Cost-effectiveness of HPV-based cervical cancer screening in the public health system in Nicaragua

Abstract

Objectives: To evaluate the cost-effectiveness of human papillomavirus (HPV) DNA testing (versus Papanicolaou (Pap)-based screening) for cervical cancer screening in Nicaragua.

Design: A previously developed Monte Carlo simulation model of the natural history of HPV infection and cervical cancer was calibrated to epidemiological data from Nicaragua. Cost data inputs were derived using a micro-costing approach in Carazo, Chontales and Chinandega departments; test performance data were from a demonstration project in Masaya department.

Setting: Nicaragua's public health sector facilities.

Participants: Women aged 30-59 years.

Interventions: Screening strategies included (1) Pap testing every 3 years, with referral to colposcopy for women with an atypical squamous cells of undetermined significance or worse result ('Pap'); (2) HPV testing every 5 years, with referral to cryotherapy for HPV-positive eligible women (HPV cryotherapy or 'HPV-Cryo'); (3) HPV testing every 5 years, with referral to triage with visual inspection with acetic acid (VIA) for HPV-positive women ('HPV-VIA'); and (4) HPV testing every 5 years, with referral to Pap testing for HPV-positive women ('HPV-Pap').

Outcome measures: Reduction in lifetime risk of cancer and incremental cost-effectiveness ratios (ICER; 2015 US$ per year of life saved (YLS)).

Results: HPV-based screening strategies were more effective than Pap testing. HPV-Cryo was the least costly and most effective strategy, reducing lifetime cancer risk by 29.5% and outperforming HPV-VIA, HPV-Pap and Pap only, which reduced cancer risk by 19.4%, 12.2% and 10.8%, respectively. With an ICER of US$320/YLS, HPV-Cryo every 5 years would be very cost-effective using a threshold based on Nicaragua's per capita gross domestic product of US$2090. Findings were robust across sensitivity analyses on test performance, coverage, compliance and cost parameters.

Conclusions: HPV testing is very cost-effective compared with Pap testing in Nicaragua, due to higher test sensitivity and the relatively lower number of visits required. Increasing compliance with recommended follow-up will further improve the health benefits and value for public health dollars.

Keywords: epidemiology; health economics; public health.

Figure 1

Pathways of care, by screening strategy. Each diagram indicates the flow of screening-eligible women (ie, women aged 30 to 59 years) through each point of contact in a screening episode, conditional on visit compliance and test results, for (A) Pap testing every 3 years (Pap), which requires four visits for screening, diagnosis and treatment; (B) HPV testing with referral to cryotherapy for all HPV-positive eligible women every 5 years (HPV-Cryo), which requires three or more visits for screening and necessary treatment; (C) HPV testing followed by visual inspection with acetic acid (VIA) triage of HPV-positive women every 5 years (HPV-VIA), which requires three or more visits for screening and necessary treatment; and (D) HPV testing followed by Pap triage of HPV-positive women every 5 years (HPV-Pap), which requires five or more visits for screening and necessary treatment. ASCUS , Pap result of atypical squamous cells of undetermined significance or worse; CIN, cervical intraepithelial neoplasia; HPV, human papillomavirus; LEEP, loop electrosurgical excision procedure; VIA, visual inspection with acetic acid.

Figure 2

Cervical cancer screening cost per woman over the duration of screening eligibility, by cost component: Pap testing (every 3 years) versus careHPV testing (every 5 years). Bars indicate the undiscounted cost (2015 US$) of screening with Pap testing (offered 10 times between ages 30 and 59 years) versus careHPV testing (offered six times between ages 30 and 59 years), by cost component. Only screening costs are shown; costs associated with recommended management following a positive screening test are not included. 6×, delivered six times over the course of screening eligible ages 30 to 59; 10×, delivered 10 times over the course of screening eligible ages.

Figure 3

Cost-effectiveness analysis: base-case results. The graph displays the discounted lifetime costs (x axis; in 2015 US$) and life expectancy (y axis) associated with each screening strategy (Pap testing every 3 years, careHPV every 5 years with cryotherapy for HPV-positive eligible women (HPV-Cryo), careHPV every 5 years with visual inspection with acetic acid (VIA) triage of HPV-positive women (HPV-VIA) and careHPV every 5 years with Pap triage of HPV-positive women (HPV-Pap)), under base-case assumptions. The cost-effectiveness associated with a change from one strategy to a more costly alternative is represented by the difference in cost divided by the difference in life expectancy associated with the two strategies. The curve indicates the strategies that are efficient because they are more effective and either (1) cost less or (2) have a more attractive cost-effectiveness ratio than less effective options. The incremental cost-effectiveness ratio (ICER) is the reciprocal of the slope of the line connecting the two strategies under comparison. In the base-case analysis, HPV-Cryo every 5 years was less costly and more effective than other screening strategies considered and was thus a dominant strategy with an ICER of US$320 per year of life saved. HPV-Cryo, HPV testing with cryotherapy for HPV-positive women; HPV-Pap, HPV testing with Pap triage of HPV-positive women; HPV-VIA, HPV testing with visual inspection with acetic acid triage of HPV-positive women; yrs, years.

Figure 4

Reduction in lifetime risk of cervical cancer, by compliance level. Bars indicate the per cent reduction in lifetime risk of cervical cancer for each screening strategy (Pap testing every 3 years, careHPV every 5 years with cryotherapy for HPV-positive women (HPV-Cryo), careHPV every 5 years with visual inspection with acetic acid (VIA) triage of HPV-positive women (HPV-VIA) and careHPV every 5 years with Pap triage of HPV-positive women (HPV-Pap)) as compliance per visit within a screening episode increases. Compliance is defined as the proportion of women who return for each clinical encounter, relative to the previous visit. Coverage of the target population is assumed to be 70%. While the base-case analysis assumed 85% compliance for visits at screening facilities and 40% compliance for visits at referral facilities (for diagnosis and treatment), the graph displays cancer risk reduction assuming the specified compliance level at all visits, regardless of facility type.

Figure 5

Base-case and sensitivity analyses: incremental cost-effectiveness ratios, HPV cryotherapy (HPV-Cryo) strategy. Incremental cost-effectiveness ratios (ICER) are presented (x-axis, 2015 US$ per year of life saved) for the base-case and sensitivity analyses (y-axis). The blue bars represent the range of the ICER for HPV-Cryo every 5 years across the 50 input parameter sets, with the ICER of the mean costs divided by the mean effects demarcated by a black line. The dashed blue line indicates Nicaragua’s per capita gross domestic product (GDP), at US$2,090, assuming this is the threshold that designates interventions as ‘very cost-effective’.