The original description of the persistent vegetative state was careful to note that no data were then available to indicate how long this state must persist before it can be declared permanent. Since then there have been a number of published reports, the analysis of which led the US Task Force in 1994 (1) to publish tables that are now widely accepted as a basis for decision making by both the medical and legal professions. Before considering these it is important to consider how data on outcome has accumulated over the years and has informed various prognostic statements before the Task Force paper.

Data on recovery

In a follow-up for 1–7 years of 62 patients who had been completely apallic after head injury, Pagni et al. (2) reported in 1977 that 38 were dead, ten severely disabled and nine independent. In 1978, Levy et al. (3) reported on the follow-up of 25 patients who had been vegetative 1 month after nontraumatic coma. By the end of a year only two had uttered any words but neither had obeyed commands; by then one of these two and 17 others had died. In 1980, Bricolo et al. (4) reported 135 cases who were unconsciousness for at least 2 weeks after head injury, of whom 102 had eye opening at 1 month. By 3 months, 52% were obeying commands, with an additional 13% doing so by 6 months, and 1.5% more by 12 months.