The featured paper is ‘Contraindicated Medication Use Among Patients in a Memory Disorders Clinic’. The idea in this study was to look at how many inappropriate medications were prescribed in a population with cognitive impairment. Judging a medication to be inappropriate in a standardised way seems at first glance to be quite tricky. It turns out however that a set of criteria have been developed – the Beer’s Criteria in fact – for identifying inappropriate medication. The criteria have been established by consensus and updated in 2003 and are perhaps a starting point for looking at this issue. The criteria do have drawbacks particularly as medications that are indicated as inappropriate may not be when an individual’s circumstances are taken into consideration. However in the paper the authors identify some reasons why the inappropriate medication are indeed inappropriate in this population. For instance the authors consider that some of these medications may give rise to reversible cognitive impairment.
Patients were selected from a memory clinic in San Francisco and as the authors point out later, the findings should if we are cautious be restricted to people from a similar population. The people entered into the study were assessed by a team comprising psychiatrists, psychologists, nurses and social workers. The team assessed history, physical examination, neuropsychological tests including (Wechsler Memory Scale, verbal fluency tests), functional activities and dementia rating scales as well as clinical investigations. The people selected for the study were 100 consecutive patients in the clinic. As these were consecutive cases, it seems as though this avoids selection bias at this stage of the study as there is no obvious way in which this should select a certain group of patients (unless there is a seasonal variation in patient characteristics).
Medications were identified and from these the inappropriate medications was identified using the Beer’s criteria. The researchers then recorded patient characteristics including age, sex, race, years of education, MMSE scores and dementia subtypes. Patient data was then grouped according to whether the person was receiving inappropriate medication or not. Statistical differences between the two populations were then identified.
22 patients were taking inappropriate medication (according to the Beer’s Criteria). The most common of these contraindicated medications were the Benzodiazepines followed by Oxybutynin and Amitriptylline. 14% of the 28 patients taking an anticholinesterase inhibitor were also taking an anticholinergic medication. One finding was a difference between the two groups of patients (taking or not taking inappropriate medications) in that those taking inappropriate medications were significantly more likely to be taking more medications (p=.004). The authors then reference a meta-analysis were it was found that in 1/3 of cases of cognitive impairment, stopping the contraindicated medications reversed the cognitive impairment.
Given the remarkable advances that are taking place in dementia research around anticholinesterase inhibitors and other innovative approaches, this research adds to an accumulating evidence base of another important and complimentary area – possible iatrogenic contributions to cognitive impairment.
Cynthia Baron, Julie Sklenicka, Philip Sayegh and Kristine Yaffe. Contraindicated Medication Use Among Patients in a Memory Disorders Clinic. The American Journal of Geriatric Pharmacotherapy. Vol 6. No 3. August 2008. pp147-152.
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