Pharmacological management of overactive bladder : a systematic and critical review of published economic evaluations

Overactive bladder is a common condition, with recent findings estimating the prevalence in adults at about 15%. Symptoms, including urinary urgency, high voiding frequency and urge incontinence, have been shown to decrease patients' quality of life. Given its high prevalence, the economic burden of overactive bladder is also substantial, with a recent estimate placing the annual cost in the US at 9.1 billion US dollars (year 2000 values). The objective of this review is to provide a critical appraisal of published economic evaluations of pharmacological and non-pharmacological treatments for overactive bladder. Published economic evaluations of treatments for overactive bladder have focused entirely on pharmacological treatments -- mainly on the two most commonly used drugs, oxybutynin and tolterodine, each of which is available in immediate- and extended-release formulations. Ten economic evaluations (more than half are cost-effectiveness studies) have been published. Modelling with decision trees or Markov models has been the predominant method. Evaluations comparing drug therapy with no treatment have concluded that drug therapy is cost effective. Analyses comparing the formulations of oxybutynin and tolterodine have produced highly inconsistent results, largely due to the sources of data employed for effectiveness and treatment discontinuation rates. There are no evaluations of drugs relative to non-pharmacological treatment, and there are other significant gaps in the economic evaluations of treatment to date. These include gaps resulting from a lack of reliable data on the performance of these drugs in real-world settings, particularly data on long-term persistence with treatment. A more definitive pharmacoeconomic comparison of oxybutynin and tolterodine formulations, incorporating all available clinical data, and other treatment options would help direct treatment.