Seventy-two patients (38%) died during the follow-up period. Survival tended to be better in the overweight⁄obese patients but this difference did not reach statistical significance. Overweight⁄obese patients had better lung function and a larger MTCSACT than those with normal BMI (P<0.001). Overweight⁄obese patients also had a significantly higher peak work rate than patients with normal BMI (P<0.001). PaO2 and PaCO2 were not significantly different in the two groups