Percent weight reduction required to achieve minimal clinically important improvements in health-related quality of life among African Americans: A secondary analysis of the fit body and soul study

Objective To calculate the percent weight reduction required to achieve minimal clinically important improvement (MCII) in health-related quality of life (HRQOL). Design Secondary data analysis from the longitudinal cohort of a single-blinded, cluster-randomized community trial to test the efficacy of the faith-based adaptation of the Diabetes Prevention Program. Setting African-American churches. Participants This study included 472 congregants with a body mass index of ≥ 25 and fasting plasma glucose < 126 mg/dl. Main outcome measure Percent weight reduction required to achieve the MCII in HRQOL measured by two instruments, SF-12 and EQ-5D, one year following baseline. Analysis The percent weight reduction required to achieve established MCII in SF-12 Physical Component Summary (PCS), SF-12 Mental Component Summary (MCS), and EQ-5D Health Status (HS) at one-year follow-up were calculated using fitted linear regression models. In addition to models for the total sample, we generated models, stratified by baseline BMI, PCS, and HS, to calculate the percent weight reduction required to achieve MCII in HRQOL for those most in need of weight reduction and those in need of improved HRQOL. Results The percent weight reduction was a significant predictor of improvement in the SF-12PCS and the EQ-5DHS but not SF-12MCS. To achieve a MCII in SF-12PCS and EQ-5DHS, 18% and 30% weight reductions were required, respectively. A smaller percent weight reduction was required when the baseline BMI was ≥ 40. Conclusions and implications Improvements in HRQOL among African-American congregants seeking weight reduction required more than the 3–5% weight reduction associated with improvements in physical health.