Race and sex differences in dropout from the STRRIDE trials

Purpose: To determine if race and sex differences exist in determinants and timing of dropout among individuals enrolled in an exercise and/or caloric restriction intervention. Methods: A total of 947 adults with dyslipidemia (STRRIDE I, STRRIDE AT/RT) or prediabetes (STRRIDE-PD) were randomized to either inactive control or to 1 of 10 exercise interventions, ranging from doses of 8–23 kcal/kg/week, intensities of 50%–75% (Formula presented.) peak, and durations of 6–8 months. Two groups included resistance training, and one included a dietary intervention (7% weight loss goal). Dropout was defined as an individual withdrawn from the study, with the reasons for dropout aggregated into determinant categories. Timing of dropout was defined as the last session attended and aggregated into phases (i.e., “ramp” period to allow gradual adaptation to exercise prescription). Utilizing descriptive statistics, percentages were generated according to categories of determinants and timing of dropout to describe the proportion of individuals who fell within each category. Results: Black men and women were more likely to be lost to follow-up (Black men: 31.3% and Black women: 19.6%), or dropout due to work responsibilities (15.6% and 12.5%), “change of mind” (12.5% and 8.9%), transportation issues (6.3% and 3.6%), or reported lack of motivation (6.3% and 3.6%). Women in general noted lack of time more often than men as a reason for dropout (White women: 22.4% and Black women: 22.1%). Regardless of race and sex, most participants dropped out during the ramp period of the exercise intervention; with Black women (50%) and White men (37.1%) having the highest dropout rate during this period. Conclusion: These findings emphasize the importance of targeted retention strategies when aiming to address race and sex differences that exist in determinants and timing of dropout among individuals enrolled in an exercise and/or caloric restriction intervention

Population differences in associations of serotonin transporter promoter polymorphism (5HTTLPR) di- and triallelic genotypes with blood pressure and hypertension prevalence

Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular reactivity to laboratory stressors and increased risk of myocardial infarction, we hypothesized that the 5HTTLPR L allele will be associated with increased blood pressure (BP) and increased hypertension prevalence in 2 large nationally representative samples in the United States and Singapore. Methods Logistic regression and linear models tested associations between triallelic (L′S′, based on rs25531) 5HTTLPR genotypes and hypertension severity and mean systolic and diastolic blood pressure (SBP and DBP) collected during the Wave IV survey of the National Longitudinal Study of Adolescent to Adult Health (Add Health, N = 11,815) in 2008–09 and during 2004–07 in 4196 Singaporeans. Results In US Whites, L′ allele carriers had higher SBP (0.9 mm Hg, 95% CI = 0.26-1.56) and greater odds (OR = 1.23, 95% CI = 1.10-1.38) of more severe hypertension than those with S′S′ genotypes. In African Americans, L′ carriers had lower mean SBP (−1.27 mm Hg, 95% CI = −2.53 to −0.01) and lower odds (OR = 0.78, 95% CI = 0.65-0.94) of more severe hypertension than those with the S′S′ genotype. In African Americans, those with L′L′ genotypes had lower DBP (−1.13 mm Hg, 95% CI = −2.09 to −0.16) than S′ carriers. In Native Americans, L′ carriers had lower SBP (−6.05 mm Hg, 95% CI = −9.59 to −2.51) and lower odds of hypertension (OR = 0.34, 95% CI = 0.13-0.89) than those with the S′S′ genotype. In Asian/Pacific Islanders those carrying the L′ allele had lower DBP (−1.77 mm Hg, 95% CI = −3.16 to −0.38) and lower odds of hypertension (OR = 0.68, 95% CI = 0.48-0.96) than those with S′S′. In the Singapore sample S′ carriers had higher SBP (3.02 mm Hg, 95% CI = 0.54-5.51) and DBP (1.90 mm Hg, 95% CI = 0.49-3.31) than those with the L′L′ genotype. Conclusions These findings suggest that Whites carrying the L′ allele, African Americans and Native Americans with the S′S′ genotype, and Asians carrying the S′ allele will be found to be at higher risk of developing cardiovascular disease and may benefit from preventive measures