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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 31  |  Issue : 5  |  Page : 221-225

Evaluation of modified STONE score in patients presenting to the emergency department with flank pain


1 Department of Emergency Medicine, Karabük University Training and Research Hospital, Karabük, Turkey
2 Department of Emergency Medicine, Health Science University, Antalya Training and Research Hospital, Antalya, Turkey
3 Department of Emergency Medicine, Akdeniz University Faculty of Medicine, Antalya, Turkey

Date of Submission26-Mar-2020
Date of Decision22-May-2020
Date of Acceptance30-May-2020
Date of Web Publication27-Oct-2020

Correspondence Address:
Cihan Bedel
Department of Emergency Medicine, Health Science University, Antalya Training and Research Hospital, Kazim Karabekir Street, Postal Zip Code: 07100, Muratpasa, Antalya
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/UROS.UROS_32_20

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  Abstract 


Purpose: Renal colic due to urinary system stone disease is one of the main complaints in emergency department (ED) admissions. The STONE score is the most used model. The “race” item in the nomogram is not useful for communities where the Black race is not dominant. Therefore, we aimed at investigating the diagnostic value of a new modified scoring system, in which we replaced the “race” item in the original nomogram by “obstruction = pelvicalyceal dilation.” Materials and Methods: The study included patients who were admitted to a tertiary university ED with flank pain and underwent ultrasonography (US) from June 2017 to November 2017. Patients' demographic data such as US findings and the STONE score parameters were recorded. “Obstruction (pelvicalyceal dilation)” replaced the “race” item of the original STONE score. The diagnostic value of the modified system was investigated by categorizing the scores as low risk (0–5 points), moderate risk (6–9 points), and high risk (10–13). Results: The study included 305 patients who met the inclusion criteria. The mean age was 39.45 ± 13.83 years, and 170 patients (55.7%) were male. Pelvicalyceal dilation was detected on US at a statistically significantly higher percentage in patients with stones compared to stone-free patients (P < 0.001). The modified STONE score was statistically significantly higher in patients with stones compared to stone-free patients (P < 0.001). Conclusion: We suggest that the replacement of the race parameter of the original STONE score by the US finding of pelvicalyceal dilation will enhance the diagnostic value of scoring in societies mostly comprising a non-Black population.

Keywords: Emergency department, renal colic, STONE score


How to cite this article:
Uzun A, Korkut M, Kartal M, Bedel C. Evaluation of modified STONE score in patients presenting to the emergency department with flank pain. Urol Sci 2020;31:221-5

How to cite this URL:
Uzun A, Korkut M, Kartal M, Bedel C. Evaluation of modified STONE score in patients presenting to the emergency department with flank pain. Urol Sci [serial online] 2020 [cited 2020 Dec 1];31:221-5. Available from: https://www.e-urol-sci.com/text.asp?2020/31/5/221/299258




  Introduction Top


Renal colic is one of the most common pain syndromes in the emergency department (ED) admissions.[1],[2],[3] The prevalence of kidney stone disease in the USA has been reported to be 7.1%–10.6%, with an increasing annual incidence.[4],[5] Several factors play a role in the etiology including age, gender, heredity, diet, and geographical characteristics. Urinary system stone disease is more common in non-Black populations, and it is twice more common in Asians.[6],[7]

Practical scoring systems, validated by several studies in literature, are available for the evaluation and clinical diagnosis of patients with urinary system stones admitted to the ED. The STONE score is the most commonly used scoring model in studies reported in literature. The STONE score is used for stratifying patients by the low, moderate, and high risks of having ureteral stones. It consists of twelve parameters that include age, sex, the duration of pain, race, nausea/vomiting, and the presence of erythrocytes in urine.[8],[9] However, the “race” parameter in the original STONE score is not a useful parameter for communities where the Black race is not dominant, i.e., where the population is mostly composed of non-Black people. Ultrasonography (US) provides a rapid and inexpensive method for the differential diagnosis of renal colic patients in EDs. The technique has gained widespread use in our country in recent years.[10],[11] In light of this information, we aimed at investigating the diagnostic value of a new modified scoring system, in which we replaced the race item in the original nomogram by “obstruction (pelvicalyceal dilation).”


  Materials and Methods Top


This is a prospective cohort study. Ethics committee approval and institutional approval (Protocol code: 2017/285-Decision number: 2017-05-10) were received from the Clinical Research Ethics Committee of Akdeniz University Faculty of Medicine. The study was conducted in the ED of a tertiary care university hospital from June 2017 to November 2017. After obtaining approval from the ethics committee, patients who were admitted to the ED due to flank pain and who underwent US were recruited. Exclusion criteria were being a pregnant woman, a trauma patient, a renal transplant patient, being younger than 18 years old, and being included in the study previously. Written informed consent was obtained from all patients who agreed to participate in the study. Patients' data were recorded in the patient data sheet that was developed for the study. The demographic data of the patients such as ultrasonographic examination findings and the STONE score parameters including sex, duration of pain, nausea/vomiting, and hematuria were recorded in the patient data sheet. The “race” parameter of the original STONE score was replaced by “obstruction (pelvicalyceal dilation)” [Table 1]. Based on the clinical findings, the modified STONE scores were stratified into three estimated risk categories similar to the original nomogram as follows: 0–5 points as low risk, 6–9 points as moderate risk, and 10–13 points as high risk.[12] The original STONE score was calculated and compared to the modified STONE for diagnostic accuracy.
Table 1: Modified STONE score categories

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Bedside US was performed by physicians having at least more than 2 years of experience, either a physician assistant or an ED specialist. These physicians were not informed of any clinical or radiological findings other than the US findings of the patient. A color-Doppler US device (Mindray DC-8, Shenzhen Mindray Bio-Medical Electronics Co. Ltd., Guangdong Sheng, China) with a convex transducer allowing for 1.5–5.5 MHz compound imaging was used for performing the bedside US examination. Any presence of pelvicalyceal dilation and hydronephrosis and aortic diameter measurements from two sites (at subxiphoid and renal artery levels) were recorded in the patient data sheet. Urine samples were collected from the patients to test for microscopic or macroscopic hematuria. The presence of more than four erythrocytes/fields in the urinalysis was accepted as hematuria. No repeat urine tests were performed when a urinalysis was performed on the same day. Patients were excluded from the study when no urine tests were performed. Analgesics were administered to patients with pain, and antiemetics were administered to patients with nausea or vomiting. Demographic data, time since the pain onset, nausea/vomiting, bedside US findings, urine test results, and vital parameters were recorded in the patient data sheet. Spiral computed tomography (CT), intravenous pyelography, and direct imaging of stone with US were performed for diagnosing the urinary stone disease.

The study data were analyzed using the SPSS 23.0 statistical software (SPSS Inc., Chicago, IL, USA). Continuous variables were expressed as mean ± standard deviation, whereas categorical variables were presented in percentages. The Kolmogorov–Smirnov test was used for normality analyses. The Mann–Whitney U-test was used for analyzing the nonnormally distributed data; the Student's t-test was used for analyzing the normally distributed data; and the Chi-square test was used for analyzing the categorical variables. The effectiveness of the modified STONE scoring system to predict urinary stones was examined with the receiver operating characteristic (ROC) curve. P < 0.05 was considered statistically significant.


  Results Top


The study included 305 patients, meeting the inclusion criteria. Among the study population, 152 (49.8%) patients had ureteral stones and 153 (50.2%) patients were free of stones. The mean age of the patients was 39.45 ± 13.83 years, and 170 patients (55.7%) were male. The comparison of the modified STONE score and baseline data of the two study groups, comprising patients with stones and those free of stones, is presented in [Table 2]. The mean age was not statistically significantly different between the two study groups. Both the study groups were characterized by male preponderance; however, males were significantly more common in the patient group with stones compared to the stone-free patients (P < 0.001). The complaints of flank pain and the medical history of stones were found significantly at higher rates in patients with stones compared to the stone-free patient group (P < 0.001 for both parameters). The incidence of nausea at admission was statistically significantly higher in patients with stones compared to stone-free patients (P = 0.029). Pelvicalyceal dilation was detected on US at a statistically significantly higher percentage in patients with stones compared to stone-free patients (P < 0.001). The modified STONE score was statistically significantly higher in patients with stones compared to stone-free patients (7.26 ± 2.36 vs. 4.22 ± 2.87; P < 0.001).
Table 2: Comparison of STONE score parameters and demographic data in patients with stone and without stone

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The ROC curve drawn for the modified STONE score by the presence of stones in the study patients is shown in [Figure 1]. The area under the curve (AUC) value of the modified STONE score for the stone diagnosis was 0.786 (95% confidence interval [CI]: 0.735–0.837). The optimal cutoff value of 7 for the modified STONE score for diagnosing urinary tract stones had 70.4% sensitivity and 61% specificity. The positive predictive value, negative predictive value, positive likelihood ratio (LR+), and negative LR − were 99.4%, 2.1%, 0.61, and 2.53, respectively. The AUC value of the original STONE score for the stone diagnosis was 0.636 (95% CI: 0.581–0.691). The optimal cutoff value of 8 for the original STONE score for diagnosing urinary tract stones had 67.5% sensitivity and 56% specificity. The distributions of the patients by the modified STONE score system risk groups were found to be 44.3%, 46.9%, and 8.9% in the low-, moderate-, and high-risk groups, respectively. Using the modified STONE score, the stone diagnosis was made at a rate of 22.2% in the low-risk group, 68.5% in the moderate-risk group, and 88.9% in the high-risk group. The distribution of patients by the risk groups of the modified STONE score is presented in [Figure 2].
Figure 1: Receiver operating characteristic curve analysis scoring systems in the discrimination between with and without stone groups

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Figure 2: Prevalence of urinary system stone by modified STONE score category

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  Discussion Top


We evaluated the likelihood of the ureteral stone disease with the modified STONE score in patients presenting to the ED due to flank pain. Our study results revealed that the mean modified STONE score was statistically significantly higher in the patient group with stones compared to the stone-free patients (7.26 ± 2.36 vs. 4.22 ± 2.87; P < 0.001).

CT is still the most important diagnostic tool in the diagnosis of urinary stone disease in ED patients with flank pain.[13] Noncontrast CT provides evidence to make a diagnosis of stone disease. Although renal colic can be diagnosed with CT findings, the radiation dose that the patients will be exposed to, the easy availability of the CT technique, interpretation inadequacies, and cost-effectiveness are the issues.[14] From this point of view, Moore et al. introduced the STONE score, gaining effective clinical use. This scoring system stratifies patients into three risk groups.[14] The rate of correct diagnosis of stones in the high-risk group is 89.6%. Consequently, it is emphasized that the high-risk patients identified based on the points obtained from the STONE score system have a high likelihood of having a stone disease and that their discharge from the ED can be planned. Daniels et al. reported a slight increase in the sensitivity of the SCORE stone system in diagnosing stone disease patients in the low- versus moderate-risk groups by the inclusion of hydronephrosis as an extra parameter into the STONE score.[15] However, no increases in the sensitivity and specificity were reported in high-risk patients. Using the modified STONE score in our study, we diagnosed stone disease correctly at a rate of 22.2% in the low-risk group, 68.5% in the moderate-risk group, and 88.9% in the high-risk group. Although previous studies in the literature reported that the inclusion of emergency bedside US findings into the STONE score system as an extra parameter was associated with increases in the sensitivity, our study is partly different from those studies. First, our country and many Asian and European countries comprise mostly the non-Black population. Therefore, the “race” parameter of the STONE score may not be useful in these countries. We presume that the replacement of the “race” parameter by the obstruction or pelvicalyceal dilation finding from a US examination in the modified STONE score will enhance the usefulness of this scoring system.

Kim et al.'s study on 700 patients in 2016 reported the AUC value of the STONE score as 0.92 and the sensitivity for the high-risk STONE scores as 56%. However, in that study, the STONE score was modified by including a C-Reactive Protein (CRP) value of <0.5 and excluding the parameters of nausea, vomiting, and race.[16] Although our study results are similar to the results of that study, the AUC value found in our study is lower to some extent regarding the diagnostic accuracy. However, we believe that the differences in the sample size and the study design between the two studies might have led to this finding.

Wang et al.'s study on 845 patients found ureteral stones in 39% of the patients with an AUC value of 0.78.[8] The presence of stones was observed in 14%, 32%, and 73% of the low-, moderate-, and high-risk STONE score groups, respectively. The sensitivity and specificity of the diagnosis were 53% and 87%, respectively, in the high-risk patients. Safaie et al.'s study reported the rates of stone diagnosis as 31.7% (n = 19/60), 65.6% (n = 61/93), and 90.5% (n = 76/84) in the low-, medium-, and high-risk STONE score groups, respectively.[17] The AUC value for the STONE score was 0.789. The sensitivity and specificity of the STONE score for diagnosing renal stones were 75.0% and 70.4%, respectively, at an optimal cutoff value of 8. In our study, the presence of stones in the low-, moderate-, and high-risk groups was 22.2%, 68.5%, and 88.9%, respectively.

Our study has some limitations. The first one is the small sample size. The second is that CT could not be performed to all the study patients though all of them were originally diagnosed based on imaging findings. These limitations should be taken into consideration in further research.


  Conclusion Top


We suggest that the replacement of the race parameter of the original STONE score by the US finding of pelvicalyceal dilation will enhance the diagnostic value of scoring in societies mostly comprising a non-Black population.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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