[Clinical characteristics of asthmatics who stop peak expiratory flow monitoring (PFM)--analysis of patients who continued PFM more than eight weeks].

To estimate the effect of treatment and for patient education, we recommend 8 weeks PFM for all asthmatics when we start their treatments. To elucidate clinical characteristics of asthmatics who stop PFM, we analyzed 311 patients (145 males aged 15-76 years and 166 females aged 17-79 years) who could measure their PEFs twice daily for more than 8 consecutive weeks. The analysis of cumulative continuation rate of PEF monitoring revealed that the patients' withdrawal rate was 19% per year. The sixty asthmatics who gave up monitoring their PEFs (group A) showed significantly younger present ages (38.8 +/- 14.2, mean +/- S.D.) and younger ages of onset of their asthma (29.8 +/- 19.6) than the other 251 asthmatics who could continue to monitor their PEFs (group B). The present ages and ages of onset of asthma of group B were 46.2 +/- 16.7 and 37.6 +/- 21.2 years, respectively. Despite no significant differences in the severity of the asthma based on both clinical symptoms and PEF between groups A and B, the asthma severity based only on the clinical symptoms of group A were significantly less than those of group B. The analysis of Cox's proportional hazards model revealed that major factors which influence patients' stopping of PFM were present age and severity of their asthma which was estimated by the patients' symptoms only, without PEF assessment. These results suggest that asthmatics whose present age is young and whose ability of perception of asthma is poor will be apt to stop PFM.