Observational studies suggest that vitamin D deficiency is associated with higher risk of pain. However, evidence on the effect of vitamin D supplementation on pain is limited and contradictory. The aim of this study was to compare the effect of monthly high-dose vitamin D supplementation on a pain impact questionnaire (PIQ-6) score and prescription of analgesics in the general population. We performed a randomized, double-blind, placebo-controlled trial of 5108 community-dwelling participants, aged 50 to 84 years, who were randomly assigned to receive monthly 100,000-IU capsules of vitamin D3 (n = 2558) or placebo (n = 2550) for a median of 3.3 years. The PIQ-6 was administered at baseline, year 1, and final follow-up. Analgesic prescription data were collected from Ministry of Health. There was no difference in mean PIQ-6 score at the end of follow-up (adjusted mean difference: 0.06; P = 0.82) between the vitamin D (n = 2041) and placebo (n = 2014) participants. The proportion of participants dispensed one or more opioids was similar in the vitamin D group (n = 559, 21.9%) compared with placebo (n = 593, 23.3%); the relative risk (RR) adjusted for age, sex, and ethnicity was 0.94 (P = 0.24). Similar results were observed for dispensing of nonsteroidal anti-inflammatory drugs (RR = 0.94; P = 0.24) and other nonopioids (RR = 0.98; P = 0.34). Focusing on vitamin D deficient participants (<50 nmol/L, 24.9%), there was a lower risk of dispensing nonsteroidal anti-inflammatory drugs in the vitamin D group compared with placebo (RR = 0.87; P = 0.009); all other subgroup analyses were not significant. Long-term monthly high-dose vitamin D supplementation did not improve mean PIQ-6 score or reduce analgesic dispensing in the general population.
Long-term monthly high-dose vitamin D supplementation did not improve mean questionnaire pain score or reduce analgesic dispensing in the general population.
aDepartment of Epidemiology and Biostatistics, School of Population Health, University of Auckland, Auckland, New Zealand
bDepartment of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
cDepartment of Surgery, University of Auckland, Auckland, New Zealand
dDepartment of Public Health and General Practice, The University of Otago, Christchurch, New Zealand
eDepartment of Public Health, University of Cambridge, Cambridge, United Kingdom
Corresponding author. Address: School of Population Health, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Tel.: +64-9-3737 599; fax: +64-9-3737 503. E-mail address: firstname.lastname@example.org (R. Scragg).
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Received November 24, 2017
Received in revised form February 08, 2018
Accepted February 14, 2018