Immediate and long term effects of weight reduction in obese people with asthma: randomised controlled study

Abstract

Objective: To investigate the influence of weight reduction on obese patients with asthma. Design: Open study, two randomised parallel groups. Setting: Private outpatients centre, Helsinki, Finland. Participants: Two groups of 19 obese patients with asthma (body mass index (kg/m²) 30 to 42) recruited through newspaper advertisements. Intervention: Supervised weight reduction programme including 8 week very low energy diet. Main outcome measures: Body weight, morning peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁); and also asthma symptoms, number of acute episodes, courses of oral steroids, health status (quality of life). Results: At the end of the weight reducing programme, the participants in the treatment group had lost a mean of 14.5% of their pretreatment weight, the controls 0.3%. The corresponding figures after one year were 11.3% and a weight gain of 2.2%. After the 8 week dieting period the difference in changes in percentage of predicted FEV₁ from baseline in the treatment and control groups was 7.2% (95% confidence interval 1.9% to 12.5%, P=0.009). The corresponding difference in the changes in FVC was 8.6% (4.8% to 12.5%, P1 (1.5% to 13.8%, P=0.02) and 7.6% for FVC (3.5% to 11.8%, P=0.001). By the end of the weight reduction programme, reduction in dyspnoea was 13 mm (on a visual analogue scale 0 mm to 100 mm) in the treatment group and 1 mm in the control group (P=0.02). The reduction of rescue medication was 1.2 and 0.1 doses respectively (P=0.03). After one year the differences in the changes between the two groups were −12 for symptom scores (range −1 to −22, P=0.04) and −10 for total scores (−18 to −1, P=0.02). The median number of exacerbations in the treatment group was 1 (0–4) and in the controls 4 (0–7), P=0.001. Conclusion: Weight reduction in obese patients with asthma improves lung function, symptoms, morbidity, and health status.