This was the first study to explicitly explore analgesic and adjuvant medication co-prescribing among nursing home residents. While the general patterns of co-prescribing were similar in Australian and Finnish residents, co-prescribing of three or more regular analgesic and/or adjuvant medications was 2.5-times more prevalent in Australian residents. The higher prevalence of co-prescribing in Australian residents was largely driven by a high level of acetaminophen co-prescribing. Further investigation into central nervous system (CNS)-active polypharmacy is needed in both countries, arising from high rates of opioid co-prescribing with adjuvant medications.
Our study identified that approximately half (44%) of Australian and one-third (33%) of Finnish residents were co-prescribed more than one analgesic and/or adjuvant medication. There was a notable 2.5-fold higher prevalence of prescribing of three or more analgesic and/or adjuvant medications in Australian residents. Given that Australian and Finnish residents have similar clinical and demographic characteristics, this difference in co-prescribing was unlikely to fully reflect or explain the apparent differences in pain prevalence [1-4, 15, 16]. The higher rates of co-prescribing may be partly explained by Australian initiatives to minimize un- or under-managed pain in nursing homes as a possible cause of behavioral symptoms [25, 26]. In the literature, an increase in the use of analgesic medications has been identified as one of the top five factors contributing to the increasing polypharmacy in Australian nursing homes [27]. Previous research has suggested that analgesic decision-making varies between countries and cultures [28]. This highlights the importance of further cross-national exchanges of knowledge, practice and perspectives between countries with ageing populations, particularly towards analgesic decision-making. These cross-national comparative studies are essential for the development of targeted interventions aimed at improving the safe and effective use of these medications in nursing homes.
Acetaminophen was the most frequently co-prescribed medication, with three quarters of Australian residents and over one quarter of Finnish residents prescribed NSAIDs, opioids, gabapentinoids, TCAs or duloxetine, were co-prescribed acetaminophen. Acetaminophen is considered the first-line analgesic for mild-to-moderate pain in older adults and may potentiate the effects of opioids, reducing the need for higher doses of opioids and adjuvant medications [29]. Our findings suggest that Australian clinicians continued regular acetaminophen when acetaminophen alone was not achieving the required level of analgesia. The efficacy of acetaminophen in the context of chronic non-cancer pain in older adults has recently been scrutinized [29]. The British Journal of Pain (2022), European Society for Clinical and Economic Aspects of Osteoporosis (ESCEO, 2019), National Institute for Health and Care Excellence (NICE, 2021) and the Australian National Prescribing Service (NPS, 2022) have highlighted the limited evidence of acetaminophen efficacy for chronic pain and potential ADEs with long-term use, particularly when co-prescribed with NSAIDs [30-33]. Favourably, the co-prescribing of acetaminophen with NSAIDs was <0.4% across all residents in our study. Further understanding of the long-term safety and efficacy of acetaminophen within older adults’ analgesic regimens is needed.
Approximately three in five Australian residents and two in five Finnish residents prescribed gabapentinoids were co-prescribed opioids. The prevalence of gabapentinoid prescribing in nursing homes has reportedly increased in Finland (1% in 2003 to 9% in 2017), Ontario (2% in 2010 to 12% in 2019) and Norway (1% in 2000 to 4% in 2011) [18, 34, 35]. Specifically, the prevalence of co-prescribed gabapentinoids with opioids in the United States was 48% higher in 2018 than in 2011 [36]. The rising use of gabapentinoids among older adults, alone and in combination with opioids, has sparked safety concerns attributed to increased CNS, sedative and respiratory ADEs [37]. This concern was reflected in the American Geriatrics Society (AGS) Beers Criteria (2019, updated in 2023), which strongly recommends against the co-prescribing of opioids and gabapentinoids, attributed to sedation-related ADEs in older adults [38, 39]. Our study highlights the importance of comprehensive, holistic interventions that consider a resident’s entire medication regimen, including combinations that increase susceptibility of analgesic-related ADEs, such as the co-prescribing of CNS-active medications with opioids.
Over 59% of Australian residents who used adjuvant medications were co-prescribed opioids, compared to 25% of Finnish residents. Adjuvant medications are recommended for alleviating certain types of neuropathic pain, yet frequently prescribed for non-neuropathic pain [40]. Though adjuvant medications provide a potentially safer alternative to opioids for pain management in the perioperative setting, the safety of adjuvants for chronic pain in older adults is not well established [41, 42]. Nevertheless, our study identified opioid and adjuvant medication co-prescribing was common in Australian and Finnish nursing homes. The value of system-level monitoring and analgesic stewardship interventions in nursing homes has been gaining international recognition in recent years [43, 44]. Analgesic indicators have been identified as a possible mechanism for nursing homes to monitor safe and effective analgesic use, ensure effective pain management and reduce analgesic-related harm [45, 46]. An indicator of residents prescribed opioids with other CNS-active medications has been proposed as a potential indicator to identify residents who may benefit from multidisciplinary medication reviews and introduction of non-pharmacological approaches [45, 47]. Advances in electronic medication management systems represent a unique opportunity to efficiently implement indicators and reform analgesic optimization in nursing homes.
The lower utilization of adjuvant medications in Finland, including a 12-fold lower prevalence of TCAs, may be partly explained by Finnish-specific guidelines recommending avoidance of TCAs in older adults due to their anticholinergic effects [48]. The Meds75+ database (the national Finnish criteria used to support clinical decision-making regarding drug treatment for people >75 years of age) lists TCAs as a medication to avoid in older adults due to significant ADEs (category D), with gabapentinoids and duloxetine listed as more suitable alternatives (category C) [49]. This may explain the preference towards duloxetine in the Finnish sample.
Strengths and Limitations
A key strength of this study was that residents who participated were representative of all residents living in the nursing homes or assisted living facilities in Helsinki. The co-prescribing matrices used in this study represent a novel approach to exploring and reporting analgesic and adjuvant utilization in nursing homes. This study contributes to a high-priority research area in nursing homes [9-11].
Australian and Finnish residents included in this study were comparable in terms of age and sex. In total, 14.5% of Australian residents were observed to be in any ‘mild/moderate pain’ using PAINAD and 69.6% of Finnish residents self-reported any ‘discomfort or pain’ using 15D. Pain measurements in the two samples were not comparable because pain prevalence and intensity varies according to the pain assessment method used (i.e. observational or self-report measures) [50]. The 15D ‘discomfort and pain’ includes symptoms of pain, ache, nausea and itching, which may have overestimated actual pain prevalence. Future comparative studies may analyze both self-reported and observed pain prevalence. Regular acetaminophen was more frequently prescribed to Australian (69%) residents, compared to Finnish (44%) residents. This may be an underestimation, as acetaminophen is often listed as a PRN drug and the decision to administer acetaminophen is given to RNs [28, 45]. Additionally, opioids account for 42% of all PRN administrations in Australian nursing homes and so the reported prevalence may underestimate true opioid use in Australia [26].
Data were derived from South Australia and Helsinki and therefore, the results may not be generalizable to all of Australia and Finland. This study did not consider pain assessment, non-pharmacological treatment, indications or prescribed doses of medications. This is important because adjuvant medications may be used for non-pain indications (e.g. depression). We were not able to investigate whether analgesics or adjuvants were co-prescribed to minimize opioid doses (i.e. opioid sparing) [29]. For this reason, it was not possible to comment on the clinical appropriateness of medication regimens and results are purely descriptive. The Finnish samples excluded residents with moderate-to-severe dementia, whereas the Australian sample did not, which may have influenced analgesic prescribing. Our data were collected in 2019 (Australia) and 2017−2018 (Finland). Further studies may explore how prescribing patterns have changed following release/updates of clinical practice guidelines. Longitudinal studies, specific to the nursing home context, are needed to explore the long-term safety and effectiveness of co-prescribed analgesic and adjuvant medications.