Relationship Between Airway Obstruction and Respiratory Symptoms in Adult Asthmatics
Clinical practice guidelines have emphasized the need to objectively measure airway obstruction when evaluating and treating patients with chronic asthma. This recommendation stems in part from clinical studies that have demonstrated a poor correlation between asthma symptoms and the degreeof underlying air-wayobstruction as determined by the FEV1 and peak expiratory flow (PEF). Although asthma patients may be more accurate than their physicians in estimating their level of PEF, other studies have emphasized the finding that asthma patients often underestimate their level of airway obstruction. In these patients, therapies based exclusively on patient-reported symptoms may result in undertreatment. We sought to further characterize the relationship between airway obstruction and the respiratory symptoms reported by adult asthmatics. Our observations form the basis of this report.
Materials and Methods
The charts of patients who had been evaluated at the adult asthma clinic of the University of Maryland Hospital between July 1, 1994, and December 31, 1996, were reviewed for inclusion into the study. Patients were excluded from the analysis if they did not have a clinical history compatible with asthma, had a current or past smoking history of >10 pack-years, or were unable to adequately perform spirometry or PEF maneuvers. During the initial clinic visit, all patients underwent a complete history and physical examination. As part of the initial history, patients were asked to quantify each of six current asthma symptoms, including cough, dyspnea, chest tightness, wheezing, sputum production, and nocturnal awakening on a 0 (none) to 4 (constant) whole integer scale. Total asthma scores ranging from 0 to 24 were possible utilizing this scale. The best of three standing PEF values was recorded (Access Peak Flow Meter; Healthscan Products, Inc; Cedar Grove, NJ). Spirometry was performed by a certified pulmonary function technician before and 20 min after two inhalations (180 μg) of albuterol (Spirometries 2500 Portable Spirometer; Spirometries Co; Auburn, Me). During the initial clinic visit, all patients received instruction on medication compliance, metered-dose inhaler technique, spacer use, and home measurement of PEF. Inhaled corticosteroids were prescribed for all patients. At the first follow-up visit, PEF was measured and asthma symptoms were again recorded using the same 0 to 4 whole integer scale.