Performance of the Thrombolysis in Myocardial Infarction (TIMI) ST-elevation myocardial infarction risk score in a national cohort of elderly patients

Background The TIMI ST-elevation myocardial infarction (STEMI) score was developed and validated in a randomized controlled trial population. We sought to assess its accuracy in a community-based cohort of elderly patients hospitalized with STEMI. Methods We evaluated the TIMI STEMI score in 47 882 patients aged ≥65 years hospitalized with STEMI in US hospitals from 1994 to 1996. We assessed TIMI STEMI score discrimination and calibration for 30-day mortality and compared observed and published TIMI mortality rates. Results The cohortʹs median TIMI score was 6 (25th-75th percentile 4, 8). Thirty-day mortality rates were higher among patients with higher TIMI scores (TIMI score 2: 4.4% vs TIMI score >8: 35.6%, P < .0001 for trend). However, the TIMI score provided only modest discrimination (c = 0.67) and calibration (goodness-of-fit P < .0001). Mortality rates for TIMI scores differed between patients who did and did not receive reperfusion therapy (P < .0001 for TIMI score × reperfusion therapy interaction). Thirty-day mortality rates in the cohort were higher than published TIMI estimates (P = .001; eg, TIMI score 2: 4.4% cohort vs 2.2% published rate). Conclusions The TIMI score provided modest prognostic discrimination and calibration among elderly patients with STEMI. Our findings highlight the difficulties in applying risk scores developed in randomized controlled trial cohorts to elderly patients.