In our tertiary hospital ED there was a 15% incidence of SIRS in the above population. Obstructing stones commonly result in ED visits but the majority of these patients are discharged home. Of the patients that require urgent renal drainage, many are for UTI or uncontrolled pain. There is no debate that patients with sepsis from an obstructing stone require emergent renal drainage. However, in a patient with an obstructing stone in the presence of SIRS, it is unclear what would be the patient outcome or disposition. Reports that biomarkers such as presepsin [7,8,9] and urine NGAL [10] improve the prognostic sensitivity of SIRS. However, these tests are experimental, costly and not commonly available in the ED in a timely manner.
Nadler et al. highlighted the stone burden on hospital admission rates and cost analysis of patients presenting with obstructing stones to the EDs across the United States [1]. Using a nationwide emergency department data sample they estimated an average of 1.2 million patients per year visiting ED yearly from 2006 to 2009 due to stones with a 19% hospital admissions. They identified infection and diabetes to be highly predictive of the need for admission on multivariate analysis. Theakston and co-authors identified stone size ≥5 mm, nitrites on urine dipstix, age > 50 years, and proximal ureteric stone as risk factors for urologic intervention within 3 months of visit to the ED. [2] Similarly, Papa et al. in addition to stone location and size, pain score upon discharge from ED was associated with urologic intervention within 1 month after initial presentation [11]. In our study apart from SIRS as a risk factor for urgent intervention and ED revisit, we found UTI on dipstix, age, presence of fever, elevated white cell count as other risk factors with OR > 1 (Table 2).
More recently the third international consensus for sepsis and septic shock updated the definitions of sepsis and septic shock [12]. The task force uses the qSOFA (quick Sequential Organ Failure Assessment) criteria RR > 22, altered mentation, systolic ≤ BP100. In the above study, qSOFA was better than SIRS criteria in the intensive care settings but similar to SIRS in an outside the ICU setting in predicting hospital mortality. The task force stresses that SIRS criteria still remain useful for the identification of sepsis. A more recent study, where the authors did a meta-analysis comparing the association of qSOFA and SIRS in predicting patient mortality in an ED setting [5]. Their results showed that both qSOFA score of ≥2 and a SIRS score of ≥2 were strongly associated with mortality in ER patients with infections. They showed qSOFA had higher specificity (88%) but lower sensitivity (42%), compared to SIRS, which had higher sensitivity (81%) and lower specificity (41%). The authors concluded that both are important at this time and that qSOFA cannot replace the use of SIRS in the ED setting until the sensitivity of qSOFA is improved.
Yamamoto et al. revealed that patient age (median 74 years) was an independent risk factor for the development of septic shock from an obstructing stone [13]. This corroborates our findings that advanced age increased the risk for requiring surgery (p = 0.026) (Table 2). Friedlander and colleagues reported that for every point increase in WBC count and pulse resulted in a 7 and 3% increase in sepsis, respectively [14]. The development of SIRS after ureteroscopy for stone disease has been reported but the role of SIRS in patients with obstructive urolithiasis presenting to the ED has not been studied [15].
To our knowledge there is no previously reported study evaluating the role of SIRS in obstructing stone patients presenting to the ED. A vast majority (77%) of our patients presenting to ED with an obstructing stone were discharged. However, SIRS patients were less likely (45%) to be discharged home compared to non-SIRS (83%) (p < 0.01). This may be because more number of SIRS patients had associated UTI and also other factors such as inadequate pain control might have contributed to this. Also, patients without infection, the presence of SIRS can be a reaction to inflammation, pain or other factors. These non-infective factors may have contributed to SIRS and the need for urgent renal drainage. Patient with SIRS who were discharged from the ED were more likely to revisit the ED (7%) compared to patients with no SIRS (2%, p = 0.05). In our cohort, patients with SIRS had higher incidence of UTI (49%)(on urine dipstix and culture) compared to those who did not have SIRS (13%), p < 0.01). However, patients with SIRS who were discharged from the ED with negative urine dipstix for infection had higher incidence of ED revisits compared to patients with no SIRS and had negative urine dipstix (Tables 3 and 4). Also, patients with SIRS had a higher likelihood of going into severe sepsis, 7% compared to 0.5% with no SIRS; albeit patients’ numbers were small. It is important to note that the judgment whether to drain the kidney or not should not be based solely on positive or negative urine dipstix but to be combined with other clinical factors including the presence of fever or chills, high white cell count etc.
Our hypothesis that SIRS impacts the disposition of patients including surgical intervention with obstructive urolithiasis was confirmed by this observational study. In the multivariate analysis SIRS was an independent factor associated with increased urgent surgical intervention and ED revisit. As our study was retrospective in nature, we could only conclude from our findings that SIRS is an independent risk factor for urgent drainage and revisits to the ED. The number of patients with critical illness (sepsis or septicemia) in our study group was very small and as many of our patients with SIRS had intervention, thereby preventing progression to severe sepsis or septic shock, it is difficult to conclude from the above study that SIRS is a predictor of critical illness in stone patients. Nevertheless, presence of SIRS should be an important factor in decision-making regarding patient disposition.
Limitations of our study include retrospective study design with lack of documentation of pain through a validated pain scale; hence, it is difficult to estimate the impact of pain on the patient disposition. However, all our patients had pain who had intervention and who revisited the ED with or without SIRS. We did not have urine cultures on all patients as many were discharged if the urine dipstix showed no infection. Also, some patients may have followed up at a different hospital following discharge from our ED, nevertheless as our data compared SIRS and non-SIRS patients, we presume the readmission percentage rates at other hospitals may be comparable to our center. Also, we did not have information on the stone type in the majority (> 95%) of our study population, we are not sure whether the stone type can influence which patients had SIRS with or without infection.
