Cost of HAART in Italy: multicentric evaluation and determinants from a large HIV outpatient cohort.

Background: As HIV infection turned into a chronic treatable disease, now ranking as one of the most costly in medicine, long-term sustainability of highly active antiretroviral treatment (HAART) expenses became a major issue, especially in countries with universal access to care. Identification of determinants of higher HAART costs may therefore help in controlling costs of care, while keeping high levels of retention in care and viral suppression.

Methods: With this aim, we enrolled a large multicentric sample of consecutive unselected human immunodeficiency virus (HIV) patients followed at five sites of care in Italy, and evaluated annual individual HAART costs in relation to a number of sociodemographic, clinical, and laboratory variables.

Results: We enrolled 2,044 patients, including 1,902 on HAART. Mean HAART costs were €9,377±€3,501 (range 782-29,852) per year, with remarkable site-based differences, possibly related to the different composition of local assisted populations. Percentages of patients on viral suppression were homogeneously high across all study sites. The factors identified by cross-validation were line of HAART, diagnosis of acquired immune deficiency syndrome, current CD4 T-cell count, and detectable HIV viremia >50 copies/mL. In the final multivariable model, HAART costs were independently directly associated with more advanced HAART line (P<0.001) and inversely correlated with current CD4 T-cell count (P=0.024). Site of care held independent prediction of higher costs, with marked control of expenses at sites 2 (P=0.001) and 5 (P<0.001).

Conclusion: Higher costs of HAART were strongly associated with previous treatment failures, detectable HIV viremia, and lower CD4 T-cell count at the time of evaluation, with no correlation at all with sex, age, hepatitis C virus coinfection, and nadir CD4 T-cell counts. Newer drugs, which are typically those associated with high prices, at the time of the analysis were still prevalently prescribed to rescue and maintain viral suppression in patients with more complex treatment history. Further analyses of the contribution of the single drug/regimen to the estimated cost are warranted.