Objective: To identify the prognostic factors of bullous pemphigoid (BP).
Design: Prospective study of patients with BP included in a randomized, controlled trial.
Setting: Twenty dermatology departments in France. Patients One hundred seventy patients with BP initially treated with a 40-g/d dosage of clobetasol propionate cream (testing sample) and 171 patients initially treated with oral corticosteroids at a dosage of 0.5 or of 1.0 mg/kg per day, depending on the extent of BP (validation samples).
Main outcome measures: The end point was overall survival during the first year after BP diagnosis. From the testing sample, associations of clinical and biological variables with overall survival were assessed using univariate and multivariate analyses. Selected predictors were included in a prognostic model. To verify that these predictors were not dependent on the treatment used, the model was then validated independently on the 2 series of BP patients treated with oral corticosteroids.
Results: Median age of the BP patients included in the testing sample was 83 years. The 1-year Kaplan-Meier survival rate was 74%. From univariate analysis, the main deleterious predictors were demographic factors (ie, older age and female sex), associated medical conditions (ie, cardiac insufficiency, history of stroke, and dementia), and low Karnofsky score, which is a measure of the patient's general condition. No factors directly related to BP, in particular extent of cutaneous lesions, were shown to be related to the patients' prognosis. From multivariate analysis, only older age (P = .02) and low Karnofsky score (P<.001) appeared independently predictive of death. From the Cox model including these 2 predictors, the predicted 1-year survival rates were 90% (95% confidence interval [CI], 85%-96%) for patients 83 years or younger with Karnofsky score greater than 40, 79% (95% CI, 69%-90%) for patients older than 83 years with Karnofsky score greater than 40, 65% (95% CI, 50%-86%) for patients 83 years or younger with Karnofsky score of 40 or less, and 38% (95% CI, 26%-57%) for patients older than 83 years with Karnofsky score of 40 or less. Kaplan-Meier survival distributions of patients from the validation samples appeared clearly separated according to these 4 categories and were in close agreement with corresponding predicted 1-year survival rates obtained from the testing sample.
Conclusions: The prognosis of patients with BP is influenced by age and Karnofsky score. These predictors are easy to use and should facilitate the management of BP.