Bariatric treatments for adult obesity - Institute of Health Economics

Considerable variation in the prevalence of obesity occurs among and within countries of theWestern hemisphere. 9,10,25,28,46,77,78,88,89 However, comparisons of the data collected by/for differentcountries are complicated by the differences in year of data collection, the age range of thepopulation studied, and the location of data collection (urban, rural, nationally representative).Adult obesity in the United StatesThe National Center for Health Statistics at the Centers for Disease Control and Prevention (CDC)in the United States released the 2009 National Health Interview Survey (NHIS)(www.cdc.gov/nchs/nhis/released201006.htm#6) in June 2010. This survey (based on interviewswith 88,129 individuals) found that 28% of US adults 20 years and older were considered obese(BMI ≥ 30 kg/m 2 ). This is slightly higher than the 2008 estimate of 27.6%. The annual prevalence ofobesity has increased steadily from the 19.4% reported in 1997. Obesity was higher among adultsaged 40 to 59 (31.6%) than among adults aged 20 to 39 (24.9%) and those aged 60 years and older(27.0%). There was no significant difference between genders. Non-Hispanic white women and menwere less likely than Hispanic women and non-Hispanic black women to be obese. Non-Hispanicwhite women were less likely than non-Hispanic white men to be obese and non-Hispanic blackwomen were more likely than non-Hispanic black men to be obese.The prevalence of obesity has increased over the past years among both genders, in all age andethnic groups, and at all educational levels. 35,44,50,51,57,73,90-93 The most rapid increases in obesityprevalence are in its most severe forms. 44,57,73,90 Approximately 5% of adult Americans suffer fromsevere obesity, 14,15,57,90 which affects 20% of the obesity-affected US population. 73 Approximately 20to 25% of children are either overweight or obese and the prevalence is even greater in someminority groups, including Pima Indians, Mexican Americans, and African Americans. 35,44Evidence from a meta-regression analysis published in 2007 predicts that 41% of adult Americanswill become obese by 2015. 50 If these trends in obesity prevalence continue, by 2030 the number ofadults with obesity will be 1.12 billion, representing more than 86% of adults in the US. 90Adult obesity in CanadaIn Canada, the overall prevalence of obesity has increased over the past several decades amongchildren, adolescents, and adults of both genders, in all areas of the country, and it continues torise. 1,3,8-12,16,17,24,28,29,31-33,47,68,69,81,88,94-96 Canadian statistics rely upon a number of different surveys ofnationally representative samples. These surveys vary in regard to cut-off points, referencepopulations, and data collection techniques (most used self-reported heights and weights; only somewere based on directly measured heights and weights). Regardless of the specific studies or surveys,both self-reported and directly measured data have shown a steady increase in obesity prevalenceamong adults aged 18 or older since 1970, with the most rapid increase being seen in obesity classesII and III.An examination of self-reported BMI data from seven surveys, conducted from 1985 through 2003,of nationally representative samples of Canadian adults found that the overall prevalence of selfreportedobesity increased from 6.1% in 1985 to 15.7% in 2003. 16,81 The investigators also found thatthe prevalence of class I obesity increased from 5.1% in 1985 to 11.5% in 2003. The prevalence ofclass II obesity increased from 0.8% to 3.0%, while class III obesity rates increased from 0.4% to1.3%.However, directly measured BMI data are considered more accurate than self-reported data, whichmay underestimate the actual prevalence of obesity given the tendency of respondents to over-Bariatric treatments for adult obesity – March 2012 9