A Nomogram to Characterize the Severity of Detrusor Overactivity during the Ice Water Test: Description of the Method and Proof of Concept.

AIMS: To develop a nomogram with severity categories for detrusor overactivity (DO).

METHODS: By conducting ice water tests (IWT) in 55 patients with Parkinson's disease, we identified criteria to describe characteristics of the detrusor pressure curves: (1) a gradient of Δpdet over Δt at the maximum detrusor pressure and (2) the area under the curve. In a nomogram, 10 severity categories of DO were established: 1 and 2 were assigned to group A (mild), 3 and 4 to group B (moderate) and 5-10 to group C (severe).

RESULTS: In the nomogram, negative IWT (20) appeared in category 1. Positive IWT (35) spread over the categories 1-8, 17 in group A, 11 in group B and 7 in categories 5-10. A relationship of incontinence episodes and nomogram category was observed. The nomogram category was reproducible in repeated IWT. Therapeutic interventions to treat DO lowered the nomogram category.

CONCLUSION: From the relationship of detrusor pressure and time in the IWT, a nomogram with 10 severity categories of DO was developed. First observations show a relationship of nomogram category and the number of incontinence episodes, reproducibility in repeated tests and the representation of effects of therapeutic interventions to treat DO.