Use of IOTA simple rules for diagnosis of ovarian cancer: meta-analysis.

OBJECTIVES: To present data on prospective evaluation of the International Ovarian Tumor Analysis (IOTA) 'simple-rules' tool for the diagnosis of ovarian cancer and to perform a meta-analysis of studies that utilized the same diagnostic method.

METHODS: In the present study a level-II ultrasound operator systematically assessed the tumors of women with an ultrasound diagnosis of adnexal tumor(s) according to the IOTA simple-rules protocol to determine the risk of the tumor being malignant. The results of simple rules were compared with the 'pattern recognition' method and with histological findings. This validation study was included in the subsequent meta-analysis, for which we searched MEDLINE, EMBASE and Cochrane from the publication of the first study in 2008. The terms used were 'simple rules', 'simple rules ovarian', 'ovar tumor' and 'ultrasound'. Quality assessment was performed using the modified Quality Assessment of the Diagnostic Accuracy of Studies (QUADAS-2) checklist. Random effects meta-analysis was used to calculate pooled estimates of sensitivity and specificity for the simple-rules tool, and meta-regression was used to investigate heterogeneity across the studies.

RESULTS: Three hundred and three women were included in the validation study with 168 (55.4%) benign, 19 (6.3%) borderline and 116 (38.3%) malignant tumors on histological examination. The rules were applicable in 237 (78.2%) of the tumors and for these tumors, sensitivity was 96.2% (95% CI, 90.5-99.0%) and specificity was 88.6% (95% CI, 82.0-93.5%). Six of the 88 discovered studies were included in the meta-analysis along with the current validation study, which resulted in inclusion of a total of 3568 patients. When the meta-analysis was performed the pooled sensitivity (when the rules were applicable) was 93% (95% CI, 90-96%) (I(2)  = 32.1%) and the pooled specificity was 95% (95% CI, 93-97%) (I(2)  = 78.1%). Heterogeneity was observed across the studies. Sensitivity was higher and specificity lower in the study populations in which the prevalence of malignant tumors was greatest.

CONCLUSION: The simple rules protocol could be used in 76-89% of tumors and is an accurate test for the diagnosis of ovarian cancer. Assessment by an ultrasound expert is required when the protocol cannot be applied.