Interobserver agreement in the interpretation of anal intraepithelial neoplasia

BACKGROUND: Anal carcinoma incidence is increasing, and is highest among men with human immunodeficiency virus (HIV) infection who have sex with men. Anal carcinoma and anal intraepithelial neoplasia (AIN) are ascertained on tissue histology, but requires invasive procedures. Screening for AIN using anal cytology was suggested. The authors evaluated agreement on cytologic and biopsy specimens from HIV-positive men undergoing anal carcinoma screening. METHODS: One hundred twenty-nine HIV-positive men with a history of anal-receptive intercourse underwent anal cytology, anoscopy, and biopsy. Four pathologists independently assessed cytology and biopsy specimens and reached consensus for discordant cases. RESULTS: Each pathologist evaluated 120 cytology and 155 biopsy specimens. The weighted kappa value for overall agreement was 0.54 (95% confidence interval [CI], 0.49-0.59) for cytology specimens and 0.59 (95%CI, 0.55-0.63) for biopsy specimens. The median kappa values for pairwise agreement among pathologists and for agreement with consensus were, respectively, 0.69 and 0.77 for cytology and 0.66 and 0.75 for biopsy. At least 3 pathologists were in agreement for 92 (76.7%) cytology and 134 (86.5%) biopsy specimens. Reliability for the Bethesda classification system was at least moderate, except for the cytologic category of atypical squamous cells of undetermined significance (kappa = 0.12). Fourteen of 29 (48.3%) cytology specimens and 36 of 47 (76.6%) biopsy specimens with consensus interpretation of high-grade squamous intraepithelial lesions (HSIL) were interpreted originally as HSIL by > or = 3 pathologists. The kappa value for agreement with consensus distinguishing HSIL from non-HSIL ranged from 0.55 to 0.88 for cytology specimens and from 0.76 to 0.94 for biopsy specimens. CONCLUSIONS: Agreement for cytologic and biopsy interpretations was generally at least moderate. Nevertheless, these results supported the need for disease indicators with greater reliability.