Two groups of subjects were responsible for a less than perfect agreement between the questionnaire and physician claims data. The first group were subjects seen by a physician for asthma (according to physician claims) who did not report an asthma attack in the previous 12 months or asthma medication use. Table 1 shows that 98 of 100 such subjects had had some asthma symptoms in the preceding 12 months, although only 64 and 71 subjects reported an asthma attack or the use of medication, respectively. Thus, a physician visit for asthma seemed to be justified by the presence of asthma symptoms. Even those who had visited a physician two to five years before the survey was taken had a more than 90% probability of asthma symptoms on survey. Of those who had not visited a physician for asthma, approximately one-half had experienced some asthma symptoms. The sensitivity of physician claims for identifying subjects with any asthma symptoms was very poor (7.8%). On the other hand, the absence of asthma symptoms on the questionnaire almost excluded the probability of being seen by a physician for asthma.
The second group responsible for a less than perfect agreement between the questionnaire and physician claims data were subjects who had had an asthma attack or were taking medication in the previous 12 months but were not seen by a physician for asthma. These subjects were checked to see whether they were seen by a physician for a respiratory diagnosis that may overlap with asthma: bronchitis not otherwise specified, chronic bronchitis, emphysema or chronic airflow obstruction. Table 2 shows that the percentage of subjects who had had an asthma attack and/or who were taking asthma medication, and who were seen by a physician for asthma increased as additional years of physician contact were considered. In addition, approximately 10% to 15% of these subjects were seen for other respiratory diagnoses. Thus, over the five years before the survey, approximately 80% of those reporting asthma attacks or the use of asthma medication were seen by a physician for asthma or an overlapping diagnosis.
Table 2. Comparison of responses to the questionnaire with physician’s claim for asthma or nonasthma respiratory cause (resp m)
|Physican contact wi||thin An||sthma attack169||Resp Use of medication172||onses to the questionn Attack or medication214||aireAttack and medication127||Any asthma symptom*1262|
|0-1 years||Asthma (%)||37.9||41.3||37.9||42.5||7.9|
|Resp m (%)t||9.5||11.6||11.2||9.4||12.0|
|0-2 years||Asthma (%)||50.9||54.1||50.0||56.7||10.4|
|Resp m (%)||10.1||12.8||12.1||10.2||18.7|
|0-5 years||Asthma (%)||63.3||65.1||60.7||70.1||14.8|
|Resp m (%)||13.0||15.1||15.0||12.6||27.5|
*Asthma attack, current use of medication, wheezing, being awakened by tightness in chest, attacks of shortness of breath or coughing; fBronchitis not otherwise specified (International Classification of Diseases, ninth revision [ICD-9] code 490), chronic bronchitis (ICD-9 code 491), emphysema (ICD-9 code 492), chronic airflow obstruction (ICD-9 code 496); *No physician claim for either asthma or resp m