Alex Nowbar’s journal reviews—22 May 2019

Alex Nowbar reviews the latest research from the top medical journals


Simultaneously open records

Electronic health records are the best. Errors happen, but this is usually (or in my case always) the user’s fault. Adelman et al tested whether restricting the number of concurrently open patient records per clinician to one compared with up to four would reduce the rate of incorrect patient orders. There was no difference in the error rate between restricted use versus the unrestricted use (up to four records could be open simultaneously). The aim was laudable, but the trial design was limited because most users don’t have multiple records open simultaneously, and even when they do, it is still possible not to make a mistake, so the chances of reducing the rates of errors with such an intervention was very low. My guess is that the bigger factors in lapses that lead to wrong patient orders are probably workload and interruption related. The number of open records are probably a sign of the problem, not the problem itself

Obstructive sleep apnoea and post-op cardiovascular risk

Chan et al performed a prospective cohort study of 1218 people over age 45 without a diagnosis of obstructive sleep apnoea (OSA) who were undergoing major non-cardiac surgery. Over half of the participants were Chinese. The investigators performed pre-operative sleep studies and then looked at the rate of myocardial injury, heart failure, thromboembolism, atrial fibrillation, stroke, and cardiac death at 30 days after the surgeries. To establish the presence of “myocardial injury,” all patients had regular troponin measurements and ECGs after the surgery. There was a strong association between severe OSA and the cardiovascular events. However almost 90% of these events were of the “myocardial injury” variety. Myocardial infarction would have been a more relevant outcome, not to mention some patient-centred outcomes like function, symptoms, and quality of life. 

Along with the sleep studies everyone received a screening questionnaire pre-operatively, the unfortunately named STOP-Bang, which stands for Snoring, Tiredness, Observed Apnea, High Blood Pressure, Body Mass Index, Age, Neck Circumference, and Gender and which one of the authors is trying to patent. Those classified as high-risk on this questionnaire had higher event rates. 

There are many confounders here. For example, did patients with and without OSA receive exactly the same care? While the clinical team were blinded to the sleep study results, features that they weren’t blinded to that often co-exist with OSA (like hypertension and BMI) could have impacted patients’ treatment and therefore also the cardiovascular outcomes.  

Overall a convincing association between OSA and post-op cardiovascular risk, but OSA is far from the only factor at play which means that interventions aimed at OSA to reduce perioperative cardiovascular risk could be misplaced. 


Antibiotics for operative vaginal delivery 

The ANODE trial was a double blinded randomised controlled trial of antibiotics after operative vaginal delivery in more than 3000 women in the UK. The trial included women having any kind of operative vaginal delivery (women already receive antibiotics after caesarean section) but excluded women who already had an indication for antibiotics such as antenatal infection or perineal tears. The antibiotic was a once-only dose of intravenous co-amoxiclav administered within six hours of delivery and was compared with a saline placebo. The primary endpoint was maternal infection within six weeks of delivery. In women who received the antibiotic, only 11% had a suspected or confirmed infection. In the placebo group, the infection rate was 19%. There were minimal adverse events, so this may well become standard of care. 

JAMA Internal Medicine 

Cervical screening evolves 

Cervical screening could be improved by reducing the numbers of women offered colposcopy (and biopsy) but without missing more pre-cancerous lesions. Dual stain cytologic testing appears to do just this. This US cohort study assessed this method of triaging women for further testing in more than 3000 women within the existing screening programme, compared with the traditionally used Papanicolaou cytologic test. The dual stain test risk stratified women better and required substantially fewer colposcopies per detection of cervical intraepithelial neoplasia grade 3 or more severe. 


Reducing cardiac device infections

The WRAP-IT trial randomised almost 7000 patients undergoing cardiac device implantation to an antibiotic eluting mesh envelope or no envelope. Patients had to be perceived to be at higher risk of an infection to be included in the study. All patients received standard of care measures for infection prevention. Infection rates were found to be lower in the envelope group. The complication rate was similar between groups. A strong result, but while the clinical events committee was unaware of the randomisation arm, the trial was otherwise unblinded. This is a shame, as a double-blinded trial could perhaps have provided an incontrovertible answer.

Dabigatran versus aspirin 

Ischaemic stroke begets more stroke. Direct oral anticoagulants are doing quite well in the realm of stroke prevention in atrial fibrillation, but do they have a role in stroke with no identified embolic source? In this double-blind randomised controlled trial, participants were randomised to dabigatran 150mg twice a day or aspirin. They were carefully selected to have non-lacunar stroke, but no significant intra or extracranial stenosis and no atrial fibrillation lasting more than six minutes on at least 20 hours of cardiac monitoring. I’m impressed they managed to recruit over 5000 people meeting these quite specific criteria, but then again they recruited at over 500 sites. There was no significant difference in the rate of recurrent stroke between the dabigatran group and aspirin group. 

A note on the bleeding rate which was fairly high in both groups but worse with dabigatran, although the rates of major bleeding were no different statistically. 

Young gastric bypass

This study compared the outcomes of Roux en Y gastric bypass between adolescents and adults in prospective cohorts. The numbers are on the small side (169 vs 396) for a five year outcome comparison, but the key findings were a similar percentage weight change in adolescents compared with the adults, more diabetes and hypertension remission in the adolescents, and more abdominal re-operations in the adolescents.

Annals of Internal Medicine 

T2Bacteria panel 

This new test has been developed as a quicker alternative to a blood culture. It uses T2 magnetic resonance to identify bacteria (specifically Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli). 1427 patients who were having blood cultures had the T2Bacteria testing in this study, but the results were only used for the research, not for clinical decision making. Only 3% of the patients had positive blood cultures. Sensitivity and specificity were both 90% for the new test. Of the 1427 patients, 146 had a negative blood culture but a positive T2Bacteria test. Of the 146, 62 had a supporting positive culture within 21 days. Of the remaining patients, 26 had T2Bacteria result supported by their clinical picture e.g. e coli with cholangitis, but the other 58 had a positive T2Bacteria result that didn’t match i.e. these were false positives. 

This test could be useful if employed with good awareness of its limitations given that the results are available within short hours rather than days. 


Glucosamine and cardiovascular risk 

Ma et al found a lower risk of cardiovascular death, coronary heart disease and stroke with use of glucosamine supplements. Their prospective cohort study included 466,039 individuals who had provided data for the UK Biobank. This association was still present after adjustment for potential confounders. Glucosamine is often taken to help with osteoarthritis. The finding of possible lower cardiovascular risk with glucosamine seems worthy of further investigation.

Tramadol tainted

Opioid misuse is bubbling away. This study looks at a potential source. Thiels et al’s observational study of opioid naïve patients undergoing elective surgery looks at the risk of persistent opioid use after discharge. They compared people receiving tramadol with those receiving other short-acting opioids and found those receiving tramadol alone had a higher risk of prolonged opioid use. Use as little tramadol as possible is the conclusion but in practice pain management is a complex field where it is hard to know how to do the best for a patient overall.

Alex Nowbar is a clinical research fellow at Imperial College London.