Increased Mortality in Patients with Bullous Pemphigoid: A Nationwide Population-based Cohort Study of 5,738 Patients in Sweden.

Bullous pemphigoid (BP) is the most common autoimmune blistering disease and has been linked to increased mortality, although previous studies have generally relied on small populations and no data have been available specifically for the Swedish population. This study aimed to evaluate the 1- and 10-year mortality rates and all-cause mortality in Swedish patients with BP compared with the general population. Using the National Patient Register, we conducted a retrospective cohort study and identified all BP cases in Sweden from 1 January 2005, to 31 December 2016. Age, sex, and county of residence matched controls without BP were drawn from the general population, and mortality data were obtained from the Swedish Cause of Death Register. In total, 5,738 patients with BP and 17,167 controls were included. BP patients had a significantly higher all-cause mortality (HR 2.15, 95% CI 2.06-2.24) than controls, with 1- and 10-year mortality rates of 21.2% and 80.2%, respectively. Cardiovascular diseases accounted for the largest proportion of deaths (25.3%). Notably, improved survival was observed among BP patients treated with methotrexate (MTX), prednisolone, and potent topical corticosteroids (HR 0.76, 95% CI 0.69-0.83). To our knowledge, this is the first nationwide Swedish study on BP mortality and one of the largest to date, confirming a significantly increased mortality risk in BP patients, particularly due to cardiovascular causes, while also suggesting that combined MTX, prednisolone, and potent topical steroid treatment may improve survival outcomes.