Leprosy classification methods: a comparative study in a referral center in Brazil

•The World Health Organization operational classification and the Ridley and Jopling classification show moderate agreement.•The operational method shows better performance than the other clinical classifications.•Clinicopathological disagreement in the Ridley and Jopling classification is common.•There may be room for improvement in the Ridley and Jopling histopathological criteria.

SummaryObjectivesDifferent methods for the classification of leprosy have been proposed since the 1930s. The aim of this study was to compare the current methods at a referral center in Brazil.MethodsThe World Health Organization (WHO) operational classification was compared to the Ridley and Jopling classification, the Madrid classification, and a classification based on the number of body areas affected by skin and/or neural lesions (NBAA). The correlation between the clinical and histopathological components of the Ridley and Jopling classification was assessed.ResultsThe agreement between the WHO operational classification and the Ridley and Jopling classification was 77.6% (kappa = 0.53). The WHO operational classification tended to overestimate the number of multibacillary patients. The WHO operational classification showed its best agreement with the NBAA. There was perfect agreement between the clinical and histopathological Ridley and Jopling classification in 46.9% of the patients.ConclusionsThe agreement between the WHO operational classification and the Ridley and Jopling classification was better than any other purely clinical classification, reinforcing the importance and simplicity of the operational method. Although major disagreement between the clinical and histopathological Ridley and Jopling classification was uncommon, perfect agreement occurred in less than half of the cases, and was even lower for the borderline lepromatous and tuberculoid forms. Possible reasons for the differences are discussed; these showed that there may be room for improvement in the Ridley and Jopling classification histopathological criteria.