Accuracy of Rome IV questionnaire: a population-based study on diagnostic definitions and clinical validity

Abstract

Rome IV questionnaire is widely used for diagnosing disorders of gut-brain interaction (DGBIs), but was developed in Western populations and may not generalize to other regions. This study aimed to validate the Persian version of this questionnaire and develop population-adapted diagnostic criteria for three prevalent DGBIs: functional dyspepsia (FD), irritable bowel syndrome (IBS), and functional constipation (FC). Using the Isfahan functional disorders (ISFUN) dataset, we developed two modified versions of Rome IV Diagnostic Criteria (R4DC): (1) the modified Iranian Criteria (mIrC), based on the 90th percentile of symptom frequency in the Iranian population, and (2) the Clinically-Adjusted Criteria (CAC), derived using receiver operating characteristic (ROC) analyses with clinical diagnoses as the reference standard. Diagnostic performance, accuracy, and agreement with the reference standard were assessed. Convergent validity was also examined using the Somatic Symptom Disorder-B Criteria Scale (SSD-12). mIrC thresholds were similar to R4DC for FD but more restrictive for IBS and FC. R4DC overestimated FC prevalence (23.4% vs. 13.9%) but underestimated FD and IBS due to high specificity and low sensitivity. mIrC improved specificity (FD: 95.6%, FC: 93%) but lowered sensitivity, whereas CAC achieved the highest sensitivity (FD: 75.0%, IBS: 84.2%, FC: 96.8%) with strong negative predictive values. R4DC showed the best agreement and accuracy. SSD-12 scores were significantly higher ( p -value < 0.001) across all diagnostic groups. The Persian Rome IV diagnostic questionnaire is valid for DGBIs diagnosis in Iran. However, locally adapted thresholds can improve diagnostic performance, with mIrC offers population-specific diagnostic accuracy while CAC provides high clinical sensitivity, suitable for screening.