Delirium is frequently disproportionately under-recognized despite its high prevalence, detrimental impact, and potential lethality. Informant-based delirium detection tools can offer structured assessment and increase the timeliness and frequency of detection. We aimed to examine the diagnostic accuracy of the Family Confusion Assessment Method (FAM-CAM) for delirium detection.We systematically searched the MEDLINE, EMBASE, PsycINFO, CINAHL, CNKI, WANFANG, and SinoMed databases from January 1988 to December 2022. Two reviewers independently screened studies and evaluated methodological quality using the revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool. A bivariate random effects model was undertaken, and univariable meta-regression was carried out to explore heterogeneity.Seven studies with 483 dyads of participants and family caregivers were identified. Pooled sensitivity and specificity were 0.74 (95% CI: 0.59, 0.86) and 0.91 (95% CI: 0.83, 0.95), respectively, with an area under curve (AUC) of 0.91. The positive likelihood ratio was 8.27 (95% CI: 3.97, 17.25), and the negative likelihood ratio was 0.28 (95% CI: 0.16, 0.50). Settings impacted specificity (p = 0.02).Available evidence indicates that FAM-CAM exhibits moderate sensitivity and high specificity for delirium screening in adults. The FAM-CAM is concise and easy to use, making it appropriate for routine clinical practice, which might benefit early delirium detection and potentially foster delirium management.CRD42022378742.© 2023 The American Geriatrics Society.