Association between bullous pemphigoid and hypovitaminosis D in older inpatients: Results from a case-control study

Objectives: To compare serum vitamin D status in older inpatients with bullous pemphigoid (BP) and matched inpatients without BP, and to examine whether hypovitaminosis D, a high comorbidity burden or their combination were associated with BP.

Methods: This prospective case-control study was performed from November 2012 to February 2014. A total of 90 consecutive older inpatients (31 consecutive inpatients with a de novo diagnosis of active BP, and 59 matched controls without BP) were recruited in the Department of Dermatology of Angers University Hospital, France. Hypovitaminosis D was defined as serum 25-hydroxyvitamin D (25OHD) concentration<50nmol/L. Age, gender, functional level, sun exposure, season, comorbidity burden and cognitive performance were used as covariates.

Results: There was no significant difference between older inpatients with and without BP. Fully adjusted logistic regression showed a significant association between BP and hypovitaminosis D (odds ratio [OR]=3.7, P=0.046). The analysis of interaction between hypovitaminosis D and comorbidity burden showed that only the association of both was significantly associated with PB (OR=3.1, P=0.042).

Conclusions: BP was significantly associated with hypovitaminosis D solely in patients with a high comorbidity burden among the older in-patients studied. This result suggests a complex interplay between hypovitaminosis D and BP, explaining the mixed results reported previously in the literature.