All ETDs from UAB

Advisory Committee Chair

Kevin R Fontaine

Advisory Committee Members

Tapan Mehta

Kirsten Ness

Jeewon Cheong

Andrea Cherrington

Document Type

Dissertation

Date of Award

2015

Degree Name by School

Doctor of Philosophy (PhD) School of Public Health

Abstract

Previous epidemiological studies observed the lack of an association between increased body mass index (BMI: kg/m2) and all-cause mortality in US-residing Hispanic adults. The purpose of this dissertation was to examine the validity of three hypothesized explanations for the absence of significant associations. Using data on Hispanic participants from the National Health and Nutrition Examination Survey (NHANES) [1988-1994 and 1999-2004] and the National Health Interview Survey (NHIS), this dissertation examined whether: (1) BMI was associated with cause-specific mortality; (2) measures of body composition was associated with all-cause mortality; and (3) the BMI-all-cause mortality association differed as a function of Hispanic ancestry subgroup. For the first paper, using NHANES data, hazard ratios were calculated for specific causes of death (e.g., cardiovascular, cancer, diabetes and other). For the second paper, also using NHANES data, proportional hazard models were fitted using seven different measures of body composition. For the third paper, using NHIS data, proportional hazards regression was used to examine the association between BMI, Hispanic ancestry subgroup and all-cause mortality and whether the association varied by subgroup. Statistical models were adjusted for age, gender and smoking status. In the first paper, BMI ≥ 35 kg/m2 associated significantly with diabetes-related mortality but only in the NHANES 1999-2004 data. In the second paper, waist circumference and waist-to-height ratio (in NHANES 1999-2004 only) associated significantly with all-cause mortality. In the third paper, when controlling for Hispanic subgroup, only BMI ≥ 35 kg/m2 associated with an increased risk of death. Stratified by subgroup, those classified as ‘Other Hispanic’ who had BMI’s ≥ 35 kg/m2 were at an increased risk of death. No other subgroup demonstrated significant elevated BMI-mortality associations. This dissertation did not find strong evidence supporting the three hypothesized explanations for the absence of obesity-mortality associations among US-residing Hispanic adults. Overall, the results of this dissertation provide support for the Hispanic paradox, an epidemiological finding where Hispanics exhibit lower mortality rates despite higher prevalence of chronic illness and lower socio-economic status. Examining genetic factors and factors such as acculturation or cultural differences in health behaviors may help to explain these results and warrant future investigation.

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