University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• In patients with asthma, does home use of a peak flow meter vs. monitoring subjective symptoms decrease utilization of health care resources?

Clinical Bottom Lines

1. Patients using a peak flow meter at home, when symptomatic, had a greater decrease in their asthma severity scores and in their utilization of health care resources than patients who used subjective symptommatic evaluation alone, although none of these results were significant (using P<0.05).
2. The subgroups with the greatest improvement among those using peak flow meters were those that had the sickest patients at baseline.
3. Patients in all groups had improvement in their symptom severity scores and hospital utilization. The only thing that all of the groups had in common was education about asthma and about symptom recognition. This emphasizes the need for us to be educating our patients about their asthma.
4. BID use of a peak flow meter is not practical. Only six percent of participants reported continued use at one year.
   

Summary of Key Evidence

1. Randomized clinical trial evaluating the effects of three different intensities of asthma symptom monitoring: subjective symptom monitoring (group 1), peak flow use when symptomatic (group 2), and peak flow use BID and when symptomatic (group 3).¹
2. Patients were age 6 to 19 and had more than three asthma-related visits in the year preceeding the study. Nurses visited the participants' homes and gathered sociodemographic data, baseline information regarding asthma morbidity, current medication use, and spirometry data. Participants were them given a journal and asked to keep symptoms for three months before being randomized into one of the three groups using a stratified randomization procedure. All groups received asthma action plans, asthma education and training in symptom recognition.
3. Results were monitored by three months of diary keeping, an exit interview at 3 months, and a 1 year post-exit interview. A chart reviewed was also performed to determine health care utilization.
4. A comparison of symptom scores at the three month exit interview revealed that group two had more symptom improvement than group one (p=0.10), group three had more symptom improvement than group one (p=0.13), and group three had more improvement than group two (p=0.002). The only one of these effects that was sustained at one year was group two had more symptom improvement than group one (p=0.07), although this was not clinically significant. When the groups were broken down into categories based on race, both groups two and three were shown to have significantly more improvement in symptoms at one year than group one (p = 0.004 and 0.05 respecitively.) Only six percent of people in group three reported continued BID use of the peak flow meter at one year.
5. Acute visits (ER and clinic) decreased from one year pre to one year post study. The most dramatic increase was in group two, who had a decline from 3.1 visits per year to 1.85 visits per year. Although this decrease was almost two-fold greater than in the other groups, the difference was not clinically significant.
   

Additional Comments

• A formal cost analysis was not done because results for the entire group (vs. the subgroup of black patients) were not significant. The authors did feel that a considerable amount of money would be saved by implementing peak flow use at home, however.
• The article was valid in that the groups had no statistical differences at baseline, the patients were analyzed in the groups to which they were randomized, and the outcome assessors were not aware of group allocation. The study did use a stratified randomization procedure to place patients in groups, but did not explain the procedure. Also, patients were aware of their group assignment. The study enrolled 168 participants, accounted for 156 at three months and 136 at one year, and made no mention of what happened to the missing patients or from what group the missing patients had come from.

Citation

1. Yoos HL, Kitzman H, McMullen A, Henderson C, Sidora K. Symptom monitoring in childhood asthma: a randomized clinical trial comparing peak expiratory flow rate with symptom monitoring. Annals of Allergy, Astham, and Immunology. 2002; 88:283-91.

CAT Author: Elizabeth Rzepka, MD

CAT Appraisers: Robert Schumacher, MD

Date appraised: March 10, 2004