What would you tell this patient who inquires about lab cancer #screening test to help him “live longer”?
What types of bias can occur in determining whether a cancer screening test reduces mortality?
2/ Take a look at the bolded arrows below that illustrate that early detection doesn’t always mean better outcomes!
Length-time bias applies to slow-growing disease in which patients have a long phase without symptoms.
3/ Lead time bias applies to situations where patients are screened earlier, so they are diagnosed earlier, so they appear to live longer solely by nature of knowing they have the disease for a longer period of time.
Therefore, survival time⬆️⬆️
4/ How would you explain these biases to our patient?
5/ So now what? How can studies mitigate length and lead time bias?
Check out our bullets below ⬇️ and let us know if you have additional ways you think about mitigating these biases in studies
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We wanted to use this opportunity to shed light on the discussion on post-menopausal hormone therapy (HT) via highlighting the important yet controversial WHI trial
2/ WHI followed the Nurses' Health Study, a prospective investigation that showed HT was associated with decreased cardiovascular disease (CVD) risk
3/ WHI, a randomized controlled trial (RCT), was believed to mitigate the effects of confounding factors better than cohort studies. WHI, in contrast to the Nurses’ Health Study, showed that HT was associated with a slightly increased risk for CVD among other conditions
Let’s jump in– can you decipher the EKG below to find out what’s wrong with this patient’s His-Purkinje system?
2/ If you thought left anterior fascicular block (LAFB), you were right!
What is the formal criteria for LAFB?!
✅Left axis deviation w/o LVH
✅qR pattern in lead aVL
✅R-peak time in lead aVL of 45 ms or more
✅QRS duration less than 120 ms
3/ Why do our patients get LAFB?!
Think fibrosis in the left anterior fascicle! This causes a slowed electrical conduction → EKG findings.