Smarter, Faster Sepsis Testing
Point-of-care diagnostics for sepsis would catalyze early intervention
David Ludvigson | | Opinion
Sepsis robs millions of people of their lives each year, but because its symptoms overlap with those of several other medical conditions, even well-trained medical professionals can have trouble recognizing it. Unfortunately, this confusion contributes to the condition’s high mortality rate; every hour of delayed treatment increases the patient’s risk of death by 8 percent (1). It is estimated that sepsis may affect over 30 million people around the world each year, causing as many as six million deaths (2). In some countries, it is one of the leading causes of death among patients who die in hospitals. And although sepsis most often occurs among patients who are already hospitalized for kidney, lung, or urinary tract infections and other problems, it can just as easily arise in the community setting, where the likelihood of a timely diagnosis is even lower.
There are a number of fronts where we must make progress to improve patient outcomes related to sepsis. At the most basic level, clinical lab professionals can participate in efforts to raise awareness among the public of the signs and symptoms of sepsis. If more people understood the condition and knew what to look for among their neighbors and loved ones, suspected cases of sepsis would likely get medical attention sooner. Other improvements must happen within clinical labs and in the research and development departments of diagnostic developers. Already, teams are working hard to design better sepsis diagnostic tools that can help clinical teams determine whether drug-resistance markers or other pathogen-specific traits are relevant to treatment selection.
But there is another critical area that tends to get less attention from the clinical lab and diagnostic communities: point-of-care triage testing. Although classifying the causative pathogen is important, the very first question – the one that will have give patients the best chance at survival – is whether or not the patient actually has sepsis. A simple yes-or-no test that could be performed right away, whether the patient is in the hospital or being picked up at home by an ambulance, would dramatically improve the speed with which antibiotics could be administered to prevent a sepsis patient from getting worse.
The introduction of such a POC triage test would entail a significant shift in the way the diagnostics community thinks about sepsis testing; instead of having just one test designed to identify the pathogen, we would need a two-stage testing protocol. The first stage would quickly reveal important information about the patient’s condition and spot the onset of sepsis. The second test would essentially be what’s available now: a more advanced test, performed in a clinical laboratory, that provides in-depth data about the pathogen and its drug resistance profile.
A POC test that provides sufficient evidence of sepsis would allow first responders to get patients started on this treatment hours or even days sooner than if they had to wait for hospital admission and clinical laboratory testing. Indeed, typical treatments for sepsis include antibiotics and fluids, which are quite effective at beating back sepsis – at its earliest stages.
For optimal results, though, the POC triage test would have to generate results incredibly quickly, during the narrow critical care window – half an hour from when the first symptoms of sepsis manifest – during which patients have the best chance of recovery with standard treatment. In other words, the POC test would have to produce actionable results in just 10–15 minutes to have an impact on patient outcomes.
A triage test for sepsis would have the added benefit of easing the burden of generating rapid results for hospital labs, allowing them to focus on the more complex pathogen identification tests without the pressure of knowing that patients are going without treatment until results are returned.
You may not be surprised to hear that a portable POC test for sepsis is currently in development and being evaluated in clinical trials. Measuring lactate, procalcitonin, and C-reactive protein – three well-documented biomarkers of sepsis – it generates results with better sensitivity and specificity than lactate-only tests.
In my view, the two-stage testing model is a better route forward. It enables emergency teams to offer early intervention while still engaging hospital laboratorians for more sophisticated strain identification testing to further hone antibiotic selection. Just as early administration of clot-busting drugs has revolutionized outcomes for stroke victims, the ability to treat patients in the initial stages of sepsis could make this common condition far less deadly.
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- A Kumar et al., “Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock”, Crit Care Med, 34, 1589–1596 (2006). PMID: 16625125.
- C Fleischmann et al., “Assessment of global incidence and mortality of hospital-treated sepsis. Current estimates and limitations”, Am J Respir Crit Care Med, 193, 259–272 (2016). PMID: 26414292.
- AJ Singer et al., “Diagnostic characteristics of a clinical screening tool in combination with measuring bedside lactate level in emergency department patients with suspected sepsis”, Acad Emerg Med, 21, 853–857 (2014). PMID: 25155163.