Complementary Alternative Cardiovascular Medicine

6 Alternative Cardiovascular Medicine
dence-based decision making are descriptive studies (published as case
reports or clinical series); however, they may be critically important in
the recognition of a medical illness or a treatment option. For example,
one of the earliest important papers that helped in the recognition of the
human immunodeficiency virus (HIV) was a case series of a cluster of
Kaposi sarcoma cases in men who were homosexual (11).
Explanatory study designs seek to examine the cause of a disease or
the efficacy of a treatment by using comparison. Studies that are observational—where
the investigators observe nature to reach conclusions—
include case-control studies, cohort or follow-up studies, and
cross-sectional studies.
In a case-control study, one begins with a group of subjects (cases)
who have the disease in question and identifies a group that is similar in
all regards except for the disease (controls). Investigation determines if
a proposed factor is significantly more or less prevalent in the history of
the cases or the controls. For example, to determine if antioxidant vitamins
are cardioprotective, a case cohort study would identify men with
myocardial infarction in a studied cohort and a control group and survey
them regarding previous and present use of antioxidant vitamins. A
significantly higher use of such vitamins in controls compared to cases
would support the hypothesis that antioxidant vitamins protect patients
from myocardial infarction.
The cohort or follow-up study involves the evaluation of a group of
subjects without the disease and incorporate a long follow-up period so
that sufficient cases of the disease to develop. The objective is usually
to determine if the presence or absence of a given factor measured at the
initial evaluation was predictive of the likelihood of developing the
disease. The Framingham Heart Study is of this design. Here a large part
of the population of Framingham, Massachusetts, served as the cohort.
This study is responsible, in large part, for our understanding of both the
traditional and newer coronary heart disease risk factors.
In a cross-sectional study, a study population is divided into those
with a disease (or outcome) and those without a disease. The population
is evaluated regarding risk factors or the use of preventive strategies for
the disease. Results are determined by a correlation of the risk factor/
preventive strategy with the presence or absence of the disease.
These three observational study designs can identify correlations and
strongly suggest an effect of the factor being measured on the studied
outcome. They are generally, except in the case of large, long-term
cohort studies, less expensive and shorter than clinical trials. However,
they are subject to variables such as selection bias, subject bias, and
observer bias. An example of such bias would be an antioxidant-heart