Effect of Folic Acid on Homocysteine Levels and Flow-mediated Dilation in HIV and HIV-HCV Coinfected Patients: a Randomized Controlled Trial

Study design: This was a randomized placebo-controlled trial, with blinding of health care team, participants, and investigators, in which the participants were randomly assigned in a 1:1 ratio to receive FA or placebo for four weeks.

Participants: Patients receiving care for HIV, at the outpatient clinic of the Hospital Universitario de Santa Maria, in southern Brazil, from October 2012 to September 2013, were recruited. Eligible participants: HIV infected or HIV-HCV coinfected patients, 18-50 years, men and women, receiving HAART, had undetectable viral load for more than six months. Patients were excluded: patients with diabetes mellitus, previous acute myocardial infarction, myocardial revascularization, or stroke, creatinine >1.5 mg/dL, clinical diagnosis or ultrasound, endoscopic, or laboratory evidence of liver cirrhosis, on treatment with statins, fibrates, hormone replacement therapy, sulfonamides, vitamin supplements, or FA in the last 30 days, and pregnant women.

Intervention Patients assigned to the intervention group received FA 5 mg, per oral, once a day, in the morning, during four weeks. Patients assigned to the placebo group received the same prescription. The trial provided FA and placebo in tablet form, identical in color, smell, taste, shape, and size. Both FA and placebo were prepared in a single batch, in an independent laboratory, by a pharmacist with no involvement in the trial. They were pre-packed in bottles containing 30 tablets each, individually labeled with an alphanumeric code and stored.

Outcomes The primary endpoint were changes in homocysteine, vitamin B12 levels, and brachial artery FMD during reactive hyperemia, as measured by Doppler ultrasound, from randomization to the end of follow-up. FMD was characterized by the variation in mean arterial flow measured as the peak change in vessel diameters relative to the baseline.

Sample size Sample size was calculated based on the results of a previous RCT,(14) which used plethysmography to measure FMD. To detect a difference of at least 6% between intervention and placebo groups, with standard deviations ranging from 5% to 7%, we calculated that a sample size of at least 17 patients per group, with randomization stratified by HCV coinfection status, was required to achieve 80% power and a 95% confidence interval.