Abstract
BackgroundVitamin D is considered to be important for a healthy immune system. The aim of this study was to test the hypothesis that vitamin D supplementation reduces number of respiratory tract infections (RTIs) and prolong the time to the first RTI in adult patients with frequent RTIs.MethodsWe performed a post hoc analysis of a randomized, placebo-controlled and double-blinded study, where adult patients with a high burden of RTIs were randomized to placebo or vitamin D (4000 IE/day for 1 year, n = 124 in the per protocol cohort presented here).ResultsVitamin D supplementation increased the probability to stay free of RTI during the study year (RR 0.64, 95 % CI 0.43–0.94). Further, the total number of RTIs was also reduced in the vitamin D-group (86 RTIs) versus placebo (120 RTIs; p = 0.05). Finally, the time to the first RTI was significantly extended in the vitamin D-group (HR 1.68, 95 % CI 1.03–2.68, p = 0.0376).ConclusionVitamin D supplementation was found to significantly increase the probability of staying infection free during the study period. This finding further supports the notion that vitamin D-status should be monitored in adult patients with frequent RTIs and suggests that selected patients with vitamin D deficiency are supplemented. This could be a safe and cheap way to reduce RTIs and improve health in this vulnerable patient population.The original trial was registered at http://www.clinicaltrials.gov (NCT01131858).
Highlights
Vitamin D is considered to be important for a healthy immune system
Numbers of respiratory tract infections during the study First, the total number of respiratory infection (RTI) was analyzed in a dichotomized way, i.e. patients were defined in two groups: having “no RTI” or “one or more RTI”
The total number of RTIs was studied on the group level
Summary
Vitamin D is considered to be important for a healthy immune system. The aim of this study was to test the hypothesis that vitamin D supplementation reduces number of respiratory tract infections (RTIs) and prolong the time to the first RTI in adult patients with frequent RTIs. The protocol did not pre-define how an episode of acute respiratory infection (RTI) would be defined. This clinically relevant information was not reported in the original publication. We wanted to test the hypothesis that vitamin D treated patients had fewer RTIs and had a longer time to their first RTI, compared to placebo treated patients. To this end we carried out a post hoc analysis of our previously performed study [8]
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