OBJECTIVE: Telephone triage manages patient flow in acute care, but a lack of visual cues and vague descriptions of symptoms challenges clinical decision making. We aim to investigate the association between the caller's subjective perception of illness severity expressed as "degree-of-worry" (DOW) and hospital admissions within 48 h.

DESIGN AND SETTING: A prospective cohort study was performed from January 24th to February 9th, 2017 at the Medical Helpline 1813 (MH1813) in Copenhagen, Denmark. The MH1813 is a primary care out-of-hours service.

PARTICIPANTS: Of 38,787 calls received at the MH1813, 11,338 met the inclusion criteria (caller being patient or close friend/relative and agreement to participate). Participants rated their DOW on a 5-point scale (1 = minimum worry, 5 = maximum worry) before talking to a call handler.

MAIN OUTCOME MEASURE: Information on hospitalization within 48 h after the call, was obtained from the Danish National Patient Register. The association was assessed using logistic regression in three models: 1) crude, 2) age-and-gender adjusted and 3) age, gender, co-morbidity, reason for calling and caller status adjusted.

RESULTS: A total of 581 participants (5.1%) were admitted to the hospital, of whom 170 (11.3%) presented with a maximum DOW, with a crude odds ratio (OR) for hospitalization of 6.1 (95% confidence interval (CI) 3.9 to 9.6) compared to minimum DOW. Estimates showed dose-response relationship between DOW and hospitalization. In the fully adjusted model, the ORs decreased to 3.1 (95%CI 2.0 to 5.0) for DOW = 5, 3.2 (2.0 to 5.0) for DOW = 4, 1.6 (1.0 to 2.6) for DOW = 3 and 0.8 (0.5 to 1.4) for DOW = 2 compared to minimum DOW.

CONCLUSION: Patients' self-assessment of illness severity as DOW was associated with subsequent hospital admission. Further, it may be beneficial in supporting clinical decision making in telephone triage. Finally, it might be useful as a measure to facilitate patient participation in the triage process.