To our best knowledge the present study is the first overview of guidelines encompassing a broad spectrum of preoperative care recommendations.
We observed higher level of evidence supporting therapeutic than risk stratification recommendations (high/moderate quality of evidence 59 vs 22%, respectively). It is not surprising, because cross sectional or cohort studies can provide high quality evidence for test accuracy but indirect evidence for patient-important outcomes. Furthermore, highs level of heterogeneity is almost the rule in risk stratifications test, downgrading even more the level of evidence because inconsistency.[26-28]
The strength of a recommendation is defined as the extent to which one can be confident that the desirable effects of an intervention outweigh its undesirable ones. We found only 12/53 (23%) ‘strong’ risk stratification recommendations statements (for and against) based on high/moderate level of evidence and 43/78 (55%) for therapeutic/preventive care recommendation. Although it would be desirable higher proportions of high-quality supporting evidence a guide panel must consider additional factors. In order to assess competing management alternatives, GRADE proposes to consider four domains: estimates of effect for desirable and undesirable outcomes, confidence in the estimates of effect, values and preferences, and resource use. Guideline panels must integrate these factors to make a strong or weak recommendation for or against an intervention.
After our search date, the updated guideline from the European Society of Anesthesiology (ESA) was published, using GRADE and searching until May 2016. This CPG addressed two main clinical questions in order to help each anesthesiologists in their daily practice: 1. how should a pre-operative consultation clinic be organized and 2. How should pre-operative assessment of a patient be performed. As in our present work, this guideline covered specific conditions that might adversely interfere with anesthesia and surgery, including cardiovascular disease, respiratory disease, smoking, obstructive sleep apnea syndrome, renal disease, diabetes, obesity, coagulation disorders, anemia and pre-operative blood conservation strategies, the geriatric patient, alcohol and drug misuse and addiction and currently also neuromuscular disease. We are hereby presenting a preoperative clinical risk criteria and categories that was complemented with established risk factors for postoperative pulmonary complications (See Online supplemental material Appendix 3). The 2018 ESA guidelines also provided independent predictors for difficult mask ventilation, a topic not specifically addressed in previous CPGs.
As described, RCTs are still few and therefore many preoperative interventions rely to a large extent on expert opinion, which in turn requires to be adapted to the reality of nations’ healthcare systems. This large evidence gap should be addressed by related researchers in order to improve the certainty in evidence-based recommendations.
Studies on prognostic or diagnostic accuracy tests, including scoring of severity of illness, usually provide low quality of evidence, even when scores such as ASA-PS, RCRI, NSQIP-MICA, POSSUM and others have been extensively validated.
Our updated overview of EB-CPGs, conducted under the rigorous Cochrane methods, may be a useful resource for the professionals involved in preoperative care to consult during decision-making. We present many strong recommendations with sufficient evidence to be routinely implemented in clinical practice. However, any decision should be taken considering local contextual factors.
In addition, cost reductions were identified at the clinical level as well as at the health system level in another study.[10-12], Two guidelines also suggested strong costs benefits both for patients and society.34,35 Another study showed that the application of EB-CPGs significantly improved the efficiency of the preoperative evaluation without negatively affecting the quality of care. These findings were consistent across different settings, like in a hospital in Barbados where the introduction of guidelines reduced the burden of presurgical tests and costs with not hampering patient’s safety. In the same way, a recent study in a hospital in New Jersey, USA, found that approximately 25% of tests were not justifiable and could be thus eliminated by complying with NICE/ASA guidelines. The evaluation of applying these changes in practice showed significant savings without altering clinical outcomes.
Recommendations can be adopted, modified or even not implemented, depending on institutional or national requirements and legislation and local availability of devices, drugs and resources. Decision-makers at the national and subnational levels should be provided with the information they need to apply the evidence and recommendations in their setting. As a limitation, including only EB-CPGs could have resulted in omitting some information, but we prioritized summarizing the highest quality evidence. Our exclusion criteria for CPGs, limiting the scope may represent an additional caveat Our inclusion/exclusion criteria focused on general recommendations provided a lower amount of evidence for certain practices than if we had also included recommendations for single conditions, specific prophylaxis or single body parts surgeries. Such approach, however would have compromised the feasibility of our systematic review due to the enormous number of such guidelines. Nonetheless, we provided detailed lists with numerous recommendations and reflected guideline’s discrepancies, suggesting that this could not have been a major limitation..
Our study will be useful for future preoperative care guideline developers or adapters. Consistently with other overviews of clinical guidelines, the domain that received the lowest mean score was the ‘applicability’ domain of the AGREE-II tool. Similarly, the heterogeneity of evidence and the strength of recommendations grading systems in this overview echo that of other clinical guideline overviews.[37-39] Low scores in the applicability domain result in inadequate adoption rates of guidelines, particularly for preoperative care where ‘defensive medicine’ (i.e. prescribing more tests than necessary just to prevent litigation) is very common. We also found some discrepancies, mainly in the evidence level, in each recommendation that did not always discriminate between universal interventions and those suitable only for special target groups or specific surgeries.
Guideline developers should ensure rigorous methodological processes and should also make recommendations that are formulated and disseminated in ways that facilitate understanding and application by end-users. For example, the DECIDE Collaboration conducted research and developed tools to improve implementation of evidence-based recommendations by different target audiences, including providers, policy makers, and the public. In that sense, GRADE provides guideline developers with a comprehensive and transparent framework for grading quality of evidence and of strength of recommendations.
Our overview identified several controversies, evidence gaps and issues regarding preoperative care guidelines that warrant future research and reveal opportunities to improve the guidelines quality.
For example, we found many discrepancies about risk stratification recommendations like electrocardiography and Chest X-ray, polysomnography, assessment of left ventricular function, stress testing and coronary angiography in certain populations. We found less discrepancies for therapeutic/preventive care mainly because antimicrobial prophylaxis, use of beta-blockers (Find these discrepancies in the Online supplemental material Appendix 6 and Appendix 8).
From the perspective of the anesthesiologist practice there still remain many unanswered questions. For example, in the patient with significant medical, surgical or obstetrical history, it would be useful to understand how early the pre-anesthetic evaluation should be performed, considering the time required to optimize the patient's status. There are also uncertainties for the recommendation of fasting for solids in adults and children since many factors can delay gastric emptying, and no fixed rules apply. Fasting should be individualized in some patients, and depending on the characteristics of the fat intake. Regarding prokinetics and antacids, patients’ comorbidities like esophageal pathology, bariatric surgery history or obesity, should be considered in the decision, but there is no formal recommendation. In the same way, suspending or not suspending aspirin should be evaluated according to the patient's history and risk of bleeding of the surgery that could be catastrophic in neurosurgery, spinal surgery or ophthalmologic surgery. It is also strange that informed consent only has a ‘weak for’, recommendation from a unique CPGs since there is enough background of litigation due to the lack of consent.
We encourage guideline developers to adopt GRADE and AGREE-II tools to elaborate future sound preoperative care guidelines. [7, 22]
The huge amount of resources involving preoperative care warrants high-quality nationwide EB-CPGs supported by all relevant stakeholders to improve the chances of a successful implementation. This probably includes the involvement of the Ministry of Health, scientific societies, and consumers working together through a formal process of implementation and monitoring.[17, 41]
Although standardization of preoperative care may be desirable, differences in recommendations could reflect differences in contextual factors such as organizational or financial arrangements, legal framework, varied values and preferences, and the acceptability and feasibility of using different interventions. Research exploring reasons for conflicting recommendations in different countries or settings could also drive overall improvements in guideline quality. The key findings are described in Box 1.
Box 1 Key points
The included evidence-based clinical practice guidelines (EB-CPGs) showed significant heterogeneity both of evidence and recommendation grading systems; GRADE was the most commonly used.
About half of the included EB-CPGs were updated in the last five years and one third of them were rated as strongly recommended based in their high AGREE-II performance.
They were generally deficient in applicability and in providing monitoring tools.
We summarized 31 risk stratification and 16 therapeutic/preventive recommendations.
We found 93 strong for and 46 strong against recommendations, all which were ready to be considered to be implemented or to be interrupted, respectively.
The level of evidence and strength of recommendation was higher for therapeutic/preventive recommendation than for risk stratification ones.
We only found 12/53 (55%) strong risk stratification recommendations based on high/moderate level of evidence and 43/78 (55%) for therapeutic/preventive care recommendations.
In conclusion we found significant heterogeneity of guidelines’ quality and rating systems, as well as deficiencies in several guideline quality domains, which reveal opportunities for quality improvement which deserve careful consideration by future guideline developers. Nevertheless, we present many strong recommendations ready to be at present considered for implementation or discontinuation.