BackgroundThe management format of the mixed-surgical intermediate care unit (IMCU) affects its performance. A format of combined supervision of surgeons with additional critical care certifications and admitting specialists, named the “joint format”, may herein be a promising new model of specialized critical care. This study aims to assess the performance of the joint management format.MethodsThis observational cohort study compared three IMCU management formats at the stand-alone, mixed-surgical IMCU of a tertiary referral hospital using interrupted time series analyses. All admissions from 2001 until 2015 were included. Predetermined criteria for performance (utilization, efficiency, and safety) were applied to three different management format periods: open (2001–2006), closed (2006–2011), and joint (2011–2015) formats.ResultsA total of 8894 admissions were analyzed. In terms of case load (utilization), there was an overall increase in the number of surgical patients (0.25%/year) (p<0.001), age (0.38/year) (p<0.001), and readmissions from the ward (0.16%/year) (p<0.001) and from the intensive care unit (ICU) (0.17%/year) (p=0.014). In terms of efficiency, the admission duration decreased (1.58 hours/year) (p<0.001). Transfer to the ICU within 24 hours, readmission within 24 hours from the ward, and unplanned mortality (eg, safety) did not change over time.DiscussionAt a time of increasingly complex case load, the joint format at the mixed-surgical IMCU is an efficient and safe management format in which the admitting specialist continues to provide specialized care. Specialty-specific supervision at IMCUs is a safe option which should be considered in healthcare policy decisions.Level of evidenceLevel IV.