Critical cardiac events like myocardial infarction (MI), possess various life-threatening instances. A large risk variation is recognized among patients with MI depending on demographics, comorbidities, and severity of MI. Risk stratification is important because it may influence the selection of secondary preventive therapy, such as intensive antiplatelet therapy where the benefit may only outweigh harm in higher-risk patients but not among lower-risk ones. In this context, the Thrombolysis in Myocardial Infarction (TIMI) Study Group recently developed a simple scoring system, the TIMI Risk Score for Secondary Prevention (TRS2°P). This tool is tested in few cohorts in some of the countries which will be discussed in the extended article.
Study Design and Participants
This study was performed as an ancillary study of CKD?PC. CKD?PC currently consists of >11 million participants from >70 cohorts with detailed clinical and outcome data (eg, mortality and end?stage renal disease) from >40 countries. For this specific study, based on data collected as part of the CKD?PC, we identified 5 studies with ≥1000 MI cases during follow?up that could be linked to data on the 9 predictors of TRS2°P.
Nine Predictors Used in TRS2°P
Nine predictors were identified such as heart failure (yes versus no), hypertension (yes versus no), age (≥ versus <75 years), diabetes mellitus (yes versus no), prior stroke (yes versus no), prior coronary artery bypass grafting (CABG) (yes versus no), peripheral artery disease (yes versus no), reduced kidney function (estimated glomerular filtration rate < versus ≥60 mL/min per 1.73 m2), and current smoking (yes versus no). Based on the presence and absence of these 9 predictors, TRS2°P ranged from 0 to 9.
The primary outcome is defined by a composite of cardiovascular death, recurrent MI, or ischemic stroke. Cardiovascular death was defined as death caused by MI, heart failure, stroke, or sudden cardiac death as the primary cause. All?cause death was investigated in RCAV since the cause of death was not available. Patients were followed until the date of MACE, death, or the end of follow?up, whichever came first.
Baseline characteristics of individuals with recent MI in each study were summarized as mean and SD or median and interquartile range for continuous variables and percentage for categorical variables. Subsequently, we determined prediction statistics in a 3?year time frame with fine categories of TRS2°P 0, 1, 2, 3, 4, 5, 6, and ≥7 as carried out in its derived data set.10 As a measure of discrimination, we estimated Harrell's C?statistic.16 For calibration, we plotted predicted risk based on TRS2°P against observed risk in each study and calculated a modified Hosmer?Lemeshow χ2 statistic.17 We also calculated the Brier score,18 the average squared deviation between predicted by TRS2°P and observed event rates (a lower score represents better calibration). Observed risk was estimated using the Kaplan–Meier method in each study.
Simple scoring system with 9 routine clinical factors predicting 3?year prognosis after recent MI, in 5 cohorts outside of a clinical trial setting with different demographic and clinical characteristics, and subsequently different adverse outcome event rates. Our cohorts tended to have higher scores than the original TRA2°P–TIMI50 population. Despite these demographic and clinical variations confirmed that higher TRS2°P was consistently associated with higher risk of MACE, indicating reasonable risk discrimination, with C?statistics ranging from 0.60 to 0.69 in most studies, which are comparable with those originally reported in the derivation data set of TRS2°P. The most common scores in our cohorts were either 2 or 3, whereas a score of 1 was most prevalent in the original TRA2°P–TIMI50. In conclusion, TRS2°P reasonably predicted secondary events among patients with recent MI in international non–clinical trial settings, with some caveats to be explored in future studies (eg, general underestimation of the risk of adverse outcomes and suboptimal discrimination in a Korean cohort). Particularly given its simple feature of a 0 to 9 scoring system with routinely collected variables, TRS2°P may be considered for classifying the prognosis and to guide risk-centered management among patients with recent MI.