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Using Biomarkers to Collect Health Data
Biomarkers are objective physical or biologic measures of health conditions. For years, DHS surveys have gathered data on height and weight to evaluate nutritional status of women and children. Now, using field-friendly technologies, The DHS Program is able to collect biomarker data relating to a wide range of health conditions, including infectious and sexually transmitted infections (STIs), chronic illnesses (such as diabetes, micronutrient deficiencies), and exposure to environmental toxins.
Traditionally, much of the data gathered in DHS surveys is self-reported. Biomarkers complement this information by providing an objective profile of a specific disease or health condition in a population. Biomarker data also contribute to the understanding of behavioral risk factors and determinants of different diseases.
The demand for biomarker data is growing worldwide. In 1995, anemia testing became a standard component of the DHS survey protocol after the Kazakhstan DHS showed that respondents were comfortable with providing blood specimens for testing. Since then, 20 more biomarkers have been added to DHS surveys in more than 50 countries. DHS surveys have tested for HIV, malaria, blood glucose, syphilis, the herpes simplex virus, serum retinol (Vitamin A), lead exposure, high blood pressure, and immunity from vaccine-preventable diseases, such as measles and tetanus. Most surveys now include testing for HIV infection in their survey design.
The DHS Program uses field-friendly equipment and rapid testing technologies whenever possible to get results quickly and reliably. Many tests can be carried out using only a few drops of blood from a finger or heel. With the development of portable analyzers, the results of some tests, such as anemia, and referrals for treatment can be provided to the respondent within minutes. Other tests still require specimens to be transported to the laboratory for analysis. Dried blood spots (DBS) on filter paper are increasingly used for many tests, including HIV. This method of specimen collection has eliminated the need for cold chain and/or refrigeration of specimens, reducing considerably the complexity of storage in the field and transport to the laboratory.
The standard DHS biomarker collection protocol is summarized in the DHS biomarker manual.
Using Biomarker Data
Biomarker data provide much needed information about the prevalence of health conditions, such as anemia or STIs. With this information, public health specialists can:
- Identify risk factors for certain conditions;
- Track trends in prevalence over time;
- Identify the health care needs in different population groups and areas;
- Evaluate the impact of health promotion and service delivery interventions;
- Improve training for health care providers; and
- Develop advocacy materials and interventions based on objective data.