Body Mass Index, Diabetes, Hypertension, and
Short-Term Mortality: A Population-Based
Observational Study, 2000–2006
Anthony Jerant, MD, and Peter Franks, MD
Background: Published studies about the association of obesity with mortality have used body mass
index (BMI) data collected more than 10 years ago, potentially limiting their current applicability, par-
ticularly given evidence of a secular decline in obesity-related mortality. The objective of this study was
to examine the association between BMI and mortality in a representative, contemporary United States
Methods: This was a population-based observational study of data from 50,994 adults aged 18 to 90
years who responded to the 2000 to 2005 Medical Expenditures Panel Surveys. Cox regression analyses
were employed to model survival during up to 6 years of follow-up (ascertained via National Death In-
dex linkage) by self-reported BMI category (underweight, <20 kg/m2; normal weight, 20-<25 [refer-
ence]; overweight, 25-<30; obese, 30-<35; severely obese, >35), without and with adjustment for
diabetes and hypertension. Survival by BMI category also was modeled for diabetic and hypertensive
individuals. All models were adjusted for sociodemographics, smoking, and Medical Expenditures Panel
Surveys response year.
Results: In analyses not adjusted for diabetes or hypertension, only severe obesity was associated
with mortality (adjusted hazard ratio, 1.26; 95% confidence interval, 1.00–1.59). After adjusting for
diabetes and hypertension, severe obesity was no longer associated with mortality, and milder obesity
(BMI 30-<35) was associated with decreased mortality (adjusted hazard ratio, 0.81; 95% confidence
interval, 0.68–0.97). There was a significant interaction between diabetes (but not hypertension) and
BMI (F [4, 235] ? 2.71; P ? .03), such that the mortality risk of diabetes was lower among mildly and
severely obese persons than among those in lower BMI categories.
Conclusions: Obesity-associated mortality risk was lower than estimated in studies employing older
BMI data. Only severe obesity (but not milder obesity or overweight) was associated with increased
mortality, an association accounted for by coexisting diabetes and hypertension. Mortality in diabetes
was lower among obese versus normal weight individuals. (J Am Board Fam Med 2012;25:422–431.)
Keywords: Body Mass Index, Diabetes Mellitus, Hypertension, Mortality, Obesity
Overweight and obesity have increased dramati-
cally,1with adverse public health implications.
Above-normal body mass index (BMI) is associated
with decreased functional ability and health status2
and increased risk of chronic conditions such as
diabetes and hypertension, which often cause fur-
ther decrements in health.3However, the contem-
porary relationship between BMI and mortality,
and how BMI interacts with diabetes and hyperten-
sion to influence mortality, are unclear.
Studies conducted more than 30 years ago sug-
gested incrementally rising mortality risk with each
increase in BMI category above normal,4prompt-
ing predictions of reduced life expectancy because
of burgeoning obesity.5However, subsequent stud-
ies of BMI data collected 10 to 30 years ago have
found consistently increased mortality risk only
This article was externally peer reviewed.
Submitted 13 October 2011; revised 17 January 2012;
accepted 23 January 2012.
From the Department of Family and Community Medi-
cine, Center for Healthcare Policy and Research, University
of California Davis School of Medicine, Sacramento, CA.
Conflict of interest: none declared.
Corresponding author: Anthony Jerant, MD, Department
of Family and Community Medicine, University of Califor-
nia Davis School of Medicine, 4860 Y Street, Suite 2300,
Sacramento, CA 95817 (E-mail: email@example.com).
July–August 2012Vol. 25 No. 4http://www.jabfm.org
among severely obese persons (BMI ?35 kg/m2),
with mixed findings among overweight (BMI 25.0–
29.9 kg/m2) and more mildly obese (BMI 30.0–
34.9 kg/m2) persons.6–19Collectively, these find-
ings suggest a secular decline in the mortality risk
of those with above-normal BMI.
Secular trends in population obesity suggest the
need for studies employing more recently collected
BMI data.1Examining the current relationships
among obesity, its principal morbidities (hyperten-
sion and diabetes), and mortality would help assess
whether these relationships have changed.20,21Elu-
cidating current relationships among diabetes,
BMI, and mortality is particularly relevant given
the adoption in the 1990s of a lower threshold for
diagnosing diabetes.22Using national data from the
2000 to 2005 Medical Expenditures Panel Surveys
(MEPSs),23linked with the National Death Index
(NDI) through 2006,24this study examined the
association between self-reported BMI and all-
cause mortality among US adults and the degree to
which BMI moderates mortality risk in diabetes
and hypertension during up to 6 years of follow-up.
MEPS is an annual national survey of health care
use and costs in the civilian, noninstitutionalized
population in the United States, employing an
overlapping panel design.23The analytic sample for
the current study included persons aged 18 to 90
years at entry. The study was exempted by the
University of California Davis Institutional Review
The MEPS Household Component (HC) in-
cludes information about respondent sociodemo-
graphics and health insurance. A self-administered
questionnaire includes items about respondent
smoking and health conditions. The full-year re-
sponse rate varied from 70% to 66.5% for the 2000
to 2005 panels we used.23The MEPS HC sample is
a subsample of households included in the previous
year’s National Health Interview Survey (NHIS),
conducted annually by the National Center for
Health Statistics. The NHIS is linked to death
certificate data in the NDI, a central computerized
index of US death record information on file in
states’ vital statistics offices, in turn permitting link-
age to the MEPS.24
BMI (kg/m2) was constructed from self-reported
height and weight. BMI categories employed in
analyses were underweight (?20 kg/m2); normal
weight (20-?25 kg/m2); overweight (25-?30 kg/
m2); obese (30-?35 kg/m2); and severely obese
(?35 kg/m2). These categories correspond to those
widely employed by clinicians, except for the un-
derweight and normal weight categories, which
typically were defined in clinical practice and most
research before 2000 as ?18.5 and 18.5 to ?25
kg/m2, respectively.25A BMI of ?20 kg/m2was
employed to distinguish underweight in the pri-
mary study analyses, on the basis of research indi-
cating that adjusted mortality increases sharply be-
low that level, likely reflecting the effects of
concurrent illnesses.26Thus, classifying individuals
with a BMI of 18.5 to ?20 kg/m2as normal weight
artificially increases the mortality risk associated
with normal weight and decreases the apparent
mortality risk associated with overweight and obe-
Mortality was assessed via the NDI with the
public-use version of the NHIS-linked mortality
files.24Calibration studies indicate that, overall,
98.5% of respondents are classified correctly by
their death date or as alive.24Survival was measured
in quarters from the time of the health measure
self-assessment until the time of death, or they were
considered censored if alive on December 31, 2006.
Health Conditions and Sociodemographics
Self-reported diabetes and hypertension status each
were dichotomized as present or not. Self-reported
smoking status was dichotomized as current smoker
or not. Sociodemographic variables examined were
age (years); sex; race/ethnicity (Hispanic, white, black,
or other; Hispanic ethnicity took categorical prece-
dence over race); US Census region (West, Midwest,
Northeast, South); urbanity (living in a metropol-
itan statistical area or not); education level (0–8
years of formal schooling [less than high school],
9–11 years [some high school], 12 years [high
school graduate], 13 to 15 years [some college],
and ?16 years [college graduate]); household in-
come level (?100%, 100–124%, 125–199%,
200–399%, or ?400% of the Federal Poverty
Level [FPL]); and health insurance status (unin-
sured, privately insured, or publicly insured).
doi: 10.3122/jabfm.2012.04.110289Body Mass Index, Diabetes, Hypertension, and Mortality423
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doi: 10.3122/jabfm.2012.04.110289Body Mass Index, Diabetes, Hypertension, and Mortality 431