Association of Bullous Pemphigoid With Dipeptidyl-Peptidase 4 Inhibitors in Patients With Diabetes Estimating the Risk of the New Agents and Characterizing the Patients

IMPORTANCE The association of bullous pemphigoid (BP) with the use of dipeptidyl-peptidase 4 (DPP-4) inhibitors among patients with diabetes has recently emerged. The risk of developing BP during treatment with new DPP-4 inhibitor agents like linagliptin is yet to be established. The clinical features and the prognostic outcomes of patients with DPP-4 inhibitor-associated BP are yet to be established. OBJECTIVES Primarily to estimate the association between DPP-4 inhibitor exposure and the development of BP, and secondarily to characterize the clinical features and history of patients with DPP-4 inhibitor-associated BP. DESIGN, SETTING, AND PARTICIPANTS A retrospective case-control study of the intake of different DPP-4 inhibitor agents and metformin and occurrence of BP among patients with diabetes in a tertiary care referral center for autoimmune bullous diseases in northern Israel. Included were 82 consecutive patients with diabetes and immunopathologically validated BP diagnosed between January 1, 2011, and December 31, 2017, and 328 age-, sex-, and ethnicity-matched control participants with diabetes but without BP. MAIN OUTCOMES AND MEASURES Patients with diabetes and BP and exposure to DPP-4 inhibitors were followed up for a median of 2.0 years and compared with other patients with diabetes and BP who were not exposed to DPP-4 inhibitors regarding clinical and immunological features, laboratory analyses, treatments, and clinical outcomes. RESULTS Eighty-two patients with BP and 328 age-and sex-matched control participants were enrolled; mean (SD) age, 79.1 (9.1) years; and 44 patients were female (53.7%). Overall, DPP-4 inhibitor intake was associated with a 3-fold increased risk for BP (adjusted odds ratio [OR], 3.2; 95% CI, 1.9-5.4). The adjusted ORs for vildagliptin and linagliptin were 10.7 (95% CI, 5.1-22.4) and 6.7 (95% CI, 2.2-19.7), respectively. The association of DPP-4 inhibitor use with BP was independent of the use of metformin and was stronger among male (OR, 4.46; 95% CI, 2.11-9.40) than female (OR, 1.88; 95%, CI 0.92-3.86) patients and strongest in patients younger than 70 years (OR, 5.59; 95% CI, 1.73-18.01). Patients with DPP-4 inhibitor-associated BP presented with higher mucosal involvement (22.2% vs 6.5%; P = .04) and lower mean (SD) peripheral eosinophil counts (399.8 [508.0] vs 1117.6 [1847.6] cells/mu L; P = .01) than those with BP who had not been exposed to DPP-4 inhibitor. Discontinuation of DPP-4 inhibitor treatment was followed by improved clinical outcomes. CONCLUSIONS AND RELEVANCE Vildagliptin and, to a lesser extent, linagliptin are associated with an increased risk of BP. This may partly explain the increasing incidence of BP in Israel. Discontinuation of DPP-4 inhibitor treatment in patients with diabetes should be considered when BP is diagnosed.