Method has merit, but scope might be too limited.
Ian Stiell and colleagues are at it again with another clinical prediction rule from Ottawa. This time, they’re tackling COPD exacerbations in the ED with the Ottawa COPD Risk Scale.
THE GOOD
Why Use It
- Allows for clinician judgment – EKG and chest x-ray interpretation are up to the clinician to decide if abnormal.
- Identifies clinically important “serious adverse events” — 30-day all-cause mortality, admission to monitored unit, intubation, MI, major procedure (e.g. CABG, PCI) or return to ED plus readmission within 14 days.
THE BAD
Limitations
- Study was done in Canada, where proportionally fewer patients are admitted for COPD exacerbation (estimated 37.5% in Canada versus 80% in the US), so may have limited usefulness for deciding disposition in settings where common practice is to admit.
- Most of the “serious adverse events” in the validation study were readmissions, so the true value of this score over gestalt is still unproven.
THE UGLY
Misapplication
- Should not be used in patients who obviously needed to be admitted, like those who are hemodynamically unstable, suspicious for ischemic chest pain, etc.
- Should be used in patients coming to the ED with an acute exacerbation of COPD – not patients with COPD who have other chief complaints.
| History | |
| Coronary bypass graft | 1 point |
| Intervention for peripheral vascular disease | 1 point |
| Intubation for respiratory distress (any history) | 2 points |
| Examination | |
| HR ≥110/min (on arrival to ED) | 2 points |
| Too ill to do walk test after treatment in ED (SaO2 <90% or HR ≥120/min) | 2 points |
| Investigations | |
| Acute ischemic changes on EKG (by clinician judgment) | 2 points |
| Pulmonary congestion on chest x-ray (by clinician judgment) | 1 point |
| Hemoglobin <10 g/dL (100 g/L) | 3 points |
| Urea ≥12 mmol/L (BUN ≥34 mg/dL) | 1 point |
| Serum CO2 ≥35 mEq/L (35 mmol/L) | 1 point |
Calculation of the Ottawa COPD Risk Scale.
Derivation Study:
Stiell IG, Clement CM, Aaron SD, et al. Clinical characteristics associated with adverse events in patients with exacerbation of chronic obstructive pulmonary disease: a prospective cohort study. CMAJ. 2014;186(6):E193-204.
- Prospective cohort study, 945 patients at six Canadian EDs
- Five variables found to have independent association with “serious adverse events,” five additional clinical variables incorporated into the score
- 2% sensitive for “serious adverse events” at a cutoff score of 2
Validation Study:
Stiell IG, Perry JJ, Clement CM, et al. Clinical validation of a risk scale for serious outcomes among patients with chronic obstructive pulmonary disease managed in the emergency department. CMAJ. 2018;190(48):E1406-E1413.
- Prospective cohort study, 1,415 patients, six Canadian EDs
- Scores were recorded for all patients, but the decision to admit or discharge was based on clinician gestalt
- 5% had a serious adverse event; score was 79% sensitive at a cutoff score of 1 with 72% at a cutoff of 2
References:
- Stiell IG, Clement CM, Aaron SD, et al. Clinical characteristics associated with adverse events in patients with exacerbation of chronic obstructive pulmonary disease: a prospective cohort study. CMAJ. 2014;186(6):E193-204.
- Stiell IG, Perry JJ, Clement CM, et al. Clinical validation of a risk scale for serious outcomes among patients with chronic obstructive pulmonary disease managed in the emergency department. CMAJ. 2018;190(48):E1406-E1413.