Urodynamic variables cannot be used to classify the severity of detrusor instability

To explore the relationship between subjective severity of symptoms of detrusor instability (DI) on presentation, outcome after treatment for DI and initial diagnostic urodynamic variables, with the aim of identifying a urodynamic variable which might, by predicting a favourable outcome from treatment, classify the severity of DI.

Women with a urodynamically proven diagnosis of DI were recruited prospectively for the study. Data on disease symptoms and variables from their diagnostic cystometrogram were collected. All women were then treated and their outcome at 6 weeks after treatment compared with the initial urodynamic variables. Data on severity of symptoms were compared with initial urodynamic variables to explore any differences in these variables attributable to symptom severity.

Of 300 women studied (mean age 54 years, SD 16), 290 were treated with oxybutynin and bladder retraining. At 6 weeks, 82 women had their treatment outcome classified as worse/no change; 218 women had improved. When good or poor outcome was compared with the urodynamic results, there was no significant difference between the groups. Likewise, the severity of symptoms did not relate to the values of urodynamic variables.

There was no statistically significant relationship between reported severity of symptoms and urodynamic variables, and no relationship between the urodynamic variables used and response to treatment. Therefore, using these values it is not possible to predict a favourable outcome from treatment or to use them to classify disease severity.