The Laryngoscope C 2015 The American Laryngological, V
Rhinological and Otological Society, Inc.
Geographic Variation of Endoscopic Sinus Surgery in the United States Luke Rudmik, MD, MSc; Chantal E. Holy, PhD; Timothy L. Smith, MD, MPH Objectives/Hypothesis: The objective of this study was to examine the rates and geographic variation of endoscopic sinus surgery (ESS) in a representative sample of the US working population. Study Design: Observational cohort study using the MarketScan Commercial Claim and Encounters database. Methods: All patients who received ESS between 2009 and 2013 were included. The annual adjusted rates of ESS per 1,000 people were calculated for each US state. Geographic variations were evaluated using the extremal quotient (EQ), weighted coefficient of variation (CV), systematic component of variance (SCV), and empirical Bayes statistic. The v2 statistic tests was used to quantify variation of the adjusted ESS rates across states within the US. Results: The annual adjusted rate of ESS was 0.94 per 1,000 people in the US. South Dakota and Alabama were observed to have the highest rates of ESS, 1.80 and 1.69, respectively. Vermont and Arkansas were observed to have the lowest rates of ESS, 0.51 and 0.57, respectively. The mean EQ was 4.54, indicating a four- to fivefold difference between the highest (South Dakota) and lowest (Vermont) states. The mean CV was 31.4 and mean SCV was 10.1, which demonstrates very high variation. Conclusions: This study observed very high geographic variation in the rates of ESS across the United States. Given that practice variation indicates the presence of potentially harmful and inefficient unwarranted care, outcomes from this study indicate a need to further evaluate the delivery of ESS to improve overall health system performance. Key Words: Endoscopic sinus surgery, chronic rhinosinusitis, sinusitis, geographic variation, practice variation, quality of care, appropriateness. Level of Evidence: 2b. Laryngoscope, 125:1772–1778, 2015
INTRODUCTION Variation in healthcare utilization has been viewed as a major threat to quality of care, because it represents the presence of potential misuse, overuse, and underuse of scarce healthcare resources.1 Common sources of surgical variation include patient preferences, lack of well-defined surgical indications, regional differences in patient access, surgeon beliefs about the procedure, and physician payment systems.2 Defining variation in the rate of specific surgical procedures is an essential first step toward reducing inefficient/unwarranted pracAdditional Supporting Information may be found in the online version of this article. From the Division of Otolaryngology–Head and Neck Surgery, Department of Surgery (L.R.), University of Calgary, Calgary, Alberta, Canada; Acclarent (C.E.H.), Menlo Park, California, U.S.A.; and the Division of Rhinology and Sinus Surgery, Oregon Sinus Center, Department of Otolaryngology–Head and Neck Surgery (T.L.S.), Oregon Health and Science University, Portland, Oregon, U.S.A. Editor’s Note: This Manuscript was accepted for publication March 13, 2015. C.E.H. is an employee of Acclarent. T.L.S. is a consultant for Intersect ENT Inc. (Menlo Park, CA). Acclarent/J&J paid for the license to access the MarketScan database. The authors have no other funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Luke Rudmik, MD, Division of Otolaryngology–Head and Neck Surgery, Department of Surgery, University of Calgary, Richmond Road Diagnostic and Treatment Centre, 1820 Richmond Road SW, T2T 5C7, Calgary, Alberta, Canada. E-mail: [email protected] DOI: 10.1002/lary.25314
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tice patterns and improving overall health system performance.3–7 With an estimated 250,000 cases per year in the United States,8 endoscopic sinus surgery (ESS) is a common and important intervention typically reserved for patients with refractory chronic rhinosinusitis (CRS),9 one of the most prevalent chronic diseases of adults in the United States.10 In the correctly selected patient, ESS has been shown to significantly improve short- and long-term quality of life,11,12 as well as reduce healthcare consumption such as physician visits and medications.13,14 Furthermore, a recent economic evaluation demonstrated that ESS had a higher probability of being a cost-effective intervention compared to continued medical therapy alone for refractory CRS.15 However, despite evidence supporting the effectiveness of ESS, there is a paucity of research on the quality of healthcare delivery for this procedure. Evaluating for geographic differences in the utilization of ESS is important to begin designing innovative systems of improved healthcare delivery to reduce potential overuse and underuse of scarce surgical resources. The objective of this study was to examine the rates and geographic variation of ESS in a representative sample of the US working population using the MarketScan database. The primary outcome is the variation in age- and sex-adjusted rates of ESS on a state level. We hypothesize that there will be significant geographic variation in the rates of ESS across in the United States. Rudmik et al.: Geographic Variation of ESS
MATERIALS AND METHODS Identification of ESS Events The MarketScan Commercial Claim and Encounters (CCE) database (Truven Health Analytics, Ann Arbor, MI) was queried in September 2014. This is a large, US-based, employment-based database that contains information on medical and drug insurance claims on employees and their dependents. The cohort involves claims from over 45 large employers covered by over 100 commercial payers, Medicare supplemental, or Medicaid plan. This database has been utilized for many prior analyses of small-area variations due to its large size and appropriate representation of all US regions.16
All sinus surgery entries (defined as outpatient and inpatient procedures with a Current Procedural Terminology code 31254, 31255, 31256, 31267, 31276, 31287, 31288, 31295, 31296, 31297, 31299) from January 1, 2009 to December 31, 2013 were identified. Procedures were grouped such that each unique patient-date combination was identified as one surgery. With this method, one patient having multiple procedures done during the same date was counted as one surgery; however, one patient coming back for sinus surgery on two or more distinct dates was identified in the final table as two or more distinct surgeries. For each surgery, the age, gender, and state of residence of the patient were collected to standardize of the surgical rates.
Fig. 1. Heat map for geographic rates of endoscopic sinus surgery across the United States for 2009 and 2013. [Color figure can be viewed in the online issue, which is available at www.laryngoscope. com.]
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TABLE I. Overall Volume and Rate of ESS in the MarketScan Population. Year
MartetScan population ESS cases
2009
2010
2011
2012
2013
43,184,422 42,354
49,018,490 44,842
56,986,620 50,178
57,488,294 51,602
50,294,798 46,704
Crude rate of ESS per 1,000 people
0.98
0.92
0.88
0.90
0.93
Age- and sex-adjusted rate of ESS per 1,000 people
0.98
0.93
0.91
0.92
0.96
ESS 5 endoscopic sinus surgery.
Determining the Geographic Rates of ESS in the United States The crude and adjusted rate of ESS per 1,000 people in each US state for each year of 2009–2013 was determined. The age- and sex-adjusted rates of ESS per 1,000 people were calculated by the direct method of standardization. For each state, the total count of patients enrolled in the MarketScan CCE database for each separate year was identified, from 2009 to 2013, and stratified by patient age and gender. Age was estimated for each year using each patient year of birth (YoB) and assuming that Age 5 Year 2 YoB. The complete tables of patient counts by age, gender, and state for each year from 2009 to 2013 constituted the standards that were used for direct age and gender standardization in each state.
Quantification of Geographic Variation Using the direct age- and gender-adjusted rates for each geographic region, the extremal quotient (EQ) and weighted coefficient of variation (CV) were calculated. The EQ describes the largest relative difference in rates by taking a ratio of the highest and the lowest rate of use. When the lowest rate of a geographic region was zero, the mean annual rate of ESS was used for that year. The CV is the standard deviation of the rates divided by the mean rate weighted by the population of each area multiplied by 100. The CV is used to compare the changes in variation over time. The EQ and CV are descriptive in nature and lack a hypothesis test to determine whether the degree in variation between locations is due to chance or not. The systematic component of variation (SCV),17 the empirical Bayes (EB) variance component,18,19 as well as the v2 statistic20 were calculated using actual counts of observed versus expected cases per age/gender per region. The SCV is considered a robust method to quantify variation, and it is derived from a model that recognizes two sources of total variation in area ESS rates: 1) across areas (a difference in their rates, which is called systematic variation), and 2) within area (random variation of observed rates around each area’s true rate). Thus, the SCV is an estimate of the true (i.e., nonrandom) total variation and is considered a robust measure of variation.17,21 The EB statistic improves upon the SCV by increasing the resolution of surgical events in small geographic regions where the annual number of events may be highly unstable and vary in frequency from year to year.22,23 The one-degree of freedom v2 is used to determine if the rate of an area is statistically different from a standard reference area.24 For these analyses, Hawaii and Puerto Rico were excluded, because their total population in the database (denominator) was less than 10,000. Formulations for the are shown in the supplementary figure. The EB statistic in this study was the variance r2 and was calculated assuming a
Laryngoscope 125: August 2015
1774
gamma model and used the method of moments.18,19 Under the null hypothesis of homogeneity among rates (e.g., same risk of surgery across all regions), both the SCV and EB statistics would be zero. A full description of the EQ, CV, SCV, EB, and v2 formulations are shown in Supporting Figure 1 in the online version of this article.
RESULTS Overall Volume and Rate of ESS in the United States The volume of ESS in the MarketScan population from 2009 to 2013 is reported in Table I. The annual age- and sex-adjusted rates of ESS varied between 0.91 and 0.98 cases per 1,000 people, with an annual mean rate of 0.94 per 1,000 people. Figure 1 graphically represents the geographic rate of ESS across the United States in 2009 and 2013.
Geographic Rates and Variation of ESS Across the United States The annual age- and gender-adjusted rates of ESS per 1,000 people for 49 US states and one district (Washington, DC) between 2009 and 2013 are reported in Table II and visually represented in Figure 1 (heat map) and Figure 2 (variation profile). The results demonstrated large variation in the rates of ESS with a mean EQ of 4.54, indicating a four- to fivefold difference between the highest (South Dakota) and lowest (Vermont) states. The mean SCV value was 10.1 (range, 8.8 to 11.9), which demonstrates very high variation (SCV scale: moderate variation 5 SCV between 3 to 5; high variation 5 SCV between 5.1 and 10; very high variation 5 SCV >10).25 The mean EB statistic was 6.1 (range, 4.8 to 8.9) demonstrating high variation. Figure 2 graphically represents the variation of ESS rates within the United States.
DISCUSSION Using the MarketScan CCE database as a representative sample of the US population, this observational study evaluated for the presence of geographic variations in the rate of ESS for patients with CRS. The mean overall rate of ESS in the United States was 0.94 per 1,000 people. After controlling for regional differences in age and gender distribution, we observed large Rudmik et al.: Geographic Variation of ESS
TABLE II. Geographic Adjusted Rates and Variation of ESS in the United States From 2009 to 2013. Rate of ESS per 1,000 People by Year Year 2009
Year 2010
Year 2011
Year 2012
Year 2013
1.7495 1.1336
1.6762 0.8085
1.5613 0.9399
1.6729 0.7419
1.7752 0.9873
Alabama Alaska Arizona
1.0106
0.8754
0.9611
0.7856
0.8303
Arkansas California
0.5666 0.6438
0.5754 0.6186
0.6294 0.6160
0.5621 0.6727
0.4937 0.6882
Colorado
1.2937
1.2640
1.1586
1.1566
1.0082
Connecticut Delaware
0.7651 0.9698
0.8301 0.8275
0.8722 0.6645
0.9371 0.6339
0.9127 0.7738
Florida
0.8826
0.8631
0.9454
0.9507
1.0939
Georgia Idaho
1.3553 1.3542
1.2881 1.1963
1.2583 1.6062
1.2637 1.2668
1.3248 1.2688
Illinois
0.9780
0.9444
0.9630
0.9315
0.9402
Indiana Iowa
1.1673 0.9538
1.0202 0.7717
0.9817 0.8826
1.0281 0.7969
0.9982 1.0774
Kansas
1.7620
1.3508
1.2396
1.3980
1.0761
Kentucky Louisiana
0.8183 1.2228
0.7905 1.0337
0.7233 1.1039
0.7461 1.1294
0.6559 1.9507
Maine
0.6890
0.7625
0.6658
0.5647
0.7324
Maryland Massachusetts
0.8384 0.6814
0.8715 0.6438
0.8797 0.7414
0.9241 0.6122
0.8353 0.6868
Michigan
0.8923
0.8632
0.9014
0.7964
0.8523
Minnesota Mississippi
0.7012 1.2597
0.6409 1.2604
0.7768 1.1355
0.6671 1.2010
0.6769 1.1919
Missouri
1.1507
1.0763
1.0375
1.0424
1.1085
Montana Nebraska
1.0689 1.2379
0.8983 1.1684
0.7711 0.8792
0.8177 1.1168
0.9400 1.3285
Nevada
1.2375
1.1607
0.9855
1.1464
1.1523
New Hampshire New Jersey
1.1631 0.8923
0.9081 0.8745
0.7529 0.8792
0.8111 0.8659
0.9162 0.8813
New Mexico
0.7658
0.7807
0.8925
0.9492
0.9952
New York North Carolina
0.6610 0.8926
0.6801 0.8192
0.7352 0.8110
0.7379 0.7639
0.7877 0.7959
North Dakota
0.6671
0.6081
0.8629
0.7694
0.8323
Ohio Oklahoma
1.0753 0.9680
0.9825 0.9023
0.9715 0.9125
0.9264 0.8386
0.8543 0.8303
Oregon
1.1150
1.0261
0.9651
0.9125
0.7545
Pennsylvania Rhode Island
0.9346 1.0589
0.9882 0.7734
0.8097 0.7848
0.8633 0.5673
0.8584 0.6940
South Carolina
1.0871
1.1198
1.1151
1.0830
1.0036
South Dakota Tennessee
1.7038 1.1508
2.2475 1.2073
1.9438 1.0432
1.6006 1.0062
1.4951 1.0892
Texas
1.0915
1.0642
1.0925
1.1409
1.4071
Utah Vermont
1.5743 0.3764
1.5008 0.5311
1.5551 0.4866
1.6485 0.6499
1.5974 0.4902
Virginia
0.8374
0.5893
0.7715
0.7358
0.7820
Washington Washington, DC
1.3557 0.5634
1.2185 0.5493
1.1529 0.6208
1.1179 0.3012
1.1126 0.6905
West Virginia
1.2177
1.0797
1.0199
1.0187
0.8625
Wisconsin
0.8716
0.8279
0.8779
0.9089
0.8381
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TABLE II. (Continued) Rate of ESS per 1,000 People by Year Year 2009
Year 2010
Year 2011
Year 2012
Year 2013
1.2211
Rhinological and Otological Society, Inc.
Geographic Variation of Endoscopic Sinus Surgery in the United States Luke Rudmik, MD, MSc; Chantal E. Holy, PhD; Timothy L. Smith, MD, MPH Objectives/Hypothesis: The objective of this study was to examine the rates and geographic variation of endoscopic sinus surgery (ESS) in a representative sample of the US working population. Study Design: Observational cohort study using the MarketScan Commercial Claim and Encounters database. Methods: All patients who received ESS between 2009 and 2013 were included. The annual adjusted rates of ESS per 1,000 people were calculated for each US state. Geographic variations were evaluated using the extremal quotient (EQ), weighted coefficient of variation (CV), systematic component of variance (SCV), and empirical Bayes statistic. The v2 statistic tests was used to quantify variation of the adjusted ESS rates across states within the US. Results: The annual adjusted rate of ESS was 0.94 per 1,000 people in the US. South Dakota and Alabama were observed to have the highest rates of ESS, 1.80 and 1.69, respectively. Vermont and Arkansas were observed to have the lowest rates of ESS, 0.51 and 0.57, respectively. The mean EQ was 4.54, indicating a four- to fivefold difference between the highest (South Dakota) and lowest (Vermont) states. The mean CV was 31.4 and mean SCV was 10.1, which demonstrates very high variation. Conclusions: This study observed very high geographic variation in the rates of ESS across the United States. Given that practice variation indicates the presence of potentially harmful and inefficient unwarranted care, outcomes from this study indicate a need to further evaluate the delivery of ESS to improve overall health system performance. Key Words: Endoscopic sinus surgery, chronic rhinosinusitis, sinusitis, geographic variation, practice variation, quality of care, appropriateness. Level of Evidence: 2b. Laryngoscope, 125:1772–1778, 2015
INTRODUCTION Variation in healthcare utilization has been viewed as a major threat to quality of care, because it represents the presence of potential misuse, overuse, and underuse of scarce healthcare resources.1 Common sources of surgical variation include patient preferences, lack of well-defined surgical indications, regional differences in patient access, surgeon beliefs about the procedure, and physician payment systems.2 Defining variation in the rate of specific surgical procedures is an essential first step toward reducing inefficient/unwarranted pracAdditional Supporting Information may be found in the online version of this article. From the Division of Otolaryngology–Head and Neck Surgery, Department of Surgery (L.R.), University of Calgary, Calgary, Alberta, Canada; Acclarent (C.E.H.), Menlo Park, California, U.S.A.; and the Division of Rhinology and Sinus Surgery, Oregon Sinus Center, Department of Otolaryngology–Head and Neck Surgery (T.L.S.), Oregon Health and Science University, Portland, Oregon, U.S.A. Editor’s Note: This Manuscript was accepted for publication March 13, 2015. C.E.H. is an employee of Acclarent. T.L.S. is a consultant for Intersect ENT Inc. (Menlo Park, CA). Acclarent/J&J paid for the license to access the MarketScan database. The authors have no other funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Luke Rudmik, MD, Division of Otolaryngology–Head and Neck Surgery, Department of Surgery, University of Calgary, Richmond Road Diagnostic and Treatment Centre, 1820 Richmond Road SW, T2T 5C7, Calgary, Alberta, Canada. E-mail: [email protected] DOI: 10.1002/lary.25314
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tice patterns and improving overall health system performance.3–7 With an estimated 250,000 cases per year in the United States,8 endoscopic sinus surgery (ESS) is a common and important intervention typically reserved for patients with refractory chronic rhinosinusitis (CRS),9 one of the most prevalent chronic diseases of adults in the United States.10 In the correctly selected patient, ESS has been shown to significantly improve short- and long-term quality of life,11,12 as well as reduce healthcare consumption such as physician visits and medications.13,14 Furthermore, a recent economic evaluation demonstrated that ESS had a higher probability of being a cost-effective intervention compared to continued medical therapy alone for refractory CRS.15 However, despite evidence supporting the effectiveness of ESS, there is a paucity of research on the quality of healthcare delivery for this procedure. Evaluating for geographic differences in the utilization of ESS is important to begin designing innovative systems of improved healthcare delivery to reduce potential overuse and underuse of scarce surgical resources. The objective of this study was to examine the rates and geographic variation of ESS in a representative sample of the US working population using the MarketScan database. The primary outcome is the variation in age- and sex-adjusted rates of ESS on a state level. We hypothesize that there will be significant geographic variation in the rates of ESS across in the United States. Rudmik et al.: Geographic Variation of ESS
MATERIALS AND METHODS Identification of ESS Events The MarketScan Commercial Claim and Encounters (CCE) database (Truven Health Analytics, Ann Arbor, MI) was queried in September 2014. This is a large, US-based, employment-based database that contains information on medical and drug insurance claims on employees and their dependents. The cohort involves claims from over 45 large employers covered by over 100 commercial payers, Medicare supplemental, or Medicaid plan. This database has been utilized for many prior analyses of small-area variations due to its large size and appropriate representation of all US regions.16
All sinus surgery entries (defined as outpatient and inpatient procedures with a Current Procedural Terminology code 31254, 31255, 31256, 31267, 31276, 31287, 31288, 31295, 31296, 31297, 31299) from January 1, 2009 to December 31, 2013 were identified. Procedures were grouped such that each unique patient-date combination was identified as one surgery. With this method, one patient having multiple procedures done during the same date was counted as one surgery; however, one patient coming back for sinus surgery on two or more distinct dates was identified in the final table as two or more distinct surgeries. For each surgery, the age, gender, and state of residence of the patient were collected to standardize of the surgical rates.
Fig. 1. Heat map for geographic rates of endoscopic sinus surgery across the United States for 2009 and 2013. [Color figure can be viewed in the online issue, which is available at www.laryngoscope. com.]
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TABLE I. Overall Volume and Rate of ESS in the MarketScan Population. Year
MartetScan population ESS cases
2009
2010
2011
2012
2013
43,184,422 42,354
49,018,490 44,842
56,986,620 50,178
57,488,294 51,602
50,294,798 46,704
Crude rate of ESS per 1,000 people
0.98
0.92
0.88
0.90
0.93
Age- and sex-adjusted rate of ESS per 1,000 people
0.98
0.93
0.91
0.92
0.96
ESS 5 endoscopic sinus surgery.
Determining the Geographic Rates of ESS in the United States The crude and adjusted rate of ESS per 1,000 people in each US state for each year of 2009–2013 was determined. The age- and sex-adjusted rates of ESS per 1,000 people were calculated by the direct method of standardization. For each state, the total count of patients enrolled in the MarketScan CCE database for each separate year was identified, from 2009 to 2013, and stratified by patient age and gender. Age was estimated for each year using each patient year of birth (YoB) and assuming that Age 5 Year 2 YoB. The complete tables of patient counts by age, gender, and state for each year from 2009 to 2013 constituted the standards that were used for direct age and gender standardization in each state.
Quantification of Geographic Variation Using the direct age- and gender-adjusted rates for each geographic region, the extremal quotient (EQ) and weighted coefficient of variation (CV) were calculated. The EQ describes the largest relative difference in rates by taking a ratio of the highest and the lowest rate of use. When the lowest rate of a geographic region was zero, the mean annual rate of ESS was used for that year. The CV is the standard deviation of the rates divided by the mean rate weighted by the population of each area multiplied by 100. The CV is used to compare the changes in variation over time. The EQ and CV are descriptive in nature and lack a hypothesis test to determine whether the degree in variation between locations is due to chance or not. The systematic component of variation (SCV),17 the empirical Bayes (EB) variance component,18,19 as well as the v2 statistic20 were calculated using actual counts of observed versus expected cases per age/gender per region. The SCV is considered a robust method to quantify variation, and it is derived from a model that recognizes two sources of total variation in area ESS rates: 1) across areas (a difference in their rates, which is called systematic variation), and 2) within area (random variation of observed rates around each area’s true rate). Thus, the SCV is an estimate of the true (i.e., nonrandom) total variation and is considered a robust measure of variation.17,21 The EB statistic improves upon the SCV by increasing the resolution of surgical events in small geographic regions where the annual number of events may be highly unstable and vary in frequency from year to year.22,23 The one-degree of freedom v2 is used to determine if the rate of an area is statistically different from a standard reference area.24 For these analyses, Hawaii and Puerto Rico were excluded, because their total population in the database (denominator) was less than 10,000. Formulations for the are shown in the supplementary figure. The EB statistic in this study was the variance r2 and was calculated assuming a
Laryngoscope 125: August 2015
1774
gamma model and used the method of moments.18,19 Under the null hypothesis of homogeneity among rates (e.g., same risk of surgery across all regions), both the SCV and EB statistics would be zero. A full description of the EQ, CV, SCV, EB, and v2 formulations are shown in Supporting Figure 1 in the online version of this article.
RESULTS Overall Volume and Rate of ESS in the United States The volume of ESS in the MarketScan population from 2009 to 2013 is reported in Table I. The annual age- and sex-adjusted rates of ESS varied between 0.91 and 0.98 cases per 1,000 people, with an annual mean rate of 0.94 per 1,000 people. Figure 1 graphically represents the geographic rate of ESS across the United States in 2009 and 2013.
Geographic Rates and Variation of ESS Across the United States The annual age- and gender-adjusted rates of ESS per 1,000 people for 49 US states and one district (Washington, DC) between 2009 and 2013 are reported in Table II and visually represented in Figure 1 (heat map) and Figure 2 (variation profile). The results demonstrated large variation in the rates of ESS with a mean EQ of 4.54, indicating a four- to fivefold difference between the highest (South Dakota) and lowest (Vermont) states. The mean SCV value was 10.1 (range, 8.8 to 11.9), which demonstrates very high variation (SCV scale: moderate variation 5 SCV between 3 to 5; high variation 5 SCV between 5.1 and 10; very high variation 5 SCV >10).25 The mean EB statistic was 6.1 (range, 4.8 to 8.9) demonstrating high variation. Figure 2 graphically represents the variation of ESS rates within the United States.
DISCUSSION Using the MarketScan CCE database as a representative sample of the US population, this observational study evaluated for the presence of geographic variations in the rate of ESS for patients with CRS. The mean overall rate of ESS in the United States was 0.94 per 1,000 people. After controlling for regional differences in age and gender distribution, we observed large Rudmik et al.: Geographic Variation of ESS
TABLE II. Geographic Adjusted Rates and Variation of ESS in the United States From 2009 to 2013. Rate of ESS per 1,000 People by Year Year 2009
Year 2010
Year 2011
Year 2012
Year 2013
1.7495 1.1336
1.6762 0.8085
1.5613 0.9399
1.6729 0.7419
1.7752 0.9873
Alabama Alaska Arizona
1.0106
0.8754
0.9611
0.7856
0.8303
Arkansas California
0.5666 0.6438
0.5754 0.6186
0.6294 0.6160
0.5621 0.6727
0.4937 0.6882
Colorado
1.2937
1.2640
1.1586
1.1566
1.0082
Connecticut Delaware
0.7651 0.9698
0.8301 0.8275
0.8722 0.6645
0.9371 0.6339
0.9127 0.7738
Florida
0.8826
0.8631
0.9454
0.9507
1.0939
Georgia Idaho
1.3553 1.3542
1.2881 1.1963
1.2583 1.6062
1.2637 1.2668
1.3248 1.2688
Illinois
0.9780
0.9444
0.9630
0.9315
0.9402
Indiana Iowa
1.1673 0.9538
1.0202 0.7717
0.9817 0.8826
1.0281 0.7969
0.9982 1.0774
Kansas
1.7620
1.3508
1.2396
1.3980
1.0761
Kentucky Louisiana
0.8183 1.2228
0.7905 1.0337
0.7233 1.1039
0.7461 1.1294
0.6559 1.9507
Maine
0.6890
0.7625
0.6658
0.5647
0.7324
Maryland Massachusetts
0.8384 0.6814
0.8715 0.6438
0.8797 0.7414
0.9241 0.6122
0.8353 0.6868
Michigan
0.8923
0.8632
0.9014
0.7964
0.8523
Minnesota Mississippi
0.7012 1.2597
0.6409 1.2604
0.7768 1.1355
0.6671 1.2010
0.6769 1.1919
Missouri
1.1507
1.0763
1.0375
1.0424
1.1085
Montana Nebraska
1.0689 1.2379
0.8983 1.1684
0.7711 0.8792
0.8177 1.1168
0.9400 1.3285
Nevada
1.2375
1.1607
0.9855
1.1464
1.1523
New Hampshire New Jersey
1.1631 0.8923
0.9081 0.8745
0.7529 0.8792
0.8111 0.8659
0.9162 0.8813
New Mexico
0.7658
0.7807
0.8925
0.9492
0.9952
New York North Carolina
0.6610 0.8926
0.6801 0.8192
0.7352 0.8110
0.7379 0.7639
0.7877 0.7959
North Dakota
0.6671
0.6081
0.8629
0.7694
0.8323
Ohio Oklahoma
1.0753 0.9680
0.9825 0.9023
0.9715 0.9125
0.9264 0.8386
0.8543 0.8303
Oregon
1.1150
1.0261
0.9651
0.9125
0.7545
Pennsylvania Rhode Island
0.9346 1.0589
0.9882 0.7734
0.8097 0.7848
0.8633 0.5673
0.8584 0.6940
South Carolina
1.0871
1.1198
1.1151
1.0830
1.0036
South Dakota Tennessee
1.7038 1.1508
2.2475 1.2073
1.9438 1.0432
1.6006 1.0062
1.4951 1.0892
Texas
1.0915
1.0642
1.0925
1.1409
1.4071
Utah Vermont
1.5743 0.3764
1.5008 0.5311
1.5551 0.4866
1.6485 0.6499
1.5974 0.4902
Virginia
0.8374
0.5893
0.7715
0.7358
0.7820
Washington Washington, DC
1.3557 0.5634
1.2185 0.5493
1.1529 0.6208
1.1179 0.3012
1.1126 0.6905
West Virginia
1.2177
1.0797
1.0199
1.0187
0.8625
Wisconsin
0.8716
0.8279
0.8779
0.9089
0.8381
Laryngoscope 125: August 2015
Rudmik et al.: Geographic Variation of ESS
1775
TABLE II. (Continued) Rate of ESS per 1,000 People by Year Year 2009
Year 2010
Year 2011
Year 2012
Year 2013
1.2211
