Audit of paired anal cytology and histopathology outcomes in patients referred to a public sexual health clinic.
BACKGROUND
The level of agreement between anal cytology and histopathology is not clear with only a few studies evaluating the reliability of anal specimen reporting. Australian data in relation to this are limited.


METHODS
The results of paired anal cytology and histopathology specimens received between 2002 and 2008 from patients who were referred within the sexual health clinic were retrieved from the anatomical pathology database. A total of 248 paired samples from 154 (21 females, 133 males) participants were extracted. Concurrent high risk human papilloma virus (hrHPV) DNA assay and HIV status for the study group were also collected. Data were tabulated according to reported grade of squamous abnormality based on the Bethesda system. Using the biopsy result as the gold standard the specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) for cytology were calculated and the association between grade of abnormality, HIV status and hrHPV infection estimated.


RESULTS
Concordance between cytology and histology showed that in 204 (85%) paired samples both tests were categorised as abnormal (Kappa statistic 0.73, P = 0.013). The cytology result showed a sensitivity of 96%, specificity 14%, PPV 89% and NPV 31% when compared with histopathology. HrHPV assay was positive in 192 (80%) samples. High-grade squamous abnormalities were reported in biopsy specimens from 60% (n = 42/67) of HIV-positive subjects and 25% (n = 22/87) of HIV-negative subjects. HIV-positive individuals were more likely to be hrHPV positive, odds ratio (OR) 6.21 [95% confidence interval (CI) 2.69 to 14.34], when compared with HIV-negative subjects.


CONCLUSIONS
Anal cytology is highly sensitive for the detection of abnormal squamous cells. While cytology has low specificity for predicting the grade of abnormality compared with biopsy outcome, its application as a screening method in asymptomatic at risk populations warrants further study.
Williams
Vincent M
VM
Western Australian Biomedical Research Institute, Curtin University of Technology, Perth, WA, Australia. v.williams@curtin.edu.au
Metcalf
Cecily
C
French
Martyn A
MA
McCloskey
Jenny C
JC
D017088:AIDS-Related Opportunistic Infections / Q000473:pathology; D000328:Adult; D001003:Anal Canal / Q000473:pathology; D001004:Anus Diseases / Q000473:pathology*; D001005:Anus Neoplasms / Q000473:pathology*; D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D015344:DNA Probes, HPV; D005260:Female; D006679:HIV Seropositivity / Q000473:pathology; D006801:Humans; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D030361:Papillomavirus Infections / Q000473:pathology*; D011230:Precancerous Conditions / Q000473:pathology*; D011237:Predictive Value of Tests; D012017:Referral and Consultation; D015229:Sexually Transmitted Diseases, Viral / Q000473:pathology*
D015344:DNA Probes, HPV