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Journal Club. Alcohol, Other Drugs, and Health: Current Evidence July–August 2013. Featured Article. Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomised, double-blind, placebo-controlled phase 3 trial.
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Journal Club Alcohol, Other Drugs, and Health: Current Evidence July–August 2013
Featured Article Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomised, double-blind, placebo-controlled phase 3 trial Choopanya K, et al. Lancet. 2013;381(9883):2083–2090.
Study Objective • To assess whether daily oral use of tenofovir disoproxil fumarate (tenofovir), an antiretroviral, can reduce HIV transmission (acquisition) in people with injection drug use. www.aodhealth.org
Study Design • Randomized, double-blind, placebo-controlled trial. • Population was 2413 volunteers from 17 drug-treatment clinics in Bangkok, Thailand who were eligible if they were aged 20–60 years, were HIV-negative, and reported injecting drugs during the previous year. • Participants were assigned to either tenofovir (N=1204) or placebo (N=1209). They were enrolled between 2005 and 2010. • Subjects chose either daily directly observed treatment or monthly visits and could switch at monthly visits. • All subjects received monthly HIV testing, individualized risk-reduction and adherence counseling, blood “safety assessments” every 3 months, and were offered condoms and methadone treatment (if indicated). www.aodhealth.org
Assessing Validity of an Article about Therapy • Are the results valid? • What are the results? • How can I apply the results to patient care? www.aodhealth.org
Are the Results Valid? • Were patients randomized? • Was randomization concealed? • Were patients analyzed in the groups to which they were randomized? • Were patients in the treatment and control groups similar with respect to known prognostic variables? www.aodhealth.org
Are the Results Valid?(cont‘d) • Were patients aware of group allocation? • Were clinicians aware of group allocation? • Were outcome assessors aware of group allocation? • Was follow-up complete? www.aodhealth.org
Were patients randomized? • Yes. • Participants were randomized in blocks of 4 to either tenofovir or placebo. www.aodhealth.org
Was randomization concealed? • Yes. • Subjects were randomized using a computer-generated randomization sequence. www.aodhealth.org
Were patients analyzed in the groups to which they were randomized? • Yes (intention-to-treat analysis). www.aodhealth.org
Were the patients in the treatment and control groups similar? • No. • Baseline characteristics differed on sexual intercourse with a casual partner in the past 12 weeks and men having sex with men in the past 12 weeks, both of which were more common in the placebo group (40% versus 36% and 6% versus 4%, respectively). www.aodhealth.org
Were patients aware of group allocation? • No. • Participants were masked to treatment group assignment. • Tenofovir and placebo tablets were similar in shape, color, and taste. www.aodhealth.org
Were clinicians aware of group allocation? • No. • Study staff were masked to treatment group assignment. www.aodhealth.org
Were outcome assessors aware of group allocation? • No. • Two researchers were unmasked after the data were locked. www.aodhealth.org
Was follow-up complete? • No. • The authors followed-up participants for 9665 person-years. There were no differences in follow-up time, withdrawal, or loss to follow-up between treatment groups. • Of the tenofovir group, 409 of 1204 participants did not provide complete follow-up. • Of the placebo group, 410 of 1209 participants did not provide complete follow-up. www.aodhealth.org
What Are the Results? • How large was the treatment effect? • How precise was the estimate of the treatment effect? www.aodhealth.org
How large was the treatment effect? • The authors confirmed HIV infection in 52 participants total: • 17 (33%) in the tenofovir group. • 35 (67%) in the placebo group. • There was a 48.9% reduction in HIV incidence in the tenofovir group compared with the placebo group in the intention-to-treat analysis (an incidence of 0.35 per 100 person-years versus 0.68 per 100 person-years). The cumulative probability of HIV infection in the two groups separated consistently after 36 months. www.aodhealth.org 17
How Can I Apply the Results to Patient Care? • Were the study patients similar to the patients in my practice? • Were all clinically important outcomes considered? • Are the likely treatment benefits worth the potential harm and costs? www.aodhealth.org
Were the study patients similar to those in my practice? • The study took place in Bangkok, Thailand. • Demographics included: • % Male: 80 • Education level of primary school or less: mean 48% • Largest age group represented: 20–29 (mean 43%) • Clinical characteristics • 63% of subjects injected drugs in the 12 weeks prior to study enrollment • Largest percentage of subjects reported injecting less frequently than every week (mean 32%) www.aodhealth.org
Were all clinically important outcomes considered? • Yes. • The trial was not powered to assess efficacy by subgroup, but tenofovir showed statistically significant reductions in HIV incidence among women (79%,P=0.03) and participants aged ≥40 years (89%, P=0.01). www.aodhealth.org
Are the likely treatment benefits worth the potential harm and costs? • Yes. • This study is the first to show that daily oral pre-exposure prophylaxis with tenofovir, used in combination with other HIV prevention strategies, reduces the risk of HIV infection among people with injection drug use. • Prevalence of nausea and/or vomiting was slightly higher in tenofovir group over placebo (8% versus 5%). • Costs were not reported. www.aodhealth.org