Background: pulmonary rehabilitation (PR) improves health status and exercise tolerance, but not respiratory function in patients with chronic obstructive pulmonary disease (COPD). Our objective was to identify predictors of improvement in the 6-min walked distance (6'WD) in elderly COPD patients after PR.

Methods: this was a prospective observational study performed in an ambulatory rehabilitation setting. We enrolled 74 patients aged 65–83 years (mean: 74.2, SD: 4.4) with stable COPD in GOLD stage 3–4. About half (45.6%) of them had a basal O₂ saturation of 90% or less. After a baseline multi-dimensional assessment, patients underwent a 20-session rehabilitation cycle including training of the upper and lower extremities, and respiratory exercises, along with education sessions. The difference between final and basal 6'WD was expressed as a per cent of the basal value (6'WD gain). Patients were divided into two groups according to whether the 6'WD gain was above or under the 75th percentile, corresponding to 33% gain.

Results: patients whose 6'WD improved more had lower baseline forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) (46.0 versus 52.2%, P = 0.03) and baseline 6'WD, both as an absolute value (329.5 versus 408.9 m, P = 0.01) and as a per cent of the predicted (71.1 versus 93.5%, P = 0.002). After correction for potential confounders, baseline 6'WD was the only variable associated with the outcome (OR for 5% increments: 0.79; 95% CI 0.65-0.95).

Conclusions: among elderly patients with COPD, a comprehensive rehabilitation programme can significantly improve the 6'WD even in the presence of chronic hypoxemia. The most physically impaired patients achieve the greatest benefit from rehabilitation, but we could not develop a model accurately predicting the response to rehabilitation.