Ann Robinson’s research reviews—4 September 2020

Ann Robinson reviews the latest research from the top medical journals

Artificial pancreas may improve glycaemic control

This small, 16 week, multicentre, randomised, open label study showed that children aged 6-13 years with type 1 diabetes who used a closed-loop system of insulin delivery (“artificial pancreas”) had better glycaemic control than those with a sensor-augmented insulin pump. Those with an “artificial pancreas” spent an average 11%, or 2.6 hours/day longer with their glucose level in the target range than the control group. Interestingly, the glycated haemoglobin level didn’t differ significantly between the two groups, just the amount of time spent in the desired range. Episodes of hypoglycaemia were rare and similar in both groups, and no episodes of diabetic ketoacidosis occurred in either group. The children with an artificial pancreas were in the target glycaemic range for 57-77% of the time. Even this state-of-the-art artificial pancreas technology, which is so liberating for children, is not yet as good as the real thing. Although the improvements in glycaemic control are likely to translate into better outcomes in later life, this study was not designed to show that. The authors can’t claim the low rates of hypoglycaemia as a victory for the artificial pancreas; rates were unusually low in both groups because almost all of the children had devices that cut out when hypoglycaemia threatened.

N Engl J Med doi:10.1056/NEJMoa2004736

Low vitamin D and asthma—supplements don’t help

This randomised clinical trial of 192 school age children asked a good question. In high risk children with persistent asthma and low vitamin D levels, does vitamin D3 supplementation help their asthma? Unfortunately, the answer was no. The rate of severe asthma exacerbations in both the vitamin D3 group (37.5%) and placebo group (34.4%) were similar and lower than expected from previous studies. The mean time until exacerbation was around eight months in both groups. The study wasn’t powered to determine whether the small difference in exacerbations was statistically significant, whether the results would be similar for preschool kids, or if the minority of children with extremely low vitamin D levels (<20 ng/mL) might gain more benefit than the majority who have levels of 20-30 ng/mL. The vitamin D group fared no better than the placebo group in terms of the time to a viral-induced severe exacerbation, the proportion whose dose of inhaled corticosteroid could be reduced, or the cumulative fluticasone dose during the trial. There may be other advantages to boosting low vitamin D levels, but improving asthma outcomes, as measured in this study, isn’t one of them.

JAMA doi:10.1001/jama.2020.12384

Less is more: treating cardiogenic shock after acute MI

A third of people who develop cardiogenic shock after acute myocardial infarction die before discharge. Early revascularisation improves long term outcomes, but the best technique is unknown, and multivessel percutaneous coronary intervention (PCI) may be associated with more harm than revascularising the culprit vessel alone, according to the CULPRIT-SHOCK trial. This US cohort study used data from a US-wide registry of all patients undergoing PCI between 2009 and 2018. It found that multivessel PCI was increasingly used as the revascularisation strategy in acute myocardial infarction and shock and that hospitals which used multivessel PCI more, especially among patients with ST-segment elevation myocardial infarction (STEMI), had worse outcomes while in hospital (greater in-hospital mortality, bleeding, stroke and recurrent myocardial infarction) and similar long term outcomes. It’s a cohort study, so there’s a possibility of confounders and the impossibility of demonstrating causality. But the results are strong enough for the authors to urge a change in practice in favour of PCI for the culprit vessel alone in STEMI patients.

JAMA Intern Med doi:10.1001/jamainternmed.2020.3276

Mifepristone and misoprostol for the management of missed miscarriage

The MifeMiso trial is not a new Japanese dish, but a well designed UK study that compared giving a combination of the anti-progesterone drug mifepristone followed by the prostaglandin misoprostol or misoprostol alone to treat missed miscarriage. The combination was more effective than misoprostol alone: 17% in the combination group did not pass the gestational sac spontaneously within seven days and required surgery, versus 24% in the placebo plus misoprostol group. Both groups had similar adverse effects. The study only included missed miscarriages and can’t be generalised to incomplete miscarriage, in which some pregnancy tissue has already been passed and mifepristone is less likely to help.

Lancet doi:10.1016/S0140-6736(20)31788-8

Flu and incidence of acute cardiovascular events

Flu can put a strain on the heart, increasing the incidence of acute cardiovascular events including acute heart failure (aHF) and acute ischaemic heart disease (aIHD) in adults hospitalised with flu. This US cross sectional study found that, among nearly 90 000 patients hospitalised with lab-confirmed flu, 11.7% had an acute cardiovascular event. Unsurprisingly, being older, diabetic, a smoker, and having pre-existing cardiovascular or renal disease were associated with a higher risk. The 11.7% is likely to be an underestimate because many sick people admitted with aIHD or aHF won’t have had a flu test. The decision to test rests with individual practitioners. Also, the study relied on discharge summaries, and acute cardiovascular events may have been coded wrongly.

Ann Intern Med doi:10.7326/M20-1509

Ann Robinson is an NHS GP and health writer and broadcaster.