Eighteen RCTs (800 patients) were included in the review.
Most of the included trials were judged to be of poor methodological quality, with concealment of random allocation or blinding not addressed in the majority of the included studies.
Supplemental oxygen during exercise (5 studies) tended to show larger improvements in HRQL and exercise duration in constant work rate tests, however, larger improvements in walking distance were observed in patients exercising on room air. There was no difference in the resting mean pulmonary artery pressure between groups (1 study).
Proportional assisted ventilation (2 studies) and noninvasive positive pressure ventilation with Heliox (1 study) during exercise did not significantly increase exercise duration and intensity. Overnight noninvasive positive pressure ventilation at home was associated with a statistically significant improvement of 72 m (95% CI: 13, 131) in walking distance (1 study).
Nutritional supplements (2 studies) did not carry any apparent benefit in terms of HRQL and exercise capacity.
In terms of anabolic steroids, the use of nandrolone (1 study) was associated with improvements in HRQL and maximum leg capacity in comparison with patients not receiving the steroid. Isometric leg strength and isokinetic legwork improved in both groups similarly. No changes in blood-pressure or androgenic side- effects were observed.
The use of testosterone (1 study) did not significantly improve exercise capacity and muscle strength among male patients with COPD and low testosterone levels. No adverse events were reported.
Tiotropium (1 study) was associated with a significant increase in exercise endurance time compared with placebo, with no adverse effects. Creatine (1 study), coenzyme Q10 (1 study) and growth hormone (2 studies) carried no additional benefit.