Simple primary care tests predict bladder outlet obstruction in men with urinary symptoms

Design

Prospective multicentre diagnostic accuracy study with independent validation

Population

601 men with lower urinary tract symptoms in 67 general practices

Primary outcome

Urodynamic diagnosis of bladder outlet obstruction, detrusor underactivity, detrusor overactivity

Effect

Obstruction c-index 0.82 in validation; underactivity 0.63; overactivity 0.62

A prospective diagnostic accuracy study in 67 practices in England and Wales recruited 601 men with lower urinary tract symptoms. Each had a symptom score, bladder diary, examination, PSA, urinary flow rate and post-void residual volume, and then invasive urodynamics as the reference standard. Models were built in 350 men and tested in a separate 251.

The model for bladder outlet obstruction discriminated well (c-index 0.80 in development, 0.82 in validation). Models for an underactive or overactive bladder muscle performed only moderately (c-indices 0.62 to 0.67).

For family physicians, the point is that a structured, non-invasive work-up can identify the man most likely to have obstruction, who stands to gain most from treatment aimed at the prostate, without a urology referral first. It is less reliable at separating the other causes of similar symptoms, which is where a bladder diary and clinical judgement still matter.

• In men with urinary symptoms, combine symptom score, bladder diary, examination, flow rate and residual volume where available.
• Use PSA as part of the work-up after counselling, not as the only test.
• A pattern suggesting obstruction supports starting prostate-directed treatment in primary care.
• Refer when the picture is unclear, the residual volume is high, or red flags are present.

Why it matters

Many men are referred or treated without knowing whether obstruction is the cause, and this work-up can be done in primary care.

Don't overread it

The models for underactive and overactive bladder performed only moderately and need more work.

The statistics, in plain English

A c-index of 0.82 means that, for a randomly chosen man with obstruction and one without, the model ranks the obstructed man higher 82% of the time. Holding up in a separate validation group is what makes this more than a fitted result.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.