The third international consensus on sepsis 2016, introduced qSOFA as a better tool than SIRS, for identifying patients with infections, at risk of adverse outcomes. We set out to compare the performance of qSOFA and SIRS scores for the prediction of in-hospital mortality as a primary adverse outcome, and prolonged length of hospital stay as a secondary adverse outcome, among patients with secondary peritonitis at Mulago National referral and teaching hospital. Majority of the patients in this study were young. This finding is consistent with what Wabwire and Saidi reported in their study on stratified evaluation of secondary peritonitis [9]. There were more males compared to females in this study. A similar observation has been reported by previous studies [3, 9,10,11,12,13,14,15].
In this study SIRS predicted mortality and prolonged hospital stay more accurately than qSOFA. These findings were similar to those in a retrospective study of 1045 patients who presented in the emergency department with infection where SIRS showed a better performance for predicting infection than qSOFA [16]. The patients in that study were non surgical patients while our study recruited patients prospectively who eventually underwent emergency surgery for secondary peritonitis. However in another study which assessed QSOFA, SOFA and SIRS scores’ accuracy at predicting infection and mortality among surgical intermediate and ICU patients, it was found that none of the scores was sufficiently able to predict suspected infection in these patients [17]. Our study stratified SIRS scores and qSOFA scores into high risk and low risk groups which could have included more low risk patients in the high risk group for SIRS. In so doing this could have resulted in higher assessment of infections and mortality than the other study.
Although the overall mortality rate in this study was comparable to what has been reported by other studies [9, 15, 18] is still quite high and underscores the need for early identification of at risk patients for prompt intervention. The higher mortality rate among elderly patients could be probably because the elderly are likely to have poor physiological reserves and or comorbidities and possibly late diagnosis and also late patient presentation. In this study, prolonged hospital stay was attributed to the attendant complications of secondary peritonitis, including but not limited to surgical site infections, burst abdomen, and relaparotomy.
A meta-analysis of 8 studies to compare qSOFA and SIRS in mortality of patients in the Emergency Department with infections showed that scores > 2 for both scores were strongly associated with mortality. QSOFA > 2 was more specific in predicting mortality while SIRS > 2 was more sensitive [19]. A prospective multi-centre clinical trial demonstrated that qSOFA was modestly better in accurately predicting mortality but was less sensitive for in-hospital mortality among patients with suspected infection in the emergency department [20]. In this study, qSOFA was also more specific, but less sensitive tool, while SIRS was a more sensitive, but less specific tool, for the prediction of both mortality and prolonged hospital stay. Findings akin to these, have been reported by Singer et al. in their sepsis 3 report [5], and subsequent studies by Finkelsztein et al., Freund et al. and Churpek et al. [7, 8, 21]. SIRS had a superior predictive value for both mortality and prolonged length of hospital stay, compared to qSOFA. This finding contrasts with that from previous studies [8, 22, 23]. SIRS was superior to qSOFA in predicting both mortality and prolonged hospital stay, in this study, consistent with the findings of Askim et al. [22].
The above findings however, contrast with those reported by several studies that found qSOFA to be superior to SIRS in predicting in-hospital mortality and ICU admission [7, 8, 21, 24]. This disparity could be because a few notable differences between the aforementioned studies and this study. Churpek and Finkelsztein included patients being transferred from wards to the ICU, since they were assessing prediction of ICU stay by both scores as a secondary outcome [7, 21]. Such patients are more likely to have high qSOFA scores since they are critically ill, with multiple organ dysfunction, compared to stable patients in the A&E. None of the patients in this study was transferred to ICU. Freund et al. calculated qSOFA scores by collecting its parameters at their worst level during the patients’ entire hospital stay, that is, the highest respiratory rate, lowest systolic blood pressure, and lowest Glasgow coma scale. It is not clear from their study though, whether the same was applied to the SIRS scores. This could have biased their results [8]. In our study, both qSOFA and SIRS scores were calculated at admission only, during the patients’ entire hospital stay, irrespective of whether there was or there was no change in the parameters, from which they are generated.
Limitations of the study
In this study, Clinical and laboratory parameters used to generate both qSOFA and SIRS scores, were collected at admission only, during the patients’ entire hospital stay. Cognizant of the fact that, these keep changing from time to time especially when patients deteriorate, could have resulted in many patients not meeting the criteria for both scores and yet developed the adverse outcomes (High false negative rate). We further acknowledge that the cause of secondary peritonitis could also have contributed to the outcomes of the patients.
Both qSOFA and SIRS scores do not consider parameters like patients’ age, sex, and presence of comorbidities, all of which have the potential to modify the outcomes of interest in this study. However, since baseline risk associated with those parameters was considered during the development of qSOFA score, this may not have affected the results significantly.