General practitioners in England and Wales appear to be seeing more and
more patients who have a substance abuse disorder and another psychiatric
illness—especially a serious psychiatric illness and a substance abuse
This trend was reported in the December Journal of Epidemiology and
Community Health by Ilana Crome, M.D., a professor of psychiatry at the
University of Keele University in Staffordshire, England, and co-workers.
Their study was based on information submitted by 230 general practitioners
in England and Wales to the General Practice Research
Database—purportedly the world's largest computerized database of
patient records. The information concerned the number of patients they had
diagnosed from 1993 to 1998 for psychiatric illnesses, substance abuse
(excluding alcohol and tobacco), or both.
The researchers used the information to determine the annual period
prevalence of psychiatric illness—substance abuse cases during each of
the five years—in other words, the annual number of comorbid patients
seen in general practice in England and Wales during each of the years.
They based their calculations on "patient years of exposure"
rather than on "number of registered cases" since the length of
time that patients visited general practitioners for their comorbid problems
varied. For example, a patient who registered with a general practitioner on
January 1, 1993, and who left on January 1, 1994, would have received a value
of "one person year" in the study. In contrast, a patient who
registered with a general practitioner on January 1, 1993, and who left on
July 1, 1993, would have received a value of 0.5 person years in the
The number of annual prevalent cases for a particular year—how many
patients were diagnosed for both substance abuse and another mental illness
within that year—was then divided by the patient years of exposure for
that particular year, giving the annual period prevalence for that year.
The investigators then compared the annual period prevalence of comorbid
cases for each of the five calendar years of interest and found that it
increased about 10 percent each year. In fact, the annual period prevalence of
comorbidity increased from 50/100,000 patient years of exposure to 80/100,000
patient years of exposure during the five-year study period, representing a 62
percent increase during the study period.
What's more, rates of serious psychiatric illness combined with substance
abuse grew even more over the five-year period—rates of schizophrenia
comorbid with substance abuse rose 128 percent, and rates of psychoses
comorbid with substance abuse rose 147 percent.
The question now is why such a surge occurred. Does it mean that more
people were seeking help for comorbid psychiatric—substance abuse
problems during the five years of the study than before? Or does it mean that
more people were experiencing comorbid psychiatric—substance abuse
problems during the five years of the study than before? The researchers
believe that the latter explanation may be correct, because, as they pointed
out in their study report, the population used in their study was around one
million patients a year.
"The prevalence observed in the study can be expected to closely
mirror that in the general population." Still, they noted, the data they
used for their study missed people "whose mental illness or drug use
never results in primary care service contact."
Regardless of reason, if the increase in the number of people with comorbid
mental illness and substance abuse continues, the researchers pointed out, the
average family doctor who saw seven such patients in 1998 will be seeing 14 in
2006. These results, the investigators said, should help inform policy debates
in the United Kingdom about general practitioners' care of patients who have
both psychiatric illness and substance abuse problems.
"The role of the general practitioner in providing shared care for
substance misusers is increasingly being encouraged," they wrote,"
and family doctors are increasingly becoming the first point of contact
for young drug misusers, although misgivings have been expressed about
treatment of drug users in primary care."
The study was funded by the Department of Health.
An abstract of the study, "Prevalence of Comorbid Psychiatric
Illness and Substance Misuse in Primary Care in England and Wales," is
posted online at<http://jech.bmjjournals.com/cgi/content/abstract/58/12/1036>.▪