Outliers in Cardiac surgery
In recent times, clinical performance has almost become synonymous with outcome measurement(4). What makes outliers in heart surgery particularly intriguing is that the outcomes guiding quality metrics are categorical and infrequent: namely mortality and major adverse cardiovascular and cerebrovascular events (MACCE). Large registries, with particular mention of the STS National Database in the US, are developing which accumulate significant amounts of patient data and have an inevitable role in defining key performance indicators.
When the standards of care are within the middle 95% of the bell-curve, our culture briefly acknowledges the equilibrium and proceeds with a practice of “maintenance”. Afterall, the majority lie in this region. Yet, extreme performers at the lower end of the curve take a larger share of the public and governance limelight. The Bristol Enquiry in the UK is the most pertinent example from recent times where the outlier detection method resulted in sizeable and justifiable repercussions(5).
The side-effect of this is a shift of quality improvement resources towards poorly performing outliers which may lead to less efficient overall improvement in a network of healthcare providers as a whole (6). In fact, newer studies are suggesting that outlier detection using outcomes analysis and the subsequent knee-jerk reward-punishment strategies can be harmful, especially when involving blame(7).