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Children With Asthma: ETS exposure

We did not demonstrate a statistically clear mechanism that would account for the effects of the intervention on asthma outcomes by its effect on measures of exposure. Compared to the main outcome (health-care utilization), which was measured on all subjects, the exposure variables were measured only on about two thirds of the subjects at follow-up. Furthermore, the less-than-perfect association among the measures of exposure indicates that there is considerable variation associated with these measures. When an intervening variable on the causal pathway between treatment and outcome is measured with error, the test of the mechanistic hypothesis loses precision and can give a false-negative result. These considerations cause us to be cautious in the interpretation of the apparently negative results with respect to the hypothesis that the effects of the intervention on health-care utilization are entirely or in part due to a reduction in ETS exposure. Larger studies, with more complete follow-up and even greater attention to reduction of error in the measurement of ETS exposure, are necessary to adequately evaluate the hypothesis that some or all of the clinical effect of our intervention is due to measurable effects on exposure. canadian neighborhood pharmacy

Nevertheless, we recognize that there may well be other explanations for the positive clinical effects of the intervention. Some behavior change associated with the intervention, other than ETS exposure reduction, could have mediated the reduction in health-care utilization, in whole or in part. For example, although both groups were on similar medication regimens, the intervention group might have been more adherent to those medications, or might have made additional modifications in their home environment, or might have responded more quickly and appropriately to the onset of asthma symptoms than the control group. If this were the case, the importance of the finding of an overall clinical benefit associated with the intervention would remain, but the interpretation of the underlying mechanism would be quite different.