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On The Pulse - November 2018

On The Pulse

Tertius Lydgate

Friday, 23 November 2018

Point-of-care tests for influenza in ambulatory care
Point-of-care tests (POCTs) for influenza are diagnostically superior to clinical diagnosis and a systematic review in Clinical Infectious Diseases set out to assess their impact on patient outcomes versus usual care in ambulatory care settings. Out of 12,928 citations screened, seven randomised studies (n=4,324) and six non-randomised studies (n=4,774) were included. In randomised trials, POCTs had no effect on admissions, returning for care, or antibiotic prescribing, but increased prescribing of antivirals (risk ratio [RR] 2.65, 95% CI 1.95-3.60). Further testing was reduced for full blood counts (FBC) (RR 0.80, 95% CI 0.69-0.92), blood cultures (RR 0.82, 95% CI 0.68-0.99) and chest radiography (RR 0.81, 95% CI 0.68-0.96), but not urinalysis. Time in the emergency department was not changed. Fewer non-randomised studies reported these outcomes, with some findings reversed or attenuated (fewer antibiotic prescriptions and less urinalysis in tested patients). The authors conclude that POCT for influenza influences prescribing and testing decisions, particularly for children in emergency departments, and note that observational evidence shows challenges for real-world implementation.

Hospital admissions in older people
Achieving optimal prescribing for adults aged 64 and over can be challenging in primary care, partly due the higher burden of multimorbidity and the increased number of drugs prescribed. As a result, potentially inappropriate prescribing is common older people and a longitudinal study in The BMJ suggests it is linked with hospital admissions. Out of 38,229 patients (mean age 76.8, 43% male), 10.4-15.0% had at least one hospital admission each year from 2012 to 2015. The overall prevalence of potentially inappropriate prescribing ranged from 45.3%-51% of patients. Independently of age, sex, number of prescription items, comorbidity, and health cover, hospital admission was associated with a higher rate of distinct potentially inappropriate prescribing criteria met - adjusted hazard ration for hospital admission 1.24 (95% CI 1.20 to 1.28). And the likelihood of potentially inappropriate prescribing after admission was higher than before admission – adjusted odds ratio 1.72 (1.63 to 1.84). The authors stress that identifying optimal management strategies for older people is vital to ensure that the risk of inappropriate drugs is minimised after transitions of care.

The effects of a low carbohydrate diet
Weight loss maintenance can be a challenge as physiological adaptation that defend against long-term weight change come into play: hunger increases and energy expenditure decreases as weight is lost. A randomised trial in The BMJ comparing the effects of diets varying in carbohydrate to fat ratio on energy expenditure during weight loss maintenance, showed that, consistent with the carbohydrate-insulin model, lowering dietary carbohydrate increases energy expenditure. Participants (n=164, aged 18-65 years, BMI ≥ 25) were randomly assigned, after 12% weight loss on a run-in diet, to three test diets according to carbohydrate content (high n=54; moderate n=53; or low n=57) for 20 weeks. Key results showed that change in total energy expenditure was 91 kcal/d and 209 kcal/d greater in participants assigned to the moderate carbohydrate diet and low carbohydrate diet, respectively, compared with the high carbohydrate diet. Overall results prompted the authors to conclude that the metabolic effect of lowering dietary carbohydrate may improve the success of obesity treatment, especially among those with high insulin secretion.

SGLT2 inhibitors and adverse events
Since the introduction of sodium glucose cotransporter 2 (SGLT2) inhibitors as a therapeutic option for the treatment of type 2 diabetes, several safety concerns have been raised. A register-based cohort study in The BMJ set out to assess whether the use of SGLT2 inhibitors was associated with an increased risk of seven serious adverse events of current concern. The study included a propensity score matched cohort of 17,213 new users of SGLT2 inhibitors (dapagliflozin, 61%; empagliflozin, 38%; canagliflozin, 1%) and 17,213 new users of the active comparator, glucagon-like peptide 1 (GLP1) receptor agonists. The results showed that the use of SGLT2 inhibitors, as compared with GLP1 receptor agonists, was associated with an increased risk of lower limb amputation (incidence rate 2.7 v 1.1 events per 1000 person years, hazard ratio 2.32, 95% confidence interval 1.37 to 3.91) and diabetic ketoacidosis (1.3 v 0.6, 2.14, 1.01 to 4.52) but not with bone fracture, acute kidney injury, serious urinary tract infection, venous thromboembolism or acute pancreatitis.

The preventive action of SGLT2 inhibitors
A separate systematic review and meta-analysis of cardiovascular outcome trials of SGLT2 inhibitors in patients with type 2 diabetes, in The Lancet, found that SGLT2 inhibitors have moderate benefits on atherosclerotic major adverse cardiovascular events that seem confined to patients with established atherosclerotic cardiovascular disease. The research, involving 34,322 patients, showed that SGLT2 inhibitors reduced major adverse cardiovascular events by 11% (HR 0·89 [95% CI 0·83–0·96]), with benefit only seen in patients with atherosclerotic cardiovascular disease. However, SGLT2 inhibitors appear to have “robust” benefits on reducing hospitalisation for heart failure and progression of renal disease, regardless of existing atherosclerotic cardiovascular disease or a history of heart failure. Results showed they reduced the risk of cardiovascular death or hospitalisation for heart failure by 23% (0·77 [0·71–0·84]), and the risk of progression of renal disease by 45% (0·55 [0·48–0·64]). The magnitude of benefit of SGLT2 inhibitors varied with baseline renal function, with greater reductions in hospitalisations for heart failure and lesser reductions in progression of renal disease in patients with more severe kidney disease at baseline.

Childhood tonsillectomy
A retrospective cohort study in the BJGP investigated the incidence of indications for tonsillectomy in UK children, and the proportion of tonsillectomies meeting evidence-based criteria. The authors included 1,630,807 children followed up for 7,200,159 person–years between 2005 and 2016. Incidence of evidence-based indications for tonsillectomy was 4.2 per 1,000 person years; 13.6% underwent tonsillectomy. Incidence of childhood tonsillectomy was 2.5 per 1,000 person years; 11.7% had evidence-based indications, almost all had Paradise criteria, i.e. documented sore throats of sufficient frequency and severity. The proportion of evidence-based tonsillectomies was unchanged over 12 years. Most childhood tonsillectomies followed non-evidence-based indications: five to six sore throats (12.4%) in one year, two to four sore throats (44.6%) in one year, sleep disordered breathing (12.3%), or obstructive sleep apnoea (3.9%). The authors conclude that in the UK, few children with evidence-based indications undergo tonsillectomy and seven in eight of those who do (32,500 of 37,000 annually) are unlikely to benefit.

Complications of polyacrylamide gel (PAAG) implants
The BMJ Case Reports describes the case of 35-year-old lactating woman with pre-existing polyacrylamide gel (PAAG) implants for 10 years presenting on numerous occasions following both her pregnancies with bilateral recurrent breast infection, pain and finally massive breast enlargement with a ruptured galactocoele necessitating surgical intervention. The authors point out that it is important to distinguish between PAAG and silicone implants. As the safety of PAAG for the breastfeeding baby is not known, breastfeeding with PAAG implants is not recommended. They also stress that is important for medical professionals to be aware of this condition as women of reproductive age may present with PAAG-related complications.

Algorithm versus practising radiologists
PLOS Medicine has published a series papers in a special issue on machine learning in health and biomedicine. One of papers explains how researchers developed and validated a deep learning algorithm that classified clinically important abnormalities in chest radiographs at a performance level comparable to practising radiologists. The algorithm was developed to concurrently detect 14 clinically important pathologies in chest radiographs and to localise parts of the image most indicative of each pathology. It was evaluated against nine practising radiologists on a validation set of 420 images for which the majority vote of three cardiothoracic specialty radiologists served as ground truth. The algorithm achieved performance equivalent to the practising radiologists on 10 pathologies, better on one pathology, and worse on three pathologies. Radiologists labelled the 420 images in 240 minutes on average, and the algorithm labelled them in 1.5 minutes. The authors concluded that once tested prospectively in clinical settings, the algorithm could have the potential to expand patient access to chest radiograph diagnostics.

Author's Image

Tertius Lydgate

Originally from Northumberland, Tertius Lydgate studied medicine in Edinburgh, London and Paris. There he developed a special interest in communicable diseases and hoped to make great advances in treating and preventing them. But, after a promising start in a provincial centre of excellence in middle England, he was forced by circumstances (please, don't inquire) to abandon his high ideals. He now scrapes a living by pouring cold water on the over-enthusiastic at his private cryohydrotherapy clinic. Dreaming of the contributions he once hoped to make himself, he finds consolation in the latest medical journals and is happy to share his discoveries with his readers. He thinks that his creator, George Eliot, would have approved.
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