Detrusor underactivity (DUA) in men is responsible for LUTS in a significant minority, the symptoms being indistinguishable from those seen in BOO. The International Continence Society (ICS) defines DUA as 'a detrusor contraction of inadequate magnitude and/or duration to effect complete bladder emptying in the absence of urethral obstruction. Whilst a reduced maximum urinary flow rate (Qmax) is indicative of voiding dysfunction, flow studies cannot distinguish between DUA and BOO, which are the two principal causes of low flow rates. DUA is diagnosed from a pressure-flow study (PFS)and is characterized by a low-pressure, poorly sustained, or wave-like detrusor contraction with an associated poor flow rate.

Overactive bladder (OAB) is the most common term currently used in clinical medicine to describe a complex of lower urinary tract symptoms (LUTS) with or without incontinence but most commonly consisting of urgency, frequency, nocturia, troublesome or incomplete emptying,and, occasionally, pain. With the exception of pain and incontinence, these symptoms are often found together; thus, the term LUTS has come to replace previous terms, such as urgency-frequency syndrome,urethral syndrome, and prostatism.

Drug treatment is frequently used as the initial management approach for LUTS in older men.Among men who desire treatment, general practice prescribing data have shown that antimuscarinics are not often given to elderly men. There is theoretical concern that the inhibitory effect of antimuscarinics on detrusor contraction could aggravate voiding difficulties or cause urinary retention in patients with BOO. There are virtually no data evaluating the safety and efficacy of solifenacin treatment in men with DUA and OAB.