Pre-existing disease: the most important factor for health related quality of life long-term after critical illness: a prospective, longitudinal, multicentre trial

Introduction: The aim of the present multicenter study was to assess long term (36 months) health related quality of life in patients after critical illness, compare ICU survivors health related quality of life to that of the general population and examine the impact of pre-existing disease and factors related to ICU care on health related quality of life. Methods: Prospective, longitudinal, multicentre trial in three combined medical and surgical intensive care units of one university and two general hospitals in Sweden. By mailed questionnaires, health related quality of life was assessed at 6, 12, 24 and 36 months after the stay in ICU by EQ-5D and SF-36, and information of pre-existing disease was collected at the 6 months measure. ICU related factors were obtained from the local ICU database. Comorbidity and health related quality of life (EQ-5D; SF-36) was examined in the reference group. Among the 5306 patients admitted, 1663 were considered eligible (>24 hrs in the intensive care unit, and age >= 18 yrs, and alive 6 months after discharge). At the 6 month measure 980 (59%) patients answered the questionnaire. Of these 739 (75%) also answered at 12 month, 595 (61%) at 24 month, and 478 (47%) answered at the 36 month measure. As reference group, a random sample (n = 6093) of people from the uptake area of the hospitals were used in which concurrent disease was assessed and adjusted for. Results: Only small improvements were recorded in health related quality of life up to 36 months after ICU admission. The majority of the reduction in health related quality of life after care in the ICU was related to the health related quality of life effects of pre-existing diseases. No significant effect on the long-term health related quality of life by any of the ICU-related factors was discernible. Conclusions: A large proportion of the reduction in the health related quality of life after being in the ICU is attributable to pre-existing disease. The importance of the effect of pre-existing disease is further supported by the small, long term increment in the health related quality of life after treatment in the ICU. The reliability of the conclusions is supported by the size of the study populations and the long follow-up period.