Patient Safety Tip of the Week
January 28, 2014
Is Polypharmacy Always Bad?
Is polypharmacy
always bad? That’s a question that a group of researchers in the UK have
recently challenged (Payne 2014).
We often consider
polypharmacy to be a measure of poor quality. There are clearly reasons why
increasing numbers of drugs taken may lead to adverse events. We know that the
likelihood of drug-drug interactions increases with the number of medications
taken. Also side effects of medications may be additive. For example, taking
multiple drugs that have anticholinergic side effects may result in clinical
anticholinergic symptoms that would not have occurred with only one drug. Or
drugs that may be associated with orthostatic hypotension may have additive
effects to make that orthostatic drop in blood pressure symptomatic. And
multiple studies have demonstrated that polypharmacy is a risk for unplanned
hospitalizations.
But Payne and
colleagues (Payne
2014) have pointed out that most previous studies linking polypharmacy to
unplanned hospitalizations have had certain flaws. First, they may have
dichotomized variables (i.e. they used “more than x medications” to define
polypharmacy vs. no polypharmacy). Second, they often did not take into context
the reasons the patients were taking multiple medications or the number of
comorbidities. And many were done on select patient populations (eg. only the
elderly or nursing home residents).
So they performed a
retrospective analysis of patients in Scotland to further study the
relationship between medications and hospitalizations. Though it was a
retrospective analysis rather than a randomized controlled trial, the study
utilized a comprehensive data set on over 180,000 patients from 40 family
practices that were representative of the population as a whole, had close to
100% capture of medications prescribed, and linked to a database that stored
hospital admission data. Also, rather than dichotomizing the polypharmacy
variable, they split the medication variable into a continuum of ranges (eg.
none, 1-3, 4-6, 7-9, and 10 or more medications).
Their findings are
interesting. Yes, they confirmed that there is a strong correlation overall
between the number of drugs taken and the risk of unplanned hospital admission.
Patients taking 4-6 medications were more than twice as likely to have an
unplanned admission than those taking 1-3 medications. And those taking 10 or
more medications were 6 times more likely to be admitted than those taking 1-3
medications.
But when they
factored in comorbidities they found that the strength of the association
between number of medications and unplanned admissions was greatly reduced as
the number of comorbidities increased. In fact, for the patients with the most
comorbidities (6 or more conditions) there was no difference in the risk of unplanned
admission between those taking 4-6 medications vs. those taking 1-3
medications. Even for those taking 10 or more medications the risk was only
moderately increased (OR 1.5).
They explain their
results by noting that many studies on polypharmacy have ignored one very
important factor that seems counterintuitive: underprescribing! That is,
patients on multiple medications may not be taking a medication that is very
important for at least one of their underlying conditions. Of course, it may
not be truly underprescribing. Rather it may reflect poor compliance, a
phenomenon we tend to see increase with the number of medications prescribed.
In their study some further data supported their assertion that
underprescribing may play a role. Those patients with 6 or more comorbidities
who were receiving no medications were more likely to be admitted than those
receiving 1-3 medications.
It certainly makes
sense. If your patient has CHF, CAD, diabetes, and several other conditions but
is not taking those medications shown to reduce hospitalizations and
complications from those diseases, they are more likely to be admitted.
The authors
therefore caution against the use of “polypharmacy” per se as a quality
indicator because it may be misleading. They suggest that measures of
inappropriate prescribing (eg. Beers’ list, STOPP list) are likely to be better
quality metrics than using total number of medications. In our June 21, 2011
Patient Safety Tip of the Week “STOPP
Using Beers’ List?” we noted the STOPP criteria identified
potentially avoidable ADE’s impacting on hospitalization over twice as often as
did Beers’ criteria.
We’ve done multiple
columns on Beers’ list, the STOPP list, and inappropriate prescribing in the
elderly (see the list at the end of today’s column). We are also strong
advocates of regular reviews of a patient’s medications (medication therapy
management or MTM). See our May 7, 2013 Patient Safety Tip of the Week “Drug
Errors in the Home” for details on MTM. We’ve mentioned multiple times that
when we do such reviews on high-risk patients we almost always come away with
medication lists that are 1-2 medications shorter (because of therapeutic
duplication or medications no longer needed). But the work of Payne and
colleagues would suggest we need to add another column to our MTM sheets – one
for evidence-based medications that are missing for a condition the patient
has!
In our hospitals we’ve already added such a column to our discharge checklists and this has helped hospitals improve their compliance with quality metrics for a variety of P4P programs. But we probably have not kept up to date on our similar MTM lists on the outpatient side.
So is polypharmacy always bad? No, what we really need to strive for is “eupharmacy”.
Some of our past columns on Beers’ List and Inappropriate
Prescribing in the Elderly:
Patient Safety Tips of the Week:
· January 15, 2008 “Managing Dangerous Medications in the Elderly
· October 19, 2010 “Optimizing Medications in the Elderly”
· September 22, 2009 “Psychotropic Drugs and Falls in the SNF”
·
June 21, 2011 “STOPP
Using Beers’ List?”
·
May 7, 2013 “Drug
Errors in the Home”
What’s New in the Patient Safety World columns:
· June 2008 “Potentially Inappropriate Medication Use in Elderly Hospitalized Patients”
· September 2010 “Beers List and CPOE”
·
December 2011 “Beers’
Criteria Update in the Works”
·
November 2013 “More
on Inappropriate Meds in the Elderly”
References:
Payne RA, Abel GA, Avery AJ, et al. Is polypharmacy always hazardous? A retrospective cohort analysis using linked electronic health records from primary and secondary care. British Journal of Clinical Pharmacology 2014; 15 January 2014
http://onlinelibrary.wiley.com/doi/10.1111/bcp.12292/pdf
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