Review Paper
Risk factors for post–intensive care syndrome: A systematic review and meta-analysis

https://doi.org/10.1016/j.aucc.2019.10.004Get rights and content

Abstract

Objective

The objective of this study was to identify the risk factors for each area of post–intensive care syndrome (PICS) and to determine their effect size.

Review method used

This study used systematic review and meta-analysis.

Data sources

PubMed, CINAHL, EMBASE, PsycINFO, and Cochrane Library were searched.

Review methods

Eighty-nine studies were selected for the review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The PICS areas and risk factors reported in the individual studies were reviewed and categorised. We used the Newcastle–Ottawa Scale to evaluate the quality of studies. The effect size of each risk factor was calculated as odds ratio (OR).

Results

There were 33 mental health studies, 15 cognitive impairment studies, 32 physical impairment studies, eight studies on two areas, and one study on all three areas. Sixty risk factors were identified, including 33 personal and 27 intensive care unit (ICU)–related factors. Significant risk factors for mental health included female sex (odds ratio [OR] = 3.37, 95% confidence interval [CI]: 1.12–10.17), previous mental health problems (OR = 9.45, 95% CI: 2.08–42.90), and negative ICU experience (OR = 2.59, 95% CI: 2.04–3.28). The only significant risk factor for cognitive impairment was delirium (OR = 2.85, 95% CI: 1.10–7.38). Significant risk factors for physical impairment included older age (OR = 2.19, 95% CI: 1.11–4.33), female sex (OR = 1.96, 95% CI: 1.32–2.91), and high disease severity (OR = 2.54, 95% CI: 1.76–3.66).

Conclusions

Although PICS is a multidimensional concept, each area has been studied separately. Significant risk factors for PICS included older age, female sex, previous mental health problems, disease severity, negative ICU experience, and delirium. To prevent PICS, the multidisciplinary team should pay attention to modifiable risk factors such as delirium and patients’ ICU experience.

Introduction

Post–intensive care syndrome (PICS) refers to new or worsened mental health, cognitive, or physical impairments after treatment in an intensive care unit (ICU).1,2 PICS has been introduced as an integrated term, but no clear operational definition or diagnostic criteria have yet been established.3,4 Nevertheless, as the survival rate of ICU patients increases, more studies are being conducted on PICS as a long-term outcome of ICU treatment.1,[5], [6], [7]

Some studies of health problems experienced by ICU survivors after discharge were conducted before the concept of PICS emerged. In the field of critical care medicine and rehabilitation medicine,2,8,9 the use of steroids, hyperglycemia, mechanical ventilation, sepsis, and immobility have been reported as risk factors for physical disability in PICS. In addition, previous cognitive problems, younger age, and physical restraints have been suggested as risk factors for mental health problems. In the fields of clinical psychology and psychiatry, researchers have focused on the mental health problems of ICU survivors. Several studies[10], [11], [12], [13] have reported benzodiazepines, delirium, lower education, unemployment, surgical ICU admission, and female sex as risk factors for mental health problems. However, other studies[14], [15], [16], [17] have found that age, sex, ICU type, and length of stay were not related to PICS. In the field of physical therapy,18,19 some researchers consider that ICU-acquired weakness is caused by immobility in the ICU. In the field of nursing, researchers4,[20], [21], [22] have sought to identify the PICS phenomenon. Studies have found that survivors experienced complex and multidimensional problems, including anxiety, depression, sleep disturbances, pain, fatigue, memory loss, poor concentration, limitations in activities of daily living, and delayed return to work. Some researchers[23], [24], [25] have reported that negative ICU experiences, including low awareness of surroundings, frightening experiences, recall problems, and dissatisfaction with care were risk factors for PICS.

To manage PICS of ICU survivors more efficiently, a clearer understanding of the risk factors is needed. The purpose of this study was to systematically review the risk factors for PICS and to determine the effect size of individual risk factors to develop a comprehensive understanding of the risk factors for PICS among ICU survivors and provide a basis for development of relevant interventions.

Section snippets

Design

This was a systematic review and meta-analysis to identify risk factors for PICS and to calculate their effect sizes. The protocol for this review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (reference number: CRD42019120656) on April 1, 2019.

Eligibility criteria

  • 1)

    Inclusion criteria

    • -

      Patients: Adult ICU survivors (≥18 years old)

    • -

      Exposures: Risk factors for PICS

    • -

      Comparators: Not having PICS risk factors

    • -

      Outcomes: Any measured assessment within the three areas of PICS (mental

Study selection

The search and selection process is shown in Fig. 1. After eliminating duplicates among the 119,049 articles identified, the title, abstract, and full-text were reviewed. As a result, a total of 89 studies were selected for the final review.

Study characteristics

The 89 studies in the final analysis had a combined total of 63,132 participants. The characteristics of the studies are shown in Table 1. The median sample size of individual studies was 167 (interquartile range [IQR]: 126–295).

Quality assessment of studies

Of the 73 cohort studies, 59

Discussion

In this study, the risk factors of PICS were systematically reviewed and the effect sizes of risk factors were calculated. More studies were published in the last 5 years than in the earlier years. This reflects the increased interest in PICS since the Society of Critical Care Medicine (SCCM) recognised PICS as a syndrome and named it in 2010.1 More studies have been conducted in the United States and European countries than elsewhere. This can be interpreted as having an interest in long-term

Conclusion

Although PICS is a multidimensional concept consisting of mental, cognitive, and physical areas, each area has been measured and studied separately. Most studies of risk factors for PICS have focused on the mental health area, and few studies have included all three areas of PICS. It is necessary to develop a measurement tool that integrates and assesses multidimensional features based on an operational definition of PICS. The significant risk factors for PICS were older age, female sex,

Conflict of interest

The authors declare that they have no conflict of interest.

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1B03936044). This funding source had no role in the study design, analysis, data interpretation, or decision to submit for publication.

CRediT authorship contribution statement

Minju Lee: Data curation, Formal analysis, Writing - original draft. Jiyeon Kang: Conceptualization, Data curation, Funding acquisition, Writing - review & editing. Yeon Jin Jeong: Data curation, Validation.

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