Schistosoma mansoni-related periportal fibrosis; can we use APRI and PSDR levels in the real-time selection of patients for targeted endoscopy in a resource-limited setting? A case–control study

BACKGROUND: Schistosoma mansoni related hepatic fibrosis is usually associated with hemodynamic alteration with increased mortality due to bleeding varices. The diagnosis of varices before bleeding imposes a big challenge in resource-limited countries using endoscopy. Published evidence on the utility of non-invasive clinical tools in predicting the presence of varices among patients with S. mansoni related periportal fibrosis is still inadequate including Aspartate to platelet ratio index (APRI) and Platelet to splenic diameter ratio (PSDR) levels. This study describes the determinants of portal varices and assesses the potential utility of the APRI and PSDR level in the discrimination of portal varices among patients with S. mansoni related periportal fibrosis (PPF). METHODS: A case–control study using cross-sectional data was done among patients with Schistosoma mansoni related periportal fibrosis at Bugando Medical Centre, in Mwanza Tanzania. The derivation cohort included patients enrolled between 2015 and 2019 and the validation cohort included patients enrolled from 2019 till March 2021. Socio-demographic, laboratory, ultrasound, and upper digestive endoscopic information were analyzed using STATA 13. The prevalence and determinants of varices were determined by logistic regression. The sensitivity and specificity of independent factors were determined to assess their utility in discriminating the presence of portal varices in patients with PPF. RESULTS: In total, 250 patients were included in the derivation cohort, 109 (43.6%; 95% CI 37.3–49.9) of them had varices. The odds of having varices were independently increased among patients with higher APRI levels than 1.51, (AOR: 5.8; 95% CI 3.1–11.1; p < 0.001) and PSDR levels that were lower than 5700 (AOR: 5.9; 95% CI 3.2–11.2; p < 0.001). Both APRI and PSDR levels had significantly high sensitivity and specificity in predicting the presence of esophageal varices. However, the combined values of APRI and PSDR had higher specificity than any of the two markers. Of the 200 patients in the validation cohort 94 (47.0%; 95% CI 40.0–54.2) had varices, the discriminative power of the final model and the predictive ability of both APRI, PSDR, and APRI-PSDR combined levels were highly maintained. CONCLUSIONS: This study indicates that varices are a common encounter among patients with S. mansoni related periportal fibrosis and it is independently associated with higher APRI and lower PSDR levels suggesting that these tools are potential discriminators of varices in this subgroup of patients. The reproducibility of these results should further be assessed longitudinally as potential non-invasive tools in selecting patients at high risk of having esophageal varices who could benefit from the targeted endoscopic intervention in a resource-limited setting like ours.