The debate about marijuana usage in transplant candidates: recent medical evidence on marijuana health effects

Purpose of review Cannabis is currently the most widely used illicit substance in the world. The issue of how to handle transplant candidates with active use of cannabis is a commonly encountered one for transplant-selection committees. Recent findings Correlates of marijuana use include increased risk of use of other illicit substances, increased risk of affective disorders and psychosis, as well as impaired cognition and motor skills. Risk of fungal infections and possible effects on cellular immunity that may increase cancer risk have also been reported. Reliability of laboratory testing for cannabis is discussed. False-negatives may occur with stealth peroxidases and false-positives with efavirenz (Sustiva). Photometric immunoassay (EMITS) has a 3% false-positive rate. Using a cutoff point of 20 ng/ml with confirmation via GC/MS will give a 'virtually 100% reliable accuracy' in detecting cannabis abuse. Summary Guidelines on management of the problem should be based on objective medical evidence on the health effects of marijuana, as well as on the implications in the transplant setting where medical urgency can drive medical decision-making. A recent survey of 16 academic transplant centers showed little consensus on guidelines for length of abstinence prior to listing candidates for transplantation.