Methods: We identified 756 cases (78% HIV infected) of incident, pathologically-confirmed AIN 3 from the Surveillance, Epidemiology, and End Results (SEER) database linked to Medicare claims from 2000-2011. We compared baseline characteristics by HIV infection status using univariate tests. We compared outcomes such as progression to SCCA and overall survival by HIV infection status using Kaplan-Meier methods and methods accounting for competing risks. We fitted Cox regression models to adjust for potential confounders.
Results: Compared to HIV uninfected patients, HIV infected patients were more likely to be male (95% vs 48%), younger (IQR 41-52 vs 51-70 years), and non-White (37% vs 22%), all p < .01. HIV infected patients were less likely to undergo treatment for AIN 3 (62% vs 77%), but more likely to undergo anal cytology (72% vs 24%) and anoscopy (54% vs 6%) thirty or more days after AIN 3 diagnosis (all p<.01). There were 41 cases of incident SCCA over the study period. AIN 3 progressed to SCCA at a rate of 0.9 per 100 person-years (95% CI 0.7-1.2). Median time to progression was 24 months (IQR 12-44 months). Cumulative risk of SCCA at 5 years was 5.7% (95% CI 4.2%-7.8%). Progression rates did not differ by HIV status (all p > .05).
Conclusion: In our population-based cohort of patients with AIN 3, we found rates of progression to invasive carcinoma similar to previous estimates. We did not detect a robust effect of HIV infection on rate of progression to SCCA; however our study lacked detailed data on AIN 3 treatment, CD4 count, and ART use, which may be more predictive of risk of progression than HIV status alone.
M. Gaisa, None
A. Burnett, None
S. Goldstone, None
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