Are ED demographics and lab values helpful in determining those patients with renal colic who have intercurrent urinary tract infections?
Study Objective: Renal stones can be caused by bacteria (infectious stones) or can be secondarily infected (stones with a UTI), leading to a septic stone/sepsis. The presence of white cells on urinalysis may indicate infection or ureteral inflammation. There is a wide practice pattern of ED physicians and urologists when treating pyuria associated with renal stones, with a lack of data in the literature to show which patients may have an infection. The goal of this study is to describe renal colic patients, confirmed by CT imaging, with culture proven (uCLX) intercurrent infections, based on demographic and lab data at the time of diagnosis. Such analysis could help to risk-stratify patients more accurately for admission/antibiotic treatment. Methods: We performed a retrospective study looking at vital signs, demographics, UA and urine culture results to determine if patients with infectious stones, or stones with infection, can be identified. Data was extracted from an electronic charting system from a sub-urban medical center with an adult/pediatric visit volume between 90-100k visits. Appropriate statistical test with a significant p of > 21 years of age with an ICD9/10 diagnosis of renal colic with a confirmed CT diagnosis between 1/3/2014 and 4/23/2015 were included. Results: 375 charts were reviewed with 261 having a CT confirmed stone. 150 were men (57.5%). The median age was 53.4 (95% CI 51.2 to 55.4; IQR 43.2 to 62.4). 33 patients (12.6%) had a UTI at > 10,000 CFU. There was a significant difference with regards to a +uCLX vs -uCLX based on gender (females 20/111 vs males 13/150; difference of proportion -0.21; [95%CI -0.39 to 0.03], p<0.04), age (median difference -8.59; [95% CI -14.0 to -3.26]; p<0.002). There was a significant difference in +uCLX based on presence of wbc’s on UA (7/181 [3.8%] for 0 wbc; 5/25 [20%] for 5-10 wbc; 1/12 [8.3%] for 10-20 wbc; 1/14 [7.1%] for 20-50 wbc; 19/29 [65.5%] for >50 wbc; p<0.0001). There was a significant difference in +uCLX based on + vs – nitrites (20/238 [8.4%] for nitrite neg vs 13/23 [56.5%] +uCLX for nitrite pos; diff of proportion 0.35 [95%CI 0.18 to 0.52]; p<0.0001). There was a significant difference in +uCLX based on + vs – bacteria on UA (8/173 [4.6%] no bacteria; 4/42 [9.5%] few; 9/15 [60%] many; 4/19 [25%] moderate; 7/10 [70%] TNTC; p<0.0001). There was a significant difference in admission vs discharge for +uCLX vs –uCLX (21/33 [63.6%] vs 51/228 [22.3%] respectively; p<0.0001). There was no difference in return within 30 days for discharged patients based on + vs -CFU (3/11 [27.3%] vs 20/175 [11.4%]; difference of proportions 0.15, [95%CI -0.11 to 0.43]; p<0.28). Conclusion: There appears to be significant correlation with several clinical and laboratory data that may aid in predicting urinary tract infections associated with kidney stones. Females are more likely to have positive uCLX while there is also correlation between being +uCLX with the number of WBCs; being nitrite positive, and increasing levels of bacteria on the UA.
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