Development of an objective score to quantify the pediatric cystometrogram

We developed a reliable tool for quantitative assessment of the pediatric cystometrogram.

Scores for expected capacity (EV), compliance (EV20), activity and sensation were developed according to established formulas for norms. Ordinal scores were derived by calculating observed over expected findings. Based on the derived percents scores of 1 to 5 were assigned. For EV--0 to 5 the formula used was EV = (age + 2) x 30 and for EV20--0 to 5 the formula used was EV20 = 17 x age + 55. Activity was determined as the volume of the first, total number and magnitude of involuntary contractions, each scored 0 to 5 and divided by 3. Sensation was scored as 0 to 3 according to volume at first sensation. A total of 87 blinded cystometrograms in 49 patients were independently scored twice by 3 pediatric urologists. The resultant 522 total and 2,088 component scores were assessed for reliability.

Intrarater reliability was strong with 80% of total scores (208 of 261) within +/- 1 point from initial to subsequent retest. Reliability component scores were stronger with 94% (983 of 1,044) within +/- 1 point from test to retest. Spearman's rank correlations for total score was 0.82 to 0.98, indicating a strong relationship between test and retest. Interrater reliability of components was strong with 89% of scores (1,851 of 2,088) between urologists within +/- 1 point. Correlation coefficients for total scores were 0.80 to 0.96, indicating a high degree of consistency between urologist assessments (p <0.05).

This score appears to reliably quantify the pediatric cystometrogram. Its application may be useful for the objective assessment of detrusor behavior before and after intervention. Further applications should allow refinement of this tool.