Best Evidence Topic Research Articles

Routine systemic antibiotic prophylaxis for burn injuries in developing countries: A best evidence topic (BET)

BackgroundBurns are common in low- and middle-income countries (LMICs) and complicated by unhygienic conditions, malnutrition, use of high-risk homemade dressings and delayed presentation. Resultantly, use of routine systemic antibiotic prophylaxis (SAP) to prevent wound infection is common practice despite this intervention being abandoned in high-income countries due to increased antimicrobial resistance and non-bacterial suprainfection. MethodsA best evidence topic (BET) was constructed using a structured protocol. The question addressed was: In LMICs, does routine use of SAP reduce burn wound infection, morbidity or mortality? ResultsFrom 704 retrieved records, 48 reports met criteria to be examined. Of those, 3 studies represented the best available evidence. Together, two randomized clinical trials (RCTs) and a retrospective cohort study reported no difference in the proportion of wound infection, any infection or length of hospital stay between SAP groups and controls. One RCT described a greater proportion of wounds infected with P. aeruginosa among SAP arms compared to controls. The studies had few participants and significant methodological weaknesses. ConclusionOn the basis of limited, currently available evidence, the use of SAP cannot be recommended for patients in LMICs that present soon after burn injury.

Should routine assessment of anastomotic integrity be undertaken using radiological contrast swallow after oesophagectomy with intra-thoracic anastomosis? Best evidence topic (BET)

Thoracic anastomotic leak is associated with significant postoperative morbidity and mortality. Routine contrast oesophagograms are consequently employed by a number of centres to routinely screen for this complication yet there exists little consensus as to if and when this assessment should occur. We have demonstrated within this BestBET analysis of five level IV case series that routine contrast oesophagograms lack adequate sensitivity or positive predictive value to be effective as screening tools, with leaks often arising clinically prior to scheduled routine assessment. We additionally demonstrate the significant risk of aspiration associated with contrast swallow use. The use of contrast swallow studies as diagnostic tools in patients for whom a leak is considered likely on the basis of clinical examination is nevertheless supported by relatively greater negative predictive values and specificity reported within the literature. There is additional evidence to support the use of CT imaging with oral contrast and endoscopic assessment of the anastomosis as valuable tools to assess for anastomotic integrity.

Should routine radiological assessment of anastomotic integrity be performed after oesophagectomy with cervical anastomosis? Best evidence topic (BET)

Rates of anastomotic leak in patients who undergo oesophagectomy with cervical anastomosis formation are reported within the literature to surpass those of patients undergoing thoracic anastomosis formation. Though preferred by a number of surgeons, cervical anastomosis is associated with higher rates of anastomotic leak, the consequences of which can be severe. Routine contrast oesophagograms are therefore utilised in a number of institutions as a means of recognising leaks early. They are not without potential complications, however, and the predictive value of contrast imaging has previously been debated. This best evidence topic reviews the use of contrast oesophagograms in screening for cervical anastamotic leak, concluding that their inherent risk of aspiration combined with poor sensitivity should preclude their use as a screening tool. High rates of specificity nevertheless indicate the potential utility of these studies in patients for whom there is clinical suspicion of a leak.

Should oesophageal stents be used before neo-adjuvant therapy to treat dysphagia in patients awaiting oesophagectomy? Best evidence topic (BET)

Patients who develop significant dysphagia secondary to a potentially curable oesophageal cancer pose a significant clinical problem. Their nutritional needs can be met either by dietary supplementation, insertion of an oesophageal stent or through nasogastric or surgical feeding tube placement. We sought to determine whether, in patients about to start neo-adjuvant therapy prior to oesophagectomy, the use of oesophageal stent improves clinical outcomes. A best evidence topic in upper gastrointestinal surgery was written according to a structured protocol in order to answer this question. Two hundred and forty eight papers were found, of which eleven level III and one level IV study were considered to best address the clinical question. These indicate that whilst oesophageal stents do successfully relieve dysphagia throughout neoadjuvant therapy, they are not consistently associated with maintenance of, or improvement in, serum albumin or body weight. They are, however, commonly associated with stent migration and chest discomfort, both of which may frequently result in the need for stent removal or replacement. There is additional evidence within the manuscripts reviewed to demonstrate that the use of oesophageal stents in the neoadjuvant setting can lead to significant complications in a small proportion of patients which can compromise opportunity for curative surgery. The use of stents in this situation cannot be recommended.

Should patients taking aspirin for secondary prevention continue or discontinue the medication prior to elective, abdominal surgery? Best evidence topic (BET)

This best evidence topic was investigated according to a described protocol. The question asked was: should patients on acetylsalicylic acid (ASA) for secondary prevention stop or continue the medication prior to elective, abdominal surgery. Using the reported search 826 papers were found of which five represented the best evidence to answer the clinical question. The strongest evidence was from a randomized controlled trial (RCT) specifically looking at elective abdominal surgery, which showed no statistically significant difference between ASA continuation and discontinuation in terms of haemorrhagic or thrombotic events. Two other RCT's examined elective non-cardiac surgery but only a minor proportion (20.6% and 23.6%) of patients underwent abdominal surgery and data were unavailable regarding adverse events in these patients. However, one of these trials did show a 7.2% absolute risk reduction in postoperative cardiac adverse events when ASA was continued. One prospective cohort study found no difference between ASA maintenance and cessation except for longer duration of surgery in the ASA continuation group. Finally one recent retrospective cohort study revealed similar bleeding rates between ASA-treated and non-ASA-treated patients but increased cardiac complication rates in the ASA group.Only two studies compared continuation versus discontinuation of ASA, while the remaining three looked at patients on ASA versus those not on ASA. This heterogeneity in methodology makes it difficult to draw justifiable conclusions from the data. However, it appears that continuing ASA isn't associated with excessive bleeding. Further adequately powered trials with well-defined end points are needed to answer this important clinical question.

Is brain natriuretic peptide a marker for adverse postoperative outcomes in patients undergoing cardiac surgery?

A best evidence topic (BET) was constructed according to a structured protocol. The question addressed was 'Is brain natriuretic peptide (BNP) a marker for adverse postoperative outcomes in patients undergoing cardiac surgery?' Nearly 200 papers were found using the reported search, of which 17 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. BNP levels have been shown by several prospective observational cohort studies to be a marker for cardiac dysfunction and adverse outcome in patients undergoing cardiac surgery. BNP levels can be used to guide the therapy of patients with heart failure which may reduce adverse cardiac events. Whether BNP-guided therapy can be applied to patients undergoing cardiac surgery is unknown. We conclude that preoperative and postoperative measurement of natriuretic peptides could help predict postoperative cardiac dysfunction and adverse outcome in patients undergoing cardiac surgery. Furthermore, they may improve the ability of commonly used risk assessment tools to predict outcome.

Does ABO-incompatible and ABO-compatible neonatal heart transplant have equivalent survival?

A best evidence topic (BET) in cardiac surgery was written according to a structured protocol. The question addressed was whether ABO-incompatible (ABO-I) heart transplant recipients have a similar survival rate as an ABO-compatible (ABO-C) transplant in the pediatric population <1 year of age. Altogether more than 112 papers were found using the reported search, of which 10 represented the best evidence to answer the clinical question. Generally, ABO-I transplantation has been associated with the neonatal population because of the relative immaturity of the immune system for the first year of life. In the BET the search-term 'pediatric' was used as a method to ensure retrieval all relevant papers. However, the vast majority of the patients reviewed were <1 year of age with specific techniques undertaken to modulate preoperative, intraoperative and postoperative isohemagglutinin titer levels with rejection monitoring. Therefore, the BET conclusions should not be applied to the pediatric group as a broad age classification. Two large series are of particular interest. Patel et al. reviewed all primary heart transplantation recipients < or =1 year of age in the United Network for Organ Sharing/Organ Procurement and Transplantation Network (UNOS/OPTN) registry (ABO-I=35 vs. ABO-C=556). There was no difference in 30-day mortality (ABO-I=5.9% vs. ABO-C=8.8%; P=0.55); one-year mortality (ABO-I=16.6% vs. ABO-C=14.7%; P=0.77); graft rejection (ABO-I=1 vs. ABO-C=0); and graft failure (ABO-I=24% vs. ABO-C=24%; P>0.99). Three-year Kaplan-Meier survival was 70% (P=0.85). Propensity score adjusted analysis did not implicate ABO-I as a predictor of mortality [hazard ratio (HR)=3.6, confidence interval (CI): 0.2-49.0; P=0.33]. The ABO-I group demonstrated an increased need for pacemaker (ABO-I=3.1% vs. ABO-C=0.4%; P=0.03) and higher stroke rate (ABO-I=12.9% vs. ABO-C=1.3%; P<0.0001). Dipchand et al. published the results of the Toronto cohort from 1992 to 2006 (ABO-I=16 vs. ABO-C=38). The median age at transplantation (ABO-I=88 days vs. ABO-C=84 days; P=0.82) and the number of neonatal transplant recipients (ABO-I=17% vs. ABO-C=22%; P=0.59) was similar. The freedom from post-transplantation death or retransplantation was equivalent at one year (ABO-I=77% vs. ABO-C=84%) and seven years (ABO-I=74% vs. ABO-C=74%; P=0.87). No significant difference was observed for the five-year freedom from: rejection (ABO-I=60% vs. ABO-C=45%; P=0.41); renal dysfunction (ABO-I=67% vs. ABO-C=72%; P=0.70); allograft vasculopathy (ABO-I=87% vs. ABO-C=78%; P=0.45); and post-transplantation lymphoproliferative disorder (PTLD) (ABO-I=87% vs. ABO-C=86%; P=0.93). We conclude that ABO-I transplantation is comparable to ABO-C transplantation, with several retrospective papers concluding there is no difference in mortality, morbidity or graft failure in the pediatric population <1 year of age.