What are the odds? Understanding Risk and Uncertainty - a podcast by BMJ Group

What are the odds? Understanding Risk and Uncertainty.

Today we welcome Dr. Rod Whiteley for the first time ever to the BJSM podcast. Rod has done a bunch of work in shoulder injuries (measuring load and strength long before it got sexy). And the rumour is he’s still got a pretty good curve ball. A clinician for well over 20 years, He is the current assistant director of the Rehab department here at Aspetar Orthopaedic and Sports Medicine Hospital, and he has also contributed heavily in the area of hamstring rehabilitation and groin injuries. Look out for him on twitter @RodWhiteley, where’s he’s happy to be unpopular to point out the obvious.Rod is a clinical researcher, interested in how practitioners can understand statistics better, and integrate that in their daily practice. In this podcast, Rod and I talk about how we understand risk, in particular percentages and odds. And no, they’re not the same thing.

2:45 The difference between odds, ratios, and percentages.3:20 An example: ACL and hamstring injuries as an example, looking at the base rate for how often these injuries happen (ACL infrequently, and hamstrings quite frequent), and then adding a likelihood ratio and how does that change the odds.

5:20 Chad Cook and Erik Hegedus really turned our ideas around interpreting risk around. Clinicians need to understand pre- and post-test odds. Find the related articles here (http://bmj.co/2m65v43) and in the links below.6:30 Mladen Jovanovic (@Physical_Prep) - heuristics and uncertainty, published recently here (http://bmj.co/2nrRUUX) in the Aspetar journal. We have to get more comfortable with the uncertainty of these tests.

7:46 Understand base rates, and using tests that have large likelihood ratios in our clinical assessment. Pre-test odds will influence how you interpret your clinical test, which then changes your post-test odds.10:14 Can we do the same for prevention, and identifying risk? IOC world conference prevention of injury and illness in sport (http://bmj.co/2m64AR8) in Monaco will focus this year on the value of screening. Screening allows us to identify modifiers and change potential interventions at a group level.

10:31 The importance of population level studies, looking for associations with subsequent injury. Screening is useful for injury prevention. “But if you’re doing a test to tell someone they are or aren’t gonna get injuried, you’re gonna make a monkey of yourself in open court pretty quickly.”12:27 WHO report on risk of cancer risk associated with eating bacon/processed meat. If we ignore the base rate, we might be fooled by the actual change in risk. And then you still need to interpret that for the individual.

14:00 Absolute vs Relative risk, and what is the actual event happening. We don’t think of delayed onset of muscle soreness (DOMS) and sudden cardiac death the same.14:15 Two players with the same risk of injury, but totally different interpretation of their result.

15:12 Predicting vs Forecasting - “An experiment that only happens once.” You only get one season and and you either get an injury or you don’t. We have to be more comfortable with that kind of uncertainty.16:35 Predicting return to play with clinical outcome measures.

18:30 How do we interpret and incorporate percentages and odds into our clinical setting.Links:

IOC world conference prevention injury and illness in sport (http://bmj.co/2m64AR8)Available for FREE from BJSM (http://bjsm.bmj.com/)

Which physical examination tests provide clinicians with the most value when examining the shoulder? Update of a systematic review with meta-analysis of individual tests (http://bmj.co/2mwMP90)

A combination of initial and follow-up physiotherapist examination predicts physician-determined time to return to play after hamstring injury, with no added value of MRI (http://bmj.co/2mx0r3Z)

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