Recruitment and retention of intensive care unit survivors in follow-up studies: A systematic review

Engaging intensive care unit survivors in research is challenging. Studies have reported recruitment and attrition rates; details are lacking on retention strategies and attrition.

The aim of this study was to explore barriers and enablers to recruitment and retention in research of people post intensive care discharge.

A convergent mixed-method review using the Joanna Briggs Institute (JBI) methodology considered studies that reported on recruitment, retention, and attrition rates of adult post-intensive care survivors in longitudinal studies. CINAHL Ultimate (CINAHL+), PubMed, Excerpta Medica Database (EMBASE), PsycINFO, Scopus, Proquest Health, and Medical Collection were searched in March 2024 using Medical Subject Headings terms and keywords related to post-intensive care survivors, patient selection, and research in peer-reviewed journals or theses published in English. Risk of bias was assessed with JBI's critical appraisal tools. Qualitative data were extracted and themed, and quantitative data were extracted using predefined data fields and qualitised. Synthesis was guided by the JBI mixed-method convergent integrated approach.

A total of 1608 records were identified; 12 high-quality articles were included, with a total of 2551 participants. Studies focussed on outcome measures following hospital discharge to the community. Three superordinate and eight subordinate themes emerged: factors influencing participation/nonengagement, retention strategies, and researcher insights. Attrition was predominantly due to mortality or ill health. Non-health-related themes included transport difficulties, expense, and inconvenience. Challenges included symptoms triggered by participation, being unaware of appointments, and not understanding study requirements. Enabling strategies included reminder calls, letters, cards, and home visits. Researcher insights included the impact of critical illness on survivors' wellbeing, finances, and communication challenges.

Recruitment and retention strategies were under-reported. Person-centred approaches considering survivors' challenges may increase recruitment and retention. Retention strategies should be evaluated to determine the impact on engagement or withdrawal from studies. The strong likelihood of attrition should be factored into sample size calculations to reduce risk of bias in longitudinal studies.

This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO [CRD42022315688]).