ORIGINAL ARTICLE
Weight Loss and Outcomes in Wait-listed, Medically Managed, and Surgically Treated Patients Enrolled in a Population-based Bariatric Program Prospective Cohort Study Raj S. Padwal, MD, MSc,*w Christian F. Rueda-Clausen, MD, PhD,*w Arya M. Sharma, MD, PhD,*w Calypse B. Agborsangaya, MSc,*w Scott Klarenbach, MD, MSc,* Dan W. Birch, MD,z Shahzeer Karmali, MD,z Linda McCargar,y and Sumit R. Majumdar, MD, MPH*w
Background: Multidisciplinary bariatric care is increasingly being delivered in Canada within publicly funded regional programs. Demand is high, wait lists are long, and clinical effectiveness is unknown. Objective: To examine the “real-world” outcomes associated with a publicly funded, population-based regional bariatric (medical and surgical) program. Research Design: Prospective observational cohort. Subjects: Five hundred consecutive patients (150 wait-listed, 200 medically treated, 150 surgically treated) from the Edmonton Weight Wise program were enrolled. Measures: The primary outcome was weight change (kg). Between-group changes were analyzed using multivariable regression adjusted for age, sex, and baseline weight and “last-observationcarried-forward” was used for missing data. Subjects transitioning
From the *Department of Medicine, University of Alberta; wAlberta Diabetes Institute; zDepartment of Surgery and CAMIS (Center for the Advancement of Minimally Invasive Surgery), Royal Alexandra Hospital; and yDepartment of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB, Canada. APPLES is funded by the Canadian Institutes of Health Research (CIHR) Grant Number 86642. R.S.P., S.R.M., SK., and A.M.S. are supported by an alternative funding plan from the Government of Alberta and the University of Alberta. S.R.M. and S.K. are supported by Alberta Innovates Health Solutions (AI-HS). A.M.S. is supported by an Alberta Health Services Chair in Obesity Research and Management. Trial registration: Clinicaltrials.gov NCT00850356. D.W.B. has received honoraria for advisory boards, teaching and research from Ethicon Endo-Surgery Inc., a Johnson and Johnson company. S.R.M. holds the Endowed Chair in Patient Health Management at the University of Alberta. C.F.R-C. is a CIHR and AI-HS Clinical Research Fellow. The remaining authors declare no conflict of interest. Reprints: Raj S. Padwal, MD, MSc, 5-134 Clinical Sciences Building,11350 - 83rd Ave, Edmonton, AB, Canada T6G2G3. E-mail: rpadwal@ ualberta.ca. Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www.lww-medical care.com. Copyright r 2013 by Lippincott Williams & Wilkins ISSN: 0025-7079/14/5203-0208
208 | www.lww-medicalcare.com
between groups (wait-list to medical or medical to surgery) were censored when crossing over. Results: At baseline, mean age was 43.7 ± 9.6 years, mean body mass index was 47.9 ± 8.1 kg/m2, and 88% were female. A total of 412 subjects (82%) completed 2-year follow-up and 143 (29%) subjects crossed over to the next treatment phase. Absolute and relative (% of baseline) mean weight reductions were 1.5 ± 8.5 kg (0.9 ± 6.1%) for wait-listed, 4.1 ± 11.6 kg (2.8 ± 8.1%) for medically treated, and 22.0 ± 19.7 kg (16.3 ± 13.5%) for surgically treated (P < 0.001) subjects. For surgery, weight reductions were 7.0 ± 9.7 kg (5.8 ± 7.9%) with banding, 21.4 ± 16.0 kg (16.4 ± 11.6%) with sleeve gastrectomy, and 36.6 ± 19.5 kg (26.1 ± 12.2%) with gastric bypass (P < 0.001). Rates of hypertension, diabetes, and dyslipidemia decreased to a significantly greater degree with surgery than medical management (P < 0.001) and stayed the same or increased in wait-listed subjects. Conclusions: Population-based bariatric care, particularly bariatric surgery, was clinically effective. Weight and cardiometabolic risk was relatively stable wait-listed patients receiving “usual care.” Key Words: Canada, bariatric care, bariatric surgery, prospective cohort, obesity, wait-list, health services research (Med Care 2014;52: 208–215)
E
xtreme obesity [defined herein as a body mass index (BMI) of Z35 kg/m2] currently affects 9% of the Canadian population and leads to substantial morbidity, premature mortality, impaired quality of life, and increased health care expenditures.1–3 Contemporary clinical practice guidelines recommend intensive lifestyle modification (diet, exercise, and behavioral therapy) for all extremely obese individuals.4 Bariatric surgery is recommended for suitable candidates considered refractory to medical management.4 In Canada, these treatments (hereafter referred to as “bariatric care”) are increasingly being jointly delivered within specialized, publicly funded, population-based bariatric programs staffed by multidisciplinary teams.5 To our knowledge, no previously published studies have examined the effectiveness of these bariatric care centers. Medical Care
Volume 52, Number 3, March 2014
Medical Care
Volume 52, Number 3, March 2014
Compared with medically treated controls, bariatric surgery is associated with substantial improvements in weight (averaging 33% after 2–3 y6 and 16% after 10 y7) and 15-year mortality rates (5.0% vs. 6.3% in well-matched controls; hazard ratio, 0.71; 95% confidence interval, 0.54–0.92).8 Surgery also increases remission rates for type 2 diabetes, hypertension, dyslipidemia and sleep apnea in 70%–86% of cases.6,9 Additional studies demonstrate that surgery significantly (P < 0.05) improves psychosocial functioning,10 quality of life,11 and physical function.12 Demand for publicly funded bariatric care in Canada is high and capacity limited. Consequently, patients face protracted, multiyear waits.5,13 The Alberta Population-based Prospective Evaluation of the Quality of Life Outcomes and Economic Impact of Bariatric Surgery (APPLES) study was designed to assess the impact of extended wait-times for bariatric care and examine effectiveness of bariatric treatments on clinical, economic, and humanistic endpoints in the extremely obese. This report details the main clinical findings of the APPLES study, including the 2-year changes in weight and other cardiometabolic risk factors among waitlisted, medically treated, and surgically treated patients.
METHODS A detailed study protocol, approved by the University of Alberta Health Research Ethics Board (Pro00003594), has been previously published.3 All subjects provided written informed consent.
Setting and Subjects The Edmonton Weight Wise program is a comprehensive bariatric initiative established in 2005 and designed to deliver integrated, patient-focused, evidence-based care to the Edmonton Zone of Alberta Health Services. This region is one of the largest integrated health delivery systems in Canada and includes a catchment population of approximately 1.6 million residents. Weight wise includes a central, region-wide single-point-of-access referral system; community education and weight management sessions; and adult and pediatric bariatric specialty clinics. Adult specialty services are offered to patients with BMI levels of Z35 kg/m2 referred from a medical practitioner. The program is structured such that patients progress from the wait-list to intensive medical management through to bariatric surgery (if indicated). When APPLES study was initiated in 2008, approximately 800 new patients were seen and B200 surgeries performed annually and about 1500 adults were waitlisted for clinic entry (2-y average wait time). Consecutive, consenting patients (150 wait-listed; 200 medical; 150 surgical) aged 18–60 years with screening BMI levels of Z40 kg/m2 or Z35 kg/m2 and an obesity-related comorbidity (eg, diabetes, sleep apnea, osteoarthritis) were enrolled. Subjects were enrolled at the point they were waitlisted, started on medical therapy or approved for surgery. It should be noted that this study was a naturalistic assessment of bariatric care—subjects were allowed to progress through the program over the 2-year study period and were not kept in their original study group for the entire 2 years. That is, wait-listed patients could progress to medical treatment and r
2013 Lippincott Williams & Wilkins
Outcomes in a Population-based Bariatric Program
medically treated patients could progress to surgery. This necessitated the censoring of patients who crossed over into the next phase of treatment (discussed below). Subjects who were pregnant or nursing, participating in obesity-related clinical trials, or who had absolute contraindications to bariatric surgery were excluded.
Study Groups Wait-listed patients were advised to attend communitybased group education sessions before clinic entry but otherwise received no specific intervention. Medically managed patients received individualized intensive medical management consisting of 24–36 weeks of lifestyle counseling (diet, exercise, behavioral modification), with visits every 4–8 weeks by a multidisciplinary staff (internists, endocrinologists, family physicians, psychiatrists, dietitians, nurses, physiotherapists, occupational therapists, and psychologists) according to current recommendations.4 Behavioral modification focuses on teaching skills to help identify and modify eating and activity behaviors. Self-monitoring of weight, food intake and activity, stimulus control, and problem solving to help overcome barriers to weight loss are all key elements of behavioral modification.14 Nurses and dieticians were the main care providers delivering intensive lifestyle counseling (diet and behavioral modification) and physiotherapists and occupational therapists provided activity counseling. Visits with other providers were scheduled to address specific issues (ie, the internist, endocrinologist or family physician would address control of medical comorbidities, the psychologist would address binge eating disorder, the psychiatrist would assess patients felt to have unstable psychiatric disease). Individualized one-on-one assessments were the norm; one exception was binge eating counseling, which was done in a group format. Medical management was individually tailored to address root causes of excess weight and barriers to achieving weight management success.15,16 Antiobesity drug therapy and structured, very low-calorie protein-sparing diets were uncommonly used (< 4% of medically treated subjects received these) during the study. Although not directly related to weight management, assessment of obesity-related comorbidities, including sleep disorders and mental health screening, was also routinely performed. Medically treated patients interested in surgery were evaluated for surgery by the interdisciplinary team and the bariatric surgeon. Those approved underwent Roux-en-Y gastric bypass, gastric banding, or sleeve gastrectomy, using previously detailed techniques.3 BMI thresholds to determine eligibility for surgery were the same as the APPLES inclusion criteria. Absolute contraindications to surgery were pregnancy, uncontrolled psychiatric disease, active substance abuse or smoking (patients were asked to quit before surgery), active eating disorders (anorexia or bulimia), or a high-risk medical condition (eg, severe coronary artery disease).
Measurements and Data Collection Detailed case report forms have been previously published and are available at http://www.biomedcentral.com/ www.lww-medicalcare.com |
209
Padwal et al
1472-6963/10/284/additional. Baseline data included age, sex, race, marital status, employment status, household income (r20 K, 20–40 K, 40–60 K, 60–80 K, Z80 K), general medical history and obesity-related comorbidities, smoking status (current, past, never), medications, weight, BMI, waist circumference, blood pressure, fasting lipids, fasting glucose, and A1c. Body weight was measured using a validated, calibrated bariatric scale (Scale Tronix serial numbers: 6702–4440 and 6702–6229) and recorded to the nearest 0.1 kg, with the subject wearing light indoor clothing with empty pockets, no shoes, and an empty bladder. Height was measured to the nearest 0.1 cm using a wall-mounted stadiometer. A single reading taken using an automated blood pressure monitor and using an appropriately sized blood pressure cuff was recorded with the subject seated in a chair and after 5 minutes of rest.
Outcomes The primary outcome was weight change (kg) at 2 years. Weight was measured every 6 months over the 2-year period so that the interim values could be carried forward if the subject dropped out or was censored (see below for full discussion of handling of missing data). Both absolute changes and percent changes from baseline were analyzed. Five percent and 10% weight reductions (ie, the proportion of subjects that achieved Z5% and Z10% weight loss), which are considered clinically important thresholds,4 were also examined. Secondary outcomes included blood pressure, fasting cholesterol levels, and glycemic control. Hypertension was considered present if self-reported, if blood pressure levels were Z140/90 mm Hg (Z130 mm Hg in patients with diabetes), or if antihypertensive medications were prescribed. Diabetes and dyslipidemia were similarly defined based upon self-report or drug therapy. In addition, an A1c > 6.5% or a fasting glucose Z7.0 mmol/L were used as diagnostic criteria for diabetes and dyslipidemia was considered present if one of the following were present: total cholesterol Z6.2 mmol/L, low-density lipoprotein cholesterolZ4.1 mmol/L, high-density lipoprotein cholesterol 80% of medically treated patients did not achieve even a 10% weight loss over 2 years. Third, results in the wait-listed arm—which received minimal intervention during the study period and which might be considered “usual care”—indicate that protracted wait-times (of 1.5–2 y www.lww-medicalcare.com |
211
Padwal et al
Medical Care
Volume 52, Number 3, March 2014
FIGURE 1. Follow-up and censoring by study group. Attrition at 24 months included dropouts (n = 78), pregnancies (n = 6), deaths (n = 3), and subjects who underwent out-of-program private bariatric surgery (n = 4) or a second (different) surgical procedure (n = 1).
as observed here) do not lead to substantial weight gain or systematic increases in cardiovascular comorbidity burden. APPLES provides a naturalistic assessment of population-based publicly funded bariatric care in Canada. To our knowledge, this is the first published report to describe the clinical outcomes of this type of integrated bariatric care program. Importantly, multidisciplinary bariatric care programs similar to Edmonton Weight Wise, delivering both intensive medical and surgical treatment, have been established across Canada and are growing in number despite the dearth of available outcomes data. Notable and distinctive characteristics of these programs include their publicly
212 | www.lww-medicalcare.com
funded (ie, universally accessible), centrally triaged and population-based nature. Given these features, these bariatric centers would be expected to care for less highly selected and more treatment-refractory patients than those seen in private payor settings. Thus, the outcomes of a publicly funded program like Weight Wise probably more accurately reflect “real-world” effectiveness compared with most of the published literature. This is of critical importance because published outcomes from randomized controlled trials or programs enrolling highly selected populations currently serve as the benchmark for expected weight loss efficacy and effectiveness. r
2013 Lippincott Williams & Wilkins
r
Wait-Listed (n = 150)
2013 Lippincott Williams & Wilkins n = 129 21.8 (19.8) 16.3 (13.6) 7.8 (7.0)
n = 100 3.2 (10.5) 2.2 (7.0) 1.2 (3.7)
0.5 0.5 0.08 0.03 0.07 0.06 0.07 0.20
(13.3) (11.5) (0.5) (0.4) (0.5) (0.7) (0.7) (1.3)
Wait-Listed (n = 150) 6.5 3.3 0.15 0.06 0.20 0.05 0.07 0.04
(13.2) (10.5) (0.7) (0.20) (0.7) (0.9) (0.7) (1.7)
Medical (n = 200) 0.7 1.5 0.12 0.31 0.06 0.29 0.17 0.50
(16.0) (12.1) (0.7) (0.4) (0.6) (0.6) (0.5) (0.9)
< 0.0001 < 0.0003 0.0007 < 0.0001 0.06 < 0.008 0.4 < 0.0001
P**
6.1 3.7 0.08 0.03 0.14 0.02 0.02 0.17
(3.1, 9.1) (1.3, 6.1) (0.22, 0.07) (0.05, 0.11) (0.27, 0.001) (0.14, 0.18) (0.13, 0.16) (0.47, 0.13)
Medical vs. Wait-List D (95% CI)w
2.4 ( 7.9, 3.9) 1.1 ( 5.1, 2.9) 0.8 ( 2.8, 1.2)
1.0 ( 3.6, 1.6) 0.6 ( 2.4, 1.2) 0.4 ( 1.3, 0.6)
3.1 ( 0.3, 5.9) 2.1 ( 0.1, 4.1) 1.1 ( 0.1, 2.1)
Medical vs. Wait-List D (95% CI)w
*Last-observation-carried-forward imputation. **Using analysis of variance. w Adjusted for age, sex, and BMI at baseline. BMI indicates body mass index; BP, blood pressure; CI, confidence interval; HDL, high-density lipoprotein; LDL, low-density lipoprotein.
Systolic BP (mm Hg) Diastolic BP (mm Hg) Total cholesterol (mmol/L) HDL cholesterol (mmol/L) LDL cholesterol (mmol/L) Triglycerides (mmol/L) A1c (%) Fasting glucose (mmol/L)
Outcome Mean (SD)
< 0.0001 < 0.0001 < 0.0001
< 0.0001 < 0.0001 < 0.0001
< 0.0001 < 0.0001 < 0.0001
P*
1.2 1.0 0.20 0.28 0.004 0.21 0.08 0.71
( 2.1, 4.4) ( 1.6, 3.6) (0.04, 0.36) (0.19, 0.36) ( 0.15, 0.14) ( 0.38, 0.03) ( 0.23, 0.07) ( 1.04, 0.37)
Surgery vs. Wait-List D (95% CI)w
22.6 ( 16.8, 27.7) 15.9 ( 11.9, 19.7) 7.9 ( 6.0, 9.8)
18.7 ( 15.9, 21.5) 13.8 ( 11.8, 15.7) 6.7 ( 5.7, 7.7)
21.9 ( 18.9, 24.9) 16.1 ( 13.9, 18.2) 7.8 ( 6.8, 8.9)
Surgery vs. Wait-List D (95% CI)w
7.2 4.7 0.28 0.25 0.13 0.22 0.10 0.54
(4.2, 10.3) (2.3, 7.1) (0.13, 0.42) (0.17, 0.33) (0.003, 0.28) (0.38, 0.06) (0.24, 0.05) (0.84, 0.24)
Surgery vs. Medical D (95% CI)w
19.8 (16.0, 23.7) 14.7 (11.9, 17.5) 7.1 (5.7, 8.5)
17.7 (15.1, 20.3) 13.2 (11.4, 15.0) 6.3 (5.4, 7.2)
18.8 (16.0, 21.6) 13.9 (11.9, 15.9) 6.7 (5.7, 7.7)
Surgery vs. Medical D (95% CI)w
Volume 52, Number 3, March 2014
TABLE 3. Two-year Changes in Cardiovascular Risk Factors* Surgery (n = 150)
18.7 (19.9) 14.0 (13.9) 6.7 (7.0)
1.6 (7.6) 1.1 (5.1) 0.6 (2.7)
*Using analysis of variance. w Adjusted for age, sex, and BMI at baseline. BMI indicates body mass index; CI, confidence interval.
22.0 (19.7) 16.3 (13.6) 7.8 (6.9)
Surgical (n = 150)
4.1 (11.6) 2.8 (8.0) 1.5 (4.1)
Medical (n = 200)
Last-observation-carried-forward imputation Weight change (kg) 1.5 (8.5) Weight change (%) 0.9 (6.1) 0.6 (3.1) BMI change (kg/m2) Baseline observation carried forward Weight change (kg) 0.9 (6.5) Weight change (%) 0.6 (4.7) 0.4 (2.4) BMI change (kg/m2) Completers analysis n = 39 Weight change (kg) 3.6 (12.4) Weight change (%) 2.5 (9.1) 1.4 (4.6) BMI change (kg/m2)
Outcome Mean (SD)
TABLE 2. Two-year Changes in Weight and BMI
Medical Care Outcomes in a Population-based Bariatric Program
www.lww-medicalcare.com |
213
Padwal et al
Intensive medical therapy delivered over 15 months led to mean weight reductions of B4% and was associated with small, but potentially clinically important, comorbidity improvements (particularly in blood pressure). Some of this comorbidity improvement likely resulted from increased antihypertensive drug use because the overall prevalence of hypertension and other cardiovascular risk factors did not fall in medically treated patients. Overall, the weight loss reductions seen with medical management are similar to or slightly lower than those reported in studies examining more highly selected extremely obese patient samples—either enrolled in other Canadian medical management programs or in clinical trials.18–20 Our findings reinforce the refractory nature of obesity, the difficulties in promoting behavior change, and the high recidivism rates associated with this condition. A notable difference from these trials is that intensive medical management was delivered for only a finite period of time in APPLES subjects, following which patients were discharged back to primary care. Patients did not receive a structured weight maintenance program, and it is possible that some type of intervention directed at weight maintenance could be considered for them. The mean weight loss following bariatric surgery was less than that reported in previous studies.7,21 For example, in the Utah obesity cohort study, which examined 1156 extremely obese subjects, mean 2-year weight reductions were 31% in patients receiving gastric bypass, 2% in controls seeking (but not receiving) surgery, and 0.2% in controls not seeking surgery.21 In contrast to medically treated subjects in APPLES, control subjects in the Utah study did not receive any specific study intervention. We speculate that 3 factors may have contributed to the lower postsurgical weight reductions seen in APPLES in comparison with other published studies. First, less highly selected, more treatment-refractory patients were likely enrolled. Second, intensive medical management, administered to all surgical patients for a minimum of 6 months before surgery, may have mitigated to some degree the potential for postsurgical weight reductions. Third, gastric banding (used in one third of the surgical patients) was of very limited effectiveness and this reduced overall mean weight reductions achieved with surgery; gastric bypass surgery–treated patients had similar results (26%). The naturalistic study design used in APPLES was both a strength and a limitation. Some baseline betweengroup imbalances occurred as a consequence of the nonrandomized design and the consecutive and progressive nature in which treatments were applied. To address this issue, between-group comparisons were adjusted for baseline factors. Because we made no attempt to ensure that subjects remained in their respective study groups for the entire 2year duration, censoring was required for a large proportion of wait-listed and medically treated subjects. Notably, additional attrition resulting from losses to follow-up was relatively low and compares favorably to other published studies.19,20 A more conservative baseline-observation-carried-forward sensitivity analysis confirmed that our results were relatively robust despite the frequent censoring although smaller weight reductions were found using this more conservative analysis. Although wait-listed subjects received
214 | www.lww-medicalcare.com
Medical Care
Volume 52, Number 3, March 2014
FIGURE 2. Weight change by study group. Last-observationcarried-forward imputation. Error bars depict ± SE. *P < 0.0001 among groups using analysis of variance. wP < 0.05 versus baseline (post hoc).
little intervention, the possibility that their outcomes improved as a result of a Hawthorne effect cannot be discounted.22 In summary, in the Canadian context, we demonstrated that a population-based bariatric program was clinically effective, with results similar to or slightly less effective than those reported in more highly selected research settings. Furthermore, it is clear that with “usual care” available in the community (ie, our wait list), most extremely obese patients do not lose weight but are relatively stable in terms of their cardiometabolic risk over 2 years. These results, although they are specific to Edmonton Weight Wise, should be generalizable to other publicly funded programs and support the use of evidence-based programmatic bariatric care delivery in Canada. REFERENCES 1. Shields M, Carroll M, Ogden C. Adult obesity prevalence in Canada and the United States. NCHS Data Brief. 2011;56:1–8. 2. Hensrud DD, Klein S. Extreme obesity: a new medical crisis in the United States. Mayo Clin Proc. 2006;81(suppl 10):S5–S10. 3. Padwal RS, Majumdar SR, Klarenbach S, et al. The Alberta populationbased prospective evaluation of the quality of life outcomes and economic impact of bariatric surgery (APPLES) study: background, design and rationale. BMC Health Serv Res. 2010;10:284. 4. Lau DC, Douketis JD, Morrison KM, et al. 2006 Canadian clinical practice guidelines on the management and prevention of obesity in adults and children. CMAJ. 2007;176(suppl 8):1–117. 5. Padwal R, Sharma AM. Treating severe obesity: morbid weights and morbid waits. CMAJ. 2009;181:777–778. 6. Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery: a systematic review and meta-analysis. JAMA. 2004;292:1724–1737. 7. Sjostrom L, Lindroos AK, Peltonen M, et al. Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl J Med. 2004;351:2683–2693. r
2013 Lippincott Williams & Wilkins
Medical Care
Volume 52, Number 3, March 2014
8. Sjostrom L, Narbro K, Sjostrom CD, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357:741–752. 9. Dixon JB, O’Brien PE, Playfair J, et al. Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial. JAMA. 2008;299:316–323. 10. Herpetz S, Kielmann R, Wolf AM, et al. Does obesity surgery improve psychosocial functioning? A systematic review. Int J Obes. 2003; 27:1300–1314. 11. Karlsson J, Taft C, Ryde´n A, et al. Ten-year trends in health-related quality of life after surgical and conventional treatment for severe obesity: the SOS intervention study. Int J Obes. 2007;31:1248–1261. 12. Dixon JB, Dixon ME, O’Brien PE. Quality of life after lap-band placement: influence of time, weight loss, and comorbidities. Obes Res. 2001;9:713–721. 13. Christou NV, Efthimiou E. Bariatric surgery waiting times in Canada. Can J Surg. 2009;52:229–234. 14. Serdula MK, Khan LK, Dietz WH. Weight loss counseling revisited. JAMA. 2003;289:1747–1750. 15. Mauro M, Taylor V, Wharton S, et al. Barriers to obesity treatment. Eur J Intern Med. 2008;19:173–180.
r
2013 Lippincott Williams & Wilkins
Outcomes in a Population-based Bariatric Program
16. Sharma AM, Padwal R. Obesity is a sign—over-eating is a symptom: an aetiological framework for the assessment and management of obesity. Obes Rev. 2010;11:362–370. 17. Sterne JA, White IR, Carlin JB, et al. Multiple imputation for missing data in epidemiological and clinical research: potential and pitfalls. BMJ. 2009;338:b2393. 18. Wharton S, VanderLelie S, Sharma AM, et al. Feasibility of an interdisciplinary program for obesity management in Canada. Can Fam Phys. 2012;58:e32–e38. 19. Goodpaster BH, Delany JP, Otto AD, et al. Effects of diet and physical activity interventions on weight loss and cardiometabolic risk factors in severely obese adults: a randomized trial. JAMA. 2010;304:1795–1802. 20. Ryan DH, Johnson WD, Myers VH, et al. Nonsurgical weight loss for extreme obesity in primary care settings: results of the Louisiana Obese Subjects Study. Arch Intern Med. 2010;170:146–154. 21. Adams TD, Pendleton RC, Strong MB, et al. Health outcomes of gastric bypass patients compared to nonsurgical, nonintervened severely obese. Obesity. 2010;18:121–130. 22. Franke RH, Kaul JD. The Hawthorne experiments: first statistical interpretation. Am Sociol Rev. 1978;43:623–643.
www.lww-medicalcare.com |
215
Weight Loss and Outcomes in Wait-listed, Medically Managed, and Surgically Treated Patients Enrolled in a Population-based Bariatric Program Prospective Cohort Study Raj S. Padwal, MD, MSc,*w Christian F. Rueda-Clausen, MD, PhD,*w Arya M. Sharma, MD, PhD,*w Calypse B. Agborsangaya, MSc,*w Scott Klarenbach, MD, MSc,* Dan W. Birch, MD,z Shahzeer Karmali, MD,z Linda McCargar,y and Sumit R. Majumdar, MD, MPH*w
Background: Multidisciplinary bariatric care is increasingly being delivered in Canada within publicly funded regional programs. Demand is high, wait lists are long, and clinical effectiveness is unknown. Objective: To examine the “real-world” outcomes associated with a publicly funded, population-based regional bariatric (medical and surgical) program. Research Design: Prospective observational cohort. Subjects: Five hundred consecutive patients (150 wait-listed, 200 medically treated, 150 surgically treated) from the Edmonton Weight Wise program were enrolled. Measures: The primary outcome was weight change (kg). Between-group changes were analyzed using multivariable regression adjusted for age, sex, and baseline weight and “last-observationcarried-forward” was used for missing data. Subjects transitioning
From the *Department of Medicine, University of Alberta; wAlberta Diabetes Institute; zDepartment of Surgery and CAMIS (Center for the Advancement of Minimally Invasive Surgery), Royal Alexandra Hospital; and yDepartment of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB, Canada. APPLES is funded by the Canadian Institutes of Health Research (CIHR) Grant Number 86642. R.S.P., S.R.M., SK., and A.M.S. are supported by an alternative funding plan from the Government of Alberta and the University of Alberta. S.R.M. and S.K. are supported by Alberta Innovates Health Solutions (AI-HS). A.M.S. is supported by an Alberta Health Services Chair in Obesity Research and Management. Trial registration: Clinicaltrials.gov NCT00850356. D.W.B. has received honoraria for advisory boards, teaching and research from Ethicon Endo-Surgery Inc., a Johnson and Johnson company. S.R.M. holds the Endowed Chair in Patient Health Management at the University of Alberta. C.F.R-C. is a CIHR and AI-HS Clinical Research Fellow. The remaining authors declare no conflict of interest. Reprints: Raj S. Padwal, MD, MSc, 5-134 Clinical Sciences Building,11350 - 83rd Ave, Edmonton, AB, Canada T6G2G3. E-mail: rpadwal@ ualberta.ca. Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www.lww-medical care.com. Copyright r 2013 by Lippincott Williams & Wilkins ISSN: 0025-7079/14/5203-0208
208 | www.lww-medicalcare.com
between groups (wait-list to medical or medical to surgery) were censored when crossing over. Results: At baseline, mean age was 43.7 ± 9.6 years, mean body mass index was 47.9 ± 8.1 kg/m2, and 88% were female. A total of 412 subjects (82%) completed 2-year follow-up and 143 (29%) subjects crossed over to the next treatment phase. Absolute and relative (% of baseline) mean weight reductions were 1.5 ± 8.5 kg (0.9 ± 6.1%) for wait-listed, 4.1 ± 11.6 kg (2.8 ± 8.1%) for medically treated, and 22.0 ± 19.7 kg (16.3 ± 13.5%) for surgically treated (P < 0.001) subjects. For surgery, weight reductions were 7.0 ± 9.7 kg (5.8 ± 7.9%) with banding, 21.4 ± 16.0 kg (16.4 ± 11.6%) with sleeve gastrectomy, and 36.6 ± 19.5 kg (26.1 ± 12.2%) with gastric bypass (P < 0.001). Rates of hypertension, diabetes, and dyslipidemia decreased to a significantly greater degree with surgery than medical management (P < 0.001) and stayed the same or increased in wait-listed subjects. Conclusions: Population-based bariatric care, particularly bariatric surgery, was clinically effective. Weight and cardiometabolic risk was relatively stable wait-listed patients receiving “usual care.” Key Words: Canada, bariatric care, bariatric surgery, prospective cohort, obesity, wait-list, health services research (Med Care 2014;52: 208–215)
E
xtreme obesity [defined herein as a body mass index (BMI) of Z35 kg/m2] currently affects 9% of the Canadian population and leads to substantial morbidity, premature mortality, impaired quality of life, and increased health care expenditures.1–3 Contemporary clinical practice guidelines recommend intensive lifestyle modification (diet, exercise, and behavioral therapy) for all extremely obese individuals.4 Bariatric surgery is recommended for suitable candidates considered refractory to medical management.4 In Canada, these treatments (hereafter referred to as “bariatric care”) are increasingly being jointly delivered within specialized, publicly funded, population-based bariatric programs staffed by multidisciplinary teams.5 To our knowledge, no previously published studies have examined the effectiveness of these bariatric care centers. Medical Care
Volume 52, Number 3, March 2014
Medical Care
Volume 52, Number 3, March 2014
Compared with medically treated controls, bariatric surgery is associated with substantial improvements in weight (averaging 33% after 2–3 y6 and 16% after 10 y7) and 15-year mortality rates (5.0% vs. 6.3% in well-matched controls; hazard ratio, 0.71; 95% confidence interval, 0.54–0.92).8 Surgery also increases remission rates for type 2 diabetes, hypertension, dyslipidemia and sleep apnea in 70%–86% of cases.6,9 Additional studies demonstrate that surgery significantly (P < 0.05) improves psychosocial functioning,10 quality of life,11 and physical function.12 Demand for publicly funded bariatric care in Canada is high and capacity limited. Consequently, patients face protracted, multiyear waits.5,13 The Alberta Population-based Prospective Evaluation of the Quality of Life Outcomes and Economic Impact of Bariatric Surgery (APPLES) study was designed to assess the impact of extended wait-times for bariatric care and examine effectiveness of bariatric treatments on clinical, economic, and humanistic endpoints in the extremely obese. This report details the main clinical findings of the APPLES study, including the 2-year changes in weight and other cardiometabolic risk factors among waitlisted, medically treated, and surgically treated patients.
METHODS A detailed study protocol, approved by the University of Alberta Health Research Ethics Board (Pro00003594), has been previously published.3 All subjects provided written informed consent.
Setting and Subjects The Edmonton Weight Wise program is a comprehensive bariatric initiative established in 2005 and designed to deliver integrated, patient-focused, evidence-based care to the Edmonton Zone of Alberta Health Services. This region is one of the largest integrated health delivery systems in Canada and includes a catchment population of approximately 1.6 million residents. Weight wise includes a central, region-wide single-point-of-access referral system; community education and weight management sessions; and adult and pediatric bariatric specialty clinics. Adult specialty services are offered to patients with BMI levels of Z35 kg/m2 referred from a medical practitioner. The program is structured such that patients progress from the wait-list to intensive medical management through to bariatric surgery (if indicated). When APPLES study was initiated in 2008, approximately 800 new patients were seen and B200 surgeries performed annually and about 1500 adults were waitlisted for clinic entry (2-y average wait time). Consecutive, consenting patients (150 wait-listed; 200 medical; 150 surgical) aged 18–60 years with screening BMI levels of Z40 kg/m2 or Z35 kg/m2 and an obesity-related comorbidity (eg, diabetes, sleep apnea, osteoarthritis) were enrolled. Subjects were enrolled at the point they were waitlisted, started on medical therapy or approved for surgery. It should be noted that this study was a naturalistic assessment of bariatric care—subjects were allowed to progress through the program over the 2-year study period and were not kept in their original study group for the entire 2 years. That is, wait-listed patients could progress to medical treatment and r
2013 Lippincott Williams & Wilkins
Outcomes in a Population-based Bariatric Program
medically treated patients could progress to surgery. This necessitated the censoring of patients who crossed over into the next phase of treatment (discussed below). Subjects who were pregnant or nursing, participating in obesity-related clinical trials, or who had absolute contraindications to bariatric surgery were excluded.
Study Groups Wait-listed patients were advised to attend communitybased group education sessions before clinic entry but otherwise received no specific intervention. Medically managed patients received individualized intensive medical management consisting of 24–36 weeks of lifestyle counseling (diet, exercise, behavioral modification), with visits every 4–8 weeks by a multidisciplinary staff (internists, endocrinologists, family physicians, psychiatrists, dietitians, nurses, physiotherapists, occupational therapists, and psychologists) according to current recommendations.4 Behavioral modification focuses on teaching skills to help identify and modify eating and activity behaviors. Self-monitoring of weight, food intake and activity, stimulus control, and problem solving to help overcome barriers to weight loss are all key elements of behavioral modification.14 Nurses and dieticians were the main care providers delivering intensive lifestyle counseling (diet and behavioral modification) and physiotherapists and occupational therapists provided activity counseling. Visits with other providers were scheduled to address specific issues (ie, the internist, endocrinologist or family physician would address control of medical comorbidities, the psychologist would address binge eating disorder, the psychiatrist would assess patients felt to have unstable psychiatric disease). Individualized one-on-one assessments were the norm; one exception was binge eating counseling, which was done in a group format. Medical management was individually tailored to address root causes of excess weight and barriers to achieving weight management success.15,16 Antiobesity drug therapy and structured, very low-calorie protein-sparing diets were uncommonly used (< 4% of medically treated subjects received these) during the study. Although not directly related to weight management, assessment of obesity-related comorbidities, including sleep disorders and mental health screening, was also routinely performed. Medically treated patients interested in surgery were evaluated for surgery by the interdisciplinary team and the bariatric surgeon. Those approved underwent Roux-en-Y gastric bypass, gastric banding, or sleeve gastrectomy, using previously detailed techniques.3 BMI thresholds to determine eligibility for surgery were the same as the APPLES inclusion criteria. Absolute contraindications to surgery were pregnancy, uncontrolled psychiatric disease, active substance abuse or smoking (patients were asked to quit before surgery), active eating disorders (anorexia or bulimia), or a high-risk medical condition (eg, severe coronary artery disease).
Measurements and Data Collection Detailed case report forms have been previously published and are available at http://www.biomedcentral.com/ www.lww-medicalcare.com |
209
Padwal et al
1472-6963/10/284/additional. Baseline data included age, sex, race, marital status, employment status, household income (r20 K, 20–40 K, 40–60 K, 60–80 K, Z80 K), general medical history and obesity-related comorbidities, smoking status (current, past, never), medications, weight, BMI, waist circumference, blood pressure, fasting lipids, fasting glucose, and A1c. Body weight was measured using a validated, calibrated bariatric scale (Scale Tronix serial numbers: 6702–4440 and 6702–6229) and recorded to the nearest 0.1 kg, with the subject wearing light indoor clothing with empty pockets, no shoes, and an empty bladder. Height was measured to the nearest 0.1 cm using a wall-mounted stadiometer. A single reading taken using an automated blood pressure monitor and using an appropriately sized blood pressure cuff was recorded with the subject seated in a chair and after 5 minutes of rest.
Outcomes The primary outcome was weight change (kg) at 2 years. Weight was measured every 6 months over the 2-year period so that the interim values could be carried forward if the subject dropped out or was censored (see below for full discussion of handling of missing data). Both absolute changes and percent changes from baseline were analyzed. Five percent and 10% weight reductions (ie, the proportion of subjects that achieved Z5% and Z10% weight loss), which are considered clinically important thresholds,4 were also examined. Secondary outcomes included blood pressure, fasting cholesterol levels, and glycemic control. Hypertension was considered present if self-reported, if blood pressure levels were Z140/90 mm Hg (Z130 mm Hg in patients with diabetes), or if antihypertensive medications were prescribed. Diabetes and dyslipidemia were similarly defined based upon self-report or drug therapy. In addition, an A1c > 6.5% or a fasting glucose Z7.0 mmol/L were used as diagnostic criteria for diabetes and dyslipidemia was considered present if one of the following were present: total cholesterol Z6.2 mmol/L, low-density lipoprotein cholesterolZ4.1 mmol/L, high-density lipoprotein cholesterol 80% of medically treated patients did not achieve even a 10% weight loss over 2 years. Third, results in the wait-listed arm—which received minimal intervention during the study period and which might be considered “usual care”—indicate that protracted wait-times (of 1.5–2 y www.lww-medicalcare.com |
211
Padwal et al
Medical Care
Volume 52, Number 3, March 2014
FIGURE 1. Follow-up and censoring by study group. Attrition at 24 months included dropouts (n = 78), pregnancies (n = 6), deaths (n = 3), and subjects who underwent out-of-program private bariatric surgery (n = 4) or a second (different) surgical procedure (n = 1).
as observed here) do not lead to substantial weight gain or systematic increases in cardiovascular comorbidity burden. APPLES provides a naturalistic assessment of population-based publicly funded bariatric care in Canada. To our knowledge, this is the first published report to describe the clinical outcomes of this type of integrated bariatric care program. Importantly, multidisciplinary bariatric care programs similar to Edmonton Weight Wise, delivering both intensive medical and surgical treatment, have been established across Canada and are growing in number despite the dearth of available outcomes data. Notable and distinctive characteristics of these programs include their publicly
212 | www.lww-medicalcare.com
funded (ie, universally accessible), centrally triaged and population-based nature. Given these features, these bariatric centers would be expected to care for less highly selected and more treatment-refractory patients than those seen in private payor settings. Thus, the outcomes of a publicly funded program like Weight Wise probably more accurately reflect “real-world” effectiveness compared with most of the published literature. This is of critical importance because published outcomes from randomized controlled trials or programs enrolling highly selected populations currently serve as the benchmark for expected weight loss efficacy and effectiveness. r
2013 Lippincott Williams & Wilkins
r
Wait-Listed (n = 150)
2013 Lippincott Williams & Wilkins n = 129 21.8 (19.8) 16.3 (13.6) 7.8 (7.0)
n = 100 3.2 (10.5) 2.2 (7.0) 1.2 (3.7)
0.5 0.5 0.08 0.03 0.07 0.06 0.07 0.20
(13.3) (11.5) (0.5) (0.4) (0.5) (0.7) (0.7) (1.3)
Wait-Listed (n = 150) 6.5 3.3 0.15 0.06 0.20 0.05 0.07 0.04
(13.2) (10.5) (0.7) (0.20) (0.7) (0.9) (0.7) (1.7)
Medical (n = 200) 0.7 1.5 0.12 0.31 0.06 0.29 0.17 0.50
(16.0) (12.1) (0.7) (0.4) (0.6) (0.6) (0.5) (0.9)
< 0.0001 < 0.0003 0.0007 < 0.0001 0.06 < 0.008 0.4 < 0.0001
P**
6.1 3.7 0.08 0.03 0.14 0.02 0.02 0.17
(3.1, 9.1) (1.3, 6.1) (0.22, 0.07) (0.05, 0.11) (0.27, 0.001) (0.14, 0.18) (0.13, 0.16) (0.47, 0.13)
Medical vs. Wait-List D (95% CI)w
2.4 ( 7.9, 3.9) 1.1 ( 5.1, 2.9) 0.8 ( 2.8, 1.2)
1.0 ( 3.6, 1.6) 0.6 ( 2.4, 1.2) 0.4 ( 1.3, 0.6)
3.1 ( 0.3, 5.9) 2.1 ( 0.1, 4.1) 1.1 ( 0.1, 2.1)
Medical vs. Wait-List D (95% CI)w
*Last-observation-carried-forward imputation. **Using analysis of variance. w Adjusted for age, sex, and BMI at baseline. BMI indicates body mass index; BP, blood pressure; CI, confidence interval; HDL, high-density lipoprotein; LDL, low-density lipoprotein.
Systolic BP (mm Hg) Diastolic BP (mm Hg) Total cholesterol (mmol/L) HDL cholesterol (mmol/L) LDL cholesterol (mmol/L) Triglycerides (mmol/L) A1c (%) Fasting glucose (mmol/L)
Outcome Mean (SD)
< 0.0001 < 0.0001 < 0.0001
< 0.0001 < 0.0001 < 0.0001
< 0.0001 < 0.0001 < 0.0001
P*
1.2 1.0 0.20 0.28 0.004 0.21 0.08 0.71
( 2.1, 4.4) ( 1.6, 3.6) (0.04, 0.36) (0.19, 0.36) ( 0.15, 0.14) ( 0.38, 0.03) ( 0.23, 0.07) ( 1.04, 0.37)
Surgery vs. Wait-List D (95% CI)w
22.6 ( 16.8, 27.7) 15.9 ( 11.9, 19.7) 7.9 ( 6.0, 9.8)
18.7 ( 15.9, 21.5) 13.8 ( 11.8, 15.7) 6.7 ( 5.7, 7.7)
21.9 ( 18.9, 24.9) 16.1 ( 13.9, 18.2) 7.8 ( 6.8, 8.9)
Surgery vs. Wait-List D (95% CI)w
7.2 4.7 0.28 0.25 0.13 0.22 0.10 0.54
(4.2, 10.3) (2.3, 7.1) (0.13, 0.42) (0.17, 0.33) (0.003, 0.28) (0.38, 0.06) (0.24, 0.05) (0.84, 0.24)
Surgery vs. Medical D (95% CI)w
19.8 (16.0, 23.7) 14.7 (11.9, 17.5) 7.1 (5.7, 8.5)
17.7 (15.1, 20.3) 13.2 (11.4, 15.0) 6.3 (5.4, 7.2)
18.8 (16.0, 21.6) 13.9 (11.9, 15.9) 6.7 (5.7, 7.7)
Surgery vs. Medical D (95% CI)w
Volume 52, Number 3, March 2014
TABLE 3. Two-year Changes in Cardiovascular Risk Factors* Surgery (n = 150)
18.7 (19.9) 14.0 (13.9) 6.7 (7.0)
1.6 (7.6) 1.1 (5.1) 0.6 (2.7)
*Using analysis of variance. w Adjusted for age, sex, and BMI at baseline. BMI indicates body mass index; CI, confidence interval.
22.0 (19.7) 16.3 (13.6) 7.8 (6.9)
Surgical (n = 150)
4.1 (11.6) 2.8 (8.0) 1.5 (4.1)
Medical (n = 200)
Last-observation-carried-forward imputation Weight change (kg) 1.5 (8.5) Weight change (%) 0.9 (6.1) 0.6 (3.1) BMI change (kg/m2) Baseline observation carried forward Weight change (kg) 0.9 (6.5) Weight change (%) 0.6 (4.7) 0.4 (2.4) BMI change (kg/m2) Completers analysis n = 39 Weight change (kg) 3.6 (12.4) Weight change (%) 2.5 (9.1) 1.4 (4.6) BMI change (kg/m2)
Outcome Mean (SD)
TABLE 2. Two-year Changes in Weight and BMI
Medical Care Outcomes in a Population-based Bariatric Program
www.lww-medicalcare.com |
213
Padwal et al
Intensive medical therapy delivered over 15 months led to mean weight reductions of B4% and was associated with small, but potentially clinically important, comorbidity improvements (particularly in blood pressure). Some of this comorbidity improvement likely resulted from increased antihypertensive drug use because the overall prevalence of hypertension and other cardiovascular risk factors did not fall in medically treated patients. Overall, the weight loss reductions seen with medical management are similar to or slightly lower than those reported in studies examining more highly selected extremely obese patient samples—either enrolled in other Canadian medical management programs or in clinical trials.18–20 Our findings reinforce the refractory nature of obesity, the difficulties in promoting behavior change, and the high recidivism rates associated with this condition. A notable difference from these trials is that intensive medical management was delivered for only a finite period of time in APPLES subjects, following which patients were discharged back to primary care. Patients did not receive a structured weight maintenance program, and it is possible that some type of intervention directed at weight maintenance could be considered for them. The mean weight loss following bariatric surgery was less than that reported in previous studies.7,21 For example, in the Utah obesity cohort study, which examined 1156 extremely obese subjects, mean 2-year weight reductions were 31% in patients receiving gastric bypass, 2% in controls seeking (but not receiving) surgery, and 0.2% in controls not seeking surgery.21 In contrast to medically treated subjects in APPLES, control subjects in the Utah study did not receive any specific study intervention. We speculate that 3 factors may have contributed to the lower postsurgical weight reductions seen in APPLES in comparison with other published studies. First, less highly selected, more treatment-refractory patients were likely enrolled. Second, intensive medical management, administered to all surgical patients for a minimum of 6 months before surgery, may have mitigated to some degree the potential for postsurgical weight reductions. Third, gastric banding (used in one third of the surgical patients) was of very limited effectiveness and this reduced overall mean weight reductions achieved with surgery; gastric bypass surgery–treated patients had similar results (26%). The naturalistic study design used in APPLES was both a strength and a limitation. Some baseline betweengroup imbalances occurred as a consequence of the nonrandomized design and the consecutive and progressive nature in which treatments were applied. To address this issue, between-group comparisons were adjusted for baseline factors. Because we made no attempt to ensure that subjects remained in their respective study groups for the entire 2year duration, censoring was required for a large proportion of wait-listed and medically treated subjects. Notably, additional attrition resulting from losses to follow-up was relatively low and compares favorably to other published studies.19,20 A more conservative baseline-observation-carried-forward sensitivity analysis confirmed that our results were relatively robust despite the frequent censoring although smaller weight reductions were found using this more conservative analysis. Although wait-listed subjects received
214 | www.lww-medicalcare.com
Medical Care
Volume 52, Number 3, March 2014
FIGURE 2. Weight change by study group. Last-observationcarried-forward imputation. Error bars depict ± SE. *P < 0.0001 among groups using analysis of variance. wP < 0.05 versus baseline (post hoc).
little intervention, the possibility that their outcomes improved as a result of a Hawthorne effect cannot be discounted.22 In summary, in the Canadian context, we demonstrated that a population-based bariatric program was clinically effective, with results similar to or slightly less effective than those reported in more highly selected research settings. Furthermore, it is clear that with “usual care” available in the community (ie, our wait list), most extremely obese patients do not lose weight but are relatively stable in terms of their cardiometabolic risk over 2 years. These results, although they are specific to Edmonton Weight Wise, should be generalizable to other publicly funded programs and support the use of evidence-based programmatic bariatric care delivery in Canada. REFERENCES 1. Shields M, Carroll M, Ogden C. Adult obesity prevalence in Canada and the United States. NCHS Data Brief. 2011;56:1–8. 2. Hensrud DD, Klein S. Extreme obesity: a new medical crisis in the United States. Mayo Clin Proc. 2006;81(suppl 10):S5–S10. 3. Padwal RS, Majumdar SR, Klarenbach S, et al. The Alberta populationbased prospective evaluation of the quality of life outcomes and economic impact of bariatric surgery (APPLES) study: background, design and rationale. BMC Health Serv Res. 2010;10:284. 4. Lau DC, Douketis JD, Morrison KM, et al. 2006 Canadian clinical practice guidelines on the management and prevention of obesity in adults and children. CMAJ. 2007;176(suppl 8):1–117. 5. Padwal R, Sharma AM. Treating severe obesity: morbid weights and morbid waits. CMAJ. 2009;181:777–778. 6. Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery: a systematic review and meta-analysis. JAMA. 2004;292:1724–1737. 7. Sjostrom L, Lindroos AK, Peltonen M, et al. Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl J Med. 2004;351:2683–2693. r
2013 Lippincott Williams & Wilkins
Medical Care
Volume 52, Number 3, March 2014
8. Sjostrom L, Narbro K, Sjostrom CD, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357:741–752. 9. Dixon JB, O’Brien PE, Playfair J, et al. Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial. JAMA. 2008;299:316–323. 10. Herpetz S, Kielmann R, Wolf AM, et al. Does obesity surgery improve psychosocial functioning? A systematic review. Int J Obes. 2003; 27:1300–1314. 11. Karlsson J, Taft C, Ryde´n A, et al. Ten-year trends in health-related quality of life after surgical and conventional treatment for severe obesity: the SOS intervention study. Int J Obes. 2007;31:1248–1261. 12. Dixon JB, Dixon ME, O’Brien PE. Quality of life after lap-band placement: influence of time, weight loss, and comorbidities. Obes Res. 2001;9:713–721. 13. Christou NV, Efthimiou E. Bariatric surgery waiting times in Canada. Can J Surg. 2009;52:229–234. 14. Serdula MK, Khan LK, Dietz WH. Weight loss counseling revisited. JAMA. 2003;289:1747–1750. 15. Mauro M, Taylor V, Wharton S, et al. Barriers to obesity treatment. Eur J Intern Med. 2008;19:173–180.
r
2013 Lippincott Williams & Wilkins
Outcomes in a Population-based Bariatric Program
16. Sharma AM, Padwal R. Obesity is a sign—over-eating is a symptom: an aetiological framework for the assessment and management of obesity. Obes Rev. 2010;11:362–370. 17. Sterne JA, White IR, Carlin JB, et al. Multiple imputation for missing data in epidemiological and clinical research: potential and pitfalls. BMJ. 2009;338:b2393. 18. Wharton S, VanderLelie S, Sharma AM, et al. Feasibility of an interdisciplinary program for obesity management in Canada. Can Fam Phys. 2012;58:e32–e38. 19. Goodpaster BH, Delany JP, Otto AD, et al. Effects of diet and physical activity interventions on weight loss and cardiometabolic risk factors in severely obese adults: a randomized trial. JAMA. 2010;304:1795–1802. 20. Ryan DH, Johnson WD, Myers VH, et al. Nonsurgical weight loss for extreme obesity in primary care settings: results of the Louisiana Obese Subjects Study. Arch Intern Med. 2010;170:146–154. 21. Adams TD, Pendleton RC, Strong MB, et al. Health outcomes of gastric bypass patients compared to nonsurgical, nonintervened severely obese. Obesity. 2010;18:121–130. 22. Franke RH, Kaul JD. The Hawthorne experiments: first statistical interpretation. Am Sociol Rev. 1978;43:623–643.
www.lww-medicalcare.com |
215
