Systematic literature review of the impact of psychiatric pharmacists: SLR2

Introduction

The American Association of Psychiatric Pharmacists Systematic Literature Review (SLR) Committee previously published a paper aimed at highlighting the role of psychiatric pharmacists in patient-level clinical outcomes.¹ That review spanned January 1, 1961, to December 31, 2022, resulting in the inclusion of 208 of 4270 identified articles. The review found heterogeneity in many aspects of the studies, including disease state, study size, study design, and outcomes. SLR1 also showed an uptrend in the number of articles published per year.

Methods

This paper (SLR2) expands on SLR1. Additional search terms were included based on feedback received on SLR1 to further support a comprehensive review.¹ The pharmacist terms (4) were expanded to include “Medication review,” “Pharmacy[Title],” and “Pharmacies[Title]”; the psychiatric terms (94) were expanded to include “Nicotine” and “Seizures.” The time frame from SLR1 (January 1, 1961, to December 31, 2022) was rerun with the new search terms to capture any previously missed articles. Articles published from January 1, 2023, to December 31, 2024, were then reviewed to expand on the original database. The literature search was conducted via PubMed in line with SLR1. The search was completed periodically throughout the review period to allow authors to incrementally process results as new articles were published. All interim results were retained in this study, including those not found in later searches due to changes in the PubMed index.

On January 10, 2025, a final PubMed search was completed with a publication date filter of January 1, 1961, to December 31, 2024. In line with SLR1, all PubMed results were loaded into a spreadsheet for manual review by the author group. Each article was documented as an inclusion or exclusion on the spreadsheet. Exclusion criteria were unchanged from the previous paper. Authors clarified that neurology-only disease states are non-psychiatric, resulting in exclusion; however, some neurology search terms, such as “seizures,” were still used as articles identified by these terms may include psychiatric pharmacist interventions, psychiatric medications, and/or psychiatric outcomes.¹

All articles were subjected to a second pass by a different study author to confirm the appropriateness of the original classification and the accuracy of the extracted characteristics. Discrepancies (ie, previously included but changed to excluded, previously excluded and changed to included) were reviewed by the entire author group.

This study also performed a second review of articles that only received one review during SLR1. Articles that were reviewed twice in SLR1 were not reevaluated for this study.¹

Results

Figure 1 illustrates the additional article identification, screening, and eligibility, and total articles included, distinguishing between new citations (2128) and those initially rejected in SLR1 (3755). The new terms in PubMed search criteria yielded a total of 5883 articles, with 2706 excluded based on title and 2711 excluded based on abstract, resulting in 466 (7.9%) articles for review after screening. There were 374 articles then excluded based on full-text and a second review. Forty-six articles initially included were excluded after group review, and 6 articles initially excluded were included after group review. Ultimately, 52 articles (0.9%) were included after 2 full-text reviews (see Appendix). Of the 202 results from SLR1, 8 should have been excluded based on the “neurology-only” decision clarified above. Thus, cumulative results of the literature search are 246 included articles (52 from SLR2 + 202 from SLR1 – 8 SLR1 corrections). The Table and all further data and statistics in this paper represent those 246 articles. Although articles identified in SLR1 are included in the cumulative characteristics data, they are excluded from the Appendix as that information is readily available.¹

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TABLEStudy characteristics

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The most common exclusion justifications were no clinical outcomes (2017), no pharmacist intervention (1807), and no treatment of psychiatric disorder (1367). Patient demographics and other study characteristics, such as disorders treated, treatment settings, and randomization, are displayed in the Table. Outcome measures and quadruple aims are also included in the Table. The outcome measures from most to least frequent were response (158 studies), medication-based (74), resource usage (63), patient experience/adherence (61), adverse outcome (38), cost-based (21), time-based (16), and retention/referral (16), noting that 149 (60.6%) studies had multiple outcome measures. Quadruple aims, which serve as a guide for providing high-quality care, documented better care (246 studies), improved patient experience (57), reduced healthcare costs (30), and provider well-being (2), with 82 (33.3%) having more than 1 applicable quadruple aim.

Included articles spanned 129 different journals, with the most coming from the Journal of the American Pharmacists Association (21), the Mental Health Clinician (15), and the American Journal of Health-System Pharmacy (8), which was consistent with the top 3 journals in SLR1.¹ The number of included articles increased year over year from 2019 to 2022 as noted in SLR1. There were 11 in 2019, 17 in 2020, and 22 in 2021, reaching a peak with 32 in 2022. However, the trend reversed after SLR1, with fewer included articles observed in 2023 (20) and 2024 (15).

Most research took place in the United States (138 articles, 56.1%), followed by the United Kingdom (21, 8.5%), Canada (16, 6.5%), Australia (11, 4.5%), and Japan (7, 2.8%).

Of the newly included articles, tobacco use disorder was the most frequently assessed disease state, with 9 articles, followed by substance use disorder and medical disease with psychiatric comorbidity (8 articles each). Pharmacist-provided tobacco cessation activities resulted in increased likelihood of smoking cessation^2-6 and reduced cigarette intake.^7,8 Improvements in depression rating scales and reduction in hemoglobin A1c were observed in patients with concomitant diabetes mellitus and major depressive disorder with pharmacist intervention.^9-11

Discussion

This was the most substantial review of primary literature, highlighting the impact of psychiatric pharmacists on patient-level outcomes, as 5833 articles were reviewed. The addition of multiple search terms expanded the review compared with SLR1 and allowed additional opportunities for review of how psychiatric pharmacists are impacting patients in their practices.

This study addressed some limitations of SLR1 by tracking the level of review (title, abstract, or full text), conducting second reviews of every article, and expanding search terms to include nicotine, seizures, medication review, pharmacy (title), and pharmacies (title) to decrease the number of potential articles not captured in the review. Other limitations present in SLR1 remain, including limiting search to PubMed and excluding articles with an inability to access full-text versions.¹

Despite the authors of SLR1’s expectation that the number of articles would continue to increase each year to deomonstrate the ability of psychiatric pharmacists to improve the quality of care, the overall pace of publications slowed over the last 2 years. The volume of published articles during the peak years may have been attributed to a sudden and significant change in priorities globally.

Tobacco cessation remains a dominant area where pharmacists are involved with patients, as previously indicated by SLR1. Of the 52 new articles included in this review, 9 (17.3%) focused on tobacco cessation. This is similar to the results of SLR1, where 19% of the articles included involved tobacco cessation.¹ It is evident that tobacco cessation continues to be a great concern within healthcare systems. While it is unclear in each article whether a Board-Certified Psychiatric Pharmacist was specifically used for tobacco cessation efforts, pharmacists are making an impact on improving patient outcomes regarding tobacco cessation.

Patient-level outcomes continue to be the essential inclusion criteria for articles in this review. This is, in part, to reflect the direct impact psychiatric pharmacists are making on patients in their daily practice. While nonpatient-level outcomes, such as costs, prescriber education, and prescribing trends, provide critical information for healthcare systems, patient-level outcomes reflect the direct work that pharmacists perform with patients. Improvement in those other outcomes does not always correlate with positive patient outcomes. For example, without reporting patient-level outcomes, decreasing costs could be due to inadequate care or even a higher mortality rate. Psychiatric pharmacists continue to strive for excellent patient service, which is evident in the articles included.

Given the noted limitations of many articles, including the lack of patient-level outcomes, it is important that studies of psychiatric pharmacist interventions follow guidance on reporting to maximize the applicability of their results. The SLR2 authors recommend the Expanded Pharmacist Patient Care Intervention Reporting Guide for Specialty Clinical Pharmacy Practice_.¹² Adherence to this guide will increase the replicability of studies and will more effectively measure the impact of integrating psychiatric pharmacists. Authors and peer reviewers alike can improve the quality of published studies by referring to that guide.

Much of the data collected continues to demonstrate the positive impact that psychiatric pharmacists have on patient outcomes. The American Association of Psychiatric Pharmacists Systemic Literature Review Committee will continue to monitor new research as it is performed and published.