Abstract General Information

Title

EVALUATION OF AGREEMENT BETWEEN TWO UROFLOWMETRY TESTS IN CHILDREN WITH LOWER URINARY TRACT SYMPTOMS

Introduction and objective

Uroflowmetry is a non-invasive examination considered as a first-line assessment for children with lower urinary tract symptoms. Currently, the performance of two uroflowmetry tests is recommended for all patients. This study aimed to evaluate the differences between two uroflowmetry tests in children with lower urinary tract symptoms and their impact on the patient's diagnostic workup.

Method

Forty patients aged 4-17 years were included. Patients underwent two uroflowmetry tests and bladder ultrasound. They were divided into two groups based on the uroflowmetry curve pattern as fractionated (staccato and intermittent) and smooth (bell, tower and plateau). Patients were also separated into three groups based on estimated bladder capacity (voided volume + post-void residual on ultrasound): high capacity (> 115%), low capacity (< 60%), or normal capacity.

Results

The study included 40 patients with a mean age of 8.0 (IQR 6.0-10.0) years and 25 (62.5%) were female. Sixteen (40%) patients had constipation. When comparing both uroflowmetry tests, the majority of curves were bell-shaped in the first (67.5%) and in the second (47.5%) tests. The curve shape between the first and second uroflowmetry tests showed a Kappa value of 0.349 (fair). There was a significant difference in the categorization of bladder capacity as high, low or normal (p = 0.001). The bladder capacity was concordant in 63,6% for high, 68,4% for normal and 50% for low capacity. The classification of curves as fractionated or smooth yielded a Kappa value of 0.714 (strong). The Bland-Altman test showed disagreement only in the uroflowmetry parameter of time to Qmax.

Conclusion

When performing two uroflowmetry tests in children with lower urinary tract symptoms, there was a difference in terms of the time to Qmax, classification of bladder capacity and the curve pattern. However, when classifying the curves as fractionated or smooth, no clinical impact was observed that justifies conducting two tests in all patients. We suggest repeating the uroflowmetry only for evaluating bladder capacity in cases of unreliable voiding diary or voiding diary divergent from the uroflowmetry.