Medicines That Backfire - StudentF

Report
Investigating Disease Patterns
Through Epidemiology
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.
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Early Example of Iatrogenic Disease
• Mid-19th century – Physician Ignaz Semmelweis
noted instance of puerperal fever (fever associated
with childbirth) was lower in poor patients than rich.
• Rich women received more supervised care.
– Doctors spreading the infection from patient to patient
• Handwashing diminished death rates from infection
in obstetrical cases.
• Semmelweis’ work anticipated Pasteur’s germ theory
and Lister’s work on antisepsis.
Areas for Investigation
• Radiation
• Medications
• Over-the-Counter Drugs
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
Connections between Radiation and
Leukemia
• Long-term cohort study conducted at Johns
Hopkins School of Public Health revealed:
– Radiologists had higher rates of leukemia than
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.
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.
Some Important Epidemics Caused by
Drug Therapies
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
DES and Ovarian Cancer
• In the 1950s, diethylstilbestrol (DES) was
given to pegnant women who were blieved at
risk for miscarriage
– Peak usage estimated as high as fiften percent of
prenant women
• I958 randomized clinical trial (Universty of
Chicago), pregant women received DES or an
inert placebo
– No benefit shown in the prevetion of miscarriage
DES and Ovarian Cancer
• In the 1970s, a significant number of cases of
vaginal cancer were reported
• A case-control study (Herbst, Ulfeder, Poskanzer –
1971) found that 7 out of 8 cases of vaginal cancer
had been exposed to DES in utero.
• Connection confirmed by animal studies and a
larger case control study.
– New York State Tumor Registry confirmed more than
600 cases of vaginal cancer were linked to prenatal
DES exposure
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
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)
Jan
Feb
Mar Apr May Jun
Jul
Aug
Sep
Oct
Nov Dec
Jan
Feb
Mar Apr May Jun
Jul
Aug Sep
Oct
Nov Dec
Jan
Feb
Mar Apr May
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.
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
• 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.
References
• Stolley, D. Lasky, T. 1995. Investigating
Disease Patterns: The Science of
Epidemiology. New York: W.H. Freeman
and Company.
2. Gordis. L. 2008.
Epidemiology. Philadelphia,
PA. W.B. Saunders
Company.
Questions?

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