  The accounts of medical trials provide very detailed information about the
patients' health conditions. In contrast, only minimal data are usually given
about demographic factors. Yet, some of these factors can have a notable impact
on the overall death rate, thereby changing the outcome and conclusions of the
trial. This paper focuses on two of these variables. The first is marital
status; this effect, which will be referred to as the Bertillon effect, may
change death rates by over 100%. The second is the age of the oldest patients;
because of the exponential nature of Gompertz's law, changes in the
distribution of ages in the oldest age group can have dramatic consequences on
the overall number of deaths. It will be seen that randomization alone can
hardly take care of these problems. Appropriate remedies are easy to formulate
however. First, the marital status of patients as well as the age distribution
of those over 65 should be documented for both study groups. Then, thanks to
these data and based on the Bertillon and Gompertz laws, it will become
possible to perform appropriate corrections. Such corrections will notably
improve the reliability and accuracy of the trial's conclusions, especially for
trials which include a large proportion of elderly subjects.
