Estimating the resources required in the roll-out of universal access to antiretroviral treatment in Zimbabwe

Abstract

Objectives: To develop projections of the resources required (person-years of drug supply and healthcare worker time) for universal access to antiretroviral treatment (ART) in Zimbabwe.

Methods: A stochastic mathematical model of disease progression, diagnosis, clinical monitoring and survival in HIV infected individuals.

Findings: The number of patients receiving ART is determined by many factors, including the strategy of the ART programme (method of initiation, frequency of patient monitoring, ability to include patients diagnosed before ART became available), other healthcare services (referral rates from antenatal clinics, uptake of HIV testing), demographic and epidemiological conditions (past and future trends in incidence rates and population growth) as well as the medical impact of ART (average survival and the relationship with CD4 count when initiated). The variations in these factors lead to substantial differences in long-term projections; with universal access by 2010 and no further prevention interventions, between 370 000 and almost 2 million patients could be receiving treatment in 2030-a fivefold difference. Under universal access, by 2010 each doctor will initiate ART for up to two patients every day and the case-load for nurses will at least triple as more patients enter care and start treatment.

Conclusions: The resources required by ART programmes are great and depend on the healthcare systems and the demographic/epidemiological context. This leads to considerable uncertainty in long-term projections and large variation in the resources required in different countries and over time. Understanding how current practices relate to future resource requirements can help optimise ART programmes and inform long-term public health planning.

Figure 1

Assumptions about course of epidemic and scale-up of antiretroviral treatment (ART) programme. A. Estimated and projected numbers of new HIV infections in Zimbabwe between 1980 and 2030. B. Estimated and projected fraction of population to whom ART is available.

Figure 2

Antiretroviral treatment (ART) and monitoring requirement in a HIV infected cohort. A. Number of simulated appointments in a cohort of 1000 HIV infected individuals over time since infection. B. The number of individuals currently receiving ART in a cohort of 1000 infected individuals over time since infection. C. The number of individuals currently receiving ART in cohorts of 1000 individuals infected in 1993, 1998, 2003 and 2007 over calendar year. Here ART is assumed to become available to all cohorts equally in 2008. D. The number of healthcare appointments to assess the need for ART with individuals in cohorts infected in 1993, 1998, 2003 and 2007 over calendar year. Unless stated otherwise, in all plots, patients are monitored every 6 months and ART is started using CD4 counts. (Note: in all these cohort simulations, it assumed that all individuals are infected at the same time.)

Figure 3

Projected numbers on antiretroviral treatment (ART) and healthcare requirements in Zimbabwe. The assumptions made are the defaults listed in table 1: symptomatic initiation, monitoring all patients every 6 months, ‘medium’ survival assumptions, high antenatal clinical referral but low testing uptake, some surviving individuals diagnosed before ART available enter the programme and no further high-impact behaviour change intervention.

Figure 4

Alternative projections in increasing case-load for doctors and nurses in A) 2010 and B) 2030. Under the ‘current’ management strategy, antiretroviral treatment (ART) is started and patients are monitored as in the default assumptions in figure 3 and table 1. In the ‘optimal’ scenario, instead ART is started using CD4 counts, patients are monitored every 3 months, testing uptake is high and many surviving individuals diagnosed before ART available enter the programme. The ‘optimal + intv’ scenario is the same as ‘optimal’ scenario but HIV incidence is assumed to decline in response to scale-up of a highly effective HIV prevention intervention. It is assumed that the number of doctors and nurses trained and in active service is constant.