Anticholinergic Burden

Background

Anticholinergic burden is defined as the cumulative effect of taking multiple anticholinergic medications resulting in an increased risk of adverse effects. High, long-term cumulative exposure has been linked to an increased risk of mortality and poor cognitive and physical function, such as poor grip strength, slower walking speeds and poor appetite. These poor outcomes have been associated with increased hospital admissions, longer hospital stays and increased GP visits.

Anticholinergic burden is a prominent issue, particularly in the older population, due to the presence of polypharmacy. It is estimated that about 35% of adults over 60 years take more than five medications at a time, and anticholinergic drugs are often the most prescribed medications. A previous study identified approximately 8.9 drug-related problems per patient in the older population.

Medications used to treat common chronic conditions such as pain, allergies, depression, and cardiovascular disease can have weak anticholinergic properties. These can be overlooked as they are typically not recognised as anticholinergic drugs.

Understanding the effects of anticholinergic drugs and their cumulative effect is essential to assessing anticholinergic burden and preventing poor clinical outcomes.

Anticholinergic Medications

 Examples of anticholinergic medications may include: 

*Varied classification of potency dependent on assessment scale

Side effects

 The side effects of anticholinergic medications can be classified as central or peripheral.

• Central effects: cognitive dysfunction, delirium, confusion, falls, brain atrophy.
• Peripheral side effects: dry mouth, urinary retention, visual disturbance, tachycardia, constipation, increased risk of pulmonary infections.

Assessing Anticholinergic Burden

Several validated tools based on expert opinions and literature review have been developed to quantify anticholinergic burden. Utilisation of these tools can be useful as part of clinical reviews and assessing the risk/benefit ratio when prescribing or deprescribing.

Incorporated aspects such as the number of medications included and dose consideration vary greatly amongst the scales. As such, calculated exposure to anticholinergic prescribing can vary as much as 8 to 17.6% depending on the assessment scale used.

Some of the more widely used scales include:

To date, there is no consensus on a standardised tool to quantify anticholinergic risk. For clinicians and pharmacists wanting to assess anticholinergic risk, an online tool (http://www.anticholinergicscales.es/) that comprises of several scales may be used to assess the anticholinergic risk comprehensively.

Summary

Anticholinergic burden is largely present in cases of polypharmacy. Often, medications with strong anticholinergic properties are recognised as inappropriate medications in the older population. However, there is widespread use of low potency anticholinergic drugs in common chronic conditions, and its additive effects may be overlooked.

Quantifying anticholinergic burden is important to identify patients at risk and evaluate the risk and benefit ratios of prescribed medications. Pharmacists can incorporate quantification of anticholinergic burden into clinical care to help identify patients at risk, refer patients as needed or monitor patients for adverse effects.