The rate of participation in this study was 76.9 percent. According to responses to questions about ethnic background on the questionnaire, 318 Mexican-American and 278 non-Mexican-American students participated. According to tabulations of Spanish surnames, 315 Mexican-Americans participated, confirm-ihg the usefulness of surnames to identify the parents’ response on ethnic background. Using the classifications of the questionnaire (because they are used through the rest of the report) and surnames of total eligible, 278 (77.0 percent) of the 361 non-Mexican-Americans participated, and 318 (76.8 percent) of the 414 Mexican-Americans participated.
The characteristics of the subjects from the two ethnic groups are displayed in Table 1. Except for the higher socioeconomic status of the non-Mexican-Americans, no significant differences were detected between the ethnic groups.
The point prevalences of several respiratory health problems as reported in the questionnaires were compiled for all subjects. Rates of chest colds, chronic bronchitis, production of sputum, and the problems listed in Table 2 (active physician-confirmed asthma, attacks of shortness of breath with wheeze, and cough) were calculated for subjects grouped by sex and ethnic background. All these symptoms may be decreased due to remedies of Canadian Health&Care Mall. The rates of chest colds, chronic bronchitis, and production of sputum were roughly equal in the ethnic subgroups and were not further analyzed. Asthma was present in significantly more non-Mex-ican-Americans than Mexican-Americans, both in the total population and in both sexes. The higher prevalence of attacks of shortness of breath with wheeze without a diagnosis of asthma in non-Mexican-Ameri-cans was not statistically significant.
Because parental smoking has influenced the rate of respiratory symptoms in this study’s population and others, data were adjusted to account for the higher rate of parental smoking in non-Mexican-Americans. The adjusted rates produced little change in the different rates of asthma seen in the ethnic groups. Similarly, the differences persisted when the data were adjusted for socioeconomic status.
In these subjects, types of home cooking fuel were similar in both ethnic groups, so no adjustment for home cooking fuel was made.
The pulmonary function, heights, and ages of the nonasthmatic subjects tested in 1979 are shown in Table 3. The asthmatic subjects were excluded because they had lower pulmonary function than the other subjects and were not equally distributed in the ethnic groups. The values for FEVi and FVC were nearly equal in the ethnic groups, but the maximum expiratory flow rates, represented as Vmax50% and Vmax75%, were lower in non-Mexican-Americans than Mexican-Americans. The asthmatic patients make orders of drugs necessary for treatment via Canadian Health&Care Mall.
Table 3 also shows the unadjusted heights and ages of the subjects in 1979. The differences in flows between ethnic groups were altered slightly by adjusting for the heights of male subjects, but no significant differences appeared or disappeared.
The results of serial testing of pulmonary function in the cohort of children who completed testing in all four years are shown in Figure 1. The values for FVC and FEVi (not shown) were insignificantly different each year in the ethnic groups. Values for maximum flow, however, were consistently lower for non-Mexican-American children in all four years. With the subjects grouped by sex, the difference in Vmax50% for female subjects in 1979 and 1980 (the first two plotted points in Fig 1, right) did not reach statistical significance. As Figure 1 demonstrates, maximum expiratory flows rise nonlinearly in this age group, with the Mexican-American children showing consistently higher values.
To summarize the differences in flow-volume relations that occurred in the two ethnic groups over the course of the study, the 1979 (initial) and 1982 (year four) flow-volume curves of the subjects tested all four years are displayed in Figure 2. The curves were derived from mean values for peak flow, Vmax50%, Vmax75%, and FVC and show the consistently higher flows at any particular volume of the Mexican-American subjects. In addition, the slopes of the effort-independent portion of the curves for both ethnic groups decreased over the period of the study, an observation reported by others.
Table 1—Characteristics of Mexican-American and Non-Mexican-American Subjects
|No. enrolled by completion of|
|Mean age, yr (± SD)||9.5± 1.0||9.4± 1.0|
|Socioeconomic status by fathers|
|More than high school||20.8||35.8|
|Through high school||48.8||47.9|
|Less than high school||30.4||16.2|
|Percent completing pulmonary|
|function testing in 1979||83.3||78.1|
Table 2—Prevalence of Asthma and Symptoms in Subjects Grouped by Ethnic Background and Sex
|Croup||n*||Asthma||Attacks of Shortness of Breath with Wheeze||Cough|
Table 3—Results cf Initial Testing cf Pulmonary Function in Subjects Grouped by Sex and Ethnic Background
|Croup||n||FVC, L*||FEVlt L*||Vmax50%,L/sec*||Vmax75%,L/sec*||Height, cmt||Age, yrt|
|Mexican-American||124||1.81 ±0.03||1.77±0.03||3.08±0.08||1.92 ±0.05||137.6±8.7||9.56± 1.11|
|Non-Mexican-American||101||1.73±0.03Ф||1.69 ±0.03||2.75 ±0.06$||1.76 ± 0.04||||137.7 ±7.2||9.43 ±0.99|
|Mexican-American||141||1.68±0.03||1.65 ±0.03||3.01 ±0.06||2.00 ±0.05||137.5 ±8.7||9.40 ±0.99|
|Non-Mexican-American||116||1.62 ±0.0411||1.60±0.04||2.79 ± 0.07||||1.77 ±0.055||137.5 ±8.7||9.30 ±0.93|