Validity of the WHO Operational Classification and Value of Other Clinical Signs in the Classification of Leprosy

Abstract

The objective of this study is to examine the validity of the WHO operational classification using skin smear results as the gold standard and explore the value of additional clinical signs independently and in combination with the WHO classification. Between 1985 and 2000, 5439 new untreated leprosy patients were registered at the Schieffelin Leprosy Research and Training Center, Karigiri. They were classified according to the Ridley Jopling classification as well as WHO operational classification based on the number of skin lesions. The sensitivity and specificity of the WHO operational classification tested, using skin smear results as the gold standard, was found to be 88.6% and 86.7% respectively. The Receiver Operator Characteristic (ROC) curve confirms that the best option for sensitivity and specificity is a cut off of 6 and more lesions for MB. The validity of the number of enlarged nerves and size of the largest skin lesion as independent criteria to classify patients was found to be poor. Addition of three enlarged trunk nerves to the WHO classification improved its sensitivity to 91.4%, while the specificity remained almost unchanged at 85.3%. Addition of the size of the largest skin lesion to the WHO classification reduced its validity considerably. The study concludes that the WHO recommendation of using six and more lesions for classifying a patient as MB is the best option available at the moment, and calls for further research to identify other clinical criteria that have a better validity and could be easily applied in the field.

Clinicohistopathological correlation of leprosy

“…A study by Norman et al (2004) reported that the sensitivity of WHO operational classification that classifies a patient with 6 or more lesions as multibacillary was 88.6% while the specificity was 86.7%. 25 Mehindiratta et al had only 74.6% cases correctly classified as multibacillary/ paucibacillary.…”

“…A study by Norman et al (2004) reported that the sensitivity of WHO operational classification that classifies a patient with 6 or more lesions as multibacillary was 88.6% while the specificity was 86.7%. 25 Mehindiratta et al had only 74.6% cases correctly classified as multibacillary/ paucibacillary. 26 Since 1966, the classification of leprosy by Ridley and Jopling into 5 subtypes (TT, BT, BB, BL, LL) based on clinical, histopathological and immunological features and bacteriological finding has been widely adopted by histopathologist and leprologist.…”

Confiabilidad y concordancia de dos escalas de lectura de baciloscopias para clasificación y seguimiento del tratamiento con múltiples medicamentos de los pacientes con lepra

“…Se observó que alrededor de 50 % de las discrepancias encontradas en las lecturas de los se debe continuar utilizando para hacer una buena clasificación de los pacientes; además, se puede continuar utilizando en el seguimiento del tratamiento de la enfermedad, así como en la detección de recaídas, sin olvidar que se debe pensar en herramientas más sensibles para el seguimiento de los pacientes (21,22).…”

“…Sin embargo, Norman, et al, consideran que los laboratorios con técnicas bien estandarizadas y con un control de calidad funcional, hacen que los extendidos sean confiables (21).…”

Avaliação da concordância entre exames clínicos e laboratoriais no diagnóstico da hanseníase

“…However, it is extremely difficult to detect Mycobacterium leprae in an individual and various clinical and laboratorial criteria are used in the absence of an exam defined as a gold standard 2 . For treatment purposes, the World Health Organization (WHO) recommends an operational classification (OC), whereby patients are divided into paucibacillar (PB) when they present 5 cutaneous lesions or less, or multibacillar (MB) when they have more than 5 lesions 28 . However, when bacilloscopic examination is available, patients whose skin-smear exam tests positive are classified as MB regardless of the number of lesions.…”