Prevalence of vitamin D deficiency among Northern Muslim women with chronic musculoskeletal pain residing in Port Harcourt, Rivers State, Nigeria: a cross-sectional study

Aim: Vitamin D deficiency is increasingly recognised as a global health concern and is associated with musculoskeletal pain. Women adhering to cultural clothing practices may be at increased risk due to limited sun exposure. This study aimed to determine the prevalence of vitamin D deficiency and identify its predictors among Northern Muslim women with chronic musculoskeletal pain living in Port Harcourt, Nigeria. Methods: A cross-sectional study of 220 Northern Muslim women aged ≥ 18 years with chronic musculoskeletal pain was conducted in Port Harcourt, Nigeria. Sociodemographic and lifestyle data were collected, and serum 25-hydroxyvitamin D levels were measured using ELISA. Participants with conditions affecting vitamin D absorption or metabolism, or those taking interfering medications, were excluded. Group comparisons (deficient vs. non-deficient) were performed using chi-square tests for categorical variables, independent-samples t-tests for continuous variables, and one-way ANOVA for pain scores across vitamin D status categories. Multivariate logistic regression was used to identify predictors of vitamin D deficiency. Analyses were conducted using IBM SPSS Statistics version 25 (IBM Corp., Armonk, NY, USA), with p < 0.05 considered significant. Results: The prevalence of vitamin D deficiency was 65.0%, a rate slightly higher yet comparable to reports from other urban populations. Significant predictors included full-body covering (adjusted OR = 3.1; 95.00% CI: 1.8–5.3), low intake of vitamin D-rich foods (OR = 2.4; 95.00% CI: 1.3–4.1), and outdoor activity < 3 hours per week (OR = 2.7; 95.00% CI: 1.6–4.6). Vitamin D-deficient participants reported higher mean pain scores (7.3 ± 1.4) than vitamin D-insufficient participants (5.9 ± 1.3). Conclusions: Vitamin D deficiency is highly prevalent among Northern Muslim women with chronic musculoskeletal pain in Port Harcourt, largely influenced by clothing practices, low sun exposure, and inadequate dietary intake. Public health strategies, including targeted education and supplementation programs, are recommended to address this burden.