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Dan Ly

@meddly.bsky.social
863 followers 306 following 83 posts

Physician and health economist. Assistant prof at UCLA GIM&HSR. Studying physician decision-making and health care disparities. sites.google.com/view/danply

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Dan Ly @meddly.bsky.social · 24/09/2026
Interesting paper by @claireboone.bsky.social in @jamainternalmed.com. When faced with incentive to "control" hypertension, docs more likely to recheck BP, choose the lower reading, document BP as controlled, and less likely to intensify BP meds. This results in ⬆️ hospitalizations for CV events!
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Dan Ly @meddly.bsky.social · 24/09/2026
After skimming the paper, I still can't quite tell, because there are multiple rounds of screening and no reported p-values. But here's an example where, because the p-value was 0.07 with a CI that just crossed 1, the authors had to declare no difference. www.nejm.org/doi/full/10....
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Dan Ly @meddly.bsky.social · 24/09/2026
Having no access to the article from home, my guess from the abstract is that it was 0.999, as they note a “between group difference in stage IV cancer” in the abstract conclusion, and nejm usually doesn’t allow the usage of “difference” without reaching conventional statistical significance.
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Reposted by Dan Ly
NIHCM @nihcm.bsky.social · 16/09/2026
NIHCM’s September Newsletter is out 🗞️ This month, we're exploring GLP-1s, prescription drug affordability, postpartum mental health, vaccines, and more. We also have an exclusive Q&A on diabetes preventive therapies with @meddly.bsky.social Read it here: bit.ly/NIHCMSept26n... #NIHCMnewsletter
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Dan Ly @meddly.bsky.social · 20/07/2026
Thank you to my coauthors @lauraburke20.bsky.social and @coussens.bsky.social. Paper link below. jamanetwork.com/journals/jam...
jamanetwork.com
Practice Pattern and Outcome Differences in the ED by Physician Sex
This cross-sectional study evaluates differences in test ordering and hospital admission rates between female and male physicians working in the Veterans Affairs system’s emergency departments.
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Dan Ly @meddly.bsky.social · 20/07/2026
Results suggest that while female docs order more tests and admit more patients, this additional care may be clinically appropriate. These diffs may arise from diffs in risk aversion or, as Sarsons has found, diffs in peer judgment after bad outcomes. 6/ drive.google.com/file/d/1YQFZ...
drive.google.com
signals.pdf
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Dan Ly @meddly.bsky.social · 20/07/2026
Further, we then drilled down on specific lab tests and looked at diffs in test positivity (one group having much lower rates of tests that were positive than the other would suggest diffs in testing appropriateness). We find no diffs by physician sex in test positivity. 5/
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Dan Ly @meddly.bsky.social · 20/07/2026
We find this additional care does not translate to 👇 mortality. But we used stays lasting <24 hours as a marker of low-clinical need, and we find that short stays do not differ between female and male docs, suggesting the additional patients hospitalized had inpatient needs. 4/
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Dan Ly @meddly.bsky.social · 20/07/2026
With this quasi-randomization foundation, we then compare practice patterns. We find modest but real differences: female docs order more radiology tests and lab tests and admit more patients, on the order of 3-5% more. 3/
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Dan Ly @meddly.bsky.social · 20/07/2026
As research has found diffs in outcomes by physician sex, we wondered if these diffs were mediated by differences in testing. To study this, we first established quasi-randomization, finding, within the same ED, patient characteristics do not differ b/t female and male docs. 2/
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Dan Ly @meddly.bsky.social · 20/07/2026
🚨New paper!🚨Who orders more testing: male physicians or female physicians? And what are the implications on patient outcomes? We examine these questions in the emergency department (ED) in @jamainternalmed.com .🧵1/
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Dan Ly @meddly.bsky.social · 19/07/2026
As the kids say, looks like this movie slaps
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Dan Ly @meddly.bsky.social · 10/07/2026
Thank you for your support @nihcm.bsky.social!
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Dan Ly @meddly.bsky.social · 25/06/2026
Congrats!!
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Ari B Friedman @abfriedman.com · 07/06/2026
Excited for our #ASHEcon panel TUESDAY 10:15am on natural experiments in acute care. Papers on decisionmaking in surgeon-anesthesiologist dyads, emergency attending peer dyads, and clustering of patient acuities. ashecon.confex.com/ashecon/2026...
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Dan Ly @meddly.bsky.social · 07/06/2026
Reminder, if you’re going to @ashecon.bsky.social 2026, come to our Wednesday session of creative uses of recession discontinuity with some of the best in the business, including @aschwartz.bsky.social, @vinisingh.bsky.social, @dzeltzer.bsky.social, and @mlbarnett.bsky.social!
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Dan Ly @meddly.bsky.social · 05/06/2026
Anticipated FOMO: Evidence from choosing among concurrent sessions during @ashecon.bsky.social 2026
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Dan Ly @meddly.bsky.social · 28/05/2026
The small diffs by race and ethnicity are swamped by the overall low rates of use of these therapies and high rates of diabetes development. Thank you to VA HSR and @nihcm.bsky.social for funding this work! link.springer.com/article/10.1...
link.springer.com
Use of Evidence-Based Type 2 Diabetes Preventive Therapies and Rates of Progression to Diabetes Among Veterans with Prediabetes by Race and Ethnicity, 2010–2019 - Journal of General Internal Medicine
Journal of General Internal Medicine -
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Dan Ly @meddly.bsky.social · 28/05/2026
Another clinically-oriented research letter from one of my grants, published in JGIM. In it, we find that low usage of diabetes preventive therapies (meds and weight management programs) among Vets with evidence of prediabetes. And 1/4 of our cohort develop diabetes! 1/2
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Dan Ly @meddly.bsky.social · 28/05/2026
I have a setting where I have to directly approve all new additions to my profile
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Dan Ly @meddly.bsky.social · 29/04/2026
Another striking study: RCT showing that a subsidy for produce did not improve outcomes such as HbA1c or ED visits (or BP or BMI). There may be other benefits, but if trying to improve these outcomes, providing such a subsidy isn't where you want to put your money in.
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Dan Ly @meddly.bsky.social · 29/04/2026
An important paper showing that, for Veterans visiting an ED with a mental health condition, having delayed follow up causes decreased engagement with mental health care and increases mortality.
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Dan Ly @meddly.bsky.social · 28/04/2026
These meds are sticky: 67% of patients with dementia starting an antipsychotic are on them a year later. Interventions to reduce prescribing should target scripts from these settings. jamanetwork.com/journals/jam...
jamanetwork.com
Initiation Setting and Persistence of Medications Affecting Older Adult Cognition
This cross-sectional study examines the clinical setting in which medications that affect cognition in older adults are initiated and the persistence of taking such medications in the same class 1 yea...
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Dan Ly @meddly.bsky.social · 28/04/2026
These side effect-laden meds are disproportionately prescribed from acute or post-acute settings. For example, for patients w/ dementia started on antipsychotics, 22% of their visits are to acute or post-acute settings, but 43% of antipsychotics are started in such settings. 2/3
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Dan Ly @meddly.bsky.social · 28/04/2026
New letter in @jamanetworkopen.com! A clinically-oriented one examining the setting where meds affecting cognition (e.g., antipsychotics) are prescribed from. We find they are disproportionately prescribed from acute or post-acute settings (i.e., emergency room, hospital, SNF). 1/3
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Dan Ly @meddly.bsky.social · 20/04/2026
“Style”
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Dan Ly @meddly.bsky.social · 02/03/2026
If you're buying plane tickets to ASHEcon '26, make sure you stay for our session (last of the conference) of 3 RDs studying heuristics, stigma, & guidelines. With @aschwartz.bsky.social, @vinisingh.bsky.social, @dzeltzer.bsky.social, and @mlbarnett.bsky.social! ashecon.confex.com/ashecon/2026...
ashecon.confex.com
Discontinuities In Clinical Practice: RD Evidence on Heuristics, Stigma, and Guideline Thresholds
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Reposted by Dan Ly
Aaron Schwartz @aschwartz.bsky.social · 27/02/2026
Looks like the ASHEcon 2026 conference agenda has dropped. Warning: Don't take an early departure flight the last day, or you'll miss a session I'm really excited about. Not 1, not 2, but 3 (!) papers using RDs to understand physician decision-making. ashecon.confex.com/ashecon/2026...
ashecon.confex.com
Discontinuities In Clinical Practice: RD Evidence on Heuristics, Stigma, and Guideline Thresholds
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Dan Ly @meddly.bsky.social · 11/01/2026
When the podcast described “three-cueing,” I got angry at its ridiculousness, and I never get angry
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Dan Ly @meddly.bsky.social · 11/01/2026
The podcast is how I found out about it.
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Dan Ly @meddly.bsky.social · 18/11/2025
You see it often because it’s a standard error
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Reposted by Dan Ly
Paul Goldsmith-Pinkham @paulgp.com · 06/11/2025
Excited to post a new working paper with @instrumenthull.bsky.social and Michal Kolesár: arxiv.org/abs/2511.03572 Will post a thread on it soon, but if you're interested in judge/examiner designs, I think you'll find this guide very helpful!
arxiv.org
Leniency Designs: An Operator's Manual
We develop a step-by-step guide to leniency (a.k.a. judge or examiner instrument) designs, drawing on recent econometric literatures. The unbiased jackknife instrumental variables estimator (UJIVE) is...
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Dan Ly @meddly.bsky.social · 02/11/2025
Kid a few years from now: “Daddy, why is my name Yoshinobu?”
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Dan Ly @meddly.bsky.social · 29/10/2025
Someone on a listserv I was on asked how to install SPSS on a server. I scoffed before realizing one day soon I'll be asking how to install Stata on a server and someone else will be rolling their eyes...
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Dan Ly @meddly.bsky.social · 20/10/2025
Congrats!!!
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Dan Ly @meddly.bsky.social · 17/09/2025
A great listen!!!
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Reposted by Dan Ly
Michael L. Barnett @mlbarnett.bsky.social · 08/09/2025
New paper w/ Brian McGarry, Ashvin Gandhi, and Drew Wilcock in @jamainternalmed.com! Hospitals are complaining across the US that patients are "stuck" waiting for rehab beds at nursing homes when they are medically stable and ready for discharge. What is going on?? jamanetwork.com/journals/jam...
Question Has hospital length of stay increased more for Medicare
Advantage beneficiaries than for traditional Medicare beneficiaries
since the COVID-19 pandemic?Findings In this cohort study involving more than 89 million
hospitalizations from 2017 to the third quarter of 2023, Medicare
Advantage beneficiaries experienced disproportionately greater
increases in extended hospital stays, especially among those
discharged to skilled nursing facilities.Meaning These findings suggest that the Medicare Advantage
plan design and practices may contribute to hospital discharge
delays, with implications for patient outcomes and hospital
capacity as enrollment continues to rise.
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Dan Ly @meddly.bsky.social · 20/04/2025
Woo Laura!!!
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Dan Ly @meddly.bsky.social · 12/04/2025
Will the panel include fixed effects?
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Dan Ly @meddly.bsky.social · 25/12/2024
So sorry! It’s so much work! Best of luck with whichever direction you take!
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Dan Ly @meddly.bsky.social · 24/12/2024
To be clear, we use the ED because it’s a clean sample largely free of prior influences from prior docs. This phenomenon of variation across docs in same facility can likely be found in length of stay for hospitalists, pneumonia read rates for radiologists, etc.
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Dan Ly @meddly.bsky.social · 24/12/2024
We agree that SDoH are important. This is why we take care to make comparisons within ED while also controlling for such things as time of arrival, ESI, and location within ED. We suspect there aren’t large differences in SDoH across docs in same ED after controlling for time, location, ESI, etc.
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Dan Ly @meddly.bsky.social · 24/12/2024
We use mortality because it’s an important measure and it’s largely non-contestable how to measure it. How would one measure an indicated vs not indicated admission? We also find that admitted patients of higher admitting docs more likely to be discharged before 24 hrs.
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Dan Ly @meddly.bsky.social · 24/12/2024
Thanks. Having more docs not trained in EM at the VA is something we acknowledge in the limitations of our paper, as is our inability to include doc characteristics such as training. But other lit using Medicare data show similar level of admit variation. www.healthaffairs.org/doi/pdf/10.1...
healthaffairs.org
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Dan Ly @meddly.bsky.social · 23/12/2024
We didn’t get that granular but that’s a great question to explore.
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Dan Ly @meddly.bsky.social · 23/12/2024
Whoops, tagging Stephen’s bluesky account, not his Twitter account. @coussens.bsky.social
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Dan Ly @meddly.bsky.social · 23/12/2024
But higher admission rates do NOT ⬇️ important adverse outcomes like mortality. Given high costs of admission ($, provider & facility capacity, pt well-being), better understanding how such variation arises could be fruitful for pts, docs, and healthcare system. 8/ jamanetwork.com/journals/jam...
jamanetwork.com
Variation in Emergency Department Physician Admitting Practices and Subsequent Mortality
This cross-sectional study using Veterans Affairs data from more than 2 million patient emergency department visits over 8 years examines the variation in physicians’ admission propensities and how th...
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Dan Ly @meddly.bsky.social · 23/12/2024
In sum, there is much variation in admit practices, likely due to diffs in skill & risk aversion. This mirrors variation in other doc specialties, who also greatly differ in their decisions. Of note, results do NOT argue for high-admit docs to indiscriminately ⬇️ admit rates. 7/
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Dan Ly @meddly.bsky.social · 23/12/2024
But seeing a higher-admitting doc does NOT reduce your likelihood of dying (either within 30 days [shown here], 7 days, 14 days, 90 days, or a year). 6/
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Dan Ly @meddly.bsky.social · 23/12/2024
Higher-admitting docs also order more radiology and laboratory tests in the ED. This suggests that admission rates may also be reflective of practice pattern intensity more generally. 5/
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