Peak expiratory flow rate shows a gender-specific association with vitamin D deficiency.

Abstract

To our knowledge, no previous studies examined the longitudinal relationship between vitamin D status and pulmonary function in a population-based sample of older persons. Our objective was to examine the cross-sectional as well as the longitudinal relationship between vitamin D status and peak expiratory flow rate (PEFR) in a representative sample of the Dutch older population. Participants included men and women in the Longitudinal Aging Study Amsterdam, an ongoing cohort study in older people. PEFR was measured using the mini-Wright peak flow meter. Men with serum 25-hydroxyvitamin D (25-OHD) levels below 10 ng/ml (25 nmol/liter) had a significantly lower PEFR in the cross-sectional analyses, and men with serum 25-OHD levels below 20 ng/ml (50 nmol/liter) had a significantly lower PEFR in the longitudinal analyses as compared with men with serum 25-OHD levels above 30 ng/ml (75 nmol/liter) (cross-sectional: β = -47.0, P = 0.01 for serum 25-OHD <10 ng/ml; longitudinal: β = -45.0, P < 0.01 for serum 25-OHD <10 ng/ml; and β = -20.2, P = 0.03 for serum 25-OHD = 10-20 ng/ml in the fully adjusted models). Physical performance (β = -32.5, P = 0.08 for serum 25-OHD <10 ng/ml) and grip strength (β = -40.0, P = 0.03 for serum 25-OHD <10 ng/ml) partly mediated the cross-sectional associations but not the longitudinal associations. In women, statistically significant associations between 25-OHD and PEFR were observed in the cross-sectional analyses after adjustment for age and season of blood collection but not in the fully adjusted models or in the longitudinal analyses. A strong relationship between serum 25-OHD and PEFR was observed in older men, both in the cross-sectional as well as longitudinal analyses, but not in older women. The association in men could partly be explained by physical performance and muscle strength.