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New preprint *NOT PEER REVIEWED* from the @opensafely team which we would love comments on! 
We looked at whether inhaled corticosteroids (ICS), used in asthma and COPD, might influence outcomes in COVID-19 THREAD 1/n https://www.medrxiv.org/content/10.1101/2020.06.19.20135491v1
We looked at whether inhaled corticosteroids (ICS), used in asthma and COPD, might influence outcomes in COVID-19 THREAD 1/n https://www.medrxiv.org/content/10.1101/2020.06.19.20135491v1
Quick background: Eons ago, back in April, there was some speculation that ICS might protect against COVID, either infection or more severe disease. For a summary, see https://erj.ersjournals.com/content/early/2020/04/20/13993003.01009-2020 2/n
Using the OpenSAFELY platform (primary care + death data for ~17 million UK adults), we compared the risk of COVID-19 related death among people with COPD receiving ICS-based dual/triple therapy vs. LABA/LAMA, and among people with asthma receiving ICS vs. SABA only. 3/n
For more details on our study design - our protocol, all code and codelists are shared here: https://github.com/opensafely/ics-research Onto results... 4/n
After adjustment, people receiving ICS had a slightly increased risk of death compared to those receiving other therapies in both cohorts but IMPORTANTLY, we think this is because of differences in underlying disease severity among our comparator groups. 5/n
Specifically, we still observed an association between ICS use and non-COVID death, our negative control outcome, in the COPD population 6/n
(side note: although we did not see this in the asthma population, we realised non-COVID death might not be a good negative control for that population as severity of asthma might be less strongly associated with all-cause mortality. Still reported as pre-specified) 7/n
we also estimated that it would only take an unmeasured confounder of moderate strength to be able to explain these associations 8/n
So - although we observed a harmful association, we do not believe this is causal but a reflection of differences in underlying disease severity that we could not account for. People currently taking ICS should continue taking them as recommended by their clinicians. 9/n
What we think we CAN say, is that based on our study, there doesn’t seem to be convincing evidence of a major protective effect of regular ICS use against COVID-19 for people with COPD or asthma, as had previously been speculated might exist. 10/n
It's important to note though that even if we could account for all unmeasured confounding, this would not answer the question of whether using ICS to treat severe COVID-19 would be beneficial or not - there are ongoing trials for that. 11/n
Finally - this preprint has not been through peer-review yet. I would love suggestions for what we could do better or differently! 12/n
Actual final finally - this is a massive team effort. Huge thanks to @alexjohnwalker @dr_c_morton @brianmackenna @DarthCTR @Ladyroho Krishnan Bhaskaran @Roxytonin Jenni Quint Ian Douglas @LiamSmeeth1 @bengoldacre @drchrisbates @helencebm @HenryMDrysdale @sebbacon AND 13/n
@_EvansD @inglesp @jonnycockburn @drjohnparry Kevin Wing @StatsFizz @wjchulme @jessRmorley @SamPDHarper and others from @ehr_lshtm @EBMDataLab @TPP_SystmOne whose twitter handles I don't have! Authorlists are woefully inadequate... END
(I lie). For those new to OpenSAFELY - this is a new platform, built by us, for analysing electronic health records and you can find out more about it here: https://opensafely.org/ (/ACTUAL END)
