Tool IDs Patients With COPD at Risk for Serious Outcomes

Lara C. Pullen, PhD

December 11, 2018

The Ottawa Chronic Obstructive Pulmonary Disease (COPD) Risk Scale (OCRS) predicts short-term serious outcomes from COPD better than current practice, suggests new research.

The study of 1415 participants with COPD found that 9.5% had short-term serious outcomes and approximately half of those were discharged home from the emergency department.

The OCRS risk-stratification tool showed better sensitivity at identifying these patients than current practice; therefore, it should improve emergency department decisions as to whether to admit such patients and should decrease both unsafe discharges and unnecessary admissions.

Ian G. Stiell, MD, MSc, distinguished professor of emergency medicine at the University of Ottawa in Canada and senior scientist at The Ottawa Hospital, and colleagues published their research on OCRS December 4 in CMAJ.

The study was conducted at the emergency departments of six tertiary hospitals and included adults seen for acute exacerbation of COPD from May 2011 to December 2013. Strengths of the study include its prospective and rigorous collection of real-time clinical data, including response to treatment.

Patients had a mean age of 70.6 years (standard deviation, 10.6) and 50.2% were female. Patients included 804 (56.8%) who arrived by ambulance, 1380 (97.5%) who had a previous diagnosis of COPD, 349 (24.7%) who were on oxygen at home, 1015 (71.7%) who were taking inhaled steroids, and 202 (14.3%) who were taking oral steroids.

Physicians evaluated patients for the OCRS criteria and recorded that evaluation as well as a total risk score (from 0 to 10) on a data form. The physician who made the final decision about admission did not have access to the OCRS score.

The researchers documented the primary outcome (short-term serious outcome) at 30 days. They defined short-term serious outcome as death, admission to a monitored unit, intubation, noninvasive ventilation, myocardial infarction, or relapse with hospital admission. They also recorded response to treatment.

Of the 636 patients who were admitted to the hospital on their index visit, 45 (7.1%) were admitted to a monitored unit, 54 (8.5%) required noninvasive ventilation or intubation, 5 (0.8%) had a myocardial infarction, and 65 (8.3%) had a relapse and were readmitted to the hospital. There were higher rates of short-term serious outcomes in patients admitted to the hospital than in those discharged from the emergency department (11.0% vs 8.3%; P < .01).

The investigators then compared the classification performance and expected admission proportions for the OCRS with current practice in the six hospitals. Patients with a score of 0 had a 4.6% incidence of serious short-term outcomes. On the other end of the spectrum, patients with a score of 10 had a 100% incidence of serious short-term outcomes.

The researchers calculated that use of the scale could improve upon the sensitivity of current practice, in which only 51.9% (70/135) of patients with short-term serious outcomes were admitted upon the first visit to the emergency department.

When compared with current practice, an OCRS score threshold of greater than 1 would increase sensitivity for short-term serious outcomes from 51.9% to 79.3%. Similarly, an OCRS score threshold greater than 1 would increase admission from 45.0% to 56.6%. When researchers examined a threshold of greater than 2, they found that application of such a threshold would improve sensitivity to 71.9%, with 47.9% of patients being admitted.

"Compared with current practice, an OCRS score threshold of 1 or more would increase sensitivity by 50% but would require 25% more admissions," the authors write. "Alternately, a threshold of 2 or more would improve sensitivity by 38% while leading to only a slight increase in admissions."

OCRS thus successfully identified which patients with COPD were at risk for death or serious complications. This is important since not all patients who present to the emergency department with COPD should be admitted to the hospital. Absent this tool, physicians can have difficulty predicting which patients will have dangerous complications and should be admitted.

The investigators explain that the current study does not include an evaluation of spirometry in the emergency department as spirometry is often not available. They also note that spirometry is likely of little use in predicting short-term outcomes.

The study is noteworthy because it documented both admitted and discharged patients. This stands in contrast to previous studies in the field that have been limited by a lack of evaluation of response to therapy and/or a lack of follow-up data on mortality.

COPD is a common condition that worsens over time. The OCRS can be used by not only emergency physicians, but also respirologists, general internists, and family physicians who care for patients with COPD.

"We intend that OCRS be used in a pragmatic fashion to ensure that patients are managed in a safe and efficient manner, and we do not advocate for a specific risk score total that would require admission," wrote the authors. "Depending on local practice, OCRS could lead to either an increase or a decrease in hospital admissions."

The authors have disclosed no relevant financial relationships.

CMAJ. Published online December 3, 2018. Full text

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