Performance of the Modified Early Warning Screen (MEWS) in primary health care: A systematic review of the literature

Abstract

Introduction: Primary Health Care (PHC) constitutes the main entry point and organizing axis of the Health Care Network, enabling the prevention of complications through the early identification of clinical deterioration using assessment scores. Objective: To conduct a systematic literature review to verify the use and performance of the Modified Early Warning Score (MEWS) in unmonitored patients treated in PHC. Methods: This is a systematic review conducted in accordance with PRISMA guidelines. The research question, based on the PICO strategy, was: What is the performance of the MEWS in the early identification of clinical deterioration in patients treated in Primary Health Care? The search was carried out between January and April 2025 in the following databases: PubMed, Scopus, Web of Science, LILACS, CINAHL (EBSCO), and Virtual Health Library (VHL). Controlled descriptors (MeSH/DeCS) and keywords were used, including: “Early Warning Score”, “Modified Early Warning Score”, “MEWS”, “Primary Health Care”, “Primary Care”, and “Clinical Deterioration”, combined using Boolean operators. The time frame included studies published between 2015 and 2025, in Portuguese, English, and Spanish. Inclusion criteria comprised original studies (quantitative or qualitative), available in full text, that evaluated the application or performance of MEWS in PHC. Exclusion criteria included studies conducted exclusively in hospital settings, reviews, editorials, letters, case reports, conference abstracts without full text, and studies without data on MEWS performance. Results: A total of 541 studies were identified, of which 11 were included in the final sample. No studies conducted in Brazil were found. The included studies indicate that MEWS can be applied in PHC, especially in specific populations such as older adults, showing relevant results in early identification of clinical deterioration and supporting decision-making for hospital referral. Conclusion: The implementation of MEWS in Primary Health Care is a promising strategy to improve the quality of care and enhance early detection of clinical deterioration, although significant gaps remain, particularly in the Brazilian context.