Prevalence of vitamin D deficiency in chronic and subacute low back pain patients in India: a triple-arm controlled study.

Vitamin D is vital for musculoskeletal health and may be associated with subacute and chronic low back pain. The objective of this study was to estimate the prevalence of vitamin D deficiency among chronic low back pain (CLBP) and subacute low back pain (SLBP), and compare the same with healthy controls. This study was designed as triple-arm case-control study comprising of CLBP, SLBP, and controls. SLBP and CLBP cases were consecutively enrolled over 3 months of winter season from November 2016 to January 2017. Serum 25- (OH) vitamin D was estimated for the study subjects and categorical comparison of severity of vitamin D deficiency was done for the cases and controls. A total of 250 CLBP, 177 SLBP cases, and 248 controls were included in the study. Mean (± SD) serum vitamin D levels among CLBP, SLBP, and controls were 20.36 (± 12.56), 21.42 (± 13.20), and 20.84 (± 6.93) ng/ml respectively, the difference being statistically insignificant. There was no significant difference in the prevalence of vitamin D deficiency among CLBP, SLBP, and controls which was 53.6, 50.8, and 51.6% respectively, in the three arms. However, the categorical analysis revealed that CLBP and SLBP cases had a significantly higher prevalence of worse categories of vitamin D deficiency. Cases had significantly larger frequency (CLBP vs. controls, 43.6 vs 20.1%, P<0.001; SLBP vs. controls, 43.5 vs 20.1%, P = 0.001) of individuals with vitamin D levels ≤ 16 ng/ml (moderate deficiency upper threshold level). Thus, the severe forms of vitamin D deficiency may be causally associated with CLBP and SLBP. The results of the present study revealed that increasing severity of vitamin D deficiency may have a pathogenetic association with chronic low back pain and subacute low back pain. These results may prove to be of significance in framing of future management guidelines for the above clinical conditions.