The SUSPEND trial is investigating the clinical and cost-effectiveness of the use of an alpha-blocker (Tamsulosin) and a calcium channel blocker (Nifedipine) in the management of symptomatic ureteric stones. It is a UK, multi-centre, double-blind placebo-controlled, randomised trial testing these two medical expulsive therapies against a placebo

Study Background

Urinary stone disease is very common, with an estimated prevalence among the general population of 2–3% and an estimated lifetime risk of 1 in 8 for white males and 5–6% for white females with males forming stones three times as often as females. Urinary stones often recur and the lifetime recurrence rate is approximately 50%.

In recent years, a growing understanding of ureteric function and pathophysiology has led to the hypothesis that drugs which cause relaxation of ureteric smooth muscle can enhance the spontaneous passage of ureteric stones. The selective α-adrenergic antagonist Tamsulosin has specificity for α-1A and α-1D receptor subtypes, whilst other α-blockers variably block all α-1 receptor sub-types in a non-specific manner. Similarly, calcium channel blockers such as Nifedipine inhibit ureteric smooth muscle contraction. The use of both classes of drugs in augmenting the passage of ureteric stones has been termed medical expulsive therapy (MET) and this is proposed as a way to enhance stone passage and avoid the need for further interventions. However, the majority of clinical trials conducted to date have been small and of poor-to-moderate quality in terms of trial methodology or design and have lacked a comprehensive economic evaluation.

Study outline

The study will recruit 1200 patients, aged between 18 and 65, presenting acutely with a ureteric stone confirmed by non-contrast computed tomography of the kidney, ureter and bladder (CTKUB), or by IVU with subsequent CTKUB confirmation within 12 hours. They will receive standard care (analgesics, fluids etc.) and follow-up as per local protocols. They will be given 28 days of study medication and will be followed-up by postal questionnaires sent from the co-ordinating office (CHaRT, Aberdeen) at four and 12 weeks after randomisation. Participants will be reviewed in clinic approximately four weeks after being randomised.

The primary clinical outcome is spontaneous passage of ureteric stones at four weeks (defined as no further intervention required to facilitate stone passage). The primary economic outcome is the incremental cost per quality adjusted life years (QALYs) gained at three months. QALYs are based on the responses to the EQ-5D.

Secondary outcome measures will be severity of pain, generic health profile as measured by the SF 36, use of analgesia, time to passage of stone, further interventions received at three months, adverse events (and serious events), NHS primary and secondary care use and costs up to three months, incremental cost per surgical interventions averted and modelled incremental cost per QALY beyond the 3-month trial follow-up.