Does vitamin D status influence lumbar disc degeneration and low back pain in postmenopausal women? A retrospective single-center study

Objective: To investigate the relationship between serum vitamin D concentration and lumbar disc degeneration (LDD) in postmenopausal women and the epidemiologic factors affecting low back pain (LBP). Methods: Between July 2017 and December 2018, 232 participants were retrospectively enrolled. Serum concentrations of bone turnover markers were measured using electrochemiluminescence assays. Disc degeneration was evaluated using the Pfirrmann grading system. Other variables were assessed using relevant questionnaires. Results: The mean age of the women was 65.6 +/- 10.1 and their serum 25(OH)D concentrations were 19.38 +/- 9.21 ng/mL. The prevalences of severe vitamin D deficiency (<10 ng/mL) and normal status (>30 ng/mL) were 12.9% and 12.5%, respectively. The severely deficient group had higher visual analog scale (VAS) scores for LBP (P = 0.002) and lower bone mineral density T scores (P = 0.004) than the other groups. Lower 25(OH)D concentration (<10 ng/mL) was significantly associated with more severe LDD in the lumbosacral region (L4-S1, L1-S1,P < 0.05), but less so in the upper lumbar region. There was an inverse relationship between vitamin D concentration and the severity of disc degeneration (L2-L3, L4-S1, L1-S1,P < 0.05). After adjustment for confounding factors, smoking, vitamin D deficiency, lack of vitamin D supplementation, high body mass index, and low bone mineral density T score were associated with higher incidence of moderate-to-severe pain in postmenopausal women (P < 0.05). Conclusions: Vitamin D deficiency is associated with LDD and LBP in postmenopausal women. Specifically, a serum vitamin D concentration < 10 ng/mL is a marker of severe LDD and LBP. Smoking, severe vitamin D deficiency, lack of vitamin D supplementation, high body mass index, and osteoporosis are associated with a higher prevalence of moderate-to-severe pain.