Outpatient THA and TKA, by reducing hospital LOS, increases bed availability and reduces direct health care costs.11 Most studies comparing outpatient to inpatient programs conclude that outpatient surgeries did not increase complication or readmission rates, and, overall, were not inferior.15 We aimed to determine if combining ERAS principles to an outpatient program could reduce adverse event rate and improve patient outcomes including postoperative pain, functional recovery and satisfaction. We found that compared to STD-inpatient practice, ERAS-outpatient program reduced complications by half while not resulting in more unplanned episodes of care. Moreover, it resulted in less opioid consumption, faster early functional recovery, and higher satisfaction.
Our results should be interpreted in light of our study limitations. Although our single subject design eliminates selection bias by controlling for interindividual confounders, all ERAS-outpatient surgeries were performed secondly. Nevertheless, studies on staged bilateral joint arthroplasty showed no clear advantage for the second surgery over the first one.16 On the other hand, for the ERAS-outpatient surgery, patients were 7 years older and had more comorbidities (higher ASA score) which could have negatively impacted the outcomes. Secondly, the health care team might have presented the ERAS-outpatient protocol as an “optimized care” and patients might expected superior results from the second surgery. As counterpart, those higher expectations required better results to achieve similar satisfaction which disfavoured the ERAS-outpatient pathway.17 Third, the retrospective data retrieved from patients’ medical record may have been incomplete which potentially reduced the number of adverse events. However, this limitation was present for both sides. Last, although our sample size was rather small limiting our study power, we were able to detect a statistically significant difference in most of our secondary outcomes.
Our ERAS-outpatient protocol was specifically designed to reduce common complications that increase LOS, such as dizziness, nausea/vomiting, pain, and urinary retention.18 Compared to STD-inpatient practice, it successfully decreased the number of complications per patient by 52.4% (2.1 vs 4.4 p < 0.001) and overall postoperative morbidity (CCI) by 35.7% (12.3 vs 19.1, p < 0.001). This reduction in the complication rate was better than what was reported in meta-analyses of ERAS joint replacements (23–26%).19 However, considering the heterogeneity of ERAS protocols,19 the difference between our results and those in the literature is probably multifactorial, making it impossible to pinpoint one element specifically. Meta-analyses comparing adverse event rates between inpatient and outpatient THA/TKA reported either increased complication rate after outpatient procedures20 or did not find a difference (outpatient considered to be non-inferior).15 These results contrast with ours, raising the point that outpatient programs may not be equal, and demonstrating the important impact of including ERAS principles in an outpatient program. Our current results are similar to our previous study comparing 114 unilateral ERAS-outpatient cases to a historical cohort of 150 matched STD-inpatient surgeries, where we found a complication rate reduction of 50%.2 In the current study, each patient being his own control reduces the potential selection bias, and thus further supports the efficacy and safety of our ERAS-outpatient program. Our selected interventions successfully prevented multiple potential adverse events. We avoided gastrointestinal complications such as nausea and vomiting by minimizing opioids, using preventive methods such as aprepitant,21 dexamethasone,22 and scopolamine patch,23 and by implementing a nutrition protocol that allows clear liquids until 2h before surgery and encourages rapid postoperative oral feeding.24 Anemia was minimized by preoperative screening25 and perioperative blood saving interventions (tranexamic acid,26 adrenaline in LIA,27 and postoperative knee flexion28).
Unplanned Episodes of Care
Our ERAS-outpatient program significantly decreased hospital LOS and achieved the discharge of 90% of patients in the prescribed time. Failure rate to discharge and their reasons are similar to those described by Shapira et al.29 To improve success, future work should focus on interventions that address specific problems preventing discharge. Similar to other studies, our ERAS-outpatient protocol did not result in more unplanned episodes of care than STD-inpatient practice.19,3,15,20 The 90-day readmission and reoperations rates of our groups are comparable to the current literature (0-4.2% and 0–4%, respectively).18 Our 3-month unplanned care episode rate is higher than that reported in similar studies (0.9%-11.2%).18 However, most unexpected visits in the ERAS-outpatient surgeries were for minor problems that did not require intervention. We believe that the ERAS-outpatient cases were provided more proactive care, where professionals were more easily accessible than for standard care procedures. These situations demonstrate the need to better educate patients on complications that truly require a consultation.
Pain Management & Opioid Consumption
Patient-reported pain levels on POD 0 were very low (1.3–1.8/10) and were similar between ERAS-outpatient and STD-inpatient surgeries.2,7,8 However, the ERAS multimodal approach in the outpatient group achieved pain control with significantly less opioids in the first 8 hours (9.3 vs 26.5 MME, p < 0.001). The systematic use of pre-emptive analgesia, dexamethasone, LIA, epidural-sedation anesthesia, and other multimodal interventions (tourniquet avoidance, cryotherapy, etc.) may explain this observation, unlike results reported by other authors.30,31 The reduced intake of opioids in the ERAS group led to significantly lower incidences of related complications such as nausea, vomiting, headache, urinary retention, and dizziness (Table 3).
Functional Recovery and PROMs
Our patients demonstrated significantly better early function following ERAS-outpatient THA/TKA in comparison to contralateral surgery performed with STD-inpatient care (Table 6). This finding is likely multifactorial and linked to the specific ERAS interventions. Minimizing postoperative pain, orthostatic hypotension, anemia, motor blockade, and urinary retention, enabled rapid mobilization, which led to faster overall recovery. Pre-emptive medications,32 dexamethasone,22 LIA,27 cryotherapy,33 early first rise, and optimized wound closure are associated with faster functional recovery. Moreover, combined epidural-sedation opioid-free anesthesia avoided prolonged and complete motor blockade, reduced cases of urinary retention, and enabled patients to walk soon after surgery. Our ERAS interventions had very important impacts on patients’ function. Patients could perform activities of daily living, shower, practice physical activities, and return to work sooner, even though they were older and had more comorbidities. To our knowledge, no other studies reported lasting effects of ERAS procedures regarding the time needed to regain important functional abilities. Yet, some studies did find better PROMs in the first few months,9,10,11 supporting the possible superiority of ERAS interventions on recovery in the acute and subacute postoperative period. However, the benefits of ERAS procedures seemed to vanish with time. Like other trials7,12,13, we did not find any difference between groups on PROMs 9 months or later after surgery. Berg et al.10 did discover slightly better PROMs in its fast-track cohort at 1 year. However, this difference was not clinically significant and multiple cofounders might explain their results, thus limiting the validity of their findings.
Patients Satisfaction and Recommendation
Our previous study2 found that our multimodal approach achieved better pain relief. Thus, it can explain why patients were more satisfied with pain management following our ERAS interventions even though we did not find a difference on the day of surgery. Patients preferred the surgical glue to seal their wound probably because they could shower earlier and did not need to have the staples removed. The faster return to their home and to their activities surely contributed to them being more content with the outpatient protocol as satisfaction is directly correlated with shorter LOS.34 Like many studies, we found that patients were very satisfied of their ERAS-outpatient experience (97% vs. 85–94%)35 and highly recommended it (85% vs 80–96%).36,37 Nevertheless, our study is the first to demonstrate that patients were significantly more inclined to recommend the ERAS-outpatient pathway after having personally experienced both outpatient and inpatient protocols.