IDENTIFYING OPTIMAL CERVICAL CANCER SCREENING APPROACHES FOR HIV-POSITIVE WOMEN IN SUB-SAHARAN AFRICA

   Purpose: The interaction between human immunodeficiency virus (HIV) and human papillomavirus (HPV) results in an increased burden of cervical cancer among HIV-positive women. However, optimal cervical cancer prevention strategies specific to the high-risk population of HIV-positive women remain unknown due, in part, to limited natural history data. Using data from a series of longitudinal natural history studies conducted in Senegal, West Africa among HIV-positive women, we quantify the costs and benefits of targeted screening strategies relevant to sub-Saharan Africa and identify optimal strategies across a wide range of willingness-to-pay (WTP) thresholds.

   Methods: Using a Markov cohort model, we quantified the relative cost-effectiveness of six screening strategies (Hybrid Capture 2 HPV testing, rapid HPV testing, cytology, visual inspection with acetic acid (VIA), HPV testing followed by cytology triage, and HPV testing followed by VIA triage) and five screening frequencies using projected life expectancy and incremental cost-effectiveness ratios (ICER) over a 15-year time horizon. Natural history inputs were estimated from data on over 600 HIV-positive women who were followed for an average of two years between 1994 and 2010. Cytology and HPV DNA testing were performed at approximately 4-month intervals. Competing risk modeling was used to estimate transition probabilities between clinically relevant precancerous natural history stages. Transitions from precancerous stages to cancer were calibrated using a Bayesian Markov chain Monte Carlo approach. One-way and probabilistic sensitivity analyses were conducted to explore the impact of uncertainty on results. Following WHO criterion, strategies with ICERs less than Senegal's 2013 per capita Gross Domestic Product (GDP) were considered ‘very cost-effective' (I$1,050) and strategies less than three times the per capita GDP were considered ‘cost-effective' (I$3,150).

   Results: In base case analyses, VIA was the most cost-effective strategy examined. Compared to no screening, annual VIA resulted in a discounted increased life expectancy of 1.9 months and a 38% reduction in cervical cancer incidence with an ICER of I$1,309 per life year saved. When accounting for uncertainty in all inputs (see Figure 1), VIA emerged as the most likely to be cost-effective at a WTP threshold greater than I$1,440. High underlying HPV prevalence among HIV-positive women substantially reduced the cost-effectiveness of HPV testing.

   Conclusion: Targeted cervical cancer screening of HIV-positive women using VIA represents an important prevention opportunity among this high-risk population.