PURPOSE: Vitamin D deficiency is common in patients with chronic obstructive pulmonary disease; however, no study has evaluated the influence of vitamin D status on effects of pulmonary rehabilitation (PR).

METHODS: We studied 311 patients, who participated in a 7-week outpatient PR. Vitamin D status was assessed at entry and examined for association with patient characteristics, dropout from PR, and effect on endurance shuttle walk time.

RESULTS: Vitamin D level 25 nM was seen in 61 (19.6%) of the patients. They were significantly younger, were more frequently on long-term oxygen therapy, had higher body mass index and fat-free mass index, had worse quality of life score, tended to have lower percent predicted value for forced expiratory volume in the first second of expiration, and more frequently were current smokers. They had a 3-time higher risk of dropout from the PR program (P = .003) compared with patients with normal vitamin D status and a poorer improvement in endurance shuttle walk time (P = .03).

DISCUSSION: In conclusion, vitamin D deficiency was significantly associated with higher dropout rates from PR, and there was a tendency toward a poorer improvement in endurance shuttle walk time.