Epidemiology of intensive care.

It is difficult to study the epidemiology of ICUs, as they lack a uniform nomenclature and/or classification. The organization and distribution of intensive care medicine depend on the size and function of the hospital. The patients in ICUs are predominantly men, with a high proportion of elderly patients (greater than or equal to 70 years) constituting 25-30% of the total. Case-mix, severity of illness and outcome differ from one unit to another, and can be compared only if the patients are classified with a common classification system. Most survivors of intensive care seem to return to normal or near normal functional level within one year. Compared to Western Europe, the United States has more ICU beds and a nearly ten times higher admission rate to intensive care. These variations can be seen as a result of a fundamental difference in the attitudes toward withdrawing or withholding life support.