Psychiatr News March 2, 2007
Volume 42, Number 5, page 24
© 2007 American Psychiatric Association
Antipsychotic Adherence Data Counter Common Belief
Aaron Levin
Psychiatric patients are reputed to be less adherent than others to
medication regimens, but a new study may upend that assumption.
A study of 1,686 veterans revealed that the extent of adherence to
antipsychotic medication regimens was significantly better than to
hypoglycemic and antihypertensive medications, but shorter prescription refill
intervals were found to be more closely correlated with nonadherence than were
types of medication.
"With adjustment, we found that people with schizophrenia are not any
worse about sticking to their medications than people without
schizophrenia," lead study author John Piette, Ph.D., an epidemiologist
and an associate professor of internal medicine at the University of Michigan,
told Psychiatric News. The study appeared in the February
Psychiatric Services.
Piette and four colleagues, all affiliated with Health Services Research
and Development in the Department of Veterans Affairs in Ann Arbor, used data
from the VA National Psychosis Registry, part of a unified electronic medical
record system. The researchers excluded patients who were on more than two
hypoglycemic and antihypertensive drugs.
They evaluated prescription-refill data for Fiscal 2002 of patients with a
diagnosis of schizophrenia or schizoaffective disorder and both diabetes and
hypertension. Most patients were male (95 percent). About 52 percent were
white, 29 percent were black, and 11 percent were Hispanic. Each group used an
average of 5.3 medications.
Before adjustment, the researchers found that patients appeared to adhere
more closely to their antidiabetic and antihypertensive medications than to
their antipsychotic drugs. However, once they controlled for characteristics
of medication regimens, including average days' supply of drugs, the odds of
poor adherence were reversed.
"The adjusted odds of poor adherence were significantly higher for
hypoglycemic and antihypertensive medications than for antipsychotic
medications," they wrote.
In fact, the shorter the hypoglycemic and antihypertensive medication
refill periods were, the worse the adherence.
"Regimens with an average 30 days' supply or less were associated
with a 3.3-fold increase in the relative odds of non-adherence compared with a
supply of 60 days or more."
Drugs to treat diabetes or high blood pressure are usually prescribed in
90-day allotments, and this study showed that the type of medication is
heavily correlated with the number of days' supply in the refills, said
Piette.
"Antipsychotic drugs are less likely to be filled on time because of
obstacles [the patient faces] in getting a prescription filled—like
going to the doctor, taking off work, finding transportation, and so
on," he said. "Often we think about adherent patients versus
nonadherent patients. But this study is a reminder that a patient's adherence
is not consistent across all medications and can depend on other factors like
refill intervals."
"Common wisdom holds that psychiatric patients should get only 30-day
supplies of their prescriptions to better maintain watch over symptoms, drug
response, and side effects," said John Newcomer, M.D., a professor of
psychiatry, psychology, and medicine and medical director of the Center for
Clinical Studies at Washington University School of Medicine in St. Louis, in
an interview. "Yet in the study, when refill intervals were held
constant [for both the schizophrenia medications and the diabetes and
hypertensive medications], there was better adherence to antipsychotic
medications."
Whether this holds true all the time requires more research, said both
Piette and Newcomer. Finding the crossover point between shorter and longer
refill times demands both knowledge and judgment.
"I suspect it varies by patient characteristics," said
Newcomer. "If you have a suicidal patient, maybe a shorter interval
makes sense, but others may find a longer interval beneficial."
Conventional thinking has also favored treating psychiatric illnesses first
as a way of overcoming the memory problems and attentional difficulties they
cause, then tackling conditions like diabetes and high blood pressure.
However, medical comorbidities cannot be solved by simply writing a
prescription for antidiabetic or antihypertensive drugs, said Newcomer, who
has studied the metabolic consequences of psychiatric drugs. Stabilizing a
patient on antipsychotics before tackling diabetes and hypertension may not
make sense, he said.
"The most important thing to realize now is that adherence problems
extend to diabetes and high blood pressure medications," he said.
"it's naïve to believe that diabetes treatment is 'easy.' It's
probably more difficult than administering psychotropics."
Piette's study should promote greater interest in primary prevention, said
Newcomer.
"In psychiatric patients, preventing diabetes is simpler than
managing it or other complex diseases. Also, secondary prevention of the
metabolic effects is not as easy as many people think. There are adherence and
financial challenges to making it work."
Another study in the same issue of Psychiatric Services found that
people with co-occurring psychotic and substance abuse disorders were four
times more likely to die over a 12-year period if they also had diabetes.
"Psychiatrists, like all physicians, should encourage patients to
take their medications as prescribed," said Piette. "But this
means more than just asking 'Do you take your medications?' The question must
be posed for each drug the patient has been prescribed."
"Differential Medication Adherence Among Patients With
Schizophrenia and Comorbid Diabetes and Hypertension" is posted at
<http://ps.psychiatryonline.org/cgi/content/full/58/2/207>.
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