Anal cytology has increasingly been used to screen for anal intraepithelial neoplasia (AIN) among men who have sex with men (MSM) at increased risk for anal cancer. Use of liquid-based cytology has been reported to reduce fecal and bacterial contamination and air-drying artifact compared with conventional cytology. Costs associated with liquid-based cytology, however, may limit its use in resource-limited settings.
Anal swab samples were collected from MSM participants and used to prepare conventional and liquid-based cytology slides. Abnormal conventional cytology results triggered referral for high-resolution anoscopy and biopsy. Agreement between the 2 cytology techniques and the positive predictive value ratios of histology confirmed AIN were calculated.
Among 173 MSM, abnormal anal cytology was identified in 46.2% of conventional and 32.4% of liquid-based slides. The results agreed in 62.4% of cases with a κ value of 0.49 (P < 0.001). HIV-infected MSM had a 3.6-fold increased odds of having discordant anal cytology results (95% confidence interval: 1.6 to 7.8; P = 0.001) compared with HIV-uninfected MSM. Histological AIN 2 and 3 were identified in 20 MSM. The positive predictive value ratios and 95% confidence interval indicated no difference between the 2 techniques.
Conventional anal cytology may be a preferred option for resource-limited settings given comparable performances to liquid-based cytology for the detection of AIN, although the agreement between the 2 techniques was lower among HIV-infected MSM. Due to high prevalence of abnormal anal cytology and AIN, health systems should prepare adequate infrastructure for high-resolution anoscopy services and AIN treatment.
*The Thai Red Cross AIDS Research Centre, Bangkok, Thailand;
†SEARCH, Bangkok, Thailand;
‡HIV-NAT, Bangkok, Thailand;
§The Kirby Institute for Infection and Immunity in Society, University of New South Wales, Sydney, NSW, Australia;
Departments of ‖Obstetrics and Gynecology;
#Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; and
**TREAT Asia/amfAR—The Foundation for AIDS Research, Bangkok, Thailand.
Correspondence to: Nittaya Phanuphak, MD, The Thai Red Cross AIDS Research Centre, 104 Rajdumri Rd, Pathumwan, Bangkok 10330, Thailand (e-mail: firstname.lastname@example.org).
The project was supported through a grant from amfAR, The Foundation for AIDS Research, through supplemental funding from the Office of the Global AIDS Coordinator for the President's Emergency Plan for AIDS Relief and the Office of AIDS Research of the US National Institutes of Health to the International Epidemiologic Databases to Evaluate AIDS (IeDEA; U01AI069907): National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute Of Child Health and Human Development, and National Cancer Institute.
The authors have no conflicts of interest to disclose.
Received November 26, 2012
Accepted March 05, 2013