One-year health-related quality of life outcomes in weight loss trial participants: comparison of three measures
1 Obesity and Quality of Life Consulting, 762 Ninth Street #563, Durham, North Carolina 27705, USA
2 Department of Community and Family Medicine, Duke University Medical Center, 318 Hanes House, Box 2914, Durham, North Carolina 27710, USA
3 Merck Research Laboratories, UG1D-60, PO Box 1000, North Wales, Pennsylvannia 19454, USA
4 Neuropsychiatric Research Institute, 120 Eighth Street South, PO Box 1415, Fargo, North Dakota 58107, USA
5 University of North Dakota School of Medicine and Health Sciences, 1919 Elm Street North, Room 118, Fargo, North Dakota 58102, USA
6 Merck Research Laboratories, 126 E Lincoln Avenue, Rahway, New Jersey 07065, USA
7 Faculdade de Motricidade Humana, Estrada da Costa, 1495-688 Cruz Quebrada, Portugal
Health and Quality of Life Outcomes 2009, 7:53 doi:10.1186/1477-7525-7-53Published: 9 June 2009
The literature on changes in health-related quality of life (HRQOL) in weight loss studies is inconsistent, and few studies use more than one type of measure. The purpose of the current study was to compare one-year changes in HRQOL as a function of weight change using three different measures: a weight-related measure (Impact of Weight on Quality of Life-Lite [IWQOL-Lite)]) and two generic measures (SF-36; EQ-5D).
Data were obtained from 926 participants (mean Body Mass Index (BMI) (kg/m2) = 35.4; 84% female; mean age = 49.5 years) in a placebo-controlled randomized trial for weight loss. At baseline and one-year, participants completed all three HRQOL measures. HRQOL was compared across weight change categories (≥ 5% and 0–4.9% gain, 0–4.9%, 5.0–9.9% and ≥ 10% loss), using effect sizes.
The weight-related measure of HRQOL exhibited greater improvements with one-year weight loss than either of the generic instruments, with effect sizes ranging from 0.24 to 0.62 for 5–9.9% weight reductions and 0.44 to 0.95 for ≥ 10% reductions. IWQOL-Lite Self-Esteem also showed a small improvement with weight gain. Changes in the two generic measures of HRQOL were inconsistent with each other, and in the case of the SF-36, variable across domains. For participants gaining ≥ 5% of weight, the greatest reductions in HRQOL occurred with respect to SF-36 Mental Health, MCS, and Vitality, with effect sizes of -0.82, -0.70, and -0.63 respectively.
This study found differences between weight-related and generic measures of health-related quality of life in a one-year weight loss trial, reflecting the potential value of using more than one measure in a trial. Although weight loss was generally associated with improved IWQOL-Lite, physical SF-36 subscale and EQ-5D scores, a small amount of weight gain was associated with a slight improvement on weight-specific HRQOL and almost no change on the EQ-5D, suggesting the need for further research to more fully study these relationships. We believe our findings have relevance for weight loss patients and obesity clinicians/researchers in informing them of likely HRQOL outcomes associated with varying amounts of weight loss or gain.