A Comparison of Obesity Prevalence: Military Health System and United States Populations,

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1 MILITARY MEDICINE, 179, 5:462, 2014 A Comparison of Obesity Prevalence: Military Health System and United States Populations, Patricia A. Eilerman, MPH*; Catherine M. Herzog, MPH*; Beverly K. Luce, FACHE, MHSA, BSN, RN*; Susan Y. Chao, MS*; Sandra M. Walker*; Lee A. Zarzabal, MS* ; Lt Col David H. Carnahan, USAF MC* ABSTRACT Overweight and obesity prevalence has increased over the past 30 years. Few studies have looked at the enrolled Military Health System (MHS) population (2.2 million per year). This descriptive study examined trends in overweight and obesity in both children and adults from fiscal years 2009 to 2012 and compared them to the U.S. population. Prevalence in MHS children decreased over time for overweight ( %) and obesity ( %). Active duty adults showed an increase in overweight prevalence ( %) and a decrease in obesity prevalence ( %). For nonactive duty, both overweight and obesity prevalence remained relatively unchanged around 33%. For both children and adults, overweight and obesity prevalence increased with age, except for obesity in the nonactive duty ³65 subgroup. When compared to the United States by gender and age, MHS children generally had a lower overweight and obesity prevalence, active duty adults had higher overweight and lower obesity prevalence, and nonactive duty adults had comparable overweight and obesity prevalence, except for obesity in both men in the 40 to 59 subgroup and women in ³60 subgroup. More research on the MHS population is needed to identify risk factors and modifiable health behaviors that could defeat the disease of obesity. INTRODUCTION Obesity prevalence in U.S. children has tripled since 1970, whereas adult prevalence has doubled in the past 30 years, making obesity a major public health concern. 1 Globally, approximately 1.4 billion adults were overweight, 0.5 billion were obese, and 40 million preschool children were overweight in The condition, defined as excessive fat accumulation in the body, is associated with an increased risk for more than 20 major chronic conditions. These conditions include coronary heart disease, hypertension, cerebrovascular disease, hyperlipidemia, type 2 diabetes, metabolic syndrome, respiratory problems, and some cancers. Although the obesity prevalence among children and adolescents increased radically in the late 1990s and early 2000s, there were no changes in obesity prevalence between (16.9%) and (16.9%). 3,4 Sharma et al noted obesity prevalence for low-income, preschool-age children (ages 2 4) increased from 12.4% to 14.5% in , but has remained stable since Others have observed a decrease in obesity prevalence for children since mid-2000s Despite conflicting reports, the economic burden of obese children is increasing with hospitalization costs estimated to be around $237.6 million. 12 Childhood and adolescent obesity has an impact on the strength of the U.S. military. Podraza and Roberts found 16.7% of children and adolescent dependents of military members, retirees, or foreign military service members were obese, and 27% of young adults cannot serve in the military because of excess body weight. 13,14 *Healthcare Informatics Division, United States Air Force Medical Support Agency, 3515 S General McMullen Suite 200, San Antonio, TX th Wing/Science and Technology, 59th Medical Detachment, Wilford Hall Ambulatory Surgical Center, 2200 Bergquist Drive, Suite 200, San Antonio, TX doi: /MILMED-D Like the prevalence in U.S. children, adult obesity prevalence increased dramatically in the 1980s, 1990s, and early 2000s, but has plateaued since Flegal et al noted U.S. obesity prevalence for (35.7%) did not differ significantly from estimates for (32.2%). 15,16 Conversely, Sherry et al reported nine states had an obesity prevalence over 30.0%, whereas no states met the Healthy People 2010 goal of obesity prevalence less than 15.0%. 17 More recently, Levi et al stated the number of states with an obesity prevalence above 30.0% increased to 12 states in Looking to the future, Finkelstein et al predicted a 33% increase in obesity prevalence for U.S. adults ³18 by 2030, based on Behavioral Risk Factor Surveillance System (BRFSS) data. 18 The rising health costs of the increasing obese adult population have a concrete impact on the U.S. health system. Finkelstein et al noted obese individuals spent $1,429 more in medical expenses than normal weight individuals in 2006, and that the cost of obesity-related diseases was estimated to be $147 billion per year in Compared to the general U.S. population, there are fewer publications on obesity within the U.S. Military Health System (MHS) population. Most of the obesity prevalence studies in the MHS population noted an increase in prevalence. There is also legitimate concern for decreased military operational readiness. Cawley and Maclean reported that from 1959 to 2008, the percentage of civilians aged 17 to 24 who exceeded Army body fat enlistment standards more than doubled for men and tripled for women. 20 Hsu et al found the combined overweight and obesity (referred to as combined throughout this article) prevalence rose from 25.6% to 33.9% in for U.S. military applicants, aged ³ Niebuhr et al also noted that overweight and obesity was the most common reason for medical disqualification from the military in Among those already serving in the military, the 462

2 Armed Forces Health Surveillance Center (AFHSC) reported the combined prevalence of active duty members more than tripled from 1.6% to 5.3% in , and more specifically that active duty women had a higher combined prevalence than active duty men. 23 Dall et al estimated that the MHS spent $1.1 billion in 2006 to treat obesity-related diseases in individuals enrolled to the TRICARE Prime program, a MHS health care program for individuals aged <65 including active duty, retirees, and their dependents. 24 Our study addresses the enrolled MHS population and reports overweight, obesity, and combined prevalence and trends. We sought to (1) examine the trends in overweight and obesity prevalence in the MHS population for children and adults from fiscal years (FYs) and (2) compare overweight and obesity prevalence between MHS and U.S. populations. METHODS Data Sources We used electric health record data collected in the Armed Forces Health Longitudinal Technology Application through the MHS Management Analysis and Reporting Tool (M2) and Clinical Data Repository. The study protocol was approved by the Department of Defense Institutional Review Board and the TRICARE Management Activity Human Protection and Privacy Department before data collection. Inclusion and Exclusion Criteria We analyzed data from FYs 2009 to 2012 for all MHS beneficiaries who were aged ³2 and continuously enrolled to TRICARE Prime or Plus for 1 year. Height and weight measurements are collected at the time of the encounter; therefore, we restricted data to individuals who had at least one outpatient visit within the measurement year. We excluded active duty service members aged ³65 because of the small number and possibility of identification. We excluded beneficiaries enrolled to Coast Guard military treatment facilities, the U.S. Family Health Plan, and the U.S. Public Health Service. Pregnant women of any age (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]: ; V22; V23; V28) were excluded. We included children who were 2 to 17 years of age, had a biologically plausible weight between 3.3 and 661 lbs, and a height between 12 and 84 in. 25 For adults, we included individuals who were ³18 years of age, had a biologically plausible weight between 70 and 700 lbs, and a height between 48 and 84 in. 26 Case Definitions We used the body mass index (BMI) English unit formula {[weight (lb) height (in)] } to identify overweight and obesity cases. For children, the most recent valid height and weight from the same visit were used to calculate BMI. We defined overweight children as 85th BMI percentile < 95th and obese children as BMI percentile ³ 95th. 27 For adults, the modal height and the median weight during the FY were used and if there were multiple height modes, the average of the modes was taken. 26 We defined overweight adults as 25.0 BMI <30.0 and obese adults as BMI ³ Statistical Analysis We calculated crude and age-adjusted overweight, obesity, and combined prevalence for children and adults. We applied direct age standardization to the U.S standard population to adjust for differences in population distributions between FYs 2009 and Age- and gender-specific crude and age-adjusted prevalence within gender were calculated for each FY. The MHS active duty population completes a medical evaluation before basic training and obesity is a disqualifying condition for entry into U.S. military service. This may cause a selection bias in our active duty population. Therefore, we stratified on active duty status and compared the resulting subgroups. Age-adjusted prevalence for men and women was compared separately for active duty and nonactive duty subgroups. Prevalence was derived from the entire MHS TRICARE Prime and Plus enrolled population; hence, we reported population parameters without standard error estimates or confidence intervals (CIs). 29,30 We compared MHS prevalence to the National Health and Nutrition Examination Survey (NHANES) prevalence because it includes prevalence for children and adults. Additionally, heights and weights are measured at the time of the NHANES interview. Statistical significance between our prevalence and NHANES prevalence was determined using 95% CIs from NHANES. Our prevalence was considered significantly different from NHANES prevalence if it was outside the NHANES 95% CI. 4,16 All analyses were performed in SAS Enterprise Guide version 5.1 (SAS Institute, Cary, North Carolina). RESULTS Overall Demographics The total TRICARE Prime and Plus population remained steady at approximately 2.2 million from FYs 2009 to The FY2012 population was 59.9% men, 21.7% children, and 41.9% active duty. For children, the demographic composition was consistent across the four FYs (52% boys, and average age approximately 9; see Table I). The demographic composition also remained relatively unchanged for adults across the study years (62% men, 54% active duty, and average age approximately 38; see Table II). Because of the stability of the data, only FY2012 results are reported in this section, unless noted otherwise. Child Overweight and Obesity Prevalence Age-adjusted prevalence for children is presented in Table III. The age-adjusted overweight, obesity, and combined prevalence 463

3 TABLE I. MHS Child Demographics, FYs Variable (n = 481,584) (n = 482,465) (n = 484,366) (n = 479,647) Gender (%) Boys Girls Age Category (%) BMI Classification (%) Underweight a Normal b Overweight c Obesity d MHS, Military Health System; FY, Fiscal Year; CDC, Centers for Disease Control and Prevention. a Underweight: <5th percentile from the 2000 CDC Growth Charts for the United States. b Normal: ³5th to <85th percentile from the 2000 CDC Growth Charts for the United States. c Overweight: ³85th to <95th percentile from the 2000 CDC Growth Charts for the United States. d Obesity: ³95th percentile from the 2000 CDC Growth Charts for the United States. TABLE II. MHS Adult Demographics, FYs Variable (n = 1,666,456) (n = 1,748,660) (n = 1,759,087) (n = 1,733,904) Gender (%) Men Women Age Category (%) ³65 a Beneficiary Category (%) Active Duty Nonactive Duty BMI Classification (%) Underweight b Normal c Overweight d Obesity e MHS, Military Health System; FY, Fiscal Year. a Only nonactive duty. b Underweight: BMI < c Normal: BMI 18.5 to d Overweight: BMI 25.0 to e Obesity: BMI ³ decreased slightly from 14.2% to 13.8%, 11.7% to 10.9%, and 25.8% to 24.7% in FYs , respectively. Girls had a higher age-adjusted overweight prevalence when compared to boys (14.1 % vs. 13.4%), whereas boys had a higher ageadjusted obesity prevalence (11.9% vs. 9.9%). Boys also had a higher age-adjusted combined prevalence (25.2% vs. 24.0%). Similar to the downward trends observed in the age-adjusted prevalence, age-specific overweight, obesity, and combined prevalence also showed minor decreases over time, overall and by gender. Prevalence increased with increasing age group, with the 12 to 17 subgroup having the highest overweight, obesity, and combined prevalence. The same trend was noted by gender. MHS child obesity and combined prevalence for FY2010 were compared to 95% CIs from 2009 to 2010 U.S. NHANES data in Figures 1A to 1D (note: different scales are used). MHS-dependent children were redefined as 2 to 19 years of age for this comparison to match the NHANES range. Overweight prevalence was not available in NHANES for comparison. Compared to U.S. prevalence, obesity prevalence in MHS boys was significantly lower in both the 2 to 5 and 6 to 11 age groups. Additionally, combined prevalence in MHS boys was significantly lower than the U.S. prevalence for the same age groups. Obesity prevalence for MHS girls was significantly lower than U.S. prevalence in the 6 to 11 and 12 to 19 age groups. The combined prevalence in MHS girls was significantly lower than U.S. prevalence in the 2 to 5 and 6 to 11 age groups. Active Duty Adult Overweight and Obesity Prevalence Age-adjusted prevalence for active duty is presented in Table IV. The age-adjusted overweight prevalence increased from 52.7% 464

4 TABLE III. Overweight, Obesity, and Combined Prevalence in MHS Children, FYs Overweight a (%) Obesity b (%) Combined c (%) Gender Age (years) Overall n d 481, , , , , , , , , , , , Crude Age Standardized e Boys n d 249, , , , , , , , , , , , Crude Age Standardized e Girls n d 232, , , , , , , , , , , , Crude Age Standardized e MHS, Military Health System; FY, Fiscal Year; CDC, Centers for Disease Control and Prevention. a Overweight: ³85th to <95th percentile from the 2000 CDC Growth Charts for the United States. b Obesity: ³95th percentile from the 2000 CDC Growth Charts for the United States. c Combined: ³85th percentile from the 2000 CDC Growth Charts for the United States. d n represents the denominator. e Age was standardized to the 2000 U.S. Census Standard population. FIGURE 1. Obesity and combined prevalence from FY2010 in MHS children vs NHANES rates: (A) boys obesity, (B) girls obesity, (C) boys combined, and (D) girls combined. The 95% CIs used in this figure are from Ogden et al Overweight prevalence was not available in NHANES for comparison. 465

5 TABLE IV. Overweight, Obesity, and Combined Prevalence in Active Duty Adults, FYs Overweight a (%) Obesity b (%) Combined c (%) Gender Age (years) Overall n d 847, , , , , , , , , , , , Crude Age Standardized e Men n d 715, , , , , , , , , , , , Crude Age Standardized e Women n d 131, , , , , , , , , , , , Crude Age Standardized e FY, Fiscal Year. a Only nonactive duty. a Overweight: BMI 25.0 to b Obesity: BMI ³ c Combined: BMI ³ d n represents the denominator. e Age was standardized to the 2000 U.S. Census Standard population. to 53.4% in FYs , whereas obesity prevalence decreased slightly from 18.9% to 18.3% in the same period. No change was observed for age-adjusted combined prevalence in FYs Men had a higher age-adjusted overweight, obesity, and combined prevalence (55.6 %, 19.6%, and 75.2%) when compared to women (41.1 %, 10.2%, and 51.4%). Among study years, the age-adjusted prevalence for active duty appeared constant for both genders. Prevalence increased with increasing age group and this trend was noted for both genders. Compared to nonactive duty, a higher overweight and lower obesity gender- and age-specific prevalence for active duty was observed. Active duty overweight, obesity, and combined prevalence in FY2010 were compared to 95% CIs from 2009 to 2010 NHANES data in Figures 2A to 2F (note: different scales are used). The lowest active duty age group was redefined as ³20 years of age for this comparison. As mentioned in the section on Methods, active duty members aged ³65 were excluded. Therefore, no comparison was made between active duty and NHANES in the ³60 age subgroup. For active duty men, overweight prevalence was significantly higher than U.S. prevalence in the 20 to 39 and 40 to 59 subgroups; conversely, obesity prevalence was significantly lower than U.S. prevalence in the same subgroups. Combined prevalence was not significantly different than U.S. prevalence for both subgroups. Like men, overweight prevalence for active duty women was significantly higher, whereas obesity prevalence was significantly lower than U.S. prevalence for women in the 20 to 39 and 40 to 59 subgroups. However, unlike prevalence in men, combined prevalence was significantly lower than U.S. prevalence in 20 to 39 and 40 to 59 subgroups for women. Nonactive Duty Adult Overweight and Obesity Prevalence Age-adjusted prevalence for nonactive duty is presented in Table V. There was no change in age-adjusted overweight ( %), obesity ( %), and combined prevalence ( %) in FYs Men had a higher age-adjusted overweight, obesity, and combined prevalence (39.3%, 39.9%, and 79.2%) when compared to women (29.7%, 30.6%, and 60.3%). Age-adjusted prevalence appeared constant across study years for both genders, similar to the stability found in the active duty subpopulation. Overweight prevalence increased with increasing age group and this trend for both genders. We noted that the overall and within gender obesity and combined prevalence increased with increasing age group until subgroup ³65 when there was a decrease. Nonactive duty overweight, obesity, and combined prevalence in FY2010 were compared to 95% CIs from 2009 to 2010 NHANES data in Figures 2A to 2F (note: different scales are used). The lowest nonactive duty age group was redefined as ³20 for this comparison. For nonactive duty men, although there was no significant difference in overweight prevalence for all age subgroups when compared to U.S. prevalence, significantly higher obesity and combined prevalence were seen in the 40 to 59 age subgroup. Like prevalence in men, overweight prevalence in nonactive duty women was not significantly different from U.S. prevalence. Obesity and combined prevalence for women aged ³60 were significantly lower than U.S. prevalence, but this finding was not observed in other age subgroup. DISCUSSION From FYs , we found that overweight, obesity, and combined prevalence in the MHS children showed a 466

6 FIGURE 2. Overweight, obesity, and combined prevalence from FY2010 in MHS adults vs NHANES rates: (A) men overweight, (B) women overweight, (C) men obesity, (D) women obesity, (E) men combined, and (F) women combined. The 95% CIs used in this figure are from Flegal et al slight decrease, which is consistent with other studies. 6 11,31 We also noted that overweight, obesity, and combined prevalence in nonactive duty MHS adults remained stable, which is similar to trends observed in the U.S. population. 15,16 In active duty, there was a slight increase in overweight prevalence, a decrease in obesity prevalence, and stabilization in combined prevalence. In MHS children, girls had a higher overweight prevalence than boys; however, boys had a higher obesity and combined prevalence. Both boys and girls had lower obesity and combined prevalence when compared to NHANES prevalence. 4 This pattern echoed findings from Choi et al who compared overweight and obesity prevalence from a subgroup of MHS children to NHANES prevalence. 32 Although MHS children in FY2010 did not meet the Healthy People 2010 objective to reduce obesity to 5% (11.2%), they have already met the Healthy People 2020 objective to reduce childhood obesity to 14.5% during FYs ( %). 33,34 Overweight prevalence in both active duty adult men and women was significantly higher than NHANES. The higher prevalence in active duty could be attributed to their higher muscle mass leading to misclassification by BMI, which was observed by Ode et al who validated BMI in athletes. 35 Our overweight, obesity, and combined prevalence were higher in active duty men than women, which was in line with findings from two self-reported Department of Defense health surveys of active duty from 2002 and AFHSC reported a higher combined prevalence in 467

7 TABLE V. Overweight, Obesity, and Combined Prevalence in Nonactive Duty Adults, FYs Overweight a (%) Obesity b (%) Combined c (%) Gender Age(years) Overall n d 819, , , , , , , , , , , , ³ Crude Age Standardized e Men n d 285, , , , , , , , , , , , ³ Crude Age Standardized e Women n d 534, , , , , , , , , , , , ³ Crude Age Standardized e FY, Fiscal Year. a Overweight: BMI 25.0 to b Obesity: BMI ³ c Combined: BMI ³ d n represents the denominator. e Age was standardized to the 2000 U.S. Census Standard population. active duty women than men in 2010, which was different than our results. 23 We suspect this was because of the difference in methods: we calculated BMI from clinical vital measurements, whereas AFHSC used outpatient encounter ICD-9-CM diagnosis codes. 37 In a separate analysis of our data, we found that the majority of overweight and obese individuals did not have an obesity-related diagnosis code. Therefore, prevalence based on height and weight was expected to be different than prevalence based on diagnosis. This may have impacted results between men and women. Compared to 2009 BRFSS, a selfreported national survey that only measured obesity prevalence, both active duty men and women had lower obesity prevalence. 17 Active duty adults in FY2010 did not meet the Healthy People 2010 objective to reduce obesity to 15% (16.6%). 33 However, active duty adults between FYs 2009 and 2012 ( %) have already met the Healthy People 2020 objective to reduce adult obesity to 30.5%. 34 In nonactive duty adult, an upward trend with increasing age in overweight prevalence was observed, similar to the trend in active duty. For obesity and combined prevalence, this trend peaked in the 45 to 64 age subgroup and subsequently fell in the ³65 subgroup. One possible explanation for the decrease in obesity and combined prevalence among ³65 nonactive duty is that fat mass decreases starting from age Another potential explanation for the decrease in our results could be the association between mortality and obesity reported in other studies. 38,39 When compared to 2009 BRFSS, both nonactive duty men and women had higher obesity prevalence, which is the opposite of findings in active duty. 17 The nonactive duty adult population did not meet either the Healthy People 2010 or Healthy People 2020 objectives to reduce obesity. 33,34 Our study was strengthened by our large sample size of approximately 2.2 million individuals. Another strength was that our study focused on all enrolled MHS children and adults, both active and nonactive duty, unlike other studies that focused on subpopulation such as active duty, retirees, spouses, or children of active duty. Third, we recognized the potential influence of the healthy worker effect on active duty overweight, obesity, and combined prevalence and we performed separate analyses on active and nonactive duty adults. Finally, we compared our overweight and obesity prevalence to U.S. prevalence from NHANES, a national survey from a representative sample, to better understand prevalence differences between the MHS and civilian populations. One limitation of our study is the use of BMI to classify overweight and obesity. Body fat percentage is considered to be the gold standard; yet, it is costly, time consuming, and was not available for this study. 40 Waist circumference is another method, but this measurement also was not available for majority of our subjects. A second limitation is the possible presence of self-reported data in our study s height and weight measurements, which is inherent in health records. Merrill and Richardson found that BMI calculated from selfreported height and weight data was lower than actual measurements. 41 This may have impacted our study results and caused prevalence to be underestimated. Furthermore, another common issue of using electronic health records is the presence of inaccurate values because of data entry errors that could lead to misclassification. 42,43 468

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