This study is the first retrospective long-term cohort study assessing the impact of the CP’s interventions on the number of PIMs through a medical review service in elderly patients with MHPs in Central Europe, which opens a new window for collaborative care implementation within primary care in Slovenia and broader in Europe. This study provides three key findings.
Firstly, the CP’s interventions led to fewer medications per patient, as in previous studies [1, 14, 16, 19]. The service examined in this study may reduce the number of medications per patient and, by extension, the frequency of polypharmacy and its related risks. [1, 14, 16]. This reduction was found although the GPs accepted less than 50% of proposed interventions, a rate comparable to a previous study in primary care . One reason for a relatively low acceptance rate could be the lack of a follow-up by a CP after the initial medical review, which was not done in the study period. Patient monitoring by CP is already a practice in the U.S. model of collaborative care, and CP in some countries can also prescribe medications. Because the health system in Slovenia (and elsewhere) faces a lack of GPs and psychiatrists, expanding the role of CP in the treatment of MHPs may be beneficial. The relatively low acceptance rate could also be because patients with MHPs are also managed by psychiatrists, who in some cases rejected the proposed pharmacotherapy changes. This contrasts with a 2015 study by Stuhec et al. , where a similar service had very high acceptance rates (88.0%) in a psychiatric hospital, in which the CP was also working daily in hospital wards (e. g. doing daily roundings). Higher acceptance rates could likely be achieved in the setting we studied through increased collaboration between CPs with psychiatrists, which was not examined in this study. These results are also interesting in terms of different intervention types because the CP suggested many treatment initiations, in one case suggesting clozapine initiation in line with the treatment guidelines [21, 22]. In addition, almost all pharmacotherapy received by the patients remained the same six months after the CP’s interventions, implying that they were positive (positive adherence) and did not cause adverse events. However, in two cases, the pharmacotherapy was switched back in 6 months, warranting further studies on the potential complications of returning to previous therapy.
The second significant result is that the number of PIMs after the CP’s interventions decreased as hypothesized for both the PRISCUS and the Beers list. Therefore we can confirm our first hypothesis (H1). The total number of PIMs (PRISCUS list) decreased by 21.1%. The most considerable PIMs reduction occurred with hypnotics and sedatives (e.g., zolpidem, bromazepam, alprazolam, diazepam) (Fig. 2), which is again in line with the recommendations because benzodiazepines should be avoided in elderly patients due to their negative effect on falls and cognitive decline [4, 9, 10, 11]. In cases of depression, anxiety disorders, and long-term treatment of insomnia, antidepressants (e.g., mirtazapine, trazodone, SSRIs) are suggested in particular, which was mostly proposed in this study, meaning that these interventions also lead to better treatment guidelines adherence [4, 9, 10, 11]. Other important PIMs observed in this study were connected with antipsychotics, clozapine, olanzapine, and haloperidol.
Interestingly, the CP suggested clozapine initiation in line with the guidelines, which were accepted by the psychiatrist and GP [21, 22]. Another important finding is the reduction of the number of patients treated with haloperidol, which is connected with very high mortality and extrapyramidal adverse effects and for which other antipsychotics (e.g., quetiapine) are suggested as a substitute [9, 10, 13]. In line with the Beers list, the use of proton pump inhibitors, zolpidem, quetiapine, bromazepam, and diazepam was reduced. Similar results also apply to the PRISCUS list. Proton pump inhibitors are often used without long-term indication, which can lead to several adverse events, including falls . Quetiapine is often used for insomnia against the treatment guidelines, and the CP suggested different medications (e.g., mirtazapine and trazodone) . These results are positive, but many PIMs remained in the patients’ pharmacotherapy, so additional monitoring and interventions could further reduce the risks, which may increase the acceptance rates by GPs. These results are similar to an Austrian study that found antipsychotics and benzodiazepines to be most frequently connected with PIMs; primary care could be improved through collaborative care that includes a clinical pharmacists’ review service .
The third set of results are those of the cohort analysis in our study. The results were only statistically significant using the Beers list, which could be because of the low sample size, and therefore we can only partially confirm our second hypothesis (H2). These results also demonstrate how the two used PIM criteria differ. In full recommendation acceptance cases, the number of PIMs decreased, opening a new question about further service implementation. These results are in line with previous studies on different populations that found improved treatment adherence because of accepted interventions [1, 16].
Our study also has many limitations that should be discussed. The sample size we used was relatively small and not calculated (high risk of type II error), which can have an impact on the statistical significance of the results as well as the calculation of CIs of the ORs, so the study should be replicated with a larger sample and calculated sample size which would reduce risk of bias. Our study also had a selection bias (e.g., no randomization) because the patients were selected by the GPs (who referred them to the CP's service). Furthermore, we included all patients with MHPs according to the ICD-10, which means that the population was very heterogeneous. On the other hand, the minimal exclusion criteria may mean that our results have higher ecological validity, which is informative for service implementation and clinical implication. Another significant limitation is the lack of direct collaboration between the CP, psychiatrist, and GP, which might account for a relatively low number of accepted interventions. Due to the retrospective study design, we also did not have contact with the study participants, and clinical outcomes were not measured. Despite its limitation, this study contributes new insights on collaborative care that includes a psychiatric CP and expands the knowledge on this type of service in Central Europe in this vulnerable population.
Collaborative care that included a CP reduced the number of PIMs as defined by both the PRISCUS and the Beers list, where almost all interventions were maintained. The ORs for PIMs were also smaller in cases of full intervention acceptance. These results confirm the positive effects of CP’s interventions within this field in clinical practice. The results are also the first published in Central Europe, although they should be replicated by studies with larger sample sizes and fewer limitations. These results could also inform future research on CPfocused collaborative care in primary care settings in elderly patients with MHPs in Central Europe.