BackgroundMany studies have compared quality of life of post-intensive care syndrome (PICS) patients with age-matched population-based controls, instead of baseline quality of life. Furthermore, many studies on PICS used the 36-item Short Form (SF-36) health survey questionnaire version 2 but lack the data for SF-36 values before and after intensive care unit (ICU) admission. Thus, the clinically important changes in the parameters of SF-36 are unknown. Therefore, we determined the frequency of co-occurrence of PICS impairments at 6 months after ICU admission. We also evaluated the changes in SF-36 health survey questionnaire subscales and interpreted the patients’ subjective significance of impairment.MethodsA prospective, multicenter, observational cohort study was conducted in 16 ICUs across 14 Japanese hospitals. Adult ICU patients expected to receive mechanical ventilation for > 48 hours were enrolled and their 6-month outcome was assessed using the questionnaires. PICS definition was based on the physical status, change in SF-36 physical component score (PCS) ≥ 10 points; mental status, change in SF-36 mental component score ≥ 10 points; cognitive function, Short-Memory Questionnaire (SMQ) score worsened and SMQ score at 6 months < 40. Multivariate logistic regression model was used to identify the factors associated with PICS occurrence. The patients’ subjective significance of physical and mental symptoms was assessed using the 7-scale Global Assessment Rating.ResultsAmong 192 patients, 48 (29.6%) died at 6 months. Among the survivors at 6 months, 96 patients responded to the questionnaire; ≥1 PICS impairment occurred in 61 (63.5%) patients, and ≥ 2 occurred in 19 (19.9%) patients. Physical, mental, and cognitive impairments occurred in 33.3%, 14.6%, and 37.5% patients, respectively. Low education level was associated with PICS occurrence (Odds ratio: 3.8, 95% confidence interval: 1.1–17.9, P=0.036). Based on the patients’ subjective assessment, a 10-point change in PCS indicated moderate negative change.ConclusionsAmong the survivors who received mechanical ventilation, 64% had PICS at 6 months; co-occurrence of PICS impairments occurred in 20%. PICS occurrence was associated with low educational level. Future studies elucidating the minimal clinically important difference of SF-36 scores among the ICU patients and standardizing the PICS definition are required.Trial registrationUMIN000034072