Multimorbidity in bullous pemphigoid: a case-control analysis of bullous pemphigoid patients with age- and gender-matched controls.

BACKGROUND: Bullous pemphigoid (BP) is the most common autoimmune blistering disease in the elderly and is associated with increased mortality. The extent of multimorbidity in patients with BP and its impact on survival are unclear.

OBJECTIVES: To describe the extent and spectrum of multimorbidity in patients with BP and to ascertain its impact on survival.

METHODOLOGY: This was a case-control study conducted in the setting of an academic medical centre. Cases defined as newly diagnosed BP patients referred to the inpatient dermatology service between 2005 and 2014. For every case, three age- and gender-matched controls were randomly selected. Retrospective review of medical records was performed. Univariate and multivariate comparisons of cases and controls were performed using conditional logistic regression.

RESULTS: A total of 105 cases and 315 controls were included in this study. Eighty-eight cases (84%) were multimorbid (≥2 chronic diseases) as compared to 205 controls (65%) (P < 0.001), while the mean number of comorbid conditions was 3.2 ± 1.6 in cases compared to 2.4 ± 1.6 in controls (P < 0.001). 43% of cases had ≥4 comorbidities compared to 27% in controls (P = 0.003). On multivariate analysis (adjusting for age, gender and comorbidities), neurological disease (OR 10.93; CI: 5.74, 20.79) and hypertension (OR 2.38; CI: 1.18, 4.77) were positively associated with BP. Charlson comorbidity index was 6.0 ± 2.5 in cases compared to 5.0 ± 2.1 in controls (P = 0.002), and the 1-year mortality of cases and controls was 32.4% and 17.8%, respectively.

CONCLUSION: Our study has shown that a significant proportion of patients with BP are multimorbid and individually have a higher number of comorbidities compared to matched controls. Disease burden and multimorbidity may well impact the prognosis of patients with BP.