A randomized comparison of microtip and air-charged catheter for the measurement of maximum urethral closure pressure.

BACKGROUND Measurements of maximum urethral closure pressure (MUCP) are a part of urodynamic investigations preceding an incontinence surgery and a part of urethral function tests. OBJECTIVES The aim of the study was to compare maximum urethral closure pressure determined by a microtip catheter with those measured by an air-charged catheter. MATERIAL AND METHODS A prospective randomized study in a tertiary referral centre. 122 female patients with urodynamic stress incontinence were randomly assigned to have their urethral pressure profiles measured at rest by both microtip and air-charged catheters. INTERVENTION AND MEASUREMENTS Each patient had three measurements taken by each catheter type. Means of the measurements were compared with regard to correlation and repeatability. For statistical analysis, an approach proposed by Bland-Altman was applied to assess the agreement between the two techniques. RESULTS Correlation coefficient between MUCP by the air-charged and the microtip catheter was r=0.8507 (95% CI 0.7928 - 0.8934; p<0.0001). MUCP by the air-charged catheter was significantly lower than MUCP measured by the microtip catheter. The two-tailed p value was <0.0001, considered extremely significant. (95% CI of the differences; mean difference = -3.033; mean of paired differences -3.730 to -2.335). Discrepancies between measurements of the microtip and the air-charged catheters suggest good agreement between the two catheters since the mean difference was 2.8 cmH2O and the 95% CI of agreement were narrow with -0.03319 to 0.3151. CONCLUSION Air-charged catheters give lower readings for MUCP than microtip catheters with a good agreement between the two catheters.