The effect of low vitamin D on chronic non-specific low back pain: A systematic review

Objectives: Vitamin D deficiency and non-specific chronic low back pain (NSCLBP) are both highly prevalent conditions that not only affect the individual but the associated absenteeism also impacts the economy. There are a number of theories that support the notion that that low vitamin D may cause back pain. The aims of this review were to (i) determine what clinical evidence exists to demonstrate an association between low vitamin D and chronic non-specific low back; (ii) evaluate the quality and strength of the evidence; (iii) identify areas for future research emerging from the evidence base. Methods: The design of the study was a systematic review where MEDLINE^®, sportDISCUS™, EMBASE, and ISI Web of Knowledge databases were searched for studies from inception to February 2016. In addition ‘grey literature’ was searched in Google and Google Scholar. The search was restricted to experimental and observational studies; those published in English; human studies that examined vitamin D and its association with NSCLBP. Study quality was evaluated using the modified Downs & Black (D&B) assessment tool. The level of evidence of each study was assessed using the Oxford Centre for Evidence-based Medicine (OCEBM) levels of evidence tool. Results: One thousand and twelve citations were identified, of which only seven matched the inclusion criteria. Of these, one was a double-blinded randomized controlled trial, two case–control studies, two cross-sectional studies, one case series, and one quasi-experimental (uncontrolled before and after study). The mean modified D&B score was 13/27 (48%) and mean OCEBM score was 3. Five of the seven studies in the review suggested an association between low vitamin D and NSCLBP. Discussion: The existing evidence to show a relationship between low vitamin D and NSCLBP is moderate and so further research is required to prove a definitive association.