[Symptoms, FEV1/FVC, and peak flow as indices of the control of asthma]

In a cross-sectional study, we evaluated success in the control of asthma as defined by criteria for symptoms, for FEV1/FVC, and for peak flow rates. One hundred and three patients with chronic asthma who had been treated with inhaled steroids were studied. Chest tightness, dyspnea, wheezing, sputum production, and coughing were each scored from 1 (worst) to 5 (best). Symptoms were said to have been controlled if the symptoms scores for the preceding 4 weeks were greater than or equal to 20; FEV1/FVC was said to be under control if it was greater than or equal to 70% when measured in the clinic; peak flow was said to have been controlled if the lowest peak flow in the preceding 4 weeks was greater than or equal to 80% of the highest measured value. Symptoms were controlled in 72% of the patients, FEV/FVC was under control in 83%, and peak flow was controlled in 66%. The patients were grouped by severity of disease into four classes, and these percentages did not differ significantly among the classes. In 22 out of 74 (30%) patients in whom symptoms were controlled, peak flow was not controlled. Furthermore, in 18 out of 64 (28%) patients in whom symptoms and FEV/FVC were controlled, peak flow was not controlled. We concluded that in treating asthma, not should symptoms be controlled, but peak flow should also be measured each day to avoid undertreatment.