Pre-print of the #COVIDSTEROID2 RCT comparing dexamethasone 6mg vs 12mg in hospitalized patients on high flow O2 or MV:
- no difference in survival or days free of MV with higher dose dex but…
- interesting “trend towards benefit” w/ higher dose dex
📄medrxiv.org/content/10.110… 1/
🔑 Question: we know from #RECOVERY that steroids are beneficial in severe COVID, but what’s the ideal dose?
#COVIDSTEROID2 was a large DB multi center RCT to answer this. It randomized patients on high flow O2 or MV to either 6mg or 12mg of dexamethasone for up to 10 days. 2/
The 1° endpoint was days alive free of lifesupport (MV, ECMO, RRT). 2° endpoints included 28 day mortality.
Based on prior studies, they powered for a 15% relative mortality reduction (ARR ~4.5%) combined w/ a 10% reduction in life support duration.
This is pretty ambitious. 3/
They randomized 1000 people (outcomes were available for 971). The two groups had similar baseline characteristics:
-mostly older (median 65), mostly male (~70%)
-comorbidities were frequent (DM, CHF, CAD, CHF)
~1/2 were on High flow O2, 1/4 on MV, & 1/4 on CPAP at enrollment 4/
The results were interesting.
Compared to 6mg, 12mg of decadron was associated with:
-numerically lower mortality (27.1% vs 32.3%, ARR 5.2%)
-more days free of support (22 vs 20.5)
-lower rates of SAEs (11.3% vs 13.2%)
However NONE of these reached statistical significance 5/
Slicing the data different ways yields similar findings: the higher dose of dexamethasone is numerically slightly better but doesn’t (quite) achieve statistical significance.
What can we conclude?
It’s tempting to round “a trend towards benefit” up to “benefit” but this isn’t good science
If we round down a p=0.06 why not, for symmetry, dismiss a p=0.04 as “trending towards insignificant”?
Thresholds may be arbitrary but we shouldn’t just ignore
7/
Perhaps better to put this finding in context in two ways: 1) #RECOVERY demonstrated a huge mortality benefit by ICU standards (NNT 8); it’s hard to power a study to improve on this 2) prior studies (#DEXAARDS) had shown that a higher dose of dex (20mg/day) was safe/effective 8/
The differences b/w studies are germane: #RECOVERY enrolled all hospitalized people w/ COVID & found a lower dose of 6mg dex was beneficial (but only in people with hypoxemia) #COVIDSTEROID2 enrolled sicker people (all on O2) and found a “trend towards benefit” at 12 mg dex
9/
#DEXAARDS enrolled people who were even sicker, those on MV who already met criteria for ARDS
This study was pre-COVID but I think we have enough data to say, uncontroversially, that COVID ARDS is ARDS
Thus it’s reasonable to conclude that sicker pts “need” more steroids🤯
10/
Although #COVIDSTEROID2 doesn’t show a clear benefit for higher dose dex, it also demonstrates that 12mg isn’t worse than 6mg. In fact 12mg has numerically fewer serious side effects, including infxn
With diverging KM curves it’ll be interesting to see the 3 & 6 mo follow up 11/
Clinical 🥡:
- this is a *NEGATIVE* study…
- yet there *IS* reason to think that a slightly higher dose dexamethasone (12mg instead of 6mg) may be safe & beneficial in sicker COVID patients (such as those with ARDS on MV)
- looking forward to reading the peer reviewed 📄
12/12
Things NOT to do:
-go above #DEXAARDS dosing; older studies found HARM w/ higher steroid doses in ARDS
-continue for longer than 10 days; NO studies demonstrate benefit for this
-substitute another steroid (unless you need to); no mineralocorticoid effects w/ dex may help
13/12
• • •
Missing some Tweet in this thread? You can try to
force a refresh
Shortly before 3am on June 4, 1993, a mechanic at Miami airport looked in the wheel well of a DC-8 cargo jet from Bogotá. He saw the body of a teenager, curled in a ball, wearing only a t-shirt and shorts and frozen like an "ice cube."
The first paramedic pronounced him dead. The second found a weak pulse.
Somehow he had just survived 5 hours at 35,000 feet without heat or air pressure.
This should have killed him three different ways.
A🧵& blog post on how he survived.
1/
At 35,000 ft, there are three simultaneous killers:
🫁 Hypoxia: PO₂ is ~37 mmHg, well below the consciousness threshold of ~60 mmHg. Most peopple lose consciousness is 15-30 seconds. Even fully acclimatized Everest summiteers (at 29,000) survive only by driving PaCO₂ to ~8 mmHg through maximal hyperventilation.
🥶 Hypothermia: Ambient temp is –55°C. Accidental hypothermia causes fatal arrhythmia below ~28°C core temp. The coldest recorded accidental hypothermia survivor (13.7°C) lived only because of ECMO.
💥 DCS: Barometric pressure 179 mmHg (23% of sea level). The risk of decompression sickness and nitrogen gas embolism approaches 100% above 30,000 ft without a pressure suit.
No reasonable physiologist, handed these parameters, would predict survival. Yet somehow a 17 year old stow-away survived all three.
2/
The key is that hypothermia and hypoxia are mutually protective. The mechanism:
1️⃣ Hypoxia disables the thermostat
The preoptic anterior hypothalamus is exquisitely sensitive to hypoxia. As PaO₂ falls during ascent, it loses the ability to defend core temperature. The body becomes poikilothermic: temperature tracks the environment and the stow-away gets cold without shivering.
2️⃣ Hypothermia suppresses VO₂
The Q10 for brain CMRO₂ is 2.2. By the time core temp hits ~27°C (threshold for unconsciousness), brain O₂ consumption is ~45% of baseline. Demand meets the catastrophically low supply.
Cardiac surgeons exploit this in deep hypothermic circulatory arrest (DHCA), cooling the brain to 15-18°C to permit operating on a bloodless field.
The stowaway essentially did this to himself!
Lots of news articles reporting "Smartphone use on the toilet increases risk of hemorrhoids" citing a small single center study.
Great headlines but also a textbook example of *reverse causation* - a common methodological flaw in observational studies
A 🧵
Reverse causation occurs when we flip the arrow of cause→effect.
Protopathic bias is a subtype: An exposure (often a treatment/behavior) is started because early symptoms are already present, making it look like the exposure caused the outcome.
2/
A common example of reverse causation/protopathic bias is increased inhaler use --> increased risk of asthma hospitalization.
Did the inhaler use cause the hospitalization?
No! The person was developing symptoms which is why they were using the inhaler...
Well designed RCT shows patients randomized to an exercise program had substantially improved survival after adjuvant chemotherapy for colon cancer.
- 5 yr disease-free survival 80.3% vs
73.9% (HR 0.72)
- 8 yr overall survival 90.3% vs 83.2% (HR 0.63)
This is groundbreaking! 1/
Some deets on the CHALLENGE trial
A 55 center trial done over 15 years (2009-2024) that randomized n=889 people with resected colon cancer after adjuvant chemotherapy to either:
- participate in a structured exercise program
- or to receive health-education materials alone
2/
The intervention was pretty comprehensive:
Personal activity consultant (PACs) - essentially trainers - got to know the participant 1:1, introduced them to the gym and came up with personalized activity goals
Regular every 2 week sessions helped participants reach the goals
Tragic news today about former president Biden's prostate cancer diagnosis. I wish him well.
As someone who follows presidential health reporting, I noticed something odd: unlike his predecessors, Biden's physician's never reported PSA.
How to interpret this absence? A🧵 1/
There are two possibilities:
1️⃣ Biden’s PSA was never checked
2️⃣ Biden’s PSA was checked but it wasn't reported
Strictly speaking, not checking PSA could be a medically correct option. Whether or not to test PSA is a complex question and is not the topic of this thread.
2/
Like many VIPs, presidents tend to have excessive testing that is not always strictly evidence-based.
For example, Bush 43 had an exercise treadmill test and a TB test for no apparent reason.
In honor of #MayThe4thBeWithYou let's consider the most difficult airways in the Star Wars universe:
1. Darth Vader
Species: human
Vader presents several challenges: Vent dependent at baseline, airway burns from Mustafar, limited neck mobility.
Discuss GOC before saving him
2. Fodesinbeed Annodue
Species: Trog
All airways require teamwork, but intubating Fodesinbeed Annodue's two heads really will require two operators.
Consider double simultaneous awake fiberoptic intubation
Be sure to consent both heads.
You will never find a more wretched hive of scum & challenging airways than Mos Eisley (except maybe at Jabba's)
3.Greedo
Species: Rodian
Micrognathia, posterior airway, no nasal intubation, green skin so no pulse ox
Approach: VL + bronchoscope. Intubate quickly (shoot first)