Cost effectiveness of a computer-delivered intervention to improve HIV medication adherence

Abstract

Background: High levels of adherence to medications for HIV infection are essential for optimal clinical outcomes and to reduce viral transmission, but many patients do not achieve required levels. Clinician-delivered interventions can improve patients' adherence, but usually require substantial effort by trained individuals and may not be widely available. Computer-delivered interventions can address this problem by reducing required staff time for delivery and by making the interventions widely available via the Internet. We previously developed a computer-delivered intervention designed to improve patients' level of health literacy as a strategy to improve their HIV medication adherence. The intervention was shown to increase patients' adherence, but it was not clear that the benefits resulting from the increase in adherence could justify the costs of developing and deploying the intervention. The purpose of this study was to evaluate the relation of development and deployment costs to the effectiveness of the intervention.

Methods: Costs of intervention development were drawn from accounting reports for the grant under which its development was supported, adjusted for costs primarily resulting from the project's research purpose. Effectiveness of the intervention was drawn from results of the parent study. The relation of the intervention's effects to changes in health status, expressed as utilities, was also evaluated in order to assess the net cost of the intervention in terms of quality adjusted life years (QALYs). Sensitivity analyses evaluated ranges of possible intervention effectiveness and durations of its effects, and costs were evaluated over several deployment scenarios.

Results: The intervention's cost effectiveness depends largely on the number of persons using it and the duration of its effectiveness. Even with modest effects for a small number of patients the intervention was associated with net cost savings in some scenarios and for durations greater than three months and longer it was usually associated with a favorable cost per QALY. For intermediate and larger assumed effects and longer durations of intervention effectiveness, the intervention was associated with net cost savings.

Conclusions: Computer-delivered adherence interventions may be a cost-effective strategy to improve adherence in persons treated for HIV.

Trial registration: Clinicaltrials.gov identifier NCT01304186.

Figure 1

Overview of cost effectiveness analysis.

Figure 2

Utilities and costs for health states defined by CD4 counts.Note: Each expression labeled “p(t)” corresponds to a probability drawn from the effectiveness scenarios listed in Table 2. For example, element p(t) for x₁ (the probability that the intervention would be associated with an increase in CD4 causing movement of patients from one group to another) would be 5% for the minimally effective scenario (first line of Table 2).

Figure 3

Cost per QALY for deployment scenarios and duration of effect.Note: For each deployment scenario, the cost per QALY at a moderate level of effectiveness for four possible durations of interventions effect. Black line marks the $50,000 cost per QALY commonly used to assess whether an intervention is considered cost effective.