The finding:
The authors of this systematic review conducted an in-depth examination of integrated inpatient medical and psychiatric care units (IMPUs) defined as “hospital wards that diagnose diseases and disorders and treat hospital inpatients who have concomitant medical and psychiatric disorders or behavioral problems.” This exhaustive review notes the lack of standardization across aims, structural characteristics (ranging from the unit size to the associated staff), procedural characteristics (ranging from treatment capabilities to length of stay), and outcomes among IMPUs. Studies involving IMPUs had various findings on economic outcomes and quality outcomes. The authors recommend that future research examine the cost-effectiveness of IMPUs.

Strength and weaknesses:
The study authors extracted data from an incredibly diverse literature base, ranging from publications in the 1970s through 2019. This diligent extraction and systematic comparison provide a clear demonstration of the incredible heterogeneity among IMPUs. The discussion of this variety highlights the need for a greater understanding of length of stay and other economic outcomes. Study quality varied significantly and limits the authors’ conclusions. Elements that warrant additional attention by the authors include differences across IMPUs over time (i.e. if there were significant differences in IMPUs over the 50 year timespan described) that may account for some of this heterogeneity found. Additionally, the practical elements involved with the delivery of care in an IMPU begged for additional discussion, from the safety of nursing staff to the ability to deliver more process-oriented psychiatric care. While reducing length of stay is undoubtedly an important role for IMPUs, staff safety, burnout, and wellness are also important considerations that should influence administrators’ decision to have an IMPU. An additional important factor to consider as studies on IMPUs proceed will be consideration on the demographics (including the race, gender, sexual orientation, and ability status) of patients requiring IMPU care and what that data psychiatrists and other physicians should consider prior to recommending IMPU treatment.

Relevance:
In the pandemic era, consultation-liaison psychiatrists have struggled to treat COVID-19 positive patients with severe psychiatric illness. This challenge is not new, as C-L psychiatrists have always worked to provide care for patients who are excluded from psychiatric units due to sometimes mild or stabile medical illness (e.g. patients requiring oxygen, patients at severe risk of falls, or patients requiring IV antibiotics).  A single C-L psychiatrist visiting with a patient with severe psychiatric illness cannot equal the value of the process-oriented specialty care received on a psychiatric unit. IMPUs might have a role in reducing the burden on C-L teams and ameliorating the ethical dilemma of persistent medical hospitalization for a patient with severe psychiatric illness and potentially mild medical symptomatology. Psychiatrists should standardize some aspects of IMPUs while simultaneously ensuring IMPUs serve the needs of their hospital system and communities. Standardization will allow for clearer studies on the benefits of IMPUs and how to optimize their operation.