Vitamin D supplementation during rehabilitation in COPD: a secondary analysis of a randomized trial

Abstract

Rationale: Pulmonary rehabilitation is an important treatment for patients with Chronic Obstructive Pulmonary Disease, who are often vitamin D deficient. As vitamin D status is linked to skeletal muscle function, we aimed to explore if high dose vitamin D supplementation can improve the outcomes of rehabilitation in Chronic Obstructive Pulmonary Disease.

Material and methods: This study is a post-hoc subgroup analysis of a larger randomized trial comparing a monthly dose of 100.000 IU of vitamin D with placebo to reduce exacerbations. 50 Subjects who followed a rehabilitation program during the trial are included in this analysis. We report changes from baseline in muscle strength and exercise performance between both study arms after 3 months of rehabilitation.

Results: Vitamin D intervention resulted in significantly higher median vitamin D levels compared to placebo (51 [44-62] ng/ml vs 15 [13-30] ng/ml; p < 0.001). Patients receiving vitamin D had significantly larger improvements in inspiratory muscle strength (-11±12 cmH2O vs 0±14 cmH2O; p = 0.004) and maximal oxygen uptake (110±211 ml/min vs -20±187 ml/min; p = 0.029). Improvements in quadriceps strength (15±16 Nm) or six minutes walking distance (40±55 meter) were not significantly different from the effects in the placebo group (7±19 Nm and 11±74 meter; p>0.050).

Conclusion: High dose vitamin D supplementation during rehabilitation may have mild additional benefits to training.

Figure 1

Flow chart of the study.

Figure 2

Change in 25-OHD (Serum Vitamin D Level) in the vitamin D group (■) and in the placebo group (□). Data are expressed as mean ± SD. Baseline results are compared with results after 3 months of rehabilitation. Results with p <0.05 are indicated with (*).

Figure 3

Changes in muscle strength (QF = Quadriceps Strength; MIP = Inspiratory Muscle Strength; MEP = Expiratory Muscle Strength) in the vitamin D group (■) and in the placebo group (□). Data are expressed as mean ± SD. Baseline results are compared with results after 3 months of rehabilitation. Results with p <0.05 are indicated with (*).

Figure 4

Changes in exercise performance (6MWD = Six Minutes Walking Distance; VO_2max = Maximal Oxygen Uptake; W_max = Maximal Workload) in the vitamin D group (■) and in the placebo group (□). Data are expressed as mean±SD. Baseline results are compared with results after 3 months of rehabilitation. Results with p <0.05 are indicated with (*).