Assessment of vitamin D status and associated risk factors in high-altitude populations affected by multiple sclerosis: A case-control study.

Several studies have suggested a correlation between serum vitamin D (VitD) level and multiple sclerosis (MS). MS has a known latitudinal distribution pattern, with greater incidence, prevalence, and mortality rates at higher latitudes. This study aims to assess levels of VitD and serum potassium in subjects with MS and the impact of gender and age as disease risk factors. A cross-sectional case-control study was conducted in a high-altitude region of Saudi Arabia. VitD deficiency was defined as serum 25 (OH)D level of ≤20 ng/mL and insufficiency as a serum level between >20 ng/mL and <30 ng/mL. Two hundred patients with MS volunteered for the study, and 160 healthy participants served as controls. VitD and serum potassium were measured in patients and controls. Student t test and regression analysis were used to analyze the data. The average MS patient age was 37.37 ± 10.8 years. Most (73.02%) MS patients suffered from deficient vitamin D, while insufficiency (20-29 ng/mL) was found in 12.17%. Only 6.35% had sufficient vitamin D (30-40 ng/mL). VitD was significantly decreased in MS patients compared to the healthy controls (17.036 vs 25.01 ng/mL, P < .001), while serum potassium was also decreased (4.278 vs 4.329 mmol/L, P = .269). Risk factors found to have a statistically significant association with MS included female gender (odd ratio [OR] = 1.72, 95% confidence interval: 1.016-2.915; P = .044) and patient age < 40 years (OR = 1.04, 95% confidence interval: 1.023-1.054; P = .044). VitD was significantly lower in MS patients. The prevalence of MS was higher among women and younger individuals in a high-altitude population in Saudi Arabia.