The Coutinho index as a simple tool for screening patients with advanced forms of Schistosomiasis mansoni: a validation study

Abstract

Background Periportal fibrosis (PPF) is the major pathological consequence of Schistosoma mansoni infection. The Coutinho index—the alkaline phosphatase (ALP) to platelet ratio ([ALP/upper limit of normality {ULN}]/platelet count [106/L] x 100)—was validated. Validation consisted of modest laboratory tests to predict advanced PPF. Methods A total of 378 individuals from an endemic area of Brazil with a previous history of the disease and/or a positive parasitological examination were evaluated. We used ultrasound examination as the gold standard for classification of the PPF pattern and measured the biological markers of the index. Results Forty-one individuals (10.8%) without PPF, 291 (77%) with moderate PPF and 46 (12.2%) with advanced PPF, were identified. ALP and platelet count were used for the index. The cut-off point ≥0.228 predicted the presence of fibrosis with an area under the receiver operating characteristic curve (AUROC) of 0.56, sensitivity of 68.6% and specificity of 46.3%. There was an absence of PPF in 46.3% of individuals without fibrosis and the presence of PPF in 68.5% of cases with moderate and advanced ultrasound fibrosis. The identification of advanced fibrosis with a cut-off point ≥0.316 revealed an AUROC curve of 0.70, sensitivity of 67.4% and specificity of 68.3%, thus confirming the advanced phase in 65.2% of cases compared with ultrasound. Conclusion The Coutinho index was able to predict advanced PPF in most individuals. It is valid as a new tool, uses routine laboratory tests and therefore is more accessible for screening patients with a severe form of the disease in endemic areas.

Noninvasive diagnosis of periportal fibrosis in schistosomiasis mansoni: A comprehensive review

“…The most prevalent markers to assess PPF are the platelet count, aspartate aminotransferase to platelet ratio index (APRI)[ 26 , 27 ], Fibrosis-4 (FIB-4)[ 4 ], gamma glutamyl transferase (GGT)[ 17 , 28 ], and the Coutinho Index[ 29 , 30 ]. Table 3 summarizes the performance of these markers that has been reported in the literature.…”

“…After analyzing different enzymes that change during the course of this disease, they developed this index. Subsequently, in another study, this index was validated in an endemic area of the same state, with 378 patients who took a parasitological test that was positive for S. mansoni [ 30 ].…”