Cost-effectiveness of HIV screening in patients older than 55 years of age

Abstract

Background: Although HIV infection is more prevalent in people younger than age 45 years, a substantial number of infections occur in older persons. Recent guidelines recommend HIV screening in patients age 13 to 64 years. The cost-effectiveness of HIV screening in patients age 55 to 75 years is uncertain.

Objective: To examine the costs and benefits of HIV screening in patients age 55 to 75 years.

Design: Markov model.

Data sources: Derived from the literature.

Target population: Patients age 55 to 75 years with unknown HIV status.

Time horizon: Lifetime.

Perspective: Societal.

Intervention: HIV screening program for patients age 55 to 75 years compared with current practice.

Outcome measures: Life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness.

Results of base-case analysis: For a 65-year-old patient, HIV screening using traditional counseling costs $55,440 per QALY compared with current practice when the prevalence of HIV was 0.5% and the patient did not have a sexual partner at risk. In sexually active patients, the incremental cost-effectiveness ratio was $30,020 per QALY. At a prevalence of 0.1%, HIV screening cost less than $60,000 per QALY for patients younger than age 75 years with a partner at risk if less costly streamlined counseling is used.

Results of sensitivity analysis: Cost-effectiveness of HIV screening depended on HIV prevalence, age of the patient, counseling costs, and whether the patient was sexually active. Sensitivity analyses with other variables did not change the results substantially.

Limitations: The effects of age on the toxicity and efficacy of highly active antiretroviral therapy and death from AIDS were uncertain. Sensitivity analyses exploring these variables did not qualitatively affect the results.

Conclusion: If the tested population has an HIV prevalence of 0.1% or greater, HIV screening in persons from age 55 to 75 years reaches conventional levels of cost-effectiveness when counseling is streamlined and if the screened patient has a partner at risk. Screening patients with advanced age for HIV is economically attractive in many circumstances.

Figure 1. Schematic Representation of the Markov Model

The square node at the left represents the decision to screen for HIV or not. The patient’s health thereafter is simulated by a Markov model shown on the right. Patients may enter the model with prevalent HIV infection (asymptomatic or symptomatic HIV or AIDS) or they may be uninfected. Each month, uninfected patients are at risk of developing HIV infection. Patients who have asymptomatic disease may progress to symptomatic HIV or remain in the asymptomatic health state. Patients that have symptomatic HIV infection may progress to an AIDS defining condition, or may remain with symptomatic HIV. Patients with AIDS may either die from their infection or remain with AIDS. Each month all patients may be identified either through a voluntary screening program in the HIV screen arm, or through symptom-based case finding in the symptomatic HIV and AIDS health states in both the HIV screen arm and the No Screening arm. Throughout the patients’ lifetime, all patients are at risk for non-HIV related mortality. Health states are further characterized by viral load level, CD4 count, and antiretroviral treatment history (not shown).

Figure 2. Effect of Early Identification of HIV Infection on Life Expectancy

The effect on undiscounted life expectancy (solid line) and quality-adjusted life expectancy (dashed line) of identifying asymptomatic HIV infection, as compared with symptom-based case finding.

Figure 3. Incremental Cost Effectiveness of HIV Screening in Patients Over 55 Years of Age with Traditional Counseling

Each figure represents the incremental cost effectiveness of HIV screening (assuming traditional counseling) compared with current practice for patients of varying ages with differing underlying prevalence of unidentified HIV. The solid line represents an unidentified HIV prevalence of 0.1%, the black dashed line represents an HIV prevalence of 0.5%, and the grey line represents an HIV prevalence of 1%. In each figure the horizontal dashed lines indicate a cost effectiveness threshold of $50,000 and $100,000 per QALY. (a) Patients with a sexual partner at risk (b) Patients without a partner at risk. QALY = quality-adjusted life year, HIV = human immunodeficiency virus

Figure 4. Incremental Cost Effectiveness of Screening in Patients Over 55 Years of Age with Streamlined Counseling

The incremental cost effectiveness of HIV screening compared with current practice for patients of varying ages with differing underlying prevalence of unidentified HIV assuming implementation of streamlined counseling. The solid line represents an unidentified HIV prevalence of 0.1%, the black dashed line represents an HIV prevalence of 0.5%, and the grey line represents an HIV prevalence of 1%. The horizontal dashed lines indicate a cost effectiveness threshold of $50,000 and $100,000 per QALY or LY gained. (a) Patients with a sexual partner at risk (b) Patients without a partner at risk. QALY = quality-adjusted life year, LY = life year, HIV = human immunodeficiency virus