As promised, the tip of 2022 noticed a trio of controversial COVID-19–associated publications.
First up is one thing that all the time causes a stir — a study on masks! Reviewing a examine on masks within the COVID-19 period is like poking a hornet’s nest with a stick, and this one is not any exception.
However let’s poke away! Except for receiving a whole lot of consideration when it first appeared on-line, it offers us an opportunity to overview some attention-grabbing scientific analysis ideas.
Right here’s the examine query — does utilizing a medical masks whereas caring for an individual with confirmed or suspected COVID-19 present healthcare staff “noninferior” safety to an N95 masks?
That “noninferior” time period is usually complicated, so finest to translate it into plain English, which is what Harvard biostatistician Michael Hughes kindly did for me a few years in the past. Noninferior merely means “not an excessive amount of worse than.” Noninferiority research are nice when the factor you’re testing has different benefits to the usual of care — it may be easier, or cheaper, or each. Because of this, a noninferiority design is kind of applicable for evaluating surgical masks (cheaper, simpler) to N95s.
Now one factor the statisticians ask us clinicians is to outline the noninferiority margin — in different phrases, if not-too-much-worse is a key determinant, how a lot worse would we tolerate? On this examine, if the higher certain of the 95% confidence interval of the hazard ratio of surgical to N95 masks was lower than 2, then they’d be declared noninferior.
That seems like quite a bit — would we actually tolerate one thing that provides us solely half the safety of an N95 masks? One factor to recollect about noninferiority margins is that the smaller the margin, the larger the required pattern dimension. I believe that something smaller would have made the examine impractically massive.
The examine was performed in 29 healthcare amenities in Canada, Israel, Pakistan, and Egypt from Might 2020 to March 2022, with 1009 members. It’s necessary to scrutinize the dates of all COVID-19 research as a result of the vaccines, prior COVID-19 (with residual immunity), and variants have tremendously modified the character of SARS-CoV-2’s transmissibility, severity, and our response to it. As I’ve noted previously, the post-Omicron period consists of vastly extra individuals who had COVID, and vastly extra individuals who stopped preventive measures whereas out and about in society.
So lastly, let’s get to the first outcomes. RT-PCR–confirmed COVID-19 occurred in 52 of 497 (10.46%) members within the medical masks group versus 47 of 507 (9.27%) within the N95 respirator group. You don’t should be a statistician to conclude that these numbers are fairly darn shut.
This yields a hazard ratio of 1.14, with a 95% confidence interval of 0.77 to 1.69. Meaning the surgical masks may very well be as a lot as 69% worse (however lower than twofold worse, the non-inferiority margin), and even 23% higher, at defending healthcare staff.
Briefly (drumroll), the technique of carrying surgical masks was noninferior to N95s amongst folks caring for folks with confirmed or suspected COVID-19.
Views on this examine:
The essential view: The examine was sloppy and, frankly, unethical. It’s already been confirmed in a number of fashions that filtration of respiratory viruses is more practical with a well-fitted N95 than common masks — and COVID-19 is clearly transmitted by an airborne respiratory virus.
A twofold noninferiority margin is approach too excessive. Even when they’re solely 69% worse, why ought to healthcare staff take the probability?
The examine didn’t even take a look at the efficacy of the masks, since undoubtedly lots of the members acquired COVID whereas not even caring for COVID-19 sufferers and never carrying the N95s — both elsewhere within the hospital or (much more probably) locally. That is very true in Egypt, which accounted for lots of the circumstances within the examine throughout the post-Omicron interval. How can we are saying the masks didn’t work when infections have been occurring exterior the affected person room?
Let’s take a look at one other nation, how about Canada? There, surgical masks have been greater than twofold worse than N95s. Shouldn’t that be our mannequin?
Lastly, the examine took a very long time to enroll and had a number of modifications earlier than completion. Doesn’t that alone make the outcomes unreliable?
The supportive view: This examine proves {that a} coverage of recommending uncomfortable, costly N95 over surgical masks is pointless. The very best type of proof — the randomized scientific trial — reveals they’re noninferior to low-cost surgical ones.
A lot of clinicians hate N95s. When the examine was first posted on-line, one of many smartest medical doctors I do know requested me flat out — “So can I lastly ditch these items? By the tip of the day, I really feel like my face has been in a vice.”
Sure, there are variations between international locations, however importantly this was a post-hoc evaluation. We must always ignore these analyses as a result of in the event you measure one thing steadily sufficient with smaller and smaller pattern sizes, you’re certain to seek out one thing that’s statistically vital that helps your speculation.
And in the event you’re going to deal with a rustic, isn’t the present panorama of COVID way more like Egypt (throughout Omicron and excessive group transmission) than Canada (early within the examine, very low occasion charges)?
As for these filtration research? Keep in mind, scientific trials enroll human beings — not mannequins or robots carrying masks.
My take: Each side have glorious factors. I discovered quite a bit from studying insightful commentaries taking each side of this debate — each praising the examine (here and here) and criticizing it. Plus, there’s an excellent accompanying editorial.
As for what I assume?
I consider that if the examine have been massive sufficient, if the N95 masks have been correctly worn and accurately match examined, if in-hospital COVID-19 transmission in break rooms throughout snacks and lunch may very well be excluded, and (a good larger process) if transmission at eating places and weddings and live shows and gymnasiums (that means locally) may very well be excluded, then this examine would have proven that surgical masks are not so good as N95 masks in defending healthcare staff.
In different phrases, they’d be an excessive amount of worse to make up for the decrease price and larger consolation. Greater than twofold worse, as outlined by the examine.
However that’s a whole lot of ifs, and isn’t the true world. The true world is messy, and such stipulations can be unattainable. In the true world, the surgical masks on this randomized scientific trial have been noninferior for the first endpoint of PCR-diagnosed COVID-19 within the healthcare staff.
Utilizing N95 masks within the post-Omicron period is like giving somebody a wonderful umbrella throughout a rainstorm, however solely throughout the temporary downpours when dashing from the automobile to the entrance door — the occasions of highest direct publicity. The remainder of the day, with regular and frequent rain, they use both a damaged umbrella or none in any respect. Loads of probabilities to get moist.
No marvel the examine confirmed surgical masks to be noninferior. COVID-19 is now in every single place, and patient-to-healthcare supplier transmission of the virus is a small fraction of the exposures occurring globally.
Do I nonetheless put on an N95 when caring for sufferers with confirmed or suspected COVID-19? Sure. In any case, I nonetheless use an umbrella when dashing from the automobile to the door throughout a downpour.
Do I additionally consider that getting COVID-19 is more likely at a restaurant or occasion or medical assembly than within the affected person’s room?
Additionally sure. That’s simply the world we dwell in now.
