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

ObjectiveTo investigate the influence of weight reduction on obese patients with asthma.DesignOpen study, two randomised parallel groups.SettingPrivate outpatients centre, Helsinki, Finland.ParticipantsTwo groups of 19 obese patients with asthma (body mass index (kg/m²) 30 to 42) recruited through newspaper advertisements.InterventionSupervised weight reduction programme including 8 week very low energy diet.ResultsAt 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%, P<0.0001). After one year the differences in the changes in the two groups were still significant: 7.6% for FEV₁ (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.ConclusionWeight reduction in obese patients with asthma improves lung function, symptoms, morbidity, and health status.