Liver toxicity after switching or simplifying to nevirapine-based therapy is not related to CD4 cell counts: results of the TOSCANA study.

Purpose: The TOSCANA study aimed to determine the relationship between CD4 cell counts and liver toxicity in patients undergoing treatment simplification or substitution with nevirapine due to the toxicity or poor tolerability of a previous regimen.

Methods: A retrospective analysis was conducted of patients with prior viral suppression who were switched to nevirapine.

Results: Overall, 221 patients were included, representing 1134.83 patient-years. The median baseline CD4 cell count at the switch was 464 cells/microL, with 75.6% showing high CD4 cell counts (> or =250 cells/microL in women or > or =400 cells/microL in men). Hepatotoxicity, defined as liver aminotransferase levels 5 times above the upper limit of normal, was detected in 6.7% of the participants with high CD4 cell counts and 13.0% in those with low counts. The relative risk was 0.51 (95% CI 0.21-1.25), and the incidence rates were 2.63 and 1.26 per 100 patient-years for the low- and high-count subpopulations, respectively. Liver toxicity was mild, reversible upon discontinuation, and more likely to appear after 6 months of nevirapine therapy.

Conclusions: Switching to nevirapine was associated with a low incidence of liver toxicity that was unrelated to high CD4 cell counts in patients on prior antiretroviral therapy undergoing simplification or substitution therapy.