Inter-reader agreement of the prostate imaging reporting and data system version v2.1 for detection of prostate cancer: A systematic review and meta-analysis

Objectives: We aimed to systematically assess the inter-reader agreement of the Prostate Imaging Reporting and Data System Version (PI-RADS) v2.1 for the detection of prostate cancer (PCa). Methods: We included studies reporting inter-reader agreement of different radiologists that applied PI-RADS v2.1 for the detection of PCa. Quality assessment of the included studies was performed with the Guidelines for Reporting Reliability and Agreement Studies. The summary estimates of the inter-reader agreement were pooled with the random-effect model and categorized (from slight to almost perfect) according to the kappa (kappa) value. Multiple subgroup analyses and meta-regression were performed to explore various clinical settings. Results: A total of 12 studies comprising 2475 patients were included. The pooled inter-reader agreement for whole gland was kappa=0.65 (95% CI 0.56-0.73), and for transitional zone (TZ) lesions was kappa=0.62 (95% CI 0.51-0.72). There was substantial heterogeneity presented throughout the studies (I-2 = 95.6%), and meta-regression analyses revealed that only readers' experience (< 5 years vs. & GE;5 years) was the significant factor associated with heterogeneity (P < 0.01). In studies providing head-to-head comparison, there was no significant difference in inter-reader agreement between PI-RADS v2.1 and v2.0 for both the whole gland (0.64 vs. 0.57, p=0.37), and TZ (0.61 vs. 0.59, p=0.81). Conclusions: PI-RADS v2.1 demonstrated substantial inter-reader agreement among radiologists for whole gland and TZ lesions. However, the difference in agreement between PI-RADS v2.0 and v2.1 was not significant for the whole gland or the TZ.