‘preindex period’; the period from the index date to the end of continuous enrollment was designated the ‘follow-up period’. Patients less than 18 years of age on the index date, with gender specified as male, less than 6 months of continuous enrollment prior to the index date, a diagnosis of primary cancer other than breast cancer prior to the index date, or with zero, missing, or negative cost data were excluded. Because diagnosis codes for primary cancer www.informahealthcare.com/jme ! 2014 Informa UK Ltd
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may sometimes be used for metastatic disease, patients were assumed to have other primary cancer only if they did not also have a corresponding claim for metastasis to the same site. For example, patients with claims with a diagnosis of primary liver neoplasm (ICD-9-CM 155.xx) as well as claims with diagnosis of metastasis to the liver (197.0x, 197.1x, 197.2x, and 197.3x) were not considered to have ‘other primary cancer’. Conversely, those with claims with diagnoses of primary liver neoplasm but without a claim for metastasis to the liver were assumed to have ‘other primary cancer’. Codes for identification of primary and secondary malignancies by site are listed in Supplementary Appendix A.
Patient characteristics For each patient, baseline demographic characteristics and comorbidities were assessed as of the index date, including calendar year, age, region, plan type, and Deyo’s version of the Charlson Comorbidity Index21. Pre-index healthcare utilization and costs also were measured including: the number of outpatient pharmacy claims or procedures for chemotherapy, systemic corticosteroids, and intravenous bisphosphonates; the number of outpatient pharmacy claims (i.e. prescriptions) for opioids, and oral bisphosphonates; and the number of claims for inpatient hospitalizations, emergency department visits, home healthcare visits, hospice care, skilled nursing facility care, physician office visits, hospital outpatient visits, laboratory tests, and other care. In counting these services, multiple claims occurring on the same day were counted once, except for outpatient prescriptions. Also tallied were the costs of inpatient hospitalizations, emergency department visits, home healthcare visits, hospice care, skilled nursing facility care, physician office visits, hospital outpatient visits, laboratory tests, and other healthcare services. Costs were approximated based on paid amounts (total gross payment after applying pricing guidelines such as fee schedules and discounts, but before applying deductibles, co-insurance, co-payments, and co-ordination of benefit).
Identification of SREs For each patient, the follow-up period was scanned to identify all medical claims indicative of an SRE (i.e. spinal cord compression, pathological fracture, surgery to bone, or radiotherapy). Diagnosis and procedure codes used to identify SREs are listed in Supplementary Appendix B. The codes used to identify SREs were based on coding algorithms used in prior studies7–9,13, supplemented with discussion with clinical and coding experts. When there was uncertainty with respect to the inclusion of codes for the identification of SREs, the coding algorithm was designed to be as specific as possible to avoid the inclusion of events ! 2014 Informa UK Ltd www.informahealthcare.com/jme
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that were not actually SREs. Regarding the identification of pathological fractures, there are two different sets of ICD-9-CM codes for fractures. Pathological or spontaneous fractures are classified in the musculoskeletal and connective tissue chapter of ICD-9-CM (i.e. ICD-9-CM 733.1x), whereas traumatic fractures are classified in the injury and poisonings chapter of ICD-9-CM (ICD-9-CM 800-824). Because pathological or spontaneous fractures may be associated with trivial trauma such as a minor fall, many such fractures may be incorrectly coded as traumatic fractures. For the purpose of this study, pathological fractures were, therefore, identified based on confirmed diagnoses of pathological fracture (i.e. ICD-9-CM 733.1x) or a confirmed diagnosis of traumatic fracture (ICD-9-CM 800-824) (see Patient Selection section for the definition of confirmed diagnosis). Claims with codes for traumatic fracture (ICD-9-CM 800-824) were only included, however, if there were no concurrent claims with codes suggesting accident (excluding accident codes for ‘falls on the same level’) or trauma. ‘Concurrent claims’ were defined as claims occurring during the 2-week period ending with the claim for the fracture. When identifying a confirmed diagnosis of fracture, all diagnosis codes for fractures to the same site were considered as confirmatory. When identifying surgery to bone, claims with concurrent claims suggesting accident (excluding falls on the same level) or significant trauma also were excluded. Because there are no body site modifiers for procedure codes for radiotherapy, claims for radiotherapy procedures were considered only if there was a concurrent claim with a diagnosis code for bone metastasis, spinal cord compression, bone pain (ICD-9-CM 733.90), or pathological fracture. For each patient with at least one SRE claim during the follow-up period, SRE episodes were identified using a gap of 90 days or more without an outpatient claim or an inpatient admission for an SRE. Gaps were defined based on the number of days without SRE claims starting with the last SRE claim (Figure 1). The choice of the 90-day gap was based on the observation that the mean daily cost of SRE-related care by time since the first SRE claim declined rapidly between 1 and 3 months after the first SRE claim and leveled off shortly thereafter. Each SRE episode was then classified into mutually exclusive categories. SREs include both diagnoses (spinal cord compression and pathological fracture) as well as procedures (surgery to bone and radiotherapy). These procedures may be used in the treatment of the diagnosed condition(s) (e.g. surgery to bone may be used for a pathological fracture). Spinal cord compression can present as an oncologic emergency, potentially leading to severe and permanent neurological damage including paresis or paralysis, loss of control of bladder and/or bowel function, loss of independence, reduced quality-of-life, and reduced survival22–25. Accordingly, in defining mutually exclusive SRE costs in breast cancer with bone metastases Hagiwara et al.
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Figure 1. Example for identifying SRE episodes with 90-day gap. Gaps were defined based on the number of days without SRE claims starting with the last SRE claim. PF, Pathological fracture; RT, Radiotherapy; SB, Surgery to bone; SCC, Spinal cord compression.
categories, we implemented a hierarchy in which the diagnoses of spinal cord compression and pathological fracture were at the top and surgery to bone and radiotherapy were at the bottom. This yielded the following hierarchy in order to identify mutually exclusive categories of SRE episodes based on evidence of confirmed diagnoses or procedures: spinal cord compression; pathological fracture without spinal cord compression; surgery to bone without spinal cord compression and without pathological fracture; and radiotherapy without any other types of SRE claims. Episodes were further classified as ‘inpatient’ or ‘outpatient’ based on the presence during the episode of one or more inpatient hospital claims with any SRE.
Table 1. Selection of study subjects. Criteria Confirmed diagnosis of bone metastases, confirmed diagnosis of breast cancer prior to bone metastases diagnosis, and one or more SRE claims during the follow-up period Exclusions (not mutually exclusive) Less than 6 months of continuous enrollment prior to index date More than one type of primary cancer prior to index date Male patients Total excluded Remaining
n
%
9142
100.0
2788
30.5
609
6.7
31 3333 5809
0.3 36.5 63.5
SRE, Skeletal-related event.
Outcome measures and analyses For each SRE episode, all the claims during the episode were scanned and classified as SRE-related or nonSRE-related according to ICD-9-CM diagnosis codes and procedure codes listed in Supplementary Appendix B. For each SRE episode, all the SRE-related costs (payments) were tallied and adjusted to calendar year 2010 US dollars26. The number and percentages of SRE episodes by type of SRE, treatment setting, and SRE claims identified during the episode, and the mean (standard error [SE]) SRE-related cost per episode by type of SRE and treatment setting were calculated. All analyses were conducted using SAS Proprietary Software, Release 9.2.3*.
Results Of 17,266 patients with bone metastases and breast cancer identified in the dataset, 9142 patients (53%) had at least one SRE. Of these, 5809 patients met all other criteria (Table 1). Mean (SD) age was 52.9 (8.0) years, 44% of patients resided in the South, followed by North Central (25%), West (17%), and Northeast (12%), and the majority had *SAS Proprietary Software, Release 9.2.3 is a registered trade name of SAS Institute Inc., Cary, NC.
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preferred provider organization (PPO) (62%), followed by health maintenance organization (HMO) (15%) plan types (Table 2). The mean (SD) Charlson index during the pre-index period was 4.7 (3.2), consistent with that in prior studies of patients with advanced breast cancer8. The mean (SD) duration of follow-up was 17.2 (15.2) months. There were 7617 SRE episodes identified among 5809 patients. Among spinal cord compression episodes (n ¼ 113), 78% of the episodes included claims for radiotherapy, while 41% included claims for pathological fracture (Table 3). Among pathological fracture episodes (n ¼ 1390), 58% of the episodes included claims for radiotherapy, while 42% included claims for surgery to bone and 28% included pathological fracture claims alone. Among surgery to bone episodes (n ¼ 191), 53% included claims for radiotherapy. Almost all episodes with claims for radiotherapy (86%) were classified as radiotherapy episodes. Twenty-three per cent of all SREs required inpatient treatment. Only 11% of radiotherapy episodes required inpatient treatment, whereas 76% of surgery to bone episodes and 73% of spinal cord compression episodes required inpatient treatment. The mean (SE) cost of SRE-related services per episode was $55,229 ($1438) for inpatient episodes and $11,080 ($200) for outpatient episodes. On average, inpatient www.informahealthcare.com/jme ! 2014 Informa UK Ltd
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Table 2. Patient characteristics at baseline (n ¼ 5809).
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Table 2. Continued.
n (%) or Mean (SD)
Index year, n (%) 2003 2004 2005 2006 2007 2008 2009 2010 2011 Age, years, Mean (SD) Males, n (%)
330 (5.7) 513 (8.8) 587 (10.1) 687 (11.8) 827 (14.2) 876 (15.1) 1055 (18.2) 721 (12.4) 213 (3.7) 52.9 (8.0) 0 (0.0)
Region, n (%) South North Central West Northeast Unknown
2568 (44.2) 1442 (24.8) 975 (16.8) 699 (12.0) 125 (2.2)
Plan type, n (%) PPO Comprehensive HMO Other Charlson index, Mean (SD)a
3586 (61.7) 385 (6.6) 871 (15.0) 967 (16.6) 4.7 (3.2)
Healthcare utilization, n (%)a Chemotherapy Systemic corticosteroid IV Bisphosphonate Opioid Oral Bisphosphonate Cardiovascular medication Diabetes medication Hospitalization Emergency department visit Homehealth Hospice Skilled nursing facility Physician office visit Hospital outpatient visit Lab visits Other encounters
388 (6.7) 1510 (26.0) 61 (1.1) 3018 (52.0) 261 (4.5) 2259 (38.9) 409 (7.0) 967 (16.6) 1346 (23.2) 1069 (18.4) 12 (0.2) 29 (0.5) 5612 (96.6) 5258 (90.5) 2272 (39.1) 1114 (19.2)
Number of healthcare claims, Mean (SD)a,b Chemotherapy Systemic corticosteroid IV Bisphosphonate Opioid Oral Bisphosphonate Diabetes medication Hospitalization Emergency department visit Hospice Skilled nursing facility Physician office visit Hospital outpatient visit Lab visits Other encounters
0.22 (1.11) 0.49 (1.09) 0.03 (0.30) 1.98 (3.45) 0.12 (0.65) 0.35 (1.63) 0.23 (0.61) 0.44 (1.37) 0.02 (0.72) 0.02 (0.41) 13.5 (11.2) 7.0 (8.2) 1.38 (2.75) 0.51 (2.19)
Characteristic Healthcare costs, $, Mean (SD)a Hospitalization Emergency department visit Homehealth Hospice Skilled nursing facility Physician office visit Hospital outpatient visit Lab visits Other encounters Duration of follow-up, months, Mean (SD)
n (%) or Mean (SD)
4073 (15,333) 373 (2895) 260 (1357) 11 (339) 50 (1468) 10,115 (18,798) 13,131 (27,216) 197 (659) 292 (2722) 17.2 (15.2)
a
(continued )
spinal cord compression episodes were most costly with mean (SE) cost per episode of $102,205 ($11,733), followed by inpatient surgery to bone episodes with mean (SE) cost per episode of $77,235 ($7070) (Figure 2). ! 2014 Informa UK Ltd www.informahealthcare.com/jme
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Calculated over 6 months prior to index date. Values are numbers of claims. Except for medications, claims on the same day are counted once. Costs are in 2010 US dollars. HMO, Health maintenance organization; IV, intravenous; PPO, Preferred provider organization; SD, Standard deviation.
b
Outpatient episodes with pathological fracture were least costly, with mean (SE) cost per episode of $10,700 ($816).
Discussion This was a retrospective, observational study using health insurance claims data to document costs associated with SRE episodes in patients with breast cancer and bone metastases. Results of this analysis suggest that, in patients with breast cancer and bone metastases, SREs episodes are associated with high costs and hospitalizations. This study differs from prior studies of the costs of SREs in that an EOC approach was employed for estimating the costs of SREs. EOC analysis is appropriate for analyzing the economic burden of clinical events when their treatments involve a series of separate but related healthcare services. By using an EOC approach, a more complete picture of the costs of events can be obtained. Future health insurance claims-based studies on the costs of SREs, as well as potential other events such as adverse events of treatment of disease progression in cancer patients, should explore the use of EOC analysis. Use of an EOC approach, however, requires a rule for defining each episode. Our decision to use a 90-day gap to define SRE episodes was based on the observation that the mean daily costs of SRE-related care declined rapidly from 30 to 90 days post-SRE, and leveled off shortly thereafter. It is instructive to compare results of this study with those reported by Barlev et al.6, which also used the MedStat MarketScan databases to evaluate the costs of inpatient SRE episodes in patients with bone metastasis secondary to prostate or breast cancer. The mean costs per inpatient episode for spinal cord compression, pathological fracture, and surgery to bone reported by SRE costs in breast cancer with bone metastases Hagiwara et al.
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Table 3. Number of SRE episodes by types of SRE claims identified within each episode among patients with breast cancer and bone metastases. SRE classification
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Spinal cord compression (SCC) SCC only SCC and PF SCC and SB SCC and RT SCC and PF and SB SCC and PF and RT SCC and SB and RT SCC and PF and SB and RT Total Pathological fracture (PF) PF only PF and SB PF and RT PF and SB and RT Total Surgery to bone (SB) SB only SB and RT Total Radiotherapy (RT) Total
Inpatient, n (%)
Outpatient, n (%)
All episodes, n (%)
6 (7.2) 3 (3.6) 1 (1.2) 26 (31.3) 3 (3.6) 14 (16.9) 5 (6.0) 25 (30.1) 83 (100.0)
12 (40.0) 0 (0.0) 0 (0.0) 16 (53.3) 0 (0.0) 1 (3.3) 1 (3.3) 0 (0.0) 30 (100.0)
18 (15.9) 3 (2.7) 1 (0.9) 42 (37.2) 3 (2.7) 15 (13.3) 6 (5.3) 25 (22.1) 113 (100.0)
105 (12.5) 173 (20.6) 214 (25.5) 346 (41.3) 838 (100.0)
277 (50.2) 31 (5.6) 213 (38.6) 31 (5.6) 552 (100.0)
382 (27.5) 204 (14.7) 427 (30.7) 377 (27.1) 1390 (100.0)
66 (45.5) 79 (54.5) 145 (100.0) 658 (100.0) 1724 (100.0)
23 (50.0) 23 (50.0) 46 (100.0) 5265 (100.0) 5893 (100.0)
89 (46.6) 102 (53.4) 191 (100.0) 5923 (100.0) 7617 (100.0)
SRE, Skeletal-related event. Percentages were calculated for each episode type: inpatient, outpatient, and all episodes.
Figure 2. Mean (95% CI) cost of inpatient and outpatient SRE episodes among patients with breast cancer and bone metastases by type of SRE (number of patients ¼ 5809): (A) Inpatient SRE episodes; and (B) Outpatient SRE episodes.
Barlev et al. are $59,854, $26,936, and 32,742, respectively, which are considerably lower than the mean costs per inpatient episode reported here ($102,205, $58,416, and $77,235, respectively). This difference may be a consequence of a number of factors. First, EOC approach was used to define SRE episodes in this study and inpatient 228
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episodes reported include follow-up outpatient care. Barlev et al. considered only the cost of hospitalization. Second, this study used wider sets of codes to identify pathological fracture and surgery to bone. Third, Barlev et al. used data from both commercial plans and Medicare. This study focused on commercial plans only because of www.informahealthcare.com/jme ! 2014 Informa UK Ltd
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the possibility that some care received by Medicare patients may not be captured in the MedStat database. Limitations of this study should be noted. This study used administrative claims data that may be subject to data coding limitations and data entry error. Also, diagnostic and procedure codes on claims may have limited sensitivity and specificity for clinical diagnoses. This may have affected the distribution of SREs if some diagnosis codes are more sensitive or specific than others. As noted above, this study used data from the MedStat commercial database, and the estimates reported herein may not be generalizable to Medicare or other elderly patients. Further, the MarketScan commercial database is geographically diverse but not entirely representative of the US population, and patients from the database may not be representative of all commercially-insured patients in the US or other settings. Approximately 15% of patients in the study sample were in HMO plans. As a consequence of capitation arrangements, the payment field for office visits for these patients may result in potential under-estimation of outpatient SRE costs. The extent of this bias is likely to be small, however, as cancer patients are likely to receive treatment from oncologists rather than primary care physicians, and the former are less likely to be in capitated payment arrangements than the latter. In calculating costs, we included only the costs of services that were considered to be related to the treatment of SREs based on diagnosis and/or procedure codes. Thus, while the cost of some routine care services unrelated to treatment of SREs may have been included, these costs are likely to be small. On the other hand, our estimates may be conservative as they do not include the costs of services that were incurred as a consequence of SREs but that could not be attributed to SREs based on diagnosis or procedure codes. Lastly, for some SRE episode categories (e.g., inpatient and outpatient surgery to bone), the number of events was small and our estimates may lack precision.
Conclusion Results of this study suggest that SREs are associated with high costs among patients with breast cancer and bone metastases, and that these costs may be greater than estimated previously for some events. This study also demonstrates the utility of EOC-based analyses for evaluating the costs of clinical events in retrospective studies using health insurance claims data.
Transparency Declaration of funding The manuscript was funded by Amgen.
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Declaration of financial/other relationships May Hagiwara, PhD and Thomas E. Delea, MSIA are employees of Policy Analysis Inc. and have received funding for the research from Amgen. At the time this research was conducted, Karen Chung, PharmD, MS was an employee of Amgen and owned stock options in Amgen, Inc. JME Peer Reviewers on this manuscript have no relevant financial or other relationships to disclose. Acknowledgments The abstract and poster were presented at American Society of Clinical Oncology, Breast Cancer Symposium in San Francisco on September 15, 2012.
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