Assessing symptoms and peak expiratory flow rate as predictors of asthma exacerbations.
OBJECTIVE
To investigate peak expiratory flow rate (PEFR) and quality of life scores for their ability to predict exacerbations of asthma.


METHODS
We identified adults who received oral or inhaled asthma medications from 36 community drugstores. We administered the McMaster Asthma Quality of Life Questionnaire (AQLQ) and measured PEFR, defining "red zone" (highest risk) as a PEFR < 50% of each patient's expected value based on gender, age, and height. We identified asthma exacerbations (breathing-related emergency department visits and hospitalizations) within 4 and 12 months after enrollment and used proportional hazards regression to assess the ability of PEFR and AQLQ scores to predict exacerbations, controlling for clinical and demographic factors.


RESULTS
A red zone PEFR was a significant univariable predictor of exacerbations within 12 months (hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.1 to 3.0; P =.027). However, neither a red zone PEFR, the raw PEFR, or percent of predicted maximal PEFR were significantly predictive when controlling for AQLQ scores, clinical characteristics, or demographic data (P >.2). However, the 4 subscales of the AQLQ were each significant univariable and multivariable predictors of asthma exacerbations. For example, the overall AQLQ scale had a multivariable HR of 0.63 (95% CI, 0.46 to 0.87; P =.005) for exacerbations occurring within 4 months and 0.66 (95% CI, 0.54 to 0.82; P <.001) within 12 months.


CONCLUSIONS
PEFR added no predictive information to that contained in AQLQ scores and clinical and demographic data. These results support the National Institutes of Health asthma guidelines' recommendation for routinely assessing symptoms but not PEFR.
Division of General Internal Medicine and Geriatrics, Department of Medicine, Indiana University School of Medicine, 1001 W. 10th Street, Room M200-OPW, Indianapolis, IN 46256, USA. wtierney@iupui.edu
William M
WM
Tierney
J Franklin
JF
Roesner
Roopa
R
Seshadri
Michael G
MG
Lykens
Michael D
MD
Murray
Morris
M
Weinberger
D000208:Acute Disease; D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D011237:Predictive Value of Tests; D011788:Quality of Life; D012008:Recurrence; D012107:Research Design