Using the quick Sequential Organ Failure Assessment (qSOFA) score to assess sepsis in women during birth can lead to an unacceptably high rate of false negatives, according to a study presented at the 2016 annual meeting of the Society for Obstetric Anesthesia and Perinatology (SOAP; abstract 01-03).
“SIRS (systemic inflammatory response syndrome) criteria and Maternal Early Warning Criteria (MEWC) better identify impending severe sepsis, compared with the quick SOFA score,” said lead study author Melissa Bauer, DO, assistant professor of anesthesiology at the University of Michigan Health System, in Ann Arbor.
In the United States, infection is responsible for 13.6% of all pregnancy-related maternal deaths (Obstet Gynecol 2015;125:5-12). For the last two decades, the definitions of sepsis and septic shock have remained unchanged. A patient was considered to have sepsis if there is a source of infection and two or more SIRS criteria are identified:
temperature greater than 38° C or less than 36° C;
a heart rate greater than 90 beats per minute;
a respiratory rate greater than 20 breaths per minute or PaCO2 (partial pressure of carbon dioxide) less than 32 mm Hg (4.3 kPa); and
a white blood cell count greater than 12,000 cells/mm3 or less than 4000 cells/mm3, or less than 10% immature bands. Sepsis with organ dysfunction, hypoperfusion and/or hypotension was considered severe sepsis.
New Sepsis Guidelines
In 2014, a 19-member task force of the Society of Critical Care Medicine and the European Society of Intensive Care Medicine was convened to reevaluate the sepsis guidelines. The task force determined that the old definition was limited by an excessive focus on inflammation, a misleading model that sepsis follows a continuum through severe sepsis to shock, and an inadequate specificity and sensitivity of the SIRS criteria. The task force released the Third International Consensus Definitions for Sepsis and Septic Shock in February (JAMA 2016;315:801-810).
The new guidelines refine the definition of septic shock, eliminate the distinction between sepsis and severe sepsis, and shift the diagnostic focus from infection with systemic inflammation to infection-triggered organ dysfunction. Organ dysfunction is defined as an increase of 2 points or more on the SOFA score. The guidelines also encourage the use of the qSOFA score to identify adult patients with suspected infection outside of the ICU “who are more likely to have poor outcomes typical of sepsis.” The score relies on only three clinical criteria:
a respiratory rate of 22 breaths per minute or greater;
altered mentation; and
systolic blood pressure of 100 mm Hg or less.
The National Partnership for Maternal Safety, of which SOAP is a member, also has recently proposed the MEWC (Table 1). “Although this tool is not specific for sepsis, it is designed to be a screening tool to help identify impending maternal morbidity,” Dr. Bauer said.
Table 1. Maternal Early Warning Criteria Proposed by the National Partnership for Maternal Safety
Systolic blood pressure <90 or >160 mm Hg
Diastolic blood pressure >100 mm Hg
Heart rate <50 or >120 beats/minute
Respiratory rate <10 or >30 breaths/minute
Oxygen saturation on room air <95% at sea level
Oliguria <35 mL/hour for ≥2 hours
Maternal agitation, confusion or unresponsiveness; patient with preeclampsia reporting an unremitting headache or shortness of breath
In the new study, investigators set out to evaluate the sensitivity and specificity of the SIRS criteria, qSOFA and the MEWC for identifying sepsis during a delivery. They analyzed data from severe maternal sepsis cases from 1995 to 2012 at seven academic medical centers in the United States and Israel. Control patients were identified and matched by date of delivery in a 4:1 ratio, with 328 controls and 82 severe sepsis patients. The most common organisms identified in patients with sepsis were Escherichia coli (14.6%) followed by group A Streptococcus (7.3%).
In a univariate analysis, the highest risk factor for sepsis was a cesarean delivery during a labor (odds ratio [OR], 20.9), followed by a primary cesarean delivery (OR, 15.6), retained products of conception (OR, 12.9) and premature rupture of membranes more than 24 hours before labor (OR, 8.9).
qSOFA Misses More
With regard to the SIRS criteria, combining a heart rate greater than 90 beats per minute and a white blood cell count that was abnormal achieved the optimal balance between sensitivity (71%) and specificity (79%; Table 2). With the qSOFA score, combining a respiratory rate of at least 22 breaths per minute and systolic blood pressure no more than 100 mm Hg provided a sensitivity of 33% and a specificity of 95% (Table 3). Having any MEWC trigger provided a sensitivity of 71% and a specificity of 87% (Table 4).
Table 2. Use of SIRS Criteria During Hospitalization for Delivery
SIRS Criteria Sensitivity Specificity
WBC count <4×109/L or >12×109/L 0.75 0.59
HR >90 beats/minute 0.96 0.45
Respiratory rate >20 breaths/minute 0.62 0.90
Temperature <36° C or >38° C 0.69 0.7
HR >90 beats/minute and WBC count <4×109/L or >12×109/L 0.71 0.79
HR, heart rate; SIRS, systemic inflammatory response syndrome; WBC, white blood cell
Table 3. Use of qSOFA During Hospitalization For Delivery
qSOFA Factor Sensitivity Specificity
RR ≥22 breaths/minute 0.62 0.91
SBP ≤100 mm Hg 0.55 0.60
Altered mentation 0.38 1.00
RR ≥22 breaths/minute and SBP ≤100 mm Hg 0.33 0.95
qSOFA, quick Sequential Organ Failure Assessment; RR, respiratory rate; SBP, systolic blood pressure
Table 4. Use of MEWC During Hospitalization For Delivery
Criteria Sensitivity Specificity
SBP <90 mm Hg 0.36 0.93
HR >120 beats/minute 0.59 0.94
RR >30 breaths/minute 0.31 1.00
Any MEWC trigger 0.71 0.87
HR, heart rate; MEWC, Maternal Early Warning Criteria; RR, respiratory rate; SBP, systolic blood pressure
“If the qSOFA was used as a screening tool in this population, there would have been quite a few patients [with sepsis] missed,” Dr. Bauer said. “Several studies that have reviewed maternal sepsis deaths have found that if there were earlier intervention or different care, there may have been a different outcome.” She said scientists should focus on better screening tools to help identify sepsis at earlier time points.
Dr. Bauer reminded the audience that if there is a clinical suspicion for sepsis, clinicians should start broad-spectrum antibiotics immediately. “Make sure that you cover E. coli and group strep, according to the resistance patterns at your institute,” Dr. Bauer said. “Mortality differences have been seen with just a one-hour delay.”
According to Rebecca Minehart, MD, MSHPEd, assistant professor at Harvard Medical School and an obstetric anesthesiologist at Massachusetts General Hospital, in Boston, this study is important. “Sepsis mortality among pregnant women is on the rise, and current efforts to ‘diagnose’ using vital signs criteria don’t take into account the unique physiologic changes that pregnancy confers,” Dr. Minehart said. “With a more specific and sensitive set of criteria, we could potentially differentiate those women who are headed down the sepsis pathway and intervene earlier with treatments, as well as increase the acuity of their care team resources.”
Based on Dr. Bauer’s data, she would advocate for clinicians to move away from the qSOFA score and toward the MEWC. “Currently, I use the Maternal Early Warning Criteria, along with fever, to try and determine if my pregnant patients have ongoing SIRS or severe sepsis/septic shock,” she said.