Statins may not affect CD4 cell count responses to HIV treatment, study suggests

An observational cohort study has found that patients taking statins to lower blood cholesterol levels do not have impaired CD4 cell count responses to HIV treatment. The study’s findings were published as a research letter in the 14^th February edition of AIDS.

Statins are widely prescribed to patients with elevated cholesterol levels. Due to their efficacy, safety and few interactions with anti-HIV drugs, they are becoming increasingly important in the treatment of HIV-positive patients.

Recently, doctors from the University of Miami Medical School expressed concern that statins could impair the immunological responses to HIV treatment through their effects on immune system ‘cytokine’ messengers and CD4 T-cells. They called for more research into the drugs’ effects in people on HIV treatment.

Now, doctors from Italy have examined the CD4 cell count increases in patients from their clinic who have been taking statins alongside their HIV drug combinations for up to 18 months. They found that these patients had similar CD4 cell count responses to patients taking fibrate drugs and those who were prescribed exercise and diet modifications to improve their blood fat levels.

The doctors recruited 267 patients for their study, all of whom had been taking antiretroviral therapy consisting of at least two nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs / NtRTIs) with a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor for at least a year. All of the patients had raised blood lipids, with cholesterol above 200mg/dl or triglycerides above 250mg/dl for at least six months.

The doctors added a statin to the anti-HIV drug regimen in 88 (33%) of the patients, in order to lower cholesterol levels. They prescribed pravastatin (Lipostat), atorvastatin (Lipitor) or rosuvastatin (Crestor).

In contrast, they prescribed the 103 patients (39%) with raised triglyceride levels either bezafibrate (Bezalip), fenofibrate (Lipantil) or gemfibrozil (Lopid), while the remaining patients began a diet and exercise programme. All three groups had similar ages, gender distributions, numbers of AIDS diagnoses, viral loads and CD4 cell counts at the start of the study.

After a mean follow-up of 17.4 months, there were no significant differences in CD4 cell counts across the three arms, with mean CD4 cell counts remaining stable at around 380 cells/mm³. However, the doctors did not report which statistical tests they used, or the tests’ results in the published letter.

These findings help to relieve some of the concern surrounding the use of statins alongside HIV treatment. However, prospective and randomised trials including more patients are needed to provide evidence of a lack of detrimental effect of statins on CD4 cell count rises.

In addition, the Italian findings do not address the concern expressed by the Miami doctors that CD4 cell count measurements might give an incomplete picture of the effects of statins on immune system recovery. The results of studies examining the effects, if any, of statins on a range of immune system markers and clinical outcomes are needed before their concerns can be put to rest.