Research Paper

Monthly vitamin D supplementation, pain, and pattern of analgesic prescription: secondary analysis from the randomized, double-blind, placebo-controlled Vitamin D Assessment study

Wu, Zhenqiang^a; Camargo, Carlos A. Jr^b; Malihi, Zarintaj^a; Bartley, Jim^c; Waayer, Debbie^a; Lawes, Carlene M.M.^a; Toop, Les^d; Khaw, Kay-Tee^e; Scragg, Robert^a,*

Author Information

^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: [email protected] (R. Scragg).

Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.

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PAIN 159(6):p 1074-1082, June 2018. | DOI: 10.1097/j.pain.0000000000001189

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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.