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Costing implications of recent treatment interruption studies

Gill, M John; Krentz, Hartmut B

doi: 10.1097/01.aids.0000252057.02187.73

Southern Alberta Clinic and Department of Medicine, University of Calgary, Calgary, Alberta, Canada.

Received 18 May, 2006

Accepted 21 June, 2006

HAART has been shown to be effective at arresting HIV replication, usually leading to a healthier immune system and ultimately improved health and survival [1]. Unfortunately, lifelong HAART is not only expensive but also exposes an individual to unknown toxicities from long-term antiretroviral exposure. Attempts to minimize both the financial burden as well the cumulative antiretroviral exposure have led to approaches such as initiating therapy at lower CD4 cell counts as well as the use of treatment interruptions. Recently, both the SMART [2] and Trivacan [3] studies, which were investigating the use of treatment interruption followed by CD4 cell-directed therapy, were prematurely stopped on safety grounds. They showed compelling evidence that the treatment interruption/CD4 cell-directed therapy strategy led to an increased risk of HIV disease progression. The SMART study also unexpectedly showed a greater risk of non-HIV-related health problems for the treatment interruption patients. Both studies suggested that continuing with antiretroviral treatment is advisable for all patients with CD4 cell counts less than 350 cells/μl. In both US [4] and Canadian [5] comprehensive costing studies, antiretroviral drugs have been shown to be the major driver of HIV care costs. We wished to explore the financial implications of these studies in a well-defined geographical population using a previously published costing model [5,6].

We identified all active HIV-infected patients followed in our population as of 1 January 2006. We distinguished between HAART-naive and HAART-experienced patients, subdividing the latter group into patients who are on or off (i.e. a treatment interruption) HAART. We examined the potential cost implications of the SMART and Trivacan findings by asking two questions: (i) what are the budgetary implications if all treatment interruption patients were restarted on HAART; and (ii) if all treatment-naive patients with CD4 cell counts of less than 350 cells/μl were immediately started on HAART? As the actual costs of antiretroviral drugs vary by region, country and healthcare system, we have reported changes in percentages rather than dollar amounts. We used the same data collection and analysis as previously reported [5,6], using a standard three-drug regimen to determine an average cost per regimen and provide upper and lower cost limits depending on the antiretroviral drug choice.

At the beginning of 2006, 867 HIV patients were being followed in our regional population; 79% were HAART experienced and 21% were HAART naive. Fourteen per cent of the HAART-experienced patients were on a treatment interruption of varying lengths. If all patients on a treatment interruption were restarted on standard HAART, the budgetary cost for our population would increase by 15% (low estimate 12%; high estimate 17%). If all antiretroviral-naive patients with a CD4 cell count less than 350 cells/μl also initiated HAART the total costs of antiretroviral drugs for the population would increase further to a total of 23% above current actual costs (low estimate 21%; high estimate 25%). Therefore, aggressive interpretation and implementation of the SMART study findings would overall increase the budgetary cost of antiretroviral drugs significantly.

We have only modeled the potential costs of the SMART and Trivacan findings on the antiretroviral drug budget. We have not examined any potential cost savings that may occur as a result of the improved health, nor have we quantified the additional costs for monitoring HAART and managing its potential toxicities, but believe these costs would be relatively small when compared with the antiretroviral drug costs. These cost implications might vary marginally between HIV centres and populations depending on the number of patients who are antiretroviral-naive or are on a treatment interruption and the antiretroviral regimen used.

The SMART and Trivacan study findings, however, have major cost implications to fund holders of the antiretroviral drug budget. In addition, delaying therapy or interrupting therapy will no longer balance the costs of using four or more antiretroviral drugs per regimen or for the higher costs of novel antiretroviral agents entering care. It is too early to determine whether the changes suggested by these studies are ‘cost-effective’ in the long term, but continuous monitoring of changing clinical practices is warranted.

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© 2006 Lippincott Williams & Wilkins, Inc.