Comparison of three methods to analyze detrusor contraction during micturition in men over 50 years of age

Aims: To grade detrusor voiding contraction three parameters are used: the Schäfer pressure-flow nomogram (LinPURR), the bladder contractility index (BCI) and the maximum Watt factor (Wmax). Because these methods to quantify detrusor contraction and/or to diagnose detrusor underactivity (DU) have not yet been mutually compared, this study compares these three methods of grading detrusor contraction. Materials and Methods: Evaluated were 1420 urodynamic pressure-flow studies from 1222 men (aged >50 years) with lower urinary tract symptoms (LUTS). Excluded were patients with abnormal urinalysis, neurological disorders, surgical correction of congenital anomalies, pelvic surgery, post radical prostatectomy, or with evidence of urethral stricture. Contractility was graded with the LinPURR, the BCI, and Wmax, making a distinction between “strong,” “normal,” “weak,” and “very weak” contractility. We calculated agreement between LinPURR and both BCI and Wmax. Results: The contractility groups LinPURR and BCI, as well as LinPURR and Wmax, showed a high agreement of 97.5% and 80.9%, respectively. Conclusion: This study demonstrates a significant correlation in grading detrusor contractility when comparing LinPURR with the BCI (97.5% agreement) and the Wmax (80.9% agreement). The LinPURR is plausible, and applicable in clinical practice and BCI is (intrinsically) well associating with the LinPURR classes, on a more continuous scale. Both are relevant to define clinically relevant patients groups