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

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.

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.

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).

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.