What Does a Sepsis Alert Gain You?

The Electronic Health Record is no longer simply that – a recording of events and clinical documentation.  Decision-support has, for good or ill, morphed it into a digital nanny vehicle for all manner of burdensome nagging.  Many systems have implemented a “sepsis alert”, typically based off vital signs collected at initial assessment. The very reasonable goal is early detection of sepsis, and early initiation of appropriately directed therapy. The downside, unfortunately, is such alerts are rarely true positives for severe sepsis in broadest sense – alerts far outnumber the instances in a change of clinical practice results in a change in outcome.

So, what to make of this:

This study describes a before-and-after performance of a quality improvement intervention to reduce missed diagnoses of sepsis, part of which was introduction of a triage-based EHR alert. These alerts fired during initial assessment based on abnormal vital signs and the presence of high-risk features. The article describes baseline characteristics for a pre-intervention phase of 86,037 Emergency Department visits, and then a post-intervention phase of 96,472 visits. During the post-intervention phase, there were 1,112 electronic sepsis alerts, 265 of which resulted in initiation of sepsis protocol after attending physician consultation.  The authors, generally, report fewer missed or delayed diagnoses during the post-intervention period.

But, the evidence underpinning conclusions from these data – as relating to improvements in clinical care or outcomes, or even the magnitude of process improvement highlighted in the tweet above – is fraught. The alert here is reported as having a sensitivity of 86.2%, and routine clinical practice picked up nearly all of the remaining cases that were alert negative.  The combined sensitivity is reported to be 99.4%.  Then, the specificity appears to be excellent, at 99.1% – but, for such an infrequent diagnosis, even using their most generous classification for true positives, the false alerts outnumbered the true alerts nearly 3 to 1.

And, that classification scheme is the crux of determining the value of this approach. The primary outcome was defined as either treatment on the ED sepsis protocol or pediatric ICU care for sepsis. Clearly, part of the primary outcome is directly contaminated by the intervention – an alert encouraging use of a protocol will increase initiation, regardless of appropriateness. This will not impact sensitivity, but will effectively increase specificity and directly inflate PPV.

This led, importantly, for the authors to include a sensitivity analysis looking at their primary outcome. This analysis looks at the differences in overall performance if stricter rules for a primary outcome might be entertained. These analyses evaluate the predictive value of the protocol if true positives are restricted to those eventually requiring vasoactive agents or pediatric ICU care – and, unsurprisingly, even this small decline in specificity results in dramatic drops in PPV – down to 2.4% for the alert alone.

This number better matches the face validity we’re most familiar with for these simplistic alerts – the vast majority triggered have no chance of impacting clinical care and improving outcomes. It should further be recognized the effect size of early recognition and intervention for sepsis is real, but quite small – and becomes even smaller when the definition broadens to cases of lower severity. With nearly 100,000 ED visits in both the pre-intervention and post-intervention periods, there is no detectable effect on ICU admission or mortality. Finally, the authors focus on their “hit rate” of 1:4 in their discussion – but, I think it is more likely the number of alerts fired for each each case of reduced morbidity or mortality is on the order of hundreds, or possibly thousands.

Ultimately, the reported and publicized magnitude of the improvement in clinical practice likely represents more smoke and mirrors than objective improvements in patient outcomes, and in the zero-sum game of ED time and resources, these sorts of alerts and protocols may represent important subtractions from the care of other patients.

“Improving Recognition of Pediatric Severe Sepsis in the Emergency Department: Contributions of a Vital Sign–Based Electronic Alert and Bedside Clinician Identification”