The effect of randomization to weight loss on total mortality in older overweight and obese adults: the ADAPT Study

Abstract

Background: Although weight loss reduces risk for comorbid diseases, many observational studies suggest that weight loss is associated with increased mortality risk, leading to reluctance by clinicians to consider weight reduction as a strategy to maintain health and independence in older adults. However, whether the observed weight loss is intentional is difficult to determine and may not accurately represent the mortality risk associated with intentional weight reduction. Data from the Arthritis, Diet, and Activity Promotion Trial (ADAPT) were used to determine whether randomization to a weight reduction program was associated with total mortality in overweight/obese older adults.

Methods: ADAPT (n = 318; mean age 69 +/- 6 years, body mass index 34 +/- 5 kg/m2, 72% female) assessed the influence of weight loss (achieved through dietary counseling and lifestyle modification) and/or exercise on function in overweight/obese older adults with knee osteoarthritis. ADAPT ended in December 1999. Participant vital was ascertained status through December 2006 using the National Death and Social Security Indexes.

Results: The mortality rate for those randomized to the 18-month weight loss intervention (n = 159, mean weight loss = -4.8 kg, 15 deaths) was lower than that for those not randomized to the weight loss intervention (n = 159, mean weight loss = -1.4 kg, 30 deaths; hazard rate ratio = 0.5, 95% confidence interval 0.3-1.0). Results were not appreciably changed when analyses were stratified by age, gender, baseline weight status, or magnitude of weight loss.

Conclusions: In older adults, intentional weight loss was not associated with increased total mortality and may reduce mortality risk. Observational studies of weight loss, especially when intentionality cannot be rigorously established, may be misleading with respect to the effect of weight loss on mortality.

Figure 1.

Participation and death ascertainment in the Arthritis, Diet, and Activity Promotion Trial (ADAPT).

Figure 2.

Unadjusted estimates of survival time among participants in Arthritis, Diet, and Activity Promotion Trial randomized to weight loss or non–weight loss intervention in intention-to-treat analyses.

Figure 3.

Adjusted rates of total mortality among participants in Arthritis, Diet, and Activity Promotion Trial randomized to weight loss or non–weight loss interventions. Asterisk indicates adjusted for age, gender, and exercise treatment, unless stratified on that variable.