Background: Emerging evidence suggests an association between vitamin D deficiency and low back pain (LBP).
Objective: To pool evidence on the prevalence of hypovitaminosis D in patients with LBP.
Study design: Meta-analysis.
Methods: A comprehensive literature search was done in PubMed, Cochrane Database, and Google scholar for observational studies including cohort, cross sectional (CS), and case control (CC) evaluating the prevalence of hypovitaminosis D in LBP patients. The primary outcome assessed was a prevalence of hypovitaminosis D in patients with LBP, presented as weighted pooled prevalence ratio (WPPR) with 95% confidence interval (CI) using the random effects model. Heterogeneity and inconsistency of the measurements were identified through Cochran's Q statistic and I² statistic. We also performed sensitivity analysis, publication bias (using funnel plot and Begg's test), and subgroup analysis.
Results: Fourteen studies (6 were CC, 6 CS, and 2 cohort) involving 2602 patients were included in the final analysis. The WPPR (95% CI) of hypovitaminosis D in patients with LBP was found to be 0.72 (0.60-0.83). Marked heterogeneity was observed, median quality score of all studies was 7.5 interquartile range (IQR) (6.2 - 8.7) on a scale of 0 to 11. Sensitivity analysis showed robustness of the results. The WPPR of hypovitaminosis D was lower in CS at 0.60 (0.35-0.85) as compared to CC studies at 0.81 (0.72-0.90) (P < 0.01). The WPPR was lower in men at 0.74 (0.63-0.86) as compared to women at 0.84 (0.78-0.89) (P < 0.01). No publication bias was observed.
Limitations: Heterogeneity in the cut off level of vitamin D to classify the included patients as vitamin D deficient.
Conclusions: The high prevalence of hypovitaminosis D was observed in patients with LBP. This provides a chance to screen the deficiency and correct it by supplementation, which can be therapeutic adjunct in the management of LBP patients.
Key words: Low back pain, hypovitaminosis D, meta-analysis, pooled prevalence, systematic review.