## 4 Discussion
compared the mortality rates of patients for those who did (78%) and for those who did not undergo surgical decompression (22%) among 1712 patients with sepsis due to ureteral calculi [15]. They reported mortality rates of 8.82% and 19.2% in the surgical decompression and nonsurgical decompression groups, respectively. In most cases, surgical decompression is performed via retrograde double J stenting or percutaneous nephrostomy. While retrograde double J stenting is performed more frequently than percutaneous nephrostomy, there is no apparent difference between the two procedures regarding patient mortality [16]. However, the timing of surgical decompression is very important to reduce morbidity and mortality associated with obstructive uropathy and urosepsis and prioritizing expeditious surgical decompression significantly reduces patient mortality [17]. Known risk factors of urosepsis include older age, diabetes mellitus, immunosuppression state, and urological treatment [18; 19; 20]. In our current study, we achieve further granularity, and we find that females and those with a prior history of UTI are at highest increased risk of developing sepsis or APN. Other comorbidity conditions such as diabetes, hypertension, and obesity also confer an increased risk, but not to the extent of female gender and a previous UTI history. Prior studies have clearly demonstrated that in females, a history of UTI is a major predisposing factor to subsequent UTI [21; 22]. Thus, prioritizing active surgical treatment in this patient population may significantly reduce the prevalence of sepsis and potentially reduce patient mortality. Our study also shows racial differences in non-sepsis and sepsis groups. Whites and Hispanics are at higher risk of sepsis than blacks and Asians. This result is similar to the study of critically ill patients who visited United States Academic medical center-affiliated hospitals from 2012 to 2014. This study concludes that blacks have lower adjusted sepsis hospital mortality than whites [23]. In cost of surgical decompression, however, there is no significant difference between the non-septic and sepsis groups. Our study also demonstrates that a history of cancer and history of urinary stones decreased the risk of sepsis. There are logical explanations to why this is the case. Those with a history of urinary stones are likely to be under pre-existing urologic care and surveillance for repeat stone episodes. Moreover, patients with a history of urinary stones will recognize symptoms of ureteral obstruction and the necessity to seek care earlier than patients without a previous history. Similarly, in patients with history of cancer who may undergo more frequent laboratory testing and imaging studies compared to general population. Accordingly, these patients may also be more likely to be incidentally discovered to have urolithiasis and, as such, undergo earlier preemptive treatment to avoid APN or sepsis. In general, small-sized urinary stones are naturally expelled, but some large-sized urinary stones are difficult to be expelled naturally [24; 25]. In a recent study using noncontrast computed tomography, 392 consecutive patients with ureteric stone for 20 weeks were analyzed and reported the spontaneous passage rate by size. The natural rate of expulsion of 98%, 3 mm to 98%, 4 mm to 81%, 5 mm to 65%, 6 mm to 33%, and greater than 6.5 mm in 9% were revealed [26]. A recent study revealed that significant increases in white blood cell count, neutrophil count, NLR, and C-reactive protein were significant relation with failure in spontaneous expulsion of ureteral stones and associated chronic inflammatory urogenital conditions [27; 28]. Of note, our work provides some significant evidence for future directions in the socioeconomic and cost-effectiveness of kidney stones management across USA. A significant economic burden is indeed associated with urolithiasis, with per-year assumptions of costs which do cross USD 5 billion [29].