Abstract P320: All-cause Mortality in Hypertensive Normal Weight Adults
Introduction: Large observational studies have generally observed that obese hypertensive adults are at similar risk of mortality relative to non-obese hypertensive adults. These null findings may be confounded by duration of hypertension. As such, we estimated the risk of all-cause mortality following incident hypertension in obese, overweight, and normal weight persons to adjust for such confounding.
Methods: Our inception cohort (n=7142) comprised participants free from cardiovascular disease to the time of incident hypertension during follow-up in five cohort studies: Atherosclerosis Risk in Communities (ARIC), Cardiovascular Health Study (CHS), Coronary Artery Risk Development in Young Adults (CARDIA), Multi-Ethnic Study of Atherosclerosis (MESA), and Framingham Offspring Study (FOS), where follow-up ranged from 7yrs (MESA) to 28yrs (FOS). Hypertension was defined as BP>140/90 or antihypertensive medication use at a single examination and diagnosis by physician. Normal weight comprised BMI<25 kg/m2. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95%CI) for mortality in normal weight and overweight persons vs. obese (referent), adjusting for age, race, sex, diabetes status, smoking status, and the ratio of total cholesterol to HDL-cholesterol at the time of incident hypertension.
Results: In our sample of newly-identified hypertensive persons, the proportion of normal weight ranged from 18% (CARDIA) to 40% (CHS). The pooled all-cause mortality rates per 1000 person-years among those obese, overweight, and normal weight were 9.8, 12.1, and 16.4, respectively. The unadjusted HR(95%CI) comparing normal weight persons to obese was 1.2 (1.1, 1.5); further adjustment for age, diabetes status, smoking status, waist circumference, triglycerides and HDL-cholesterol strengthened the association, HR(95%CI )= 1.3 (1.1, 1.6). All-cause mortality risk in overweight and obese participants did not differ in minimally or fully adjusted models. Patterns were similar across individual cohorts.
Conclusion: The risk of all-cause mortality in hypertensive normal weight persons was higher relative to hypertensive overweight or obese persons, suggesting differences in the pathophysiology between normal weight and obese. However, unmeasured or residual confounding, such as comorbidities prior to incident hypertension, may also explain these findings.
- © 2013 by American Heart Association, Inc.