Incidence and prevalence of the vegetative and minimally conscious states.

The methodological difficulties of obtaining accurate epidemiological data for vegetative state (VS) and minimally conscious state (MCS) are considered, and prompt the conclusion that published data are of uncertain validity, partly due to variation in the criteria for diagnosis. On the basis of these data, incidence of VS continuing for at least six months arises at a rate of between 5 and 25 per million population (PMP). The prevalence of VS in adults in the US is between 40 and 168 PMP, and may be lower in the UK, but precise figures are not available. The incidence and prevalence of MCS have yet to be established.