Analytical approach:
The analysis was based on a published model of HIV infection, which consisted of a state-transition first-order Monte Carlo simulation. A short-term and a lifetime horizon were considered. The authors stated that a modified societal perspective was adopted.
Effectiveness data:
The clinical data came from a selection of relevant studies. Most of the evidence was from the 262 patients in the US arms of the published AIDS Clinical Trials Group (ACTG) A5164 trial, which provided data on the baseline characteristics of patients, the rates of opportunistic infection at presentation to care, and the efficacy of first-line treatment. Additional data to extend the short-term evidence to the long-term and to estimate the natural progression of disease were from other sources, including the Multicenter AIDS Cohort Study. Early versus late ART efficacy was the key clinical input for the analysis.
Monetary benefit and utility valuations:
The utility values were from a published study.
Measure of benefit:
Quality-adjusted life-years (QALYs) were the summary benefit measure and were discounted at an annual rate of 3%.
Cost data:
The economic analysis included in-patient and out-patient costs, emergency department visits, and ART regimens (including personnel time). The resource use data were from a cohort of patients enrolled at HIV Research Network sites (59,093 patient-months). It was assumed that the resources required for early ART were at least 5% of the annual work of a physician, a registered nurse, and a case manager. The costs were from the medical literature, the University Health System Consortium, average wholesale prices, and average annual salaries from the Bureau of Labor Statistics. All costs were in US dollars ($) and a 3% annual discount rate was applied. The price year was 2008.
Analysis of uncertainty:
Several one-way sensitivity analyses were carried out on the per-patient intervention cost, the cluster of differentiation 4 (CD4) cell count and opportunistic infection distribution at presentation to care, the rates of successful referral to and retention in out-patient care, the delay from presentation to ART initiation for patients on late ART, the efficacy of first-line ART, the incidence of immune reconstitution inflammatory syndrome (IRIS), and the assumption of no IRIS-related deaths in patients on early ART.