Table 3.
Points | Variable | Stratification | Prevalence, % | |
---|---|---|---|---|
Derivation Population (2011–2013) | Validation Population (2014–2015) | |||
1 | Comorbidity | Chronic obstructive pulmonary disease | 10.0 | 10.1 |
2 | Comorbidity | Hypertension | 85.2 | 82.0 |
2 | Laboratory value | Anemia (hematocrit <36%) | 23.0 | 21.6 |
3 | Patient age | >80 y | 18.1 | 16.0 |
3 | Comorbidity | Non–insulin‐dependent diabetes mellitus | 18.2 | 19.0 |
3 | Laboratory value | Renal insufficiency (GFR <40 mL/min per 1.73 m2) | 10.6 | 9.1 |
3 | Symptomatic | Presentation with a transient ischemic attack | 15.7 | 16.4 |
3 | High‐risk features | High‐risk anatomical characteristics | 11.9 | 10.8 |
3 | Contralateral carotid artery stenosis | High‐grade stenosis (80%–99%), occlusion, or imaging not obtained | 22.9 | 21.3 |
4 | Comorbidity | Insulin‐dependent diabetes mellitus | 10.8 | 12.1 |
4 | High‐risk features | High‐risk physiological characteristics | 4.9 | 4.7 |
4 | Admission type | Hospital transfer, emergency department, or nursing home | 6.7 | 7.2 |
4 | Case urgency | Emergent | 2.5 | 2.8 |
4 | ASA classification | IV–V | 16.5 | 20.3 |
5 | Symptomatic | Presentation with a stroke | 18.4 | 20.0 |
5 | Modified Rankin Scale | Score 2–5 | 7.8 | 7.6 |
47 | Maximum potential score | … | … |
High‐risk anatomical characteristics were defined by the NSQIP registry as prior ipsilateral CEA or carotid artery stent placement, prior ipsilateral neck dissection, contralateral carotid artery occlusion, prior radiation to the neck, or contralateral laryngeal nerve injury or palsy. High‐risk physiological characteristics were defined as New York Heart Association class III/IV congestive heart failure, left ventricular ejection fraction <30%, unstable angina, or myocardial infarction within 30 days. ASA physical classification designation IV is a severe systemic disease with constant threat to life and includes, but is not limited to, recent (<3 months) myocardial infarction or cardiac stent placement, severe valve dysfunction, sepsis, and renal dysfunction. ASA class V designation is a moribund patient not expected to survive without the operation. Modified Rankin Scale score of 2 to 5 indicates at least slight disability and is only recorded among patients who presented with a stroke. ASA indicates American Society of Anesthesiologists; CEA, carotid endarterectomy; GFR, glomerular filtration rate; NSQIP, National Surgical Quality Improvement Program.