An exploration of the prevalence of post-intensive care syndrome and its associated factors among patients discharged from one ICU in the People's Republic of China

Post-Intensive Care Syndrome (PICS) is recognised as encompassing a spectrum of physical, psychological, cognitive, and social impairments experienced by survivors of critical illness. An increasing number of studies indicate that intensive care unit (ICU) survivors frequently encounter PICS after their ICU admission globally. However, research on the prevalence and factors contributing to its occurrence is limited in China. The aims and objectives of this thesis were to determine the prevalence of PICS in its various forms among Chinese adults after ICU treatment and to identify demographic and clinical variables, including age, gender, educational level, employment status, APACHE II scores at admission, length of ICU stays, the use of mechanical ventilation, administration of sedatives, and early mobilisation, their association with PICS severity in this population. A concept analysis of PICS was first conducted following Walker and Avant's eight-step framework. An operational definition was developed by identifying its attributes, antecedents, consequences, and empirical referents. PICS is defined as "a new or worsening co-occurrence of physical dysfunctions, psychological disorders, cognitive impairments, or failed social reconstruction, with these impairments persisting beyond ICU and hospital discharge." This definition highlights the critical, yet often overlooked, aspect of social well-being in PICS and its profound impact on patients. Building upon the operational definition and identified attributes of PICS established in the concept analysis, a scoping review was carried out to map the existing instruments used to assess PICS. The review demonstrated various assessment tools, yet none fully and accurately captured all the defining attributes of PICS. Furthermore, none of the included studies conducted content validity analyses, and reporting on other psychometric properties was inconsistent and incomplete. To achieve the aims of this thesis, an instrument- the post-intensive care syndrome assessment scale (PICSAS)- was developed and validated. The item pool was developed based on concept analysis and scoping review findings. Experts with PICS research or ICU work backgrounds and ICU patient representatives reviewed this item pool. In addition, structural validity and Cronbach’s α were analysed. The 22-item instrument exhibited an acceptable S-CVI of 0.85, and Cronbach’s α for the total PICSAS was 0.96. Factor analysis revealed a four-factor structure and explained 73.5% of the total variance, and item factor loadings all exceeded 0.5. Finally, a cross-sectional survey design was undertaken with conveniently selected patients discharged from the ICU between July 2023 and January 2024. Participants were recruited if they were 1) aged 18 years or older, 2) in the ICU for more than 48 hours, and 3) given written informed consent (or by their legal representative). Exclusion criteria were 1) receiving hospice or palliative care services, 2) inability to read Chinese or not being able to fill in the questionnaire, 3) being readmitted to ICU in less than one month, and 4) being discharged from pediatric or neurological ICUs. The data was collected using the 22-item PICSAS and a structured demographic and clinical characteristics questionnaire. Statistical evaluation of multiple variables was performed through multiple linear regression and descriptive analyses. The prevalence of PICS was 94.5% (n=310). Three variables were associated with developing PICS. The number of days spent in the ICU (β=0.16, t=2.77, 95% CI [0.08, 0.18], p<0.05), the APACHE II score at admission (β=0.13, t=2.19, 95% CI [0.03, 0.60], p<0.05), duration of mechanical ventilation (β=0.25, t=4.48, 95% CI [0.19, 0.66], p < 0.001) positively correlated with the total PICSAS score, suggesting that longer mechanical ventilation, longer days of ICU stay, and increased APACHE II score are predictive of greater PICS severity.