Validation of the Nelwan Score as a screening tool for the diagnosis of typhoid fever in adults in Indonesia

Abstract

Introduction Typhoid fever diagnosis is challenging for clinicians in areas with limited laboratory facilities. Scoring methods based on signs and symptoms are useful for screening for probable cases of typhoid fever. The Nelwan Score variables are derived from the clinical signs and symptoms of patients with suspected typhoid. We validated the Nelwan Score compared to laboratory tests as the gold standard. Methods This cross-sectional study was conducted between July 2017 and January 2018 in five hospitals and two primary health care centers in Jakarta and Tangerang, Indonesia. Patients with fever for 3–14 days and gastrointestinal symptoms were evaluated using the Nelwan Score. Blood cultures, samples for polymerase chain reaction testing, and additional rectal swab cultures were collected simultaneously to confirm the diagnosis of typhoid. Data were analyzed using a contingency table to measure sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and the optimal cut-off of the Nelwan Score for typhoid diagnosis was determined using a receiver-operating characteristic curve. Result Typhoid was confirmed in 11 of the 233 patients (4.7%) with suspected typhoid. Among laboratory-confirmed typhoid cases, the median Nelwan Score was 11 (range: 9–13) and the optimal cut-off value was 10, with an area under the curve of 71.3%, sensitivity of 81.8%, specificity of 60.8%, PPV of 9.3%, and NPV of 98.5%. Conclusion A Nelwan Score of 10 is the best cut-off value for screening for typhoid fever. It is useful as screening tool for typhoid fever, where laboratory resources are limited, and could help to decrease irrational antibiotic use.