A structured review of randomized controlled trials of weight loss showed little improvement in health-related quality of life

Abstract

Objective

To estimate the effect of weight-loss interventions on health-related quality of life (HrQoL) in randomized controlled trials (RCTs); to conduct a meta-analysis of weight-loss treatment on depressive symptoms; and, to examine methodological and presentation issues that compromise study validity.

Study Design and Setting

We conducted a structured review of 34 RCTs with weight-loss interventions that reported the relationship between HrQoL and treatment at two or more time points. We also evaluated study quality.

Results

Trials lasted 6 weeks to 208 weeks and evaluated behavioral, surgical, or pharmacologic interventions. Nine of 34 trials showed HrQoL improvements in generic measures. Obesity-specific measures were more likely to show improvement in response to treatment than non-obesity-specific measures. Meta-analysis showed no treatment effect on depressive symptoms. Most trials tracked loss to follow-up and conducted intent-to-treat analysis, but only four trials concealed recruitment staff to randomization and 14 blinded the investigation team to randomization.

Conclusion

HrQoL outcomes, including depression, were not consistently improved in RCTs of weight loss. The overall quality of these clinical trials was poor. Better-designed RCTs using standardized HrQoL measures are needed to determine the extent to which weight loss improves HrQoL.

Introduction

With the increasing prevalence of obesity in the United States since the 1980s [1], [2], [3], a variety of treatments have been evaluated to determine whether patients can lose weight in the short term and maintain that weight loss over the long term [4]. Treatments have been based on clinical interventions or behavioral changes in diet and exercise aimed at reducing caloric intake, changing nutritional content, and/or increasing exercise frequency [5], [6]. Clinical interventions include gastric bypass, stapling surgeries, and pharmaceuticals (weight-loss drugs with varying mechanisms) [7]. Recently, the U.S. Preventive Services Task Force recommended that obese adults should be offered “intensive counseling and behavioral interventions to promote sustained weight loss” [8]. There is evidence that weight-loss interventions reduce blood pressure, blood glucose, or cholesterol [8], [9], intermediate outcomes that may result in long-term benefits.

More recently, studies have considered the effects of obesity treatment on patient-reported outcomes, including health-related quality of life (HrQoL). Self-reported outcomes, referred to as patient-reported outcomes in the context of health care, include any report coming directly from affected persons concerning their life, health conditions, and treatment [10]. Although health outcomes are equated with improvements in health-related quality of life, HrQoL is a distinct set of concepts related to a patient's perception of physical, psychological, and social functioning; well-being; and signs, symptoms, and perceptions such as stigma and coping [9], [11]. The specific HrQoL concepts that relate to obesity and weight loss are not clearly defined, although several aspects of patients' lives are relevant to obesity and weight loss [12], [13].

The most commonly assessed HrQoL outcomes in obesity studies are social function, depressive symptoms, mobility, pain, and perceived health status [13]. Obesity treatment studies that have included HrQoL assessments typically examined the effect of treatment on weight loss as a primary outcome and HrQoL assessments as secondary outcomes. HrQoL outcomes have also been measured in other studies to assess the impact of being obese and the impact of trying to lose weight (see Kushner and Foster [12] and Fontaine and Barofsky [13] for reviews).

Here we examine whether weight-loss treatments have improved HrQoL outcomes in randomized controlled trials (RCTs) including behavioral, surgical, or pharmacologic interventions. We also present a meta-analysis of the effect of weight-loss treatment on depressive symptoms. Finally, we address study quality and methodological and presentation issues that compromise study validity.