Impact of a National Enhanced Recovery After Surgery Programme on Patient Outcomes of Primary Total Knee Replacement: an Interrupted Time Series Analysis from "The National Joint Registry of England, Wales, Northern Ireland and the Isle of Man"

Objective: We aimed to test whether a national Enhanced Recovery After Surgery (ERAS) Programme in total knee replacement (TKR) had an impact on patient outcomes. Design: Natural-experiment (April 2008-December 2016). Interrupted time-series regression assessed impact on trends before-during-after ERAS implementation. Setting: Primary operations from the UK National Joint Registry were linked with Hospital Episode Statistics data which contains inpatient episodes undertaken in NHS trusts in England, and PROMs. Participants: Patients undergoing primary planned TKR aged ≥18 years. Intervention: ERAS implementation (April 2009-March 2011). Outcomes: Regression coefficients of monthly means of LOS, bed day costs, change in Oxford knee scores (OKS) 6-months after surgery, complications (at 6 months), and rates of revision surgeries (at 5 years). Results: 486,579 primary TKRs were identified. Overall LOS and bed-day costs decreased from 5.8 days to 3.7 and from £7607 to £5276, from April 2008 to December 2016. OKS change improved from 15.1 points in April 2008 to 17.1 points in December 2016. Complications decreased from 4.1 % in April 2008 to 1.7 % March 2016. 5-year revision rates remained stable at 4.8 per 1000 implants years in April 2008 and December 2011. After ERAS, declining trends in LOS and bed costs slowed down; OKS improved, complications remained stable, and revisions slightly increased. Conclusions: Different secular trends in outcomes for patients having TKR have been observed over the last decade. Although patient outcomes are better than a decade ago ERAS did not improve them at national level.