Death or revascularization among nonadmitted ED patients with low-positive vs negative troponin T results

Compare outcomes among emergency department (ED) patients with low-positive (0.01-0.02 ng/mL) vs negative troponin T.

Retrospective cohort study of nonadmitted ED patients with troponin testing at a tertiary-care hospital. Trained research assistants used a structured tool to review charts from all nonadmitted ED patients with troponin testing, 12/1/2009 to 11/30/2010. Outcomes of death and coronary revascularization were assessed at 30 days and 6 months via medical record review, Social Security Death Index searches, and patient contact.

There were 57596 ED visits; with 33388 (58%) discharged immediately, 6410 (11%) assigned to the observation unit, and 17798 (31%) admitted or other. Troponin was measured in 2684 (6.7%) of the nonadmitted cases. Troponin was negative in 2523 (94.0%), low positive in 78 (2.9%), and positive (≥0.03 ng/mL) in 83 (3.1%). Of troponin-negative cases, 0.8% (95% CI, 0.4-1.1%) died or were revascularized by 30 days, vs 2.8% (95% CI, 0.0-6.7%) of low-positive cases (risk difference [RD], 2.0%; 95% CI, -1.8 to 5.9%). At 6 months, the rates were 1.7% (95% CI, 1.1-2.2%) and 12.9% (95% CI, 5.0-20.7%) (RD, 11%; 95% CI, 3.3-19.1%). Death alone at 30 days occurred in 0.4% (95% CI, 0.1-0.6%) vs 1.3% (95% CI, 0.0-3.8%) (RD, 0.9%; 95% CI, -1.6 to 3.4%). Death at 6 months occurred in 1.2% (95% CI, 0.8-1.6%) vs 11.7% (95% CI, 4.5-18.9%) (RD, 10%; 95% CI, 3.3-17.7%).

Among patients not initially admitted, rates of death and coronary revascularization differed insignificantly at 30 days but significantly at 6 months. Detailed inspection of our results reveals that the bulk of the added risk at 6 months was due to non-cardiac mortality.