Including a 'no active intervention' arm in surgical trials is possible: evidence from the CLasP randomised trial

To examine the impact of including a 'no active intervention' arm (called 'conservative management') in a randomised controlled trial comparing treatments (including surgery) for men with lower urinary tract symptoms related to benign prostatic enlargement.

Outcomes 7.5 months after randomisation were acceptability of randomisation, overall acceptability of and satisfaction with conservative management, impact on quality of life, perceived need for further treatment and treatment failure (defined a priori).

In total, 177 (out of 755) patients refused randomisation, including 31% who did not want surgery and 22% who wanted surgery. Most men randomised to conservative management were willing to undertake it as part of a trial but at the end of the trial they were divided between those who wanted to continue with it and those who expected surgery. At follow-up, 39% of conservative management patients requested surgery, and interference of symptoms with life and an unsuccessful outcome were more commonly reported in this arm. There were no appreciable differences between treatment groups in terms of treatment failures.

Including a 'no active intervention' arm did not appear to have a detrimental effect on patient recruitment or the completion of this trial in the short-term; overall, conservative management was successfully completed by the majority of patients during the trial period, suggesting that researchers need not avoid including a no-intervention arm in surgical trials as long as they take care with its presentation.