Usefulness of extreme body weight and weight loss in predicting follow-up mortality risk of older Taiwanese

[[abstract]]Background--Extreme body weight or extreme weight change poses health thread. Studies conducted in Western countries have shown that underweight or extreme body weight increases risk of mortality whereas overweight may impact functional ability but does not increase mortality risk in older adults. These issues have not been robustly examined in Taiwanese. Objective--The objective of this study, therefore, is to examine the impact of extreme body weight and weight changes on mortality risk in elderly Taiwanese. Methods--This study analyzed the 1999 and 2003 data of the “Survey of Health and Living Status of the Elderly in Taiwan” (SHLSET), a cohort study initiated in 1989 with a multi-stage national probability sample of 4049 non-institutionalized Taiwanese 60 years of age or older. The 1999 weight status (BMI status derived from self-reported weight and height) and weight change of each subject were used to predict follow-up four-year mortality risk. Results were analyzed with Cox regression adjusted for age, gender and smoking statuses. Results--Compared to elderly with desirable weight (BMI=21-27 kg/m2), elderly underweight (BMI≤21) had increased risk of mortality regardless of age. Elderly over-weight or obese (BMI≥27) were not different from those had desirable BMI. Severe weight reduction (≥3kg) significantly increased mortality risk in all age ranges and in those who had lighter weight. Weight loss of 3 kg or more had less impact in overweight/obese males. Conclusion--Underweight or severe weight loss predicts increased follow-up 4-year mortality risk in older Taiwanese whereas overweight/obese does not increase mortality risk. These results suggest that we need to reexamine our current policy of encouraging weight reduction in over-weight/obese elderly