Weight loss required by the severely obese to achieve clinically important differences in health-related quality of life: two-year prospective cohort study.

Lindsey M Warkentin,Daniel W Birch,Scott W Klarenbach,Calypse B Agborsangaya,Raj S Padwal,Christian F Rueda-Clausen,Jeffrey A Johnson,Sumit R Majumdar,Shahzeer Karmali,Arya M Sharma

doi:10.1186/s12916-014-0175-5

Lindsey M Warkentin, Daniel W Birch + Show 8 more

Open Access

https://doi.org/10.1186/s12916-014-0175-5

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Abstract

BackgroundGuidelines and experts describe 5% to 10% reductions in body weight as ‘clinically important’; however, it is not clear if 5% to 10% weight reductions correspond to clinically important improvements in health-related quality of life (HRQL). Our objective was to calculate the amount of weight loss required to attain established minimal clinically important differences (MCIDs) in HRQL, measured using three validated instruments.MethodsData from the Alberta Population-based Prospective Evaluation of Quality of Life Outcomes and Economic Impact of Bariatric Surgery (APPLES) study, a population-based, prospective Canadian cohort including 150 wait-listed, 200 medically managed and 150 surgically treated patients were examined. Two-year changes in weight and HRQL measures (Short-Form (SF)-12 physical (PCS; MCID = 5) and mental (MCS; MCID = 5) component summary score, EQ-5D Index (MCID = 0.03) and Visual Analog Scale (VAS; MCID = 10), Impact of Weight on Quality of Life (IWQOL)-Lite total score (MCID = 12)) were calculated. Separate multivariable linear regression models were constructed within medically and surgically treated patients to determine if weight changes achieved HRQL MCIDs. Pooled analysis in all 500 patients was performed to estimate the weight reductions required to achieve the pre-defined MCID for each HRQL instrument.ResultsMean age was 43.7 (SD 9.6) years, 88% were women, 92% were white, and mean initial body mass index was 47.9 (SD 8.1) kg/m2. In surgically treated patients (two-year weight loss = 16%), HRQL MCIDs were reached for all instruments except the SF-12 MCS. In medically managed patients (two-year weight loss = 3%), MCIDs were attained in the EQ-index but not the other instruments. In all patients, percent weight reductions to achieve MCIDs were: 23% (95% confidence interval (CI): 17.5, 32.5) for PCS, 25% (17.5, 40.2) for MCS, 9% (6.2, 15.0) for EQ-Index, 23% (17.3, 36.1) for EQ-VAS, and 17% (14.1, 20.4) for IWQOL-Lite total score.ConclusionsWeight reductions to achieve MCIDs for most HRQL instruments are markedly higher than the conventional threshold of 5% to 10%. Surgical, but not medical treatment, consistently led to clinically important improvements in HRQL over two years.Trial registrationClinicaltrials.gov NCT00850356.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-014-0175-5) contains supplementary material, which is available to authorized users.

Highlights

Guidelines and experts describe 5% to 10% reductions in body weight as ‘clinically important’; it is not clear if 5% to 10% weight reductions correspond to clinically important improvements in health-related quality of life (HRQL)
Many studies have examined HRQL changes following weight loss [9,10], to our knowledge, none have attempted to calculate the amount of weight loss required to achieve minimal clinically important differences (MCIDs) in HRQL or verify that 5% to 10% weight reductions result in clinically important HRQL improvements
Weight loss thresholds to achieve minimal important differences in HRQL Weight losses required to achieve the HRQL MCIDs for each instrument (Table 3) were 23%

Summary

Introduction

Guidelines and experts describe 5% to 10% reductions in body weight as ‘clinically important’; it is not clear if 5% to 10% weight reductions correspond to clinically important improvements in health-related quality of life (HRQL). Our objective was to calculate the amount of weight loss required to attain established minimal clinically important differences (MCIDs) in HRQL, measured using three validated instruments. Empirically determining the weight reduction thresholds corresponding to these MCIDs is needed. These instrument-specific weight loss thresholds could be used to assess whether new or existing treatments are producing clinically important HRQL improvements

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