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San Diego, CA
Boston, MA
Dr. Schatz is affiliated with the Department of Allergy, Kaiser Permanente. Dr. Camargo is affiliated with the Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School.
Correspondence to: Michael Schatz, MD, MS, Chief, Department of Allergy, Kaiser Permanente Medical Care Program, 7060 Clairemont Mesa Blvd, San Diego, CA 92111; e-mail: michael.x.schatz{at}kp.org
Asthma caused an average of 467,000 hospitalizations per year between 1995 and 2002.1 Most asthma hospitalizations are preceded by an emergency department visit (Emergency Medicine Network; unpublished data), and asthma accounts for a total of nearly 1.8 million emergency department visits per year.2 Although exact figures are not available, many of these emergency asthma visits are preventable. Since a prior asthma hospitalization or emergency department visit is the strongest risk factor for subsequent emergency hospital utilization,3 follow-up after an asthma hospitalization or emergency department visit presents a golden opportunity for tertiary prevention. However, there are substantial knowledge gaps regarding the type of follow-up that will significantly improve asthma outcomes.
Two randomized controlled studies45 have shown that achieving a primary care follow-up visit after an asthma emergency department visit can be facilitated but may not significantly improve asthma outcomes. Another nonrandomized controlled study6 also showed that reminder phone calls after an emergency department visit could increase primary care physician follow-up office visits, but this improved follow-up was not associated with a significant decrease in subsequent emergency hospital care or improved asthma control scores over the next 12 months. In addition, a large survey7 of patients presenting to the emergency department with acute asthma showed that frequency of emergency department visits in the prior year was not related to having a primary care provider. This is not necessarily an indictment of primary care. Most patients who are followed up in primary care presumably do not require emergency hospital care. However, those who do require it apparently require something more than a return to primary care to significantly improve outcomes.
Several clinical trials have suggested that specialist follow-up may be more successful at preventing subsequent asthma hospitalizations than primary care follow-up. Mayo et al8 studied 104 adult asthmatic patients who had previously been admitted to the hospital due to asthma. Forty-seven patients were randomly assigned to an intensive outpatient treatment program in the chest clinic, and 57 patients continued to receive their previous outpatient care. Intervention patients required one third the number of hospital admissions per patient (p < 0.004) compared to usual-care patients. Hughes et al9 studied 95 children and adolescents who had been admitted with a diagnosis of asthma in the prior 5 years. Forty-seven intervention patients were randomized to follow-up by one pediatric respirologist, and 48 patients continued to receive regular care from their family physician or pediatrician. Intervention subjects had less school absenteeism than control subjects (mean, 10.7 vs 16.0 days, respectively; p = 0.04), but there were no significant differences in the rates of hospitalizations or emergency department visits during the study year. However, fewer days were spent in the hospital by the intervention patients compared to control patients (mean, 3.7 vs 11.2 days, respectively; p = 0.02). Castro et al10 reported the results of a nurse specialist intervention program in asthmatic patients with a history of frequent health-care use. The intervention group consisted of 50 patients, and 46 patients who continued their usual care with their private primary care physician were assigned to the control group. There were 21 hospital readmissions for asthma in the intervention group compared to 42 readmissions for asthma in the control group (p = 0.04). Significant reductions in lost work or school days and health-care costs were also achieved in the intervention group. Finally, two nonrandomized (alternate assignment) controlled intervention studies1112 have shown a reduced number of emergency department visits in patients who had received prior emergency asthma care and had been followed up by allergists compared to patients followed up by generalists. These data suggest that follow-up by asthma specialist physicians or nurses after an asthma hospitalization or emergency department visit can reduce the frequency of subsequent exacerbations as well as improve other asthma outcomes.
The study by Nathan et al13 in the current issue of CHEST (see page 51) adds to this body of knowledge regarding follow-up after an asthma hospitalization in order to prevent subsequent exacerbations. These authors report the first direct comparison of specialist nurse vs specialist physician follow-up and conclude that outcomes achieved by a visit with a specially trained nurse practitioner are equivalent to those achieved by a respiratory physician. Although we believe that the data support this conclusion, there are some methodological issues that suggest confirmatory studies are necessary. First, < 50% of eligible subjects were enrolled in the study, suggesting the potential for selection bias. Second, by the authors’ admission and calculations, the final study sample achieved was underpowered to demonstrate actual "equivalence" between the two groups in the primary outcome variable. Finally, although randomization should balance measured and unmeasured confounders, in this relatively small study (n = 66–70 per group) confounding by age, sex, history of exacerbations, socioeconomic status, smoking, or hospital discharge pulmonary function cannot be excluded.
Nevertheless, if we accept that the conclusions are correct, the study suggests that successful follow-up is determined not so much by who performs it than by what is done. First, the diagnosis should be confirmed. In the study Nathan et al,13 the diagnosis of nearly 10% of patients who were apparently hospitalized for asthma was not confirmed, although the correct diagnoses for those patients are not presented. Second, studies have documented that the following factors, which could be addressed on a follow-up appointment, are related to an increased risk of asthma-related emergency department visits or hospitalizations: inadequate asthma knowledge14; not having an action plan1516; incorrect use of metered-dose inhalers17; adverse environmental exposures, especially regarding environmental tobacco smoke18 and mites1920; and adverse psychosocial circumstances.2122 Finally, a 2004 metaanalysis23 has confirmed that therapy with inhaled steroids, long-acting ß-agonists, and leukotriene modifiers reduces the number of asthma exacerbations, with inhaled steroids being most effective agent used in that regard. The successful nurse-led intervention by Castro et al10 appeared to address most of the factors listed above as well as to facilitate necessary ongoing follow-up. Many of these factors also appear to have been addressed in the study by Nathan et al,13 in which "the consultation in either arm of the study consisted of an evaluation of the events leading to the hospital admission, an assessment of the patients’ understanding of their asthma, initiation or reinforcement of asthma education, an assessment of their understanding of asthma therapy, assessment of inhaled technique, a self management plan and appropriate change in asthma medication."
One important question raised by the study of Nathan et al13 is why 47% of the patients who were seen by the respiratory nurses or physicians still experienced exacerbations during the 6 months of follow-up, including 10% who required rehospitalization. In addition to inadequate pharmacologic therapy and education regarding trigger avoidance or self-management, we suspect that poor patient adherence to treatment, psychosocial factors, and inherent asthma severity are likely explanations. Most of these factors could presumably be addressed by more effective interventions by both nurses and physicians, although specific recommendations cannot be made from the available information.
In conclusion, specialist care after an asthma hospitalization can improve outcomes, and a specially trained respiratory nurse practitioner may do just as well as a respiratory physician in this regard. However, further studies in larger populations of patients will be necessary to confirm these conclusions. Further studies also are needed to address larger issues, such as what aspects of follow-up care actually result in improved outcomes and what additional interventions are necessary for those whose outcomes are not improved despite asthma specialist care.
Footnotes
The authors have no conflicts to disclose.
References
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