All research involving human participants poses challenges. Studies of health behavior, and of the effectiveness of educational and behavioral interventions pose special challenges. These include obtaining reliable and valid measurements, designing interventions that actually change behavior, and recruiting and retaining participants over prolonged time periods (especially persons with low income or education, who may be most adversely affected by the health problems being studied).

Measurement Challenges in the LET’S Study

The LET'S Manage Asthma study illustrates some of the measurement problems being confronted in current studies. LET'S (for "lowering environmental tobacco smoke") is testing an educational intervention designed to motivate and assist parents to reduce their children's exposure to environmental tobacco smoke (ETS). The basic hypotheses are that: 1) participation in the study will be associated with improved lung function and a decreased need for medical care for acute asthma episodes; and 2) these improved outcomes will result from reduced ETS exposure.

Throughout the study, children's asthma symptoms, medication use, health care utilization for asthma, and quality of life will be assessed. Parents' readiness to quit smoking or otherwise reduce the child's exposure also will be measured. The intervention group will be compared to a control group of children.

Accurate measurement of ETS exposure of the children is critical. Questions for gathering information on individuals' smoking practices have been developed and used by researchers for years. However, self-reported parental smoking has limitations as a reliable indicator of a child's exposure. Further, parents actually may be unable to give an accurate appraisal of a child's exposure to their own smoking or the smoking of others with whom the child spends time.

The "gold standard" quantitative biomarker of exposure to nicotine, a component of ETS, is the substance cotinine. Cotinine, found in body fluids of persons exposed to ETS, is a breakdown product of nicotine. The LET'S study will measure children's urine cotinine prior to and at intervals following their enrollment in the study, as well as gather parental reports concerning their own and others' smoking and smoking restrictions within the home.

Recent evidence suggests that even measurement of cotinine may not reliably track exposure to those components of ETS that affect asthma, namely, particulates. To meet this added challenge, monitors under development at the Lawrence Berkeley National Laboratory will be used to measure other components of ETS in a subset of participating children. These measurements will be compared to the children's urine cotinine levels to investigate the reliability of cotinine as a biomarker of exposure.


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