Comorbid Diseases Not Accounted for by the Revised Cardiac Risk Index
The RCRI only includes 6 specific risk factors and notably excludes many common and clinically significant comorbidities including chronic obstructive pulmonary disease (COPD), anemia, obesity, atrial fibrillation, peripheral vascular disease, smoking history, age >75 years, and abnormal stress testing. 1, 2
What the RCRI Actually Includes
The RCRI calculates risk based on only these 6 factors: 1, 3
- History of ischemic heart disease
- History of congestive heart failure
- History of cerebrovascular disease (stroke/TIA)
- Preoperative insulin-dependent diabetes mellitus
- Chronic renal dysfunction (creatinine >2 mg/dL)
- High-risk surgery type
Major Comorbidities Excluded from RCRI
Respiratory Disease
- COPD is completely absent from the RCRI despite being independently associated with increased perioperative cardiac risk (OR 1.6) and appearing as a top-10 comorbidity in cardiovascular disease patients. 4, 2
- Smoking history, which predicts cardiac complications (OR 1.3), is not included. 2
Hematologic Conditions
- Anemia is not accounted for, despite being one of the most prevalent comorbidities (38.7-51.2%) in patients with cardiovascular disease and hematocrits <28% being associated with increased perioperative ischemia. 4, 5
Cardiac Arrhythmias
- Atrial fibrillation is excluded despite being present in 18.7-28.8% of patients with cardiovascular disease and being an independent predictor in vascular surgery populations. 4, 2
Vascular Disease
- Peripheral vascular disease is not included as a separate risk factor, though it independently predicts complications in multiple studies. 4
Age-Related Risk
- Advanced age (>75 years) is not a component of the RCRI, despite age being an independent predictor with odds ratios ranging from 1.7-2.8 for increasing age categories. 4, 2
Functional and Diagnostic Testing
- Abnormal cardiac stress testing results are not incorporated (OR 1.2 for adverse events), nor is poor functional capacity (<4 METs). 2, 1
- Long-term beta-blocker therapy (OR 1.4), which may indicate underlying cardiac disease severity, is not included. 2
Other Common Comorbidities
- Hyperlipidemia (present in 62.6-69.9% of cardiovascular patients) is absent. 4
- Arthritis (40.6-45.6% prevalence) is not included. 4
- Depression (29.7% in atrial fibrillation patients) is excluded. 4
- Alzheimer's disease/dementia (26.3-33.8% in heart failure and stroke patients) is not accounted for. 4
Clinical Implications of These Omissions
The RCRI substantially underestimates cardiac risk in vascular surgery patients, with actual event rates being 1.7- to 7.4-fold higher than predicted, particularly for lower extremity bypass, EVAR, and open AAA repair. 2, 6
The RCRI performs poorly in specific populations: 7, 8
- In patients with chronic kidney replacement therapy, the RCRI overestimates risk with an expected-to-observed ratio of 6.0,5.1, and 2.5 for scores of 1,2, and ≥3 respectively. 8
- In older Chinese patients with known coronary artery disease, the RCRI performed no better than chance (AUC 0.53). 7
Alternative Risk Assessment Tools
The Gupta MICA calculator uses 21 components from the NSQIP database and demonstrates superior discrimination compared to RCRI, with a median delta c-statistic of 0.11 higher for predicting myocardial infarction and cardiac arrest. 1
The Vascular Study Group Cardiac Risk Index (VSG-CRI) includes additional factors (age, smoking, COPD, abnormal stress test, beta-blocker use) and more accurately predicts cardiac complications in vascular surgery patients (AUC 0.71 vs 0.53-0.64 for RCRI). 2
Biomarker enhancement with NT-proBNP and/or troponin improves discrimination with a median delta c-statistic of 0.08-0.15 over RCRI alone in patients with RCRI ≥2. 1