The overall pooled RDs of ROM in TBSRTC categories considering NIFTP a non-malignant tumour. The inclusion criteria in these studies were relevant data for analysis (change of ROM, available data of the number of NIFTP cases). The ROM was reduced by 2.4% (I² was 0%) in ND, 2.7% (I² was 2%) in benign, 8.2% (I² was 43%) in AUS/FLUS, 8.2% (I² was 53%) in FN, 7.3% (I² was 89%) in SM, and 1.1% (I² was 45%) in malignant category. NIFTP, non-invasive follicular thyroid neoplasm with papillary-like nuclear features; TBSRTC, The Bethesda System for Reporting Thyroid Cytopathology; ND, non-diagnostic; AUS/FLUS, atypia of undetermined significance or follicular lesion of undetermined significance; FN, follicular neoplasm; SM, suspicious for malignancy; ROM; risk of malignancy; RD, risk difference.