Summary of findings
The rapid review identified five clinical protocols for ER after CS (all from the UK) involving a total of 25 clinical components [
30‐
33]. Only 3/25 components were common to all five pathways (early oral intake, mobilization and removal of catheter) demonstrating considerable differences in the composition of enhanced recovery packages between UK maternity units. Of the systematic reviews evaluating single component ERAS interventions in CS, only minimally invasive Joel-Cohen surgical technique [
41], early removal of catheter [
47] and post-operative antibiotic prophylaxis [
44] appeared to show effects that were statistically significant at the 5 percent level. These interventions reduced length of stay by 0.49 to 1.5 days (catheter removal was presented as increased length of stay for indwelling catheter [
47]), but the quality of evidence was moderate at best.
Since only a minority of ER interventions for CS have been subject to systematic review, reviews of ER interventions / packages from other settings were included. The rationale for their inclusion was to allow expert decision-makers to assess the functional logic and assumed mechanisms of action associated with particular interventions and determine whether they should be deemed transferable from one surgical setting to another. For example, whilst ER for colorectal cancer targets optimising compromised perioperative bowel function in an older population function, ER interventions for elective CS are deployed in a younger population without compromised digestive tract.
Of those reviews evaluating components in any other surgical setting, almost all (except patient warming [
42] and delayed umbilical cord clamping [
43], of which the latter, for infants only, actually showed the most significant LoS reduction) demonstrated statistically significant effects at the 5 percent level. These interventions reduced length of stay by 0.3 to 0.97 days, but again, the quality of evidence was moderate at best. Meta-analysis was undertaken in ten systematic reviews of multi-component ERAS packages (eight for colorectal surgery, one for upper gastrointestinal surgery and one for all elective surgery), which consistently demonstrated results that were statistically significant at the 5 percent level. Mean effect sizes for LoS were larger in reviews of ERAS packages than in reviews of single components (median reduction in length of stay versus control of −2.45 days and median range −3.28 days to −1.45 days, values rounded to two decimal places), indicating the likelihood that multiple components provide additive effects. The quality of evidence was generally low.
Strengths and limitations of review
Our study used multiple approaches to identify and synthesise evidence relevant to the design of enhanced recovery programmes for elective CS. Systematic review of complex interventions is challenging [
82], and there are areas where a better resourced study might have better described the complexity of the primary data. Where systematic reviews investigated the effect of individual components, it was rarely clear what other clinical components that might affect length of stay might be present in the included trials.
ERAS packages evaluated in systematic reviews varied greatly in the number of individual components employed. For instance 23 RCTs in one systematic review [
57], used a minimum of four and a maximum of 13 out of 21 components. Most of the systematic reviews of pathways did not make it clear whether there was flexibility over the delivery of research and control interventions in the included trials and, if so, how much leeway was available to professionals in adapting pathways to local circumstances [
83,
84]. Similarly, Paton and colleagues make the point that components of elements of early enhanced recovery pathways, become widely adopted in usual care, making the synthesis of studies from different time points questionable [
17].
Rapid reviews generally employ methods that are rigorous and transparent, with compromises on best practice made because of time and resource constraints [
24,
25,
85,
86]. There is little guidance on which methodological concessions should be sanctioned, although the use of more limited search strategies is one generally thought legitimate [
25]. We searched the Cochrane Library and DARE for systematic reviews to maximise the completeness and timeliness of the search without being burdened with an excessively large number of references for screening. In this, and other respects, our umbrella review of systematic reviews broadly followed the methods recommended by the Cochrane Collaboration for overviews of systematic reviews and in some cases went beyond them [
87]. The process followed a protocol specified in advance and published via PROSPERO [
88]. As recommended, we used a validated tool, AMSTAR [
28], widely used in previous overviews, to assess the limitations of included systematic reviews. An assessment of the overall quality of evidence is another important feature of systematic review overviews. For Cochrane overviews it is recommended to assess the quality of evidence across reviews based on GRADE assessments in the included systematic reviews; where these were not present, we performed our own GRADE assessments of the quality of evidence for length of stay [
29].
Data collection was limited to our primary outcome of interest; we did not seek to obtain additional data, for example by contacting authors, because of resource constraints. Similarly, although differences in the reporting of length of stay were noted, we were not able to investigate these in any depth. A further potential limitation was our restriction of the searches to two indexed databases and only one source of grey literature to identify other enhanced recovery pathways for elective CS in grey literature. English language restrictions also meant that we knowingly, excluded one relevant article [
89]. The exclusion of non-English language papers from systematic reviews is not thought to bias estimates of effectiveness for most types of intervention [
90]. The abstract of the single non-English language clinical pathway publication which we noted, seemed to confirm the findings of other studies, that enhanced recovery pathways reduce length of hospital stay after elective CS, without safety concerns or increased readmissions [
89].
The searches for our umbrella review were run 18 months after those of the last umbrella review of the enhanced recovery after surgery [
17,
26], work that was better resourced than our own. Our review identified an additional 28 systematic reviews on ERAS to the seventeen included by Paton and colleagues [
17]. Unlike the Paton review, we also included reviews evaluating single intervention components, rather than entire pathways. Shortcomings of our umbrella review are that we did not investigate overlap between eligible systematic reviews or search for relevant RCTs not included by the reviews. Whether reviews are contemporary (‘up-to-date’) is often neglected in overviews [
91], but the risk of bias to our own is small, with the Paton review of RCTs itself so recently conducted [
26]. However, overlap of included studies between systematic reviews of ERAS packages has been shown to be substantial for colorectal surgery [
26].
Differences in resourcing aside, the methods used in our review and the Paton review reflect the differences in objectives, with theirs undertaken to inform commissioning of services and further research, and ours to inform intervention synthesis [
22]. In other words, our aim was to inform the development of an enhanced recovery pathway for elective CS by reference to the best available evidence for enhanced recovery components and pathways in elective CS and other settings. Overall, the sample of pathways we reviewed can be considered fit-for-purpose in that it shows a diversity of intervention content which is nonetheless limited in scope when compared with ERAS programmes from other clinical settings, signalling the need for consensus work.
Implications for health professionals, policymakers and patients
Given that enhanced recovery programmes were developed and implemented initially for patients undergoing cancer surgery, not all the interventions we review in the umbrella review are relevant to enhanced recovery in elective CS. However, by adopting a broad scope, we have ensured we offer decision-makers for a consensus exercise (see below) information on the widest range of potentially relevant interventions, to inform the production of durable guidelines [
92]. Additional file
10: Figure S3 and Additional file
11: Table S7 presents a programme theory of the proposed mechanisms of action for broad categories of ERAS components, and how they might work together in an enhanced recovery pathway.
The adoption of recommended healthcare innovations is neither a linear process nor guaranteed by the availability of robust evidence, with many other factors influencing the change process [
93]. The Paton review dedicated a chapter to studies charting the implementation of ER pathways [
17], identifying facilitators which are summarised in Additional file
12: Table S8, mapped to a classes of knowledge transfer targets from the taxonomy by Wensing and colleagues [
94]. These themes are echoed by recent [
95‐
97] and ongoing [
98] theory-based quality improvement studies as important considerations in the reliable implementation of a clinical pathway. Of particular interest is the tension between the desire to implement clinical protocols rigidly, and the requirement by some stakeholders or centres, to maintain a flexibility of approach based on the needs of particular patients or due to local circumstances [
99,
100]. These tensions have wider resonances in the differences between those who advocate the demonstration of fidelity in the implementation of complex interventions [
101‐
103] and those who favour adaptation of complex interventions to circumstance [
84,
104‐
106]. Those designing both clinical pathways and further research need to consider carefully which clinical and quality improvement components are essential and on which flexibility of approach can be permitted.
Further research
A meeting of women who have given birth by elective-CS, midwives, obstetricians, obstetric anaesthetists, neonatologists and Quality Improvement (QI) experts, held in London on 5th March 2015, generated a consensus on a package of core clinical and QI components for enhanced recovery. The resulting guideline, which will be current, specific, clinically relevant, based on an up-to-date evidence base and patient-important outcomes [
107], will be reported separately. There is currently a paucity of existing evidence to support structured ER interventions in CS, the components of such interventions are heterogeneous and their effect has not yet been investigated in the setting of controlled studies. However, it is reasonable to say that there is wide acceptance that ER pathways in general are useful quality improvement tools to streamline surgical care, despite variation in pathways between institutions resulting from incorporation of local expertise. The challenge for future research will be the rigorous study of the facilitators and barriers to the implementation of ER in CS, monitoring the adoption and spread of the principles of ER as they embed into practice and the search for evidence of a permanent improvement in quality of care over time. Further work should concentrate on these domains to meaningfully assess the impact of the intervention and establish if its impact is sustained.