Risk factors for stroke-related pneumonia in patients with ischaemic stroke: A systematic evaluation and meta-analysis

Background: Stroke-associated pneumonia (SAP) is a frequent and severe complication occurring within the first week after a stroke, particularly in ischemic stroke (IS) patients. SAP is primarily driven by stroke-induced immune suppression, dysphagia, and impaired consciousness, leading to aspiration and subsequent pneumonia. Its incidence ranges from 3.9 % to 12 %, making it a leading cause of mortality and morbidity in stroke survivors. Despite previous studies identifying risk factors such as age, and dysphagia, the results have often been inconsistent due to methodological differences and the inclusion of both ischemic and hemorrhagic stroke patients.

Objective: This study aims to provide a comprehensive and targeted analysis of SAP risk factors specific to IS patients through a systematic review and meta-analysis, with the goal of enhancing clinical risk assessment and prevention strategies.

Methods: This study searched eight databases-PubMed, EMBASE, Web of Science, Cochrane Library, CNKI, VIP, CBM, and Wanfang-for literature on risk factors for SAP in IS patients, with a timeframe of January 1, 2014, to April 6, 2024. Using Revman 5.4, the odds ratio values and 95 % confidence intervals for each collected risk factor were combined and analysed to explore the risk factors for the development of SAP in patients with ischemic stroke.

Results: A total of 25 studies were included, involving 4,251,064 patients and 153,431 SAP patients. We identified 68 potential risk factors for SAP in IS patients from 25 studies, with detailed analysis performed on 13 factors. The remaining factors were not included in the combined analysis due to insufficient supporting literature (fewer than five studies). Out of 13 risk factors, 11 were determined to be associated with the occurrence of SAP, including age, gender, smoking, diabetes, swallowing disorders, with a timeframe of January 1, 2014, to April 6, 2024. chronic lung disease, consciousness disorders, a high NIHSS score, elevated white blood cell count, elevated CRP, and nasogastric tube.

Conclusion: This study identified major risk factors for SAP in IS patients, confirming some existing factors in current assessment scales, such as advanced age, impaired consciousness, and dysphagia. Additionally, new risk factors were identified, including nasogastric tube use, and diabetes. These findings will help improve risk assessment tools, facilitate early identification of SAP risk factors, and prevent SAP occurrence, thereby improving outcomes for IS patients.

Registration: This systematic review according to the Preferred Reporting Items for Systematic Evaluation and Meta-Analysis (PRISMA) guidelines [1] and is registered in PROSPERO (Registration No: CRD42024548441).