Vitamin D Supplementation Boosts COPD Rehabilitation

Nancy A. Melville

May 27, 2011

May 27, 2011 (Denver, Colorado) — Patients with chronic obstructive pulmonary disease (COPD) who received high doses of vitamin D supplementation during rehabilitation show significant improvements in respiratory muscle strength and exercise capacity, according to research presented here at the American Thoracic Society 2011 International Conference.

The study was also published in the May issue of the American Journal of Respiratory and Critical Care Medicine.

The improvement in respiratory muscle weakness is a key focus of respiratory rehabilitation for COPD patients, and because low circulating vitamin D levels are commonly associated with muscle weakness, researchers in Belgium theorized that vitamin D supplementation would help with COPD rehabilitation.

"Since muscle weakness, the major target for respiratory rehabilitation, is a common phenomenon in COPD, we explored the additional effect of vitamin D supplementation on rehabilitation," said Miek Hornikx, physiotherapist and doctoral student in the Department of Pneumology at the Katholieke Universiteit Leuven, in Belgium.

For the study, 50 COPD patients with a history of exacerbations who were referred for rehabilitation were randomly assigned to receive either a monthly dose of 100,000 IU of vitamin D or placebo.

All subjects participated in a 3-month pulmonary rehabilitation program. At the end of the program, vitamin D levels in the treatment group had increased significantly, compared with the placebo group — from 22.8 ± 15.3 ng/mL at baseline to 53.8 ± 15.6 ng/mL at 3 months.

Patients receiving vitamin D had significant improvements in nearly all measures of COPD. Compared with patients in the placebo group, those receiving vitamin D showed a larger improvement in maximal oxygen consumption (+0.11 ± 0.21 vs –0.02 ± 0.19 L/min; = .029).

The vitamin D group also showed improvements in maximal workload (P = .060); 6-minute walking distance (36 ± 55 vs 11 ± 74 m; P = .179); quadriceps force (15 ± 16 vs 6.8 ± 19 Nm; P = .121); inspiratory muscle force (–11 ± 12 vs 0 ± 14 cm H2O; P = .06), expiratory muscle force (P = .376); and Chronic Respiratory Disease Questionnaire score for dyspnea (P = .337).

A small increase in forced expiratory volume in 1 s was similar in both groups (4.70% ± 17.1% vs 2.61 ± 23.8%; P = .727).

The findings offer promising evidence that a nonpharmaceutical therapy might help to improve outcomes in pulmonary rehabilitation, noted Richard Casaburi, PhD, MD, director of Clinical Respiratory Physiology Laboratories at Harbor–University of California at Los Angeles (UCLA) Medical Center, in Torrance, California.

"We have been seeking pharmacologic options to boost the effectiveness of pulmonary rehabilitation for some time," said Dr. Casaburi, who is also associate chief for research and professor of medicine in Harbor–UCLA Medical Center's division of respiratory and critical care physiology and medicine.

"So far, no drugs have been shown to amplify the effects of rehabilitation on exercise endurance," he said. "The trends shown here indicate that vitamin D supplementation is worth pursuing in this context."

"Although the results are encouraging, the largely nonstatistically significant trends cannot be considered definitive. A larger, adequately powered study would be of great interest," Dr. Casaburi noted.

Mr. Hornikx and Dr. Casaburi have disclosed no relevant financial relationships.

American Thoracic Society (ATS) 2011 International Conference: Abstract A2533. Presented May 16, 2011.

Am J Respir Crit Care Med. 2011;183:A2533.

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