Background: The use of cannabis (marijuana) or of its psychoactive ingredient delta-9-tetrahydrocannabinol (THC) as a medicine has been highly contested in many settings.There have been claims that smoked or ingested cannabis, either in its natural form or artificial form (pharmaceutically manufactured drug such as dronabinol), improves the appetites of people with AIDS, results in weight gain and lifts mood, thus improving the quality of life.
Objectives: The objectives of this review were to assess whether cannabis (in its natural or artificially produced form), either smoked or ingested, decreases the morbidity or mortality of patients infected with HIV.
Search methods: The search strategy was conducted to July 2012 and was based on that of the Cochrane HIV/AIDS Review Group. We searched the following databases: CENTRAL/CCTR, MEDLINE and EMBASE. In addition, searching was performed where necessary of journals, reference lists of articles, and conference proceedings.
Selection criteria: The review included randomised controlled trials (RCTs) of any cannabis intervention, in any form, and administered by any route, in adults with HIV or AIDS, compared with placebo or with a known effective treatment, and conducted in a hospital, outpatient clinic, or home care setting. Quasi-randomised studies using any form of cannabis as an intervention in patients with HIV or AIDS were also included.
Data collection and analysis: Data from the eligible studies were extracted and coded independently by two researchers, using a standardised data extraction form. Data were then analysed using RevMan 5.0. No meta-analyses were performed.
Main results: A total of seven relevant studies were included in the review, reported in eight publications. All were randomised controlled studies, with four utilising a parallel group design, two a within-subject randomisation and two a cross-over design. All of the studies were of a fairly short duration, ranging from 21 days to 84 days. In only four papers (in effect, three studies) were sequence generation and allocation concealment judged to be adequate. The use of cannabis and rapidly acting cannabinoids posed considerable challenges for blinding, as the psychoactive effects are expected to be quickly discernible to study participants, particularly those who have been previous users of such products. Dronabinol was expected to be more easily blinded. The outcomes measured were variable, including change in weight, change in body fat (measured as a percentage of total body weight), change in appetite (measured on a visual analogue scale), change in caloric intake (measured in kcals/kg/24hr), change in nausea and vomiting (measured on a visual analogue scale), change in performance (measured by Karnofsky performance score or specific tests for memory and dexterity) and change in mood (measured on a visual analogue scale).The evidence for substantial effects on morbidity and mortality is currently limited. Data from only one relatively small study (n=139, of which only 88 were evaluable), conducted in the period before access to highly-active antiretroviral therapy (HAART), showed that patients administered dronabinol were twice as likely to gain 2kg or more in body weight (RR 2.09), but the confidence interval for this measure (95% CI 0.72 - 6.06) included unity. The mean weight gain in the dronabinol group was only 0.1kg, compared with a loss of 0.4kg in the placebo group. However, the quality of sequence generation and allocation concealment in this study, in which participants were randomised by centre, could not be assessed.
Authors' conclusions: Despite dronabinol being registered by at least some medicines regulatory authorities for the treatment of AIDS-associated anorexia, and some jurisdictions making allowances for the "medical" use of marijuana by patients with HIV/AIDS, evidence for the efficacy and safety of cannabis and cannabinoids in this setting is lacking. Such studies as have been performed have been of short duration, in small numbers of patients, and have focused on short-term measures of efficacy. Long-term data, showing a sustained effect on AIDS-related morbidity and mortality and safety in patients on effective antiretroviral therapy, has yet to be presented. Whether the available evidence is sufficient to justify a wide-ranging revisiting of medicines regulatory practice remains unclear.