Worldwide mortality rate high for bullous pemphigoid

A multi-continental meta-analysis showed high mortality rates for patients with bullous pemphigoid.

“The 1-year standardized mortality ratio (SMR) of bullous pemphigoid (BP) has been reported as 2.15 to 7.56 and lower in the U.S. than in Europe,” Billal Tedbirt, MD, of the department of dermatology at Centre Hospitalier Universitaire Rouen and Institut National de la Santé et de la Recherche Médicale U1234, Centre de Référence des Maladies Bulleuses Auto-immunes, at Normandie University, in Rouen, France, and colleagues wrote.

In the review of PubMed, Embase, Cochrane Library, Google Scholar, Lissa and gray literature databases, the researchers aimed to determine an estimate of worldwide 1-year SMR for BP.

Retrospective and prospective studies reporting 1-year all-cause mortality rates in patients with BP from database inception through June 10, 2020, were included in the analysis. Comparison of 1-year SMRs between continents served as the key secondary outcome measure.

Overall, the researchers reported on data for 12,340 unique patients from 56 unique studies. Patients had a mean age of 77.3 years, while 55.9% of the cohort were women.

Breaking the numbers down by continent, there were 260 patients from three studies in the U.S., 1,903 patients from 16 studies in Asia, 10,132 patients from 36 studies in Europe and 45 patients from one study in South America.

Mean patient ages were 75.6 years in the U.S., 73.8 years in Asia and 78.1 years in Europe.

Overall results from the full cohort showed a worldwide 1-year SMR of 2.93 (95% CI, 2.59-3.28).

In the U.S., this rate was 2.40 (95% CI, 0.89-3.90) compared with 3.53 (95% CI, 2.85-4.20) in Asia and 2.77 (95% CI, 2.35-3.19) in Europe.

The researchers then adjusted the analysis for the expected 1-year mortality rate. Results showed no significant differences between this rate in Europe compared with the U.S. (0.48 vs. Europe; 95% CI, 2.09 to 1.14) or between Europe and Asia (0.51 vs. Europe; 95% CI, 0.56 to 1.58).

With a censorship rate of 10% or greater, the risk of attrition bias was high in 16 studies (28.6%). However, a low risk of attrition bias was reported in 28.6% of studies, while attrition bias was unclear in 42.9% of the data sets.

Just four studies used a sampling method that guaranteed representation of BP cases as a function of total population.

“Although heterogeneity was high and overall quality of follow-up was poor, this meta-analysis confirms the high mortality rate among patients with BP,” the researchers wrote.