A Critical Review of a the article: scientific research paper published in CHEST, 1999
Reviewed for the Pennsylvania Society of Respiratory Care
by Desmond Allen, PhD, RCP
Prospective Multicenter Study of Relapse Following Treatment for Acute Asthma Among Adults Presenting to the Emergency Department. Charles L. Emerman, MD; Prescott G Woodruff, MD; Rita K. Cydulka, MD; Michail A Gibbs, MD; Charles V. Pollack, Jr., MD; and Carlos A. Camargo, Jr., DrPH, FCCP; on behalf of the MARC Investigators. CHEST 1999; 115 (4): 919‑927.
The determination of those factors associated with acute asthma relapse among patients sent home from the emergency department would be a guide to the ED’s management of acute asthma, thereby targeting high‑risk individuals for such programs as intense outpatient management.
Method & Sample:
The data of two multi‑centered cohort studies involving thirty‑six emergency departments located in eighteen states is combined. A total of 1,301 patients diagnosed with acute asthma were treated and released from the ED. Due to co‑morbidities only 939 patients were analyzed for the study. Ages ranged from 18 to 54 years, including both male and female, various races, as well as smokers and non‑smokers.
Data included demographics, asthma Hx, current exacerbation and triggers. Structured telephone follow‑ups, conducted two weeks after discharge documented episodes of relapse, i.e. "any urgent medical treatment for asthma, regardless of location of care," since the ED visit.
Complete telephone follow‑up data was collected from 641 patients. 17% had relapsed. Clinically, there was little significant difference between those contacted compared to those not contacted. There were differing demographic factors, but none that was deemed to play a significant role in predicting relapse among the contacted group.
Between the relapse and the non-relapse groups, there was no difference in the mean initial PEFR at 52 ± 21% of predicted and the final PEFR at 80 ± 23% before discharge. Nor was there a difference in treatment.
Over a 4 week period prior to the ED visit, patients receiving inhaled short‑acting $‑agonists, inhaled and systemic corticosteroids, as well as other asthma medications were more likely to relapse. Home nebulizer use was associated with a more than twofold increase in risk for relapse.
A history of hospital admissions and ED visits during the previous year were also associated with relapse. The risk factor > by 40% with >5 ED visits, and > by 50% with >5 urgent clinic visits. Each asthma trigger increased the risk of relapse by 10%. Finally, those with symptoms longer than 24 hours, but less that 7 days also seemed at higher risk.
17% patients of those sent home from the ED reported relapse. “PEFR does not predict relapse among this patient group. Patients at increased risk for relapse have a history of numerous asthma-related ED and urgent clinic visits within the last year, and are using more outpatient medications, including nebulizers. These patients also appear to have a longer duration of symptoms.”
Problems With the Study:
The primary problem with the paper is the inadequate analysis of the data in relationship to the basic research question. “What factors are associated with relapse for acute asthmatics discharged from the ED?” The authors concluded that the primary factor associated with relapse is the patient’s history of frequent visits to the ED. This begs the question and is an error in logic. The basic problem they are trying to address is the frequent visits to the ED. Therefore, the frequent visits to the ED cannot be the answer to the problem. Essentially they have concluded that these patients returned for urgent care because these patients often return for urgent care.
A few other, minor, issues exist as well. There is an inconsistent conclusion about the importance of triggers. At one point it is calculated that, “Each asthma trigger reported by the subjects increased the risk of relapse by approximately 10%.” The next paragraph states that, “There is not a consistent increase in risk of relapse as the number of asthma triggers increases, . . .” The qualifying remarks that follow do not address this confusion.
Another inconsistent statement concerns the duration of symptoms. At one point it is said that “patients with symptoms >7 days have a lower risk of relapse . . . .” Later it is concluded that “patients who have relapse also appear to have longer duration of symptoms.”
The final issue of dispute is the validity of PEFR studies. They observed that “PEFR was not associated with risk for relapse. . . .” Others sources were sited to agree with this conclusion, thereby, inferring that the PEFR is not a valid tool for predicting relapse. While this might be the case, there is a logical problem in jumping to this conclusion based upon the data collected in this particular study. Because this study prospectively analyzed data that was collected with a specific intent other than targeting PEFR indicators for relapse, and in that the PEFR was initially used as a tool to determine a patients viability for discharge from the ED or admission to the observation unit, to extrapolate that PEFR is not an indicator for relapse is remiss. There is no evidence or data concerning patients discharged with various PEFR studies. Such comparison groups are necessary to draw such a conclusion. What would be the relapse risk for those discharged with PEFRs at 40%, 50%, 90%, etc.?
Value of the Study:
Nevertheless, there is value in this study. Although it fails to achieve its primary goal of identifying actual indicators for relapse, it does achieve its stated underlying objective, to validate the need for closer follow-up of those acute asthmatics sent home from the ED. Others have documented the positive effect that education and close follow-up can have on these patients. Therefore, by exposing the magnitude of the relapse problem, this study does lend support to the need for closer follow-up programs and could be used in an argument for the initiation of such programs in local institutions.
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