EFFECT OF MANAGEMENT STRATEGIES AND CLINICAL STATUS ON COSTS OF CARE FOR MULTI-DRUG RESISTANT HIV

Purpose: We evaluated the cost incurred by patients with multi drug resistant HIV who participated in OPTIMA, a randomized factorial trial of two interventions: a 12 week structured treatment interruption and intensification of anti-retroviral therapy (ART) to a target of 5 or more drugs.

Method:  Information on anti-retroviral medications, inpatient stays, and outpatient visits was obtained via case report forms.  We used U.S. unit costs. Pharmacy unit cost was the estimated cost to the U.S. AIDS Drug Assistance Program. Other unit costs were based on VA, which accounted for 78% of study enrollments.  Cost was adjusted to 2007 dollars using the Consumer Price Index. ART cost was adjusted by patient reported adherence.  Quarterly observations were created to include cost, serious adverse events, AIDS defining events, CD4 count and viral load (VL).  Data were analyzed with repeated measures generalized linear regression applying gamma distribution and log link function. 

Results: There were 367 participants with cost data.  They were followed for a mean of 15.1 quarters (range 1 – 26).  Cost averaged $8,176 per quarter, including $5,482 for ART, $2,166 for inpatient care, and $516 for outpatient care.  Randomization to structured treatment interruption resulted in $4,009 less cost in the first quarter of the trial (p<.001), because of lower ART cost.  Randomization to ART intensification resulted in $1,847 greater quarterly cost throughout the trial (p<.01).  Interaction between treatment groups was not significant.  Multivariate regressions of the relationship between quarterly cost and clinical characteristics found cost was greater in quarters in which the participant had a serious adverse event, an AIDS defining event, a low CD4 count (<100/mm³), or lower viral load (VL <50,000 copies/ml).  Low ART cost was associated with low CD4 count and high VL (>50,000 copies/ml).  Greater inpatient cost was associated with low CD4 count.  Greater outpatient cost was associated with an AIDS defining event, very low CD4 count, and high VL.

Conclusions: Anti-retroviral drugs accounted for a majority of the cost incurred by patients with multi-drug resistant HIV.  Structured treatment interruption temporarily reduced cost. ART intensification increased cost.  The relationship between cost and serious adverse events, AIDS defining events, CD4 count, and VL provide parameters needed to model the cost-effectiveness of treatments for patients with multi-drug resistant HIV.