Adverse events – when bad things happen to patients because of what we as medical professionals do – are a leading cause of suffering and death in the U.S. and globally. Indeed, as I have written before, patient safety is a major issue in American healthcare, and one that has gotten far too little attention. Tens of thousands of Americans die needlessly because of preventable infections, medication errors, surgical mishaps, and so forth. As I wrote previously, according to Office of Inspector General (OIG), when an older American walks into a hospital, he or she has about a 1 in 4 chance of suffering some sort of injury during their stay. Many of these are debilitating, life-threatening, or even fatal. Things are not much better for younger Americans.
Given the magnitude of the problem, many of us have decried the surprising lack of attention and focus on this issue from policymakers. Well, things are changing – and while some of that change is good, some of it worries me. Congress, as part of the Affordable Care Act, required Centers for Medicare and Medicaid Services (CMS) to penalize hospitals that had high rates of “HACs” – Hospital Acquired Conditions. CMS has done the best it can, putting together a combination of infections (as identified through clinical surveillance and reported to the CDC) and other complications (as identified through the Patient Safety Indicators, or PSIs). PSIs are useful – they use algorithms to identify complications coded in the billing data that hospitals send to CMS. However, there are three potential problems with PSIs: hospitals vary in how hard they look for complications, they vary in how diligently they code complications, and finally, although PSIs are risk-adjusted, their risk-adjustment is not very good — and sicker patients generally have more complications.
So, HACs are imperfect – but the bottom line is, every metric is imperfect. Are HACs particularly imperfect? Are the problems with HACs worse than with other measures? I think we have some reason to be concerned.








