Delayed diagnosis of acute coronary syndrome in out-of-hours primary care: insights from a case-control study

Adequate triage of acute chest discomfort in out-of-hours services in primary care (OHS-PC) is crucial for minimising delays in the diagnosis of acute coronary syndromes (ACS) and subsequently limit myocardial damage. The objective was to identify predictors of delayed ACS diagnosis in OHS-PC and examine differences between females and males to further improve telephone triage of acute chest discomfort. This is a retrospective unmatched case-control study which analysed telephone triage conversations of individuals with acute chest discomfort due to ACS who contacted the OHS-PC in the Netherlands. Call characteristics, symptoms, and patient characteristics were compared between cases- those with a delayed ACS diagnosis during the initial diagnostic phase at the OHS-PC- and controls, who were adequately triaged. Additionally, sex differences were examined. Delay was defined as low urgency allocation (U3-U5) or high urgency allocation (U1 or U2) without immediate hospital referral. Of 2,428 callers with acute chest discomfort, 267 (11.0%) had an ACS, of whom 35 (13.3%) were classified as cases and 229 (86.7%) as controls. Cases were more common during daytime (42.9% vs. 19.7%, p = 0.002) and had a longer median call duration compared to controls (08:21 [07:07–13:27] min vs. 05:37 [03:53 − 07:35] min, p < 0.001). Cases less often contacted the OHS-PC within 12 h of pain onset (71.0% vs. 86.9%, p = 0.031). Patient characteristics were largely similar between cases and controls, but cases less often reported oppressive or heavy-feeling chest pain (64.3% vs. 84.3%, p = 0.011) and more often stabbing chest pain (21.4% vs. 7.0%, p = 0.025) and palpitations and/or tingling sensations (28.6% vs. 14.0%, p = 0.028). No significant differences were observed between female and male cases. Delays in ACS diagnosis were more prevalent during daytime and were associated with a longer median call duration. Patients with ACS and a delayed diagnosis less often contacted the OHS-PC within 12 h of pain onset, more often reported stabbing than oppressive or heavy-feeling chest pain, and more often reported palpitations and/or tingling sensations than patients with ACS without a delayed diagnosis. No differences were observed between female and male cases. We could not identify easily modifiable determinants of delay in the triage and referral of ACS at the OHS-PC among patients calling with acute chest discomfort. NL7134.