A comparative, epidemiological study of acute renal colic presentations to emergency departments in Doha, Qatar, and Melbourne, Australia

This was a retrospective observational study of acute renal colic presentations to two major EDs. Cases were identified using ICD-9/10-CM codes for renal colic from ED attendance registries. The ED at Hamad General Hospital (HGH-ED) in Doha, Qatar, has an annual census of approximately 470,000 that serves as the only tertiary-care ED in a country with a population of 2,700,000. The HGH is the major academic center and teaching hospital in Doha Qatar, and the ED presentations reflect the population of Qatar. The Alfred ED is a major adult quaternary referral center and has an annual census of approximately 60,000 patients per year. Urology consultation and services were present at both centers at all hours. Computed tomography (CT) imaging was available at both the centers round the clock. The practice at The Alfred ED was similar to most developed countries and included a CT non-contrast study for most of the patients presenting with renal colic [9]. There were pre-defined protocols for the imaging in renal colic at the HGH-ED during the study period, dictating selective imaging among patients at a high risk of complications. A CT scan was requested in the ED only for higher risk patients such as those with a single kidney, renal transplant, known renal impairment, having multiple comorbid conditions, frequent visits to the ED for similar pain within the last 2 weeks, signs of renal injury or sepsis, or patients with persistent pain not responding to parenteral analgesia. For females in reproductive age group, ultrasound was the initial imaging test at the HGH-ED. The limited CT and ED resources, a high volume of ED renal colic presentations in an otherwise healthy young population, were the main contributors to selective imaging approach at the HGH-ED.

The study period chosen was August 1, 2012, to July 31, 2013. A pre-piloted Microsoft office Access 2007 electronic version form was used to extract the data by explicit chart review. The patients included in the study were aged 18 years and above. Variables included were patient demographics, ED presentation and triage priority assigned, investigation results (urine microscopy, blood cell counts, serum chemistry, and the CT or USG imaging results), treatment at the time of discharge and disposition from ED. Stone characteristics such as size, location, and the presence or absence of hydronephrosis, hydroureter, or fat stranding were extracted from diagnostic imaging reports. The maximum dimension of stone reported was recorded in millimeters. Patient medical records and the urology procedure registers were checked for 30 days from the index visit to ED or from the date of stone detection on imaging.

All data were initially collected through Microsoft Access 2007 (Microsoft Corporation, USA), then imported to Stata 12.1 (College Station, TX 77845, USA). The Shapiro-Wilk or the Shapiro-Francia tests was used to test for normality as appropriate. The Student’s t test or the Wilcoxon rank-sum test was used to analyze the statistical significance of differences, as appropriate. A two-sided P value of less than 0.05 was considered to indicate statistical significance. Continuous outcomes are reported as mean (SD) for normally distributed data, and median (IQR) is reported for non-parametric data. Categorical outcomes are presented as proportions with 95% confidence interval.

The Alfred Research and Ethics Committee and Monash University Human Research Ethics Committee proposal number CF15/4323 - 2015001863 and Medical Research Center, Hamad Medical Corporation, proposal number 13380/13 approved the study, granting a waiver of consent from patients to extract information from medical records.

During the study period, from August 1, 2012, to July 31, 2013, total ED visits were 438,100 to the HGH-ED and 57,313 to The Alfred ED. Prevalence of renal colic among the ED attendance population was 27.9 per 1000 visits (95%CI, 27.4 to 28.4) in the HGH-ED and 6.7 per 1000 visits (95%CI, 6.0 to 7.4) in The Alfred ED. A total of 12,223 from the HGH-ED, and 384 from The Alfred ED, were identified as being due to renal colic. Most patients presenting to The Alfred ED group were from Oceania, whereas, those in the HGH-ED group were from South Asia (51.2%), West Asia (22.2%), and North Africa (19.9%). The median age of patients in the HGH-ED group was 34.9 years (29.0–43.4), significantly lower than those in The Alfred ED group at 48 years (37–60) (P < 0.001). In both centers, most patients were assigned priority three at triage (Table 1).

Overall, hematuria on urine examination was absent in 270 (30.1%; 95% CI, 27.1–33.3) of 896 patients. A significantly higher proportion of patients in The Alfred ED group had blood examination performed in the ED (87.2%) compared to the HGH-ED group (28.7%; P < 0.001). Among patients who had blood examination in the ED, the proportion of patients with abnormal creatinine levels, defined as > 110 μmol/L in males and > 90 μmol/L in females, were not significantly different (22.9% in HGH-ED vs 25.7% in Alfred ED; P = 0.257). The incidence of leukocytosis, defined as white blood cell counts > 10 × 1000/μL, was significantly higher in The Alfred ED group (56.8%) compared to the HGH-ED group (42.7%; P < 0.001). The use of ultrasonographic (USG) examination was low at 6.5% (95%CI, 6.0–6.9). The rate of performing non-contrast CT scans in The Alfred ED group (72.4%) was significantly higher than that in the HGH-ED group (24.6%; P < 0.001). Stone positive rates, in those patients who had an imaging test performed in the ED, were similar in the HGH-ED group (89.6%) and The Alfred ED group (89.9%, P = 0.882) (Table 1).

The median stone size detected on CT examination was larger in the HGH-ED group (6 mm; IQR, 4–8 mm) compared to The Alfred ED group (4 mm; IQR, 3–6 mm; P < 0.001). The overall incidence of renal stones was 35.7% (95%CI, 33.9–37.4) and ureteral stone was 57.5% (95%CI, 55.7–59.3). In the HGH-ED group, the most common stone locations were the lower ureter (26.7%) followed by the vesico-ureteric junction (22.4%). Among the patients presenting to The Alfred ED, the most common locations were the vesico-ureteric junction (35.7%) followed by the lower ureter (18.9%). The incidence of hydronephrosis was higher is the HGH-ED group (75.5%) compared to The Alfred ED group (60.4%, P < 0.001). The HGH-ED population had a higher incidence of multiple stones (28.3%) compared to The Alfred ED group (15.6%, P < 0.001) as detected on the CT examination (Table 2).

The rate of urological interventions was significantly higher in the HGH-ED group (30.8%) compared to The Alfred ED group (13.2%, P < 0.001). Most patients in the HGH-ED group were prescribed analgesia at the time of discharge (83.5%), and a smaller proportion was also prescribed the oral alpha-blocker, tamsulosin (11.7%). In contrast, there were more tamsulosin prescriptions in The Alfred ED group (25.3%; P < 0.001). The admission rates, among renal colic presentations, were 7.8% (95%CI, 7.4–8.3) from the HGH-ED and 16.4% (95%CI, 12.8–20.5) from The Alfred ED (P < 0.001).

This study is limited in analyzing data from two single centers. We were unable to collect all clinically relevant information such as chronic illnesses, dietary habits, environmental factors, and follow-up. Our conclusion about stone size in the Qatar population may have some selection bias as the CT imaging at HGH-ED was mostly performed in a population at risk of complicated stone disease. Finally, the true prevalence of renal colic cannot be accurately estimated as the prevalence measured in this study was per ED visit to single centers in the two countries. However, presentations to HGH-ED, Qatar, account for the majority of ED presentations for renal colic in the country, and renal colic presentations to The Alfred ED are expected to be representative of those presenting to other tertiary referral centers in Australia.