Abstract
Older adults comprise a significant proportion of the population of New Zealand (NZ) and are known to be prescribed the highest number of medications. Several medications have to be prescribed with caution in older adults due to their compromised biological functions that can impact and reduce drug clearance. Potentially inappropriate medications (PIMs) may be defined as the prescription of drugs where the risks outweigh the clinical benefits or there may be under-prescribing of beneficial treatments. Over the last 3 decades, the global prevalence of prescribing PIMs has been reported from 5.2% to over 85%. PIMS may be identified by the application of criterion based explicit screening tools, of which the Beers criteria are commonly used to assess potentially inappropriate prescribing of medications in older adults.
The overarching aim of the thesis was to assess medication appropriateness in older adults and suggest therapeutic alternatives for the currently prescribed medications with anticholinergic properties in individuals with dementia.
In the first phase of our project, a literature review of the existing tools for reducing PIMS was undertaken to assess the merits and demerits of each tool with a view to suggest methods to reduce inappropriate prescribing which include medication review for each individual, deprescribing, and developing guidelines for appropriate prescribing. Through the literature review of existing explicit and implicit tools for identifying PIMS prescription, we could substantiate that the Beers criteria is a comprehensive screening tool that has been validated by a systematic literature review, evaluated by a Delphi consensus, and has shown good predictor validity in different settings. Hence, the Beers criteria was utilized for all the analytical studies conducted thereafter.
We observed a high prevalence of prescription of potentially inappropriate medications in community dwelling older adults in NZ utilizing the Beers criteria and the PHARMS- interRAI-HC dataset. The International Resident Assessment Instrument-Home Care (interRAI-HC) is a standardized and internationally validated comprehensive geriatric risk assessment for older adults living in the community with complex care needs. In NZ a standardized interRAI-HC has been implemented for conducting all community care assessments in older adults needing publicly funded long-term community services or aged residential care. The ubiquitous nature of the interRAI-HC assessment accounts for numerous social, psychological, and clinical risk factors when examining health outcomes in older adults. The interRAI-HC database is linked to several NZ Ministry of Health national collections, including prescription use [the Pharmaceutical Claims Data Mart (PHARMS database)], hospital discharges (National Minimum Dataset), mortality data, and laboratory collections. The Pharmaceutical Claims Data Mart (PHARMS) is utilized by the Pharmaceutical Management Agency (PHARMAC) and the Ministry of Health, NZ to remunerate pharmacists for dispensing medications that are publicly funded, as well as to help PHARMAC in its management of the national budget of medications. The Ministry of Health provides PHARMS extracts with individual‐level prescription data along with the unique encrypted National Health Index (NHI) number for each individual.
We then analysed the factors associated with prescribing PIMS, and found that there was a higher probability of prescribing PIMs in males, individuals aged 65-75 years, NZ Europeans, those who were prescribed a greater number of medications, and those who reported poor self-health, compared to their counter-parts. Individuals diagnosed with certain disorders like dementia, insomnia, depression, cancer, anxiety; or those who were hospitalized were more likely to be prescribed PIMs than the other individuals.
Dementia is one of the principal syndromes linked with disability and dependence among older adults, and is a major challenge to individuals, communities, and societies worldwide. The global incidence of dementia is expected to rise to 81 million by 2040, primarily due to the progressive nature of the disorder, which involves worsening neurocognitive impairment and loss of basic functions in daily life. In 2016, the estimated prevalence of dementia in NZ was more than 62,000, which is predicted to increase to 170,000 in 2050. In one of our studies utilizing the PHARMS and interRAI-HC linked dataset, we observed that the prevalence of dementia was 13%, which was diagnosed by the Minimum Dataset Cognitive Performance Scale. 67% of the individuals with dementia were prescribed PIMs, and the medications with anticholinergic properties (MAP) constituted 60%.
MAP bind to the muscarinic receptors and block acetylcholine neurotransmission, which regulates many central nervous system (CNS) and peripheral nervous system (PNS) actions MAP are prescribed excessively for Parkinson’s disease, depression, overactive bladder, allergies, inflammatory bowel disorders, and epilepsy. MAP are specifically associated with negative outcomes in older adults diagnosed with dementia, such as worsening of cognitive function, sustained cognitive defects, and increased mortality. They are notorious for their central side effects such as impaired concentration, confusion, attention deficit, and impairment of memory, and peripheral side effects, which include dry mouth, constipation, urinary retention, and bowel obstruction. MAP may also inhibit the potential benefits of cholinesterase inhibitors such as Donepezil, Rivastigmine, and Galantamine, which is the main pharmacological class, currently approved for the management of dementia.
Based on the current literature review of the anticholinergic burden (ACB) scales and serum anticholinergic activity of various medications, we collated known information of the level of anticholinergic activity for medications listed in the NZ formulary, and developed recommendations for prescribers, focussing on pharmacological alternatives for the currently prescribed MAP for older adults with dementia presenting with co-morbidities. Medications were classified according to the ATC-DDD methodology. We sorted all the medications based on the high/moderate anticholinergic activity, and their low/no anticholinergic activity substitutes. To achieve an adequately comprehensive range of medications, all the existing scales measuring the anticholinergic activity of various medications were utilized. The current intervention was an attempt to identify medications with high or moderate anticholinergic activity (HOMAA) and substitute a low or no anticholinergic activity (LONAA) alternative for them wherever possible, according to the therapeutic classification of medications. The ACB is the cumulative effect of prescription of MAP to each individual. The tool was applied to the New Zealand’s PHARMS and interRAI-HC linked dataset to test the amendment in the ACB. Of the 75,410 community dwelling older adults aged 65 and above, 17 % were diagnosed with dementia. Almost half of these individuals were prescribed at least one MAP. Using a Paired-Samples Test, we compared the results of the ACB before and after the theoretical intervention of the pharmacological alternatives to MAP. By incorporation of the recommendations, we observed a significant reduction of the ACB by 0.49 (95% CI, 0.47-0.51).
The implementation of the recommendations for prescribing therapeutic alternatives to anticholinergic medications in this vulnerable population along with an awareness created among prescribers has the potential to reduce untoward effects associated with the prescription of these medications, slower cognitive decline, and decrease the risk of mortality; supporting individuals with dementia to live longer independently.