Health care utilization of patients with acute abdominal pain before and after emergency department visits

Acute abdominal pain (AAP) is a major driver for capacity-use in emergency departments (EDs) worldwide. Yet, the health care utilization of patients with AAP before and after the ED remains unclear. The primary objective of this study was to describe adult patients presenting to the ED with AAP and their outpatient care (OC) use before and after the ED. Secondary objectives included description of hospitalization rates, in-hospital mortality, ED re-visits, and exploration of potential risk factors for hospitalization and ED re-visits. For the analysis, we combined routine hospital data from patients who visited 15 EDs in Germany in 2016 with their statutory health insurance OC claims data from 2014 to 2017. Adult patients were included based on a chief complaint or an ED diagnosis indicating unspecific AAP or the Manchester Triage System indicator “Abdominal pain in adults”. Baseline characteristics, ED diagnosis, frequency and reason of hospitalization, frequency and type of prior-OC (prOC) use up to 3 days before and of post-OC use up to 30 days after the ED visit. We identified 28,085 adults aged ≥ 20 years with AAP. 39.8% were hospitalized, 33.9% sought prOC before the ED visit (48.6% of them were hospitalized) and 62.7% sought post-OC up to 30 days after the ED visit. Hospitalization was significantly more likely for elderly patients (aged 65 and above vs. younger; adjusted OR 3.05 [95% CI 2.87; 3.25]), prOC users (1.71 [1.61; 1.90]) and men (1.44 [1.37; 1.52]). In-hospital mortality rate was 3.1% overall. Re-visiting the ED within 30 days was more likely for elderly patients (1.32 [1.13; 1.55) and less likely for those with prOC use (0.37 [0.31; 0.44]). prOC use was associated with more frequent hospitalizations but fewer ED re-visits. ED visits by prOC patients without subsequent hospitalization may indicate difficulties of OC resources to meet the complex diagnostic requirements and expectations of this patient population. Fewer ED re-visits in prOC users indicate effective care in this subgroup.