Acute patients discharged without an established diagnosis: risk of mortality and readmission of nonspecific diagnoses compared to disease-specific diagnoses

TL;DR

This study finds that patients discharged with nonspecific diagnoses have similar risks of mortality and readmission as those with specific diagnoses after adjusting for various factors.

Contribution

The study introduces a detailed analysis of 509 nonspecific diagnosis subgroups and their varied outcomes.

Findings

Nonspecific diagnoses showed similar mortality and readmission risks as disease-specific ones after adjustments.

Abdominal and chest pain were the most common nonspecific diagnoses.

Subgroups of nonspecific diagnoses varied widely in patient characteristics and outcomes.

Abstract

Nonspecific discharge diagnoses after acute hospital courses represent patients discharged without an established cause of their complaints. These patients should have a low risk of adverse outcomes as serious conditions should have been ruled out. We aimed to investigate the mortality and readmissions following nonspecific discharge diagnoses compared to disease-specific diagnoses and assessed different nonspecific subgroups.

Register-based cohort study including hospital courses beginning in emergency departments across 3 regions of Denmark during March 2019–February 2020. We identified nonspecific diagnoses from the R- and Z03-chapter in the ICD-10 classification and excluded injuries, among others—remaining diagnoses were considered disease-specific. Outcomes were 30-day mortality and readmission, the groups were compared by Cox regression hazard ratios (HR), unadjusted and adjusted for socioeconomics, comorbidity, administrative information and laboratory results. We stratified into short (3–<12 h) or lengthier (12–168 h) hospital courses.

We included 192,185 hospital courses where nonspecific discharge diagnoses accounted for 50.7% of short and 25.9% of lengthier discharges. The cumulative risk of mortality for nonspecific vs. disease-specific discharge diagnoses was 0.6% (0.6–0.7%) vs. 0.8% (0.7–0.9%) after short and 1.6% (1.5–1.7%) vs. 2.6% (2.5–2.7%) after lengthier courses with adjusted HRs of 0.97 (0.83–1.13) and 0.94 (0.85–1.05), respectively. The cumulative risk of readmission for nonspecific vs. disease-specific discharge diagnoses was 7.3% (7.1–7.5%) vs. 8.4% (8.2–8.6%) after short and 11.1% (10.8–11.5%) vs. 13.7% (13.4–13.9%) after lengthier courses with adjusted HRs of 0.94 (0.90–0.98) and 0.95 (0.91–0.99), respectively. We identified 50 clinical subgroups of nonspecific diagnoses, of which Abdominal pain (n = 12,462; 17.1%) and Chest pain (n = 9,599; 13.1%) were the most frequent. The subgroups described differences in characteristics with mean age 41.9 to 80.8 years and mean length of stay 7.1 to 59.5 h, and outcomes with < 0.2–8.1% risk of 30-day mortality and 3.5–22.6% risk of 30-day readmission.

In unadjusted analyses, nonspecific diagnoses had a lower risk of mortality and readmission than disease-specific diagnoses but had a similar risk after adjustments. We identified 509 clinical subgroups of nonspecific diagnoses with vastly different characteristics and prognosis.

The online version contains supplementary material available at 10.1186/s13049-024-01191-4.

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