Importance: Understanding the role of vitamin D-which regulates inflammatory responses-in noninfectious uveitis (an inflammatory disease) may provide insight into treatment and prevention of this disease.
Objective: To investigate whether there is an association between hypovitaminosis D and incident noninfectious uveitis.
Design, setting, and participants: In a retrospective case-control study, data from a health care claims database containing deidentified medical claims from a large private insurer were used to identify 558 adults enrolled from January 1, 2000, to December 31, 2016, who received a diagnosis of noninfectious uveitis from an eye care clinician (with receipt of a confirmatory diagnosis within 120 days of the initial diagnosis) and who had a vitamin D level measured within 1 year before the first diagnosis. Exclusion criteria included having systemic disease or receiving medication known to lower vitamin D levels, having undergone intraocular surgery, and having infectious uveitis. Each case patient was matched with 5 controls on the basis of age, sex, race/ethnicity, and index date (2790 controls). The controls had vitamin D level determined either within 1 year before or within 6 months after receiving an eye examination with normal findings. Multiple logistic regression models were used to examine the association between hypovitaminosis D and noninfectious uveitis.
Main outcomes and measures: The primary, prespecified analysis assessed the association of noninfectious uveitis with hypovitaminosis D (vitamin D level ≤20 ng/mL).
Results: The 558 cases and 2790 controls were matched on age, and each group had a mean (SD) age of 58.9 (14.7) years. Among the cohort of 3348 patients, 2526 (75.4%) were female, and the racial/ethnic distribution in the matched samples was 2022 (60.4%) white, 552 (16.5%) black, 402 (12.0%) Hispanic, 162 (4.8%) Asian, and 210 (6.3%) unknown. Patients with normal vitamin D levels had 21% lower odds of having noninfectious uveitis than patients with low vitamin D levels (odds ratio [OR], 0.79; 95% CI, 0.62-0.99; P = .04). In a race-stratified analysis, an association between vitamin D and uveitis was found in black patients (OR, 0.49; 95% CI, 0.30-0.80; P = .004) and was qualitatively similar but nonsignificant in white patients (OR, 0.87; 95% CI, 0.62-1.21; P = .40) and Hispanic patients (OR, 0.60; 95% CI, 0.33-1.10; P = .10).
Conclusions and relevance: This and other reports have found an association between hypovitaminosis D and noninfectious uveitis. However, these studies cannot establish a causal relationship. Prospective studies are warranted to evaluate whether hypovitaminosis D causes increased risk of uveitis and the role of vitamin D supplementation in prevention and treatment of uveitis.