The Cost-Effectiveness of Human Immunodeficiency Virus Testing and Treatment Engagement Initiatives in British Columbia, Canada: 2011-2013

Abstract

Background: Recognition of the secondary preventive benefits of antiretroviral therapy (ART) has mobilized global efforts to "seek, test, treat, and retain" people living with human immunodeficiency virus [HIV]/AIDS (PLHIV) in HIV care. We aimed to determine the cost-effectiveness of a set of HIV testing and treatment engagement interventions initiated in British Columbia, Canada, in 2011-2013.

Methods: Using a previously validated dynamic HIV transmission model, linked individual-level health administrative data for PLHIV, and aggregate-level HIV testing data, we estimated the cost-effectiveness of primary care testing (hospital, emergency department [ED], outpatient), ART initiation, and ART retention initiatives vs a counterfactual scenario that approximated the status quo. HIV incidence, mortality, costs (in 2015$CDN), quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios were estimated. Analyses were executed over 5- to 25-year time horizons from a government-payer perspective.

Results: ED testing was the best value at $30216 per QALY gained and had the greatest impact on incidence and mortality among PLHIV, while ART initiation provided the greatest QALY gains. The ART retention initiative was not cost-effective. Delivered in combination at the observed scale and sustained throughout the study period, we estimated a 12.8% reduction in cumulative HIV incidence and a 4.7% reduction in deaths among PLHIV at $55258 per QALY gained. Results were most sensitive to uncertainty in the number of undiagnosed PLHIV.

Conclusions: HIV testing and ART initiation interventions were cost-effective, while the ART retention intervention was not. Developing strategies to reengage PLHIV lost to care is a priority moving forward.

Figure 1.

Historical trends and estimated British Columbia Ministry of Health Seek and Treat for Optimal Prevention of HIV/AIDS intervention effects for human immunodeficiency virus (HIV) test initiatives. Historical aggregate-level HIV testing rates (left-hand sides of panels A–C) were extrapolated to generate counterfactual HIV testing rates, approximating the status quo (ie, no additional public health investments to scale-up testing) for the intervention period (dashed lines). Information on actual testing rates in Vancouver Coastal Health Authority, adjusted using external data, were used to estimate testing rates for each setting and by HIV risk group during the intervention period. Abbreviations: ED, emergency department; HIV, human immunodeficiency virus; MSM, men who have sex with men; PWID, people who inject drugs.

Figure 2.

Historical trends and estimated British Columbia Ministry of Health Seek and Treat for Optimal Prevention of human immunodeficiency virus/AIDS intervention effects for highly active antiretroviral treatment (ART) initiation and retention initiatives. The observed monthly probability of ART initiation among diagnosed people who inject drugs (PWID; panel A) and non-PWID (panel B) for British Columbia from 1996–2010 was used to generate counterfactual ART initiation probabilities approximating the status quo (ie, no additional public health investments to support ART initiation) for the intervention period (dashed line). ART initiation probabilities in Vancouver Coastal Health Authority, observed in linked individual-level data, were used to determine the intervention effect. The same procedure was used to determine probabilities of ART reentry (panels C and D). To adequately capture changes in the probability of ART dropout within the dynamic simulation model, we extrapolated counterfactual CD4-based transition probabilities using multistate Markov models for PWID and non-PWID (panels E and F) and estimated observed dropout probabilities during the intervention period using similar procedures as described above. Abbreviations: ART, highly active antiretroviral treatment; PWID, people who inject drugs.

Figure 3.

Epidemiological effects of the British Columbia Ministry of Health Seek and Treat for Optimal Prevention of HIV/AIDS initiative interventions evaluated (25-year time horizon). Estimated effects of each human immunodeficiency virus (HIV) care intervention on averted incident cases (panel A) and deaths among people living with human immunodeficiency virus (panel B), by HIV risk group, over the complete study time horizon. *Combined initiatives to prevent treatment dropout and enhance reengagement. **Reverting back to the counterfactual status quo-levels of HIV testing and treatment engagement for the remainder of the study time horizon. Abbreviations: ART, highly active antiretroviral treatment; ED, emergency department; HET, heterosexual; HIV, human immunodeficiency virus; MSM, men who have sex with men; PLHIV, people living with human immunodeficiency virus; PWID, people who inject drugs.

Figure 4.

Results of sensitivity analyses on human immunodeficiency virus (HIV) prevalence. The size of population of people living with HIV in 2010 was set to the lower or upper bounds of provincial HIV prevalence estimates in 2010 from the public health agency of Canada. All results were for the combined intervention, sustained over the complete study time horizon. Abbreviations: ICER, incremental cost-effectiveness ratio; QALY, quality-adjusted life-years.

Figure 5.

Sensitivity analysis on proportion of risk groups in human immunodeficiency virus (HIV) testing in hospital, outpatient clinic, and emergency department (ED) settings. The baseline distribution of HIV testing in each setting was as follows: hospital-based: 92.7% heterosexual, 3.3% men who have sex with men (MSM), 4.0% people who inject drugs (PWID); outpatient clinic: 96.6% heterosexual, 2.1% MSM, 1.3% PWID; ED: 94.7% heterosexual, 3.2% MSM, 2.0% PWID. The proportions of heterosexuals tested in each scenario were adjusted accordingly. All results were for the combined intervention, sustained over the complete study time horizon. Abbreviations: HIV, human immunodeficiency virus; ICER, incremental cost-effectiveness ratio; MSM, men who have sex with men; PWID, people who inject drugs; QALY, quality-adjusted life-years.

Figure 6.

Sensitivity analysis on the effectiveness of the combined British Columbia Ministry of Health Seek and Treat for Optimal Prevention of human immunodeficiency virus/AIDS pilot interventions. All results were for the combined intervention, sustained over the complete study time horizon. Abbreviations: ICER, incremental cost-effectiveness ratio; QALY, quality-adjusted life-years.