Mortality of Bullous Pemphigoid in China

Bullous pemphigoid (BP) is the most common acquired autoimmune blistering disorder that occurs mostly in elderly people. The first-year mortality has been reported to range from 6% to 41%.^1-3 This study determined the 1-, 2-, and 5-year mortality of patients with BP in China and identified risk factors affecting survival. The mortality of patients with BP was compared with age-matched persons in the general population.

This was a retrospective cohort study. Inclusion criteria were a diagnosis of BP based on clinical characteristics and confirmed by at least a typical histologic pattern and the presence of autoantibodies against the basement membrane zone detected by direct and/or indirect immunofluorescence testing. The treatment for BP was oral corticosteroids with or without adjuvant therapy such as dapsone, cyclophosphamide, and others. Data were obtained of all patients with a discharge diagnosis of BP between January 1991 and 2011. Information on the status of patients who became unavailable for follow-up by the hospital department was obtained by telephone calls.

The mortality at 1, 2, and 5 years after first hospitalization was calculated based on the Kaplan-Meier survival estimate. Cox logistic regression in multivariate analysis was used. For the analysis, if no predefined cutoff points were available, continuous variables were categorized on the basis of the median. The ratio of the observed to expected death rates, or the standardized mortality ratio (SMR), was calculated for age categories. The study was approved by the ethics committee of Peking Union Medical College.

A total of 140 patients with BP and a follow-up time 1 year or longer were included. The median age was 67 years, and the mean (SD) age was 64.3 (13.6) years (age range, 18-93 years). The median time from onset of disease to hospitalization was 2.94 months (range, 7 days to 30 years). The median follow-up time was 3 years. The 1-year mortality was 12.9% (95% CI, 8.3%-19.6%); the 2-year mortality was 20.1% (95% CI, 14.4%-28.0%); and the 5-year mortality was 33.5% (95% CI, 25.6%-43.1%) (Figure).

In the univariate analysis, several variables increased mortality (Table 1). Nonsignificant comparisons included smokers vs never smokers (P = .20), drinkers vs never drinkers (P = .33), urban vs rural population (P = .06), duration of disease longer than 2.94 months vs 2.94 months or shorter (P = .25), and erythrocyte sedimentation rate higher than 23 mm/h vs 23 mm/h or less.

The SMR varied from 3.08 to 6.14 depending on age group (Table 2). Based on these data, we concluded that the mortality of patients in our BP cohort was higher than would be expected in age-matched persons in the general Chinese population.

In our study, the 1-year mortality was 12.9%, which is similar to rates reported in previously pub lished US studies⁴ but lower than reports in European studies. The European studies found a 1-year mortality varying between 19% and 41%. The younger age of patients with BP in our study (64.3 years) compared with the patient age in the European studies (74.0-82.6 years) might be responsible for this difference. The age distribution of the Chinese population differs from that of the European population in that Chinese persons 65 years or older represent only 6.83% of the total Chinese population, and those 80 years or older are only 0.88% of the total Chinese population.

Our SMR results are in accord with those reported in previously published European studies (SMR ranged from 2.15 to 15.3). A US study did not find a difference in mortality for patients with BP.³ Only hospitalized patients were included in our study, and time to death after first BP hospitalization was evaluated rather than time to death from BP diagnosis,³ which may explain our relatively higher SMR.

Several studies have suggested a relationship between BP and neurologic diseases.⁵ The presence of neurologic disease was related to elevated mortality in our study. Results from recent reports, in which neurological diseases also correlated with higher mortality, support our findings.³ The association of oral corticosteroid treatment alone with increased mortality may be because this treatment was used when patients with BP had poor general health.

Correspondence: Dr Li, Department of Dermatology and Venereology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China 100730 (lijun35@hotmail.com).

Accepted for Publication: June 27, 2012.

Author Contributions: All authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Li. Acquisition of data: Zuo and Zheng. Drafting of the manuscript: Li, Zuo, and Zheng. Critical revision of the manuscript for important intellectual content: Li. Statistical analysis: Li. Administrative, technical, and material support: Zuo. Study supervision: Li.