Patterns of Vitamin D Levels and Exposures in Active and Inactive Noninfectious Uveitis Patients

Abstract

To compare serum vitamin D levels and patterns of ultraviolet light and dietary exposure among patients with active and inactive noninfectious uveitis and population controls. Prospective case-control study. All participants (n= 151) underwent serum 25-hydroxy vitamin D measurement and completed a questionnaire on vitamin D intake and ultraviolet light exposure. Serum 25-hydroxy vitamin D levels were compared between active and inactive uveitis groups and with local population estimates. Adult patients with active and inactive noninfectious uveitis were recruited from 2 Victorian tertiary hospitals and 1 private ophthalmic practice. Serum 25-hydroxy vitamin D levels were compared between patients with active and inactive uveitis and population-based estimates of serum 25-hydroxy vitamin D levels, stratified by geographic region and season. Vitamin D intakes and exposures based on questionnaire results, including vitamin D supplementation and sunlight exposures on weekdays and weekends, were compared between active and inactive uveitis groups. Serum vitamin D levels, intake of vitamin D, and exposure to sources of vitamin D. The median level of serum vitamin D in those with active uveitis (n= 74) was 46 nmol/l (interquartile range [IQR], 29-70 nmol/l), significantly lower than in the inactive control group (n= 77) at 64 nmol/l (IQR, 52-79 nmol/l; P < 0.001). The active uveitis group also showed lower median serum vitamin D levels than the local population median of 62 nmol/l (IQR, 46-77 nmol/l). Vitamin D supplementation also was associated significantly with uveitis inactivity (P= 0.026, Kendall's τ test). In a subanalysis of vitamin D-deficient participants, sun exposure was associated significantly with uveitis inactivity (P= 0.014 for weekday and weekend analyses). Participants with active uveitis showed significantly lower serum 25-hydroxy vitamin D levels than inactive uveitis patients and local population-based estimates. Vitamin D supplementation was found to be associated with decreased uveitis activity, as was sun exposure in those with vitamin D deficiency. These results suggest that vitamin D supplementation should be studied as an option for the prevention of uveitis relapse in at-risk patients.