Long-term survival following intensive care: subgroup analysis and comparison with the general population

This study aimed to compare the very long-term survival of critically ill patients with that of the general population, and examine the association among age, sex, admission diagnosis, APACHE II score and mortality. In a retrospective observational cohort study of prospectively gathered data, 2104 adult patients admitted to the intensive care unit (ICU) of a teaching hospital in Glasgow from 1985 to 1992, were followed until 1997. Vital status at five years was compared with that of an age- and sex-matched Scottish population. Five-year mortality for the ICU patients was 47.1%, 3.4 times higher than that of the general population. For those surviving intensive care the five-year mortality was 33.4%. Mortality was greater than that of the general population for four years following intensive care unit admission (95% confidence interval included 1.0 at four years). Multivariate analysis showed that risk factors for mortality in those admitted to ICU were age, APACHE II score on admission and diagnostic category. Mortality was higher for those admitted with haematological (87.5%) and neurological diseases (61.7%) and septic shock (62.9%). A risk score was produced: Risk Score = 10 (age hazard ratio + APACHE II hazard ratio + diagnosis hazard ratio). None of the patients with a risk score > 100 survived more than five years and for those who survived to five years the mean risk score was 57. Long-term survival following intensive care is not only related to age and severity of illness but also diagnostic category. The risk of mortality in survivors of critical illness matches that of the normal population after four years. Age, severity of illness and diagnosis can be combined to provide an estimate of five-year survival.