Hypothesis-Generating Interviews

1. Hypothesis-Generating Interviews

2. Goals • Discuss the uses of hypothesis-generating interviews • Present information on case-patient selection, questions to ask and when and where to conduct hypothesis-generating interviews. • Provide useful tips on how to conduct an interview during an outbreak.

3. Why use hypothesis-generating interviews? • To obtain initial clues on possible sources of exposure • To develop a hypotheses-testing questionnaire • To identify signs and symptoms of the disease

4. Why use hypothesis-generating interviews? • To help develop or refine the case definition • To develop a develop a demographic profile and identify the population at risk • To develop a list of potential exposures

5. Who Do We Interview? • Case-patients • 8 to 10 • Differing demographic profiles • Typical clinical presentation • Occurring in the middle of the outbreak • Family member or friend if case-patient is unavailable • Parent or guardian if case-patient is a child • Health care providers, lab workers, clinical staff

6. Who Do We Interview? • Examples: • 1984-1985 Minnesota outbreak of Thyrotoxicosis • 1997 Michigan and Virginia Salmonella outbreaks

7. What Do We Ask? • Use existing hypothesis-generating resources as a template and guide • However, each outbreak is unique and questions should meet the needs of the investigation at hand • Contact others who have investigated similar outbreaks • Adapt the questionnaires used to the particular setting

8. What Do We Ask? • Basic demographic information • Clinical details • Activities • Food consumption

9. What Do We Ask? • Known or suspected agent • Likely exposures • Known reservoirs • Modes of transmission • Activities occurring during a specific period based on known incubation period and date of onset • Unknown agent • Broad, less specific questions • Activities, clinical signs and symptoms

10. When And Where Do We Conduct The Interview • Early in the investigation • Case-patients’ homes or health care setting • Other settings • e.g. the local health department, if several case-patients need to be brought together • Unusual approaches may be required • 1981 epidemic of listeriosis in Canada • 1983 epidemic of listeriosis in Massachusetts

11. How Do We Conduct The Interview? • Face to face • Telephone (under special circumstances) • Language considerations • Age, level of education, and other case-patient characteristics • Culturally sensitive wording • Mindful of uncomfortable topic areas • Avoid jargon and abbreviations

12. How Do We Conduct The Interview? • Standardized forms • Types of questions • Closed-ended • Open-ended

13. How Do We Conduct The Interview? • Tips: • Review the literature • Obtain background information • Enhance interviewing and people skills • Act friendly and professional • Use memory aids

14. How Do We Conduct The Interview? • Tips: • Introduce yourself and give your credentials • Explain the purpose of the interview and tell the case-patient how long the interview will take • Be systematic but flexible when questioning • Provide contact information • Thank the interviewee for participating • Acknowledge his or her contribution to the investigation

15. Conclusions • Hypothesis-generating interviews increase efficiency of outbreak investigations by • helping confirm the existence of an outbreak • providing insights on potential causative agents • identifying potential sources of exposure and modes of transmission • From the information obtained, investigators • create case definitions • construct epi-curves • proceed to test hypotheses through analytic studies

16. References 1. Reingold, A. Outbreak investigations—a perspective. Emerg Infect Dis. Jan-Mar 1998;4:21-27. 2. Cummings SR, Stewart AL, Hulley SB. Designing questionnaires and data collection instruments. In Hulley SB, Cummings SR, Browner WS et al, eds. Designing clinical research. 2nd ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2001:231-245. 3. CDC Epidemiology Program Office. Case studies in applied epidemiology. No 873-703. An epidemic of Thyrotoxicosis. Available at: http://www.cdc.gov/eis/casestudies/Xthyrotox.instruct.873-703.pdf.

17. References 4. Breuer T, Benkel DH, Shapiro RL, et al. A multistate outbreak of Escherichia coli O157:H7 infections linked to alfalfa sprouts grown from contaminated seeds.  Emerg Infect Dis. 2001;7(6):977-982. Available from http://wwwcdc.gov/ncidod/eid/vol7no6/breuer.htm. 5. US Department of Health and Human Services. Principles of epidemiology. An introduction to applied epidemiology and biostatistics. 2nd ed. Self-study course 3030-G. Lesson 6: Investigating an outbreak. Available at http://www.phppo.cdc.gov/PHTN/catalog/pdf-file/Epi_Course.pdf.  

18. References 6. Schlech WF, Lavigne PM, Bortolussi RA, et al. Epidemic listeriosis—evidence for transmission by food. N Engl J Med. 1983;308:203-206. 7. Fleming DW, Cochi SL, MacDonald KL, et al. Pasteurized milk as a vehicle of infection in an outbreak of listeriosis. N Engl J Med. 1985;312:404-407.