Friday, January 13, 2012

Heart Failure, Informatics, and The Future

Studies like these are a window into the future of medicine - electronic health records beget clinician decision-support tools that allow highly complex risk-stratification tools to guide clinical practice.  Tools like NEXUS will wither on the vine as oversimplifications of complex clinical decisions - oversimplifications that were needed in a pre-EHR era where decision instruments needed to be memorized.

This study is a prospective observational validation of the "Acute Heart Failure Index" rule - derived in Pittsburgh, applied at Columbia.  The AHFI branch points for risk stratification are...best described below, in this extraordinarily complex flow diagram:


Essentially, the research assistants in the ED applied an electronic version of this tool to all patients given by the Emergency Physician a diagnosis of decompensated heart failure - and then followed them for the primary outcome(s) of death or readmission within 30 days.  In the end, in their small sample size, they find 10% of their low-risk population meets the combined endpoint, while 30.2% of their high-risk population meets their combined endpoint.  Neither group had a very high mortality - most of the difference between groups comes from re-admissions within 30 days.

So, what makes this study important isn't the AHFI, or that it is reasonable to suggest further research might validate this rule as an aid to clinical decision-making - it's the progression forwards of using CDS in EHR to synthesize complex medical data into potentially meaningful clinical guidance.

"Validating the acute heart failure index for patients presenting to the emergency department with decompensated heart failure"
http://www.ncbi.nlm.nih.gov/pubmed/22158534

Wednesday, January 11, 2012

Can We Stop Placing NG Tubes?

One of the worst-tolerated procedures in Emergency Medicine - placement of the NG tube.  Unfortunately, when I call my GI fellow on-call for any upper GI bleeding, the first question is invariably - what did the NG lavage show?

There is good evidence demonstrating that positive NG lavage tends to identify the presence of high-risk lesions found on subsequent endoscopy.  There is also evidence that endoscopic treatment of high-risk lesions decreases rebleeding and mortality.  So, if NG lavage identifies high-risk lesions, and endoscopic treatment of high-risk lesions decreases mortality, then patients who undergo NG lavage for their upper GI bleeds should have lower mortality, right?

This is a retrospective review of all the patients admitted to the West LA VA with a diagnosis of upper GI bleeding - a sample of 632 meeting inclusion criteria.  Of these, 255 did not undergo NGL and 378 did.  What's interesting in this article is that the authors attempted to statistically create two identical cohorts using propensity scoring.  They ended up with two nearly identically matched cohorts of 193 patients from the original 632 based on demographics, triage, lab values, physiologic characteristics, and medical interventions.

Between these two groups, they found no significant difference between mortality, hospital stay, emergency surgery, and blood transfusion requirements.  There was a statistically significant difference in the number of patients who underwent endoscopy - patients who didn't receive NGL had 60% endoscopy vs. 72.3% in the NGL group.  This is mildly interesting - considering that, in theory, the identification and endoscopic treatment of high-risk lesions is associated with increased survival - and if you're doing less endoscopy on an identical patient cohort, you should be missing the opportunity to treat those lesions.  Yet, there was no significant difference outcomes between cohorts.

So, yes, if you wanted to stop placing NG tubes because they're uncomfortable for patients and apparently don't change ultimate outcomes - certainly, that may be reasonable.  Some gastroenterology literature suggests patient-specific risk factors are more important in predicting the impact of endoscopic intervention on outcomes, rather than the limited information derived from the NG lavage.

However, this is just statistical calisthenics in an attempt to replicated a randomized-controlled trial and doesn't give us the prospective evidence needed to change practice.  Or argue over the phone with the GI fellow.

"Impact of nasogastric lavage on outcomes in acute GI bleeding"
http://www.ncbi.nlm.nih.gov/pubmed/21737077

Monday, January 9, 2012

So, NEXUS Is Invalid?

Another doom and gloom trauma article that wants to take one of our most cherished tools away from us regarding the evaluation of the blunt trauma patients.  Certainly, nothing is sacred, but these authors want to take NEXUS out to the woodshed and make sure every trauma patient gets a CT of the c-spine.

The premise of their argument is reasonable - NEXUS was derived in an era of plain films for radiographic clearance of the cervical spine, and now, many studies have observed that CT with 3D reconstruction picks up potentially significant injuries that could be missed by plain x-rays.  Therefore, the gold standard incorporating plain radiography for NEXUS renders it invalid due to missed injuries.

These authors performed a prospective evaluation of the NEXUS rules by applying them to 2,606 adult trauma patients, all of whom underwent 16 multidetector CT scanning with 2mm thick axial cuts.  They found 157 patients with a total of 258 fractures - and note that 26 patients had fractures identified despite meeting NEXUS criteria.  Of these 26, 16 were managed in a c-collar, 2 underwent operative stabilization, and 1 had a halo placed.  Therefore, they simply conclude that NEXUS is not externally valid to their trauma population and everyone should receive a CT of the c-spine based on mechanism.

Finding flaws with NEXUS - excellent, let's identify the subset at higher-risk so we can prevent missed injuries.  However, this article doesn't help us at all.  They don't do any sort of descriptive analysis of the NEXUS-negative patients who end up with significant injuries with which to educate our practice.  They simply conclude with the blanket statement that the dollar cost of performing all the CTs is less than the dollar cost of potential malpractice payouts.

In an era where we're trying to cut healthcare costs and reduce the practices of defensive medicine, this is precisely the sort of article that we don't need.  This is fantastic data presented in a non-constructive fashion that will likely, as the authors seem to intend, ensure the 97% of NEXUS-negative patients who had no injuries get their CT of the c-spine.

"National Emergency X-Radiography Utilization Study Criteria Is Inadequate to Rule Out Fracture After Significant Blunt Trauma Compared With Computed Tomography"
http://www.ncbi.nlm.nih.gov/pubmed/21610391