Investigating Disease Patterns Through Epidemiology

1. MEDICINES THAT BACKFIRE Investigating Disease Patterns Through Epidemiology

2. Introduction • Unfortunately, physicians sometimes induce disease in their efforts to cure it. Some drugs, diagnostic tests, and therapies can inadvertently cause disease and health problems. Diseases of these origins are referred to as “iatrogenic.” The word iatrogenic comes from the Greek words “iatros,” meaning healer or physician and “gennan,” meaning as a product of – hence, physician-induced disease. The principles of epidemiology have been applied to investigate these unfortunate relationships and provide insight into iatrogenic illnesses. Patterns of iatrogenic disease usually reveal not error but ignorance. Doctors were simply unaware of the potential side effects or consequences of seemingly helpful procedures and therapies. I couldn’t delete this, so I just changed the text to white.

3. Areas for Investigation • Radiation • Medications • Over-the-Counter Drugs

4. Radiation and Leukemia • X-ray imaging introduced to medicine in early 20th century • Dangers of ionizing radiation were not recognized • Radiologists placed hands and body in path of radiation

5. Connections between Radiation and Leukemia • Long-term cohort study conducted at Johns Hopkins School of Public Health revealed: • Radiologists had higher rates of leukemiathan their counterparts in specialties where they were exposure to radiation was minimal • Experimental studies with animals went on to demonstrate that ionizing radiation can initiate leukemia. • Long-term cohort study conducted at Johns Hopkins School of Public Health revealed: • Radiologists had higher rates of leukemiathan their counterparts in specialties where they were exposure to radiation was minimal • Experimental studies with animals went on to demonstrate that ionizing radiation can initiate leukemia.

6. Implications • X-RAYS ARE NOW DEPLOYED IN THE LOWEST DOSES POSSIBLE • SHIELDING PRECAUTIONS ARE THOROUGH • CURRENT RESEARCH CONTINUES TO INVESTIGATE THE LONG-TERM RISK OF SCREENING TESTS SUCH AS THE MAMMOGRAM.

7. Some Important Epidemics Caused by Drug Therapies

8. Medications and Disease • Disease Linked to Adverse Drug Reactions • Nebulizers containing isoproternol • Linked to death in asthmatics • Supplements of DES (diethylstilbestrol) for pregnant women with threatened miscarriage • Linked to vaginal cancer in adolescent girls • Unopposed estrogen used for hormone replacement • Linked to uterine cancer in women

9. Over-the-Counter Drugs and Disease • Although these illnesses are not strictly iatrogenic, epidemiological studies can be used to investigate illnesses arising from self-medication • Example: Natural food supplement containing amino acid L-tryptophan

10. Over-the-Counter Drugs and Disease • Cluster of individuals presented with: • Severe muscle aches • Skin rashes • Neurologic symptoms • Eosinophilia (increase in white blood cells) • Most patients were young or middle-aged women • Disease was sudden onset, clustering in time (late 1989) and place (New Mexico)

11. Cases of this disease appeared in late 1989, with the majority of the cases appearing in September and October. Doctors struggled to identify this bizarre new illness as well as determine the contributing factors to the development of disease. Doctors began to associate the appearance of disease with exposure to specific over-the-counter medications. 1989 1988 1990

12. Over-the-Counter Drugs and Disease • Physicians reviewed drug records • Most women reported use of natural product for depression and insomnia • Link confirmed by a case-control study • All cases had ingested L-tryptophan pills • Epidemic of this disease, eosinophilia mylagia syndrome (EMS), traced to a single Japanese manufacturer

13. Conclusions • Most advanced industrial nations have strict laws to ensure safety and efficacy of both prescription and OTC drugs. • Does the medication do what it is supposed to? • Does the medication have harmful side effects? • Epidemiologic surveillance of drugs and other therapies provides a safeguard for doctors and patients.

14. References • Stolley, D. Lasky, T. 1995. Investigating Disease Patterns: The Science of Epidemiology. New York: W.H. Freeman and Company. Gordis. L. 2008. Epidemiology. Philadelphia, PA. W.B. Saunders Company.

15. Questions?