Lower serum 25-hydroxyvitamin D3 concentration is associated with higher pain and disability in subjects with low back pain: a case–control study

Low back pain (LBP) is a common medical problem worldwide. The aim of this study is to evaluate the association between serum concentration of 25-hydroxivitamin D3 and functional disability in patients suffering from LBP in a sample of Azeri middle-aged subjects, North West of Iran. In this case–control study, 63 eligible patients with LBP and 55 healthy subjects enrolled in the study. Peripheral venous blood was taken for evaluating the serum concentration of 25-hydroxivitamin D3. We recognized factors related with LBP by multiple regression analyses. The average serum 25-hydroxivitamin D3 concentration in case group was significantly lower than that of the matched controlled group (26.25 ± 15.95 vs. 34.20 ± 14.92, p-value < 0.01 respectively). Subjects with vitamin D deficiency or insufficiency were more likely to exhibit LBP than subjects with normal serum 25-hydroxivitamin D3 concentration [(OR = 2.388, 95% CI (1.114 to 5.119)]. According to the partial correlation analysis, there was a reverse correlation between serum 25-hydroxivitamin D3 concentration with functional disability measured by Modified Oswestry Questionnaire (r = − 0.307, p = 0.017) and also with pain intensity according to Visual Analogue Scale (VAS) score (r = − 0.268, p = 0.040) whilst adjusting for age, sex and body mass index (BMI).