Asthma health status: influence of disease severity categorized by peak expiratory flow.

To evaluate the health status of patients with stable asthma and determine how disease severity affects the status, 68 consecutive patients were recruited from an outpatient clinic at an university hospital. Health status was assessed with the St. George's Respiratory Questionnaire and the Asthma Quality of Life Questionnaire (AQLQ). The results of the questionnaires revealed that the mean % predicted peak expiratory flow (PEF) in the preceding 2 weeks correlated most significantly with each total score for the two health status measures. We also found that, in the groups classified by mean % predicted PEF (mild, PEF > or = 80%; moderate, 60 to 79%; severe, < 60%), there were significant differences in all SGRQ scores (p < 0.05). In a subgroup analysis, the scores for moderate and severe patients were significantly worse than for mild patients in all four components (p < 0.05). Almost the same tendency was observed in the score distribution on the AQLQ. We conclude that mean % predicted PEF correlated most with the health status of the patients. Patients with PEF higher than 80% of predicted value generally maintained a better health status than did those with less than 80% of predicted PEF. Achieving higher than 80% of predicted PEF is important in managing asthma from the viewpoint of health status.