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Jul 19, 2019

Impact factors

The story

If your trainee salary only grew at the same rate as worldwide obesity, well, you'd probably spend less time in the hospital cafeteria. Here's a decades-long look at how genes and environment fueled obesity in Norway.

The background

Worldwide obesity has increased to the tune of 0.5 kg/m2 per woman per decade since 1980. That means a dress made to fit Marilyn Monroe’s waist would be between sizes 8 - 12 in 1958 but a size double zero today. It's widely assumed that diet and lifestyle – think supersize portions of energy rich foods, driving to work and sitting in front of a computer –  are at play, but what makes some individuals more susceptible than others remains an open queston.

The long run

The HUNT study followed BMIs in Norway over 5 decades. Using polygenic risk scores to measure genetic susceptibility to obesity, the authors found that BMI for the study's 70,000 participants increased in the 1980's to mirror known Norwegian obesity trends. The highest fifth of susceptible patients put on more weight in a manner that increased over time compared to the lowest fifth. In practical terms, that means a 35-year-old man of average height would be 7.1 kg heavier at baseline today compared to the 1960's, but would add an additional 6.8 kg because of high susceptibility genes. Those same genes would only prompt a 3.9 kg weight gain in the 60's.
BMJ

The takeaway

In today's 'obesogenic' environment, diet and lifestyle have outsized impact on the genetically predisposed. Many hope that a strong link to genes will help destigmatize obesity.

Say it on rounds

When nightfloat started every antibiotic

Maybe time to pull back. With a lack of robust evidence around when to start antibiotics in acute COPD exacerbation, PACE evaluated use of C-reactive protein (CRP) to guide decision making. An open-label RCT of 650 patients presenting with concern for COPD exacerbation in the UK found that point-of-care CRP testing together with guidance on how to interpret results reduced antibiotic usage (55% vs. 77%) at 4 weeks compared to usual care. Clinical outcomes were similar between groups. Fewer antibiotics could spare vulnerable patients from airway colonization with multi-drug resistant bacteria. 
NEJM

When Stranger Things has you reaching for your hairspray

With 80’s nostalgia everywhere this summer, researchers have turned back the clock on migraine. The ‘-gepant’ class of small molecule CGRP inhibitors was shelved for liver toxicity in 1988 but have seen a comeback thanks in part to the efficacy of anti-CGRP antibodies in migraine prophylaxis. A phase 3 study of orally disintegrating rimegepant, a safer gepant than predecessors, found that the med reduced pain symptoms in acute migraine in as fast as 1 hour without major adverse effects. Many are upset that the investigators used a placebo control instead of treatment options with proven efficacy.
Lancet

When you search for 'bleeding' on TMZ instead of UpToDate

Things get weird with the wrong guide. INR, PTT, and platelets are often abnormal even in well compensated cirrhotics. Thromboelastography (TEG) is a POC blood test that assesses the clotting potential of whole blood. A RCT of 96 patients with cirrhosis and nonvariceal upper GI bleeding found that a TEG-guided transfusion strategy safely reduced use of FFP, cryo, and platelets compared to standard of care (26% of TEG patients needed all 3 compared to 87% of controls). TEG patients had fewer ICU days and were less likely to develop severe transfusion reactions.
Hepatology

Brush up

Diabetes insipidus

Think of diabetes insipidus when patients complain of extreme thirst and buckets of clear urine. Central DI occurs when the brain fails to make enough vasopressin, while nephrogenic DI (less common) stems from vasopressin resistance. Concentrated plasma osmolality and dilute urine osmolality are hallmark lab findings. Primary polydipsia presents similarly, and the water deprivation test (WDT) has classically been used to differentiate between the 3 syndromes. Treat central DI with desmopressin. Nephrogenic DI often requires lifestyle modification and paradoxical diuretics.

What's the evidence

For shiny new DI testing? WDT is labor intensive and old school. A 2018 study of 150 patients with hypotonic polyuria found that measurement of the vasopressin precursor copeptin after hypertonic saline infusion identified the correct final diagnosis – central DI, nephrogenic DI, or primary polydipsia – in 96% of patients compared to 77% with indirect WDT.  The copeptin test requires close monitoring, which newer tests hope to avoid by excluding hypertonic saline infusion.

What your global health friends are talking about

After stopping short of the move on 3 separate occasions, the World Health Organization declared that the year-old Ebola epidemic in the Democratic Republic of Congo is a global health emergency. The virus has killed about 1,700 people in the past year.

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