Factors associated with undertriage in patients classified by the need to visit a hospital by telephone triage: a retrospective cohort study

BACKGROUND: Prehospital telephone triage stratifies patients into five categories, “need immediate hospital visit by ambulance,” “need to visit a hospital within 1 hour,” “need to visit a hospital within 6 hours,” “need to visit a hospital within 24 hours,” and “do not need a hospital visit” in Japan. However, studies on whether present and past histories cause undertriage are limited in patients triaged as need an early hospital visit. We investigated factors associated with undertriage by comparing patient assessed to be appropriately triaged with those assessed undertriaged. METHODS: We included all patients classified by telephone triage as need to visit a hospital within 1 h and 6 h who used a single after-hours house call (AHHC) medical service in Tokyo, Japan, between November 1, 2019, and November 31, 2020. After home consultation, AHHC doctors classified patients as grade 1 (treatable with over-the-counter medications), 2 (requires hospital or clinic visit), or 3 (requires ambulance transportation). Patients classified as grade 2 and 3 were defined as appropriately triaged and undertriaged, respectively. RESULTS: We identified 10,742 eligible patients triaged as need to visit a hospital within 1 h and 6 h, including 10,479 (97.6%) appropriately triaged and 263 (2.4%) undertriaged patients. Multivariable logistic regression analyses revealed patients aged 16–64, 65–74, and ≥ 75 years (adjusted odds ratio [OR], 2.40 [95% confidence interval {CI} 1.71–3.36], 8.57 [95% CI 4.83–15.2], and 14.9 [95% CI 9.65–23.0], respectively; reference patients aged < 15 years); those with diabetes mellitus (2.31 [95% CI 1.25–4.26]); those with dementia (2.32 [95% CI 1.05–5.10]); and those with a history of cerebral infarction (1.98 [95% CI 1.01–3.87]) as more likely to be undertriaged. CONCLUSIONS: We found that older adults and patients with diabetes mellitus, dementia, or a history of cerebral infarction were at risk of undertriage in patients triaged as need to visit a hospital within 1 h and 6 h, but further studies are needed to validate these findings. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12873-021-00552-x.