Using qSOFA to Predict Sepsis after Percutaneous Nephrolithotomy
Key findings
- In a cohort of 320 patients from eight major academic medical centers, the overall rate of septic shock after percutaneous nephrolithotomy (PCNL) was about 1%
- The quick Sequential Organ Failure Assessment (qSOFA) screening tool demonstrated significantly better specificity for post-PCNL septic shock compared with the systemic inflammatory response syndrome (SIRS) criteria
- The qSOFA also had a higher positive predictive value than the SIRS criteria
- The SIRS criteria were not superior to the qSOFA for any study parameter
Sepsis is a dreaded potential complication of percutaneous nephrolithotomy (PCNL). Along with other infectious complications, it accounts for a substantial number of unplanned emergency room visits and is one of the leading causes of death after the procedure.
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The criteria for the systemic inflammatory response syndrome (SIRS) are widely used to assess the risk of infection after PCNL, but recent data suggest they are poor predictors. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) identifies the quick Sequential Organ Failure Assessment (qSOFA) as a potentially more accurate predictor of sepsis. However, the statement covers sepsis as it relates to various medical conditions and surgery in general, not any type of urologic surgery.
To investigate, Alan Yaghoubian, MD, clinical fellow in Surgery, Timothy Batter, MD, former fellow, Brian H. Eisner, MD, co-director of the Kidney Stone Program in the Department of Urology at Massachusetts General Hospital, and colleagues in the Endourologic Disease Group for Excellence (EDGE) Research Consortium conducted a multicenter retrospective comparison. In The Journal of Urology, they report that the qSOFA screening tool was superior to the SIRS criteria for predicting sepsis after PCNL.
Study Details
The researchers identified 320 patients who underwent PCNL at one of the eight EDGE Consortium medical centers between April 2016 and November 2017.
A patient was considered to meet the SIRS or qSOFA criteria if two or more criteria were recorded concomitantly in the medical record within 24 hours of admission to the post-anesthesia care unit:
- SIRS criteria: Heart rate >90 bpm, temperature <36 °C or >38 °C, white blood count >12,000 or <4,000 cells/mm3 and respiratory rate >20 breaths per minute
- qSOFA criteria: Altered mental status, quantified as any change in the Glasgow Coma Scale score, respiratory rate >22 breaths per minute and systolic blood pressure <100 mm Hg
Prognostic Value of SIRS and qSOFA
Within the first 24 hours after PCNL, 103 patients (32%) met the SIRS criteria and 23 (7%) met the qSOFA criteria. Three patients (0.9%) required ICU admission for postoperative sepsis (or ICU-level care with vasopressor administration), and each met the SIRS and qSOFA criteria.
The clinical relevance of the criteria was as follows:
- Specificity for septic shock: 93.3% for qSOFA vs. 68.4% for SIRS (P < .001)
- Sensitivity: 100% vs. 100%
- Positive predictive value: 13% vs. 2.9%
- Negative predictive value: 0% vs. 0%
Secondary Outcomes
Neither SIRS nor qSOFA criteria were significantly associated with a difference in the length of stay, the 90-day emergency department revisit rate, the 90-day readmission rate, re-intervention secondary to operative complications, the need for blood transfusion or the stone-free rate (no radiographic evidence of stones at the first postoperative follow-up visit).
SIRS criteria were not superior to the qSOFA for any parameters studied.
Multivariate Analyses
Multivariate logistic regression was adjusted for previously published risk factors for post-PCNL infectious complications: operative time, presence of struvite stone or staghorn stone, preoperative urine culture and intraoperative stone culture. They found:
- Meeting the SIRS criteria did not significantly predict any secondary endpoint
- Meeting the qSOFA criteria was associated with decreases in emergency department visits within 30 days (OR, 0.18, P < .05) and operative complications (OR, 0.10, P < .001)
The latter results are counterintuitive, and a prospective trial may be necessary to provide an explanation.
Explaining the Superiority of qSOFA
As described in Sepsis-3, the parameters assessed by the qSOFA tool are generally more accurate indicators of end-organ perfusion, the basis for septic shock, than those assessed by the SIRS criteria.
In addition, tachycardia, leukocytosis and fever are common developments after PCNL even in patients who do not have a systemic infection. Those measures are part of the SIRS criteria but not the qSOFA, so some patients could be SIRS-positive after PCNL but not at increased risk of sepsis or infectious complications.
The qSOFA is an easy, rapid test, and clinicians should consider using it to evaluate outcomes after PCNL. Its criteria should also be included as endpoints in future studies of risk factors for infection after PCNL.
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