Month: September 2015

A Very Odd Look at CT In the ED

Why do we perform CTs in the Emergency Department?  It’s fair to say the primary indication is diagnostic certainty: the ruling-in or ruling-out of a disease process of substantial clinical relevance.  However, this study begs the question: have we lost touch with this concept of “substantial clinical relevance”?

This is a qualitative study evaluating physician decision-making in the context of CT ordering.  These authors provided physicians, approximately 2/3rds attending physicians, a questionnaire pre- and post-CT for 1,280 patients in the Emergency Department.  The main gist: what are you worried about?  How confident are you in the diagnosis?  And, then, after CT, how about now?

The bullet-point summary:

  • Physician confidence in their diagnosis grew after CT.  Splendid.
  • CT excluded or confirmed alternative diagnoses in 95+% of cases.  Excellent.
  • Increasing pre-CT confidence in a leading diagnosis was associated with lesser changes in leading diagnosis post-CT.  OK.
  • Many pre-CT leading diagnoses were benign, but with low physician confidence.  Except for CT head.
  • Nearly 3/4ths of CT scans performed of the head had a leading diagnosis of “Benign headache” or other, had no change in diagnosis following CT, and confidence was generally pretty high.  This is awful.
  • Finally, if you were hoping a CT would prevent bouncebacks: no.  15% of abdominal pain returned within a month for related reasons, as well as 14% of chest pain/dyspnea, and 11% of headache.

CT is an important tool.  It certainly makes the life of the risk-averse physician much, much easier.  However, the instances in which CT identified an important diagnosis in this study are certainly in the minority – most final diagnoses were either benign or could have been achieved through other means.  Unfortunately, very few specific actionable items can be taken away from this study – excepting CT for headache (ugh) – but it certainly shows there is fertile ground for a culture change to take root and decrease low-yield CT utilization.

“CT in the emergency Department: A Real-Time Study of Changes in Physician Decision Making”
http://www.ncbi.nlm.nih.gov/pubmed/26402399

The “Routine” Chest X-Ray

Many presenting complaints in the Emergency Department call for cardiothoracic imaging.  Some can be assessed by point-of-care ultrasound, but, for the most part, plain radiography is the established routine.  Whether the pretest probability of disease warrants such widespread use is one matter.  This article documents yet another – duplication of imaging.

These authors review four years of radiology from their institution and document 3,627 patients for whom both CXR and chest CT were ordered.  Their main analysis breaks down the use of radiology mostly looking at the order of which these studies were requested, and whether results from one were available prior to the completion of the other.

For the most part, the CXR was ordered first, and the images were available for review before the subsequent CT chest.  However, in 354 (9.8%) cases, the CXR images hadn’t even yet been acquired when the CT chest was ordered.  This probably generally overlaps the 134 (3.7%) cases where the CT chest was ordered simultaneously or prior to the CXR.  Regardless – if the results were clinically irrelevant, why order the test?

I think it’s fair to say many of the CXRs included in this study were pointlessly redundant – especially when the decision for CT was obviously made prior to their acquisition.  No doubt the CXR is included in most ED protocols for certain chief complaints, and is ordered reflexively without thought.

Looking for waste to target in the system?  Here you go.

“Inefficient Resource Use for Patients Who Receive Both a Chest Radiograph and Chest CT in a Single Emergency Department Visit”
http://www.ncbi.nlm.nih.gov/pubmed/26387774

Central Line Showdown

Major complications related to insertion of central line catheters remain: infection, thrombosis, and “mechanical complications”(read: pneumothorax, arterial puncture).  And, central lines have three typical locations:  subclavian, jugular, and femoral.

Wouldn’t it be cute if each of these catheter insertion sites each had their own specific realm of superiority?

And, based on this randomized trial of 3,471 catheter insertion events, they just about do:

  • The femoral site has the fewest mechanical complications, but the most thrombosis (1.4%).
  • The subclavian site had the fewest infections (0.5%) and thrombotic events (0.5%), but the most mechanical complications (2.1%).
  • And the jugular site was essentially a middle ground between the two, although, had the greatest infection rate (1.4%).

However, many of these differences need be taken with a grain of salt.  Ultrasound was not mandated, which probably led to the unusual incidence of mechanical complications for the jugular approach.  Specific antimicrobial dressings were not used regularly.  There was a high rate of failure and crossover in the subclavian arm (14.7%).  Then, the number of complications for each were measured typically in the near-single digits, while 469 patients died before catheter removal – a large enough number of potentially unmeasured events to significantly affect the primary outcome.  Only symptomatic patients were screened for thrombosis – again, leaving many patients with potentially missed outcomes.

So, in the end, what’s likely best?  A skilled subclavian – or one guided by an ultrasound approach – is probably ideal, but should be avoided if clinician comfort is low.  Following that, an ultrasound-guided jugular approach is likely best.  It is not reasonable to suggest the femoral site would routinely be superior to either approach, but these very low rates of complications indicate it need not be shunned when clinically appropriate.

“Intravascular Complications of Central Venous Catheterization by Insertion Site”
http://www.nejm.org/doi/full/10.1056/NEJMoa1500964

The “No Objective Testing” Rule for Chest Pain

As “zero-miss” philosophies for chest pain proliferated, so did the “early objective testing” phenomenon.  Chest pain presentations of all colors and ages, following an initial evaluation in the Emergency Department, have been invariably referred for inpatient observation and stress testing.  The problem?  Most of these tests are performed in patients for whom the pretest likelihood of coronary artery disease is low, and the incidence of false-positives outweighs that of true-positives.

This rehash of prior observational data aims to address this issues – specifically deriving a prediction rule for those who are so low risk any follow-up testing ought be obviated.  Based on cohorts enrolled for two previous studies of potential acute coronary syndrome presentations in New Zealand and Australia, these authors track 2,396 patients for 30 days.  Following an initial negative ED evaluation, 5.6% were diagnosed with acute coronary syndrome within 30 days – mostly “unstable angina”, and mostly based on follow-up objective testing.  Using standard statistical bootstrapping techniques, the authors partition out 31.1% of this cohort as having a <1% risk of ACS within 30-days: age <50, <3 risk factors, and no prior CAD or MI.  The authors suggest patients meeting these criteria, following a negative ED evaluation, need not be referred for any objective testing.

The puzzle here is in the outcomes measured: 30-day AMI, cardiovascular death, unstable angina, or revascularization.  The leap, then, involves associating a lack of these outcomes with the disutility of provocative or anatomic testing.  It is probably true there is colinearity between clinically important coronary artery disease and incidence of major adverse cardiac outcomes, but this is a bit tenuous of a foundation for their conclusions.  A lack of 30-day adverse event does not exclude benefit from cardiac imaging, and, vice versa, the presence of a 30-day adverse event does not imply a benefit from cardiac imaging.  However, given the lack of other useful evidence, this is as valid a proxy as we have to inform practice.

Finally, what tends to disappoint me most in these sorts of articles is something of a disconnect between the study design and the clinical questions relevant in practice.  Chest pain presentations lay somewhere on a bell curve.  At the low end, a subset of young and healthy folks are mostly harmed by overdiagnosis and additional resource utilization.  Then, at the high end, patients with multiple risk factors and known disease can no longer be substantially helped by additional invasive interventions.  Each of these cohorts is appropriate for early discharge from the Emergency Department without additional cardiac imaging, yet the focus is persistently on only the very low-risk end of the spectrum.  I hope future study is able to provide a more sophisticated analysis of the features of moderate- and high-risk patients to identify the individuals within these cohorts who do benefit from cardiac imaging, and which specific testing best informs downstream care.

“A Clinical Decision Rule to Identify Emergency Department Patients at Low Risk for Acute Coronary Syndrome Who Do Not Need Objective Coronary Artery Disease Testing: The No Objective Testing Rule”
http://www.ncbi.nlm.nih.gov/pubmed/26363570

The Internet Knows If You’ll Be Dead

As another Clinical Informatics “window into the future” – a window into the future.

These authors used three years of electronic health record data to derive a predictive Bayesian network for patient status.  Its scope: home, hospitalized, or dead.  There are many simple models for predicting such things, but this one is interesting because it attempts to utilize multiple patient features, vital signs, and laboratory results in a continuously updating algorithm.  Ultimately, their model was capable of predicting outcomes up through one week from the initial hospitalization event.

Some fun tidbits:

  • What mattered most on Day 1?  Neutrophils, Hct, and Lactate.
  • As time goes by, the network thinks knowing whether you’re on the Ward at Day 3 is prognostic.
  • By Day 5, variables like a simple count of the total number of tests received, the presence of cancer, and albumin levels start to gain importance.

Their Bayesian prediction network was best at predicting death, with an average accuracy of 93% and an AUROC of 0.84.  Similarly, the prediction engine was most accurate on Day 1, with an average accuracy for each outcome of 86% and an AUROC of 0.83.  Overall, for the entire week and all three outcomes, the AUROC was 0.82.

What was also quite interesting was the model, while also predicting outcomes during the index hospitalization, also detected readmission events within the time period scope.  The authors provide a few validation examples as demonstrations, and include a patient whose probability of hospitalization was trending upwards at the time of discharge – and subsequently was readmitted.

Minority Report, medicine style.

“Real-time prediction of mortality, readmission, and length of stay using electronic health record data”
http://www.ncbi.nlm.nih.gov/pubmed/26374704

Tissue, Not Time, for Stroke

The new AHA guidelines for the use of endovascular therapy in acute ischemic stroke broadly include any patient within six hours of symptom onset.  These criteria are based, mostly, on MR-CLEAN – in spite of the follow-up EXTEND-IA, ESCAPE, and SWIFT-PRIME showing the highest yield patients are clearly those with salvageable tissue.  Treatment beyond six hours, however, is still considered reasonable – and this cohort from DEFUSE-2 seems to indicate as such.

Based on 78 patients with target mismatch volume on MRI prior to endovascular therapy, they found: time doesn’t matter, only reperfusion.  The reperfusion outcomes for intervention under six hours are, grossly, no different than the outcomes for those greater than six hours.  And, this makes sense – salvageable tissue is salvageable:

Frankly, this is probably the paradigm for which we should ultimately be moving for all stroke treatment.  Time should not be a limiting factor – and, vice versa, should not be the sole indicating factor.  Dead brain simply can’t benefit from revascularization – no matter how quickly it is provided, regardless of time window.  The traditional “non-contrast head CT” is no longer adequate to provide optimal stroke care – CT angiography with perfusion calculations, or a rapid MRI protocol, should probably form the basis of modern stroke care moving forward.

“Response to endovascular reperfusion is not time-dependent in patients with salvageable tissue”
http://www.ncbi.nlm.nih.gov/pubmed/26224727

Not So Fast on Race-Related Oligoanalgesia

This recent study regarding pain control received a lot of press, covered by both Reuters and NBC News.  The general gist of the breathless coverage seems to indict physicians for latent biases against treating African American children with opiates.

I’m not so certain.

This is a retrospective evaluation of a national Emergency Department database of seven years of ED visits for appendicitis, looking at pain control disparity between white children and minorities.  Pain management was documented in only 57% of children, 41% of which was opiates.  Children of African American descent received opiate medication only 12% of the time, leading to the authors’ observations of an apparent reluctance to treat this population with opiates.

But, I think the foundation of their analysis may be misleading.  The authors state: “The following covariates were included in our analyses to adjust for potential confounding: ethnicity, age, sex, insurance status, triage acuity level, pain score, geographic region, ED type, and survey year.”  However, I think these data need to be addressed at a within-hospital level, not as a pooled cohort.  African Americans have been previously shown to be over-represented at low-quality, safety-net hospitals – the sort of hospitals almost assuredly do a poor job of addressing and managing pain across all their patients.  Indeed, when other researchers have looked at racial disparities in care for acute myocardial infarction, performing within-hospital analyses dramatically altered their findings, with individual hospital inadequacies accounting for a greater effect than ethnicity.

The foundational issues in race-related difference in care may yet be present, but I do not believe to the magnitude these data reflect.  Rather than suggesting “there may be a higher threshold of pain score for administering analgesia to black patients with appendicitis,” these data probably reflect the underlying under-resourced care available to this population.  A tremendous and embarrassing problem, to be sure, but with a different approach needed for a solution.

“Racial Disparities in Pain Management of Children With Appendicitis in Emergency Departments”
http://archpedi.jamanetwork.com/article.aspx?articleid=2441797

It’s Time to Fix NIHSS

The purpose of the National Institute of Health Stroke Scale is to describe stroke severity.  Every point represents a deficit on exam, so, higher is worse – except it’s not that simple.

Every point on the scale is, unfortunately, clearly unequal.  Partial paralysis of the face is 2 points.  Profound hemi-inattention is also 2 points.  One of those patients – unless they’re Derek Zoolander – is not disabled.

This is a study, along with others in a similar vein, that translates that common sense directly into an indictment of the NIHSS as currently used.  These authors retrospectively evaluate six “profiles” of patients with discrete clinical manifestations of stroke, by basing their analysis on specific NIHSS item.  They use the NIHSS data from 6,843 patients in the SITS-MOST data, and, essentially, they find very different survival curves for patients with similar NIHSS when specifically categorized by clinical syndromes.

This leads to two main points:

  • We shouldn’t be using the NIHSS the way we’re used to using it.
  • The clinical variability of patients with similar NIHSS can vastly affect stroke trials with low sample sizes.

Time to fix the NIHSS!

“National Institutes of Health Stroke Scale Item Profiles as Predictor of Patient Outcome”

Social Media & Medicine: It’s Great! No, it’s Worthless! Wait, What?

In the pattern of the old “Choose Your Own Adventure” novels, you can be for, or against, the Iran deal – or for, or against, the utility of social media in dissemination of medical knowledge and clinical practice.

In the far corner, the defending champion, the curmudgeons of the old guard, for whom the journals and textbooks hold primacy.  The American Academy of Neurology attempted to determine whether a “social media strategy” for dissemination of new clinical practice guidelines had any effect on patient or physician awareness.  They published new guidelines regarding alternative medicine therapies and multiple sclerosis through their traditional member e-mails and literature.  Then, they posted a podcast; a YouTube video; added Facebook, LinkedIn, and YouTube advertisting; and hosted a Twitter chat with Time magazine and others.  Based on survey responses, they were not able to measure any increased awareness of the guidelines resulting from their social media interventions.

Then, the challenger: Radiopedia.org.  This second study evaluates the online views of three articles concerning incidental thyroid nodules on CT and MRI.  Two of the articles were in the American Journal of Neuroradiology and the American Journal of Roentgenology, and the third was hosted on Radiopedia.org.  The Radiopedia blog – with some cross-polination and promotion by traditional means – received 32,675 page views, compared with 2,421 and 3,064 for the online journal publications, respectively.  This matches the anecdotal experience of many blogging physicians, that their online content exposure far exceeds that of their traditional publications.

What’s my takeaway?  Audience matters, content matters, and execution matters just as much as the medium.  When engaging an audience like those attending or presenting at, say, a conference entitled “Social Media and Critical Care”, digital scholarship may easily exceed the value of traditional vehicles.  Alternatively, for a topic as rockin’ as esoteric neurology guidelines, there might simply be a maximal ceiling of interested parties.

“The Impact of Social Media on Dissemination and Implementation of Clinical Practice Guidelines: A Longitudinal Observational Study.”
http://www.ncbi.nlm.nih.gov/pubmed/26272267

“Using Social Media to Share Your Radiology Research: How Effective Is a Blog Post?”
http://www.ncbi.nlm.nih.gov/pubmed/25959491

The Old Man and the Tamiflu

Winter is coming, and so is Tamiflu.  And, this year, we saw two meta-analyses regarding Tamiflu – the Roche puppet-sponsored analysis was pro-Tamiflu, and the non-sponsored analysis was anti-Tamiflu.  However, it should be made clear – anti-Tamiflu still agrees there’s still some small magnitude of effect that must be weighed against the side effects and cost.

The CDC has been repeatedly castigated regarding their continued zealotry regarding Tamiflu, despite the controversy surrounding its use.  The official statement contends their stance is based on more than just RCT data, including the whole of the observational data regarding its use.

And, so, they’ve gone and created some more junk observational data.

Through torturing the Influenza Hospital Surveillance Network (FluSurv-NET), these authors gathered three years of elderly patients hospitalized for influenza.  They extracted the date of influenza onset and the date of initiation for antivirals, and then examined these for a surrogate outcome for effectiveness: discharge to an extended-care facility.  They found, of course, that antiviral treatment was significantly associated with independent discharge, with an absolute unadjusted magnitude of effect of 4%.  However, they also found age, ethnicity, weight, chronic medical conditions, cardiovascular disease, neurologic disorders, influenza vaccination status, influenza virus type, time of illness onset to hospitalization, and surveillance site to be associated with outcomes – many with similar or larger absolute effect sizes.

So, the conclusions here are based on: the outputs of the statistical black box.  Given the degree of adjustments, and allocation and selection bias, there’s not much can be said here – except to make it into a HealthDay and ACEP daily news headline.  Unfortunately, the authors use these data to support early care and antiviral intervention.  This may be true, of course.  However, in the context of the current study, the suggestion ought not be to inform clinical practice – but, rather, to generate hypotheses for future trials, or to serve as surveillance safety for current practice.

That said, once the overall costs and potential morbidity of hospitalized influenza patients are taken into account, the additive penalty of Tamiflu administration is likely far less than even any small magnitude of benefit.

“Impact of prompt influenza antiviral treatment on extended care needs after influenza hospitalization among community-dwelling older adults”