[Available evidence about efficacy of different restoring agents of glycosaminoglycans for intravesical use in interstitial cystitis]

Abstract

Objectives: To compare the different endovesical therapeutic regimes in terms of clinical effectiveness based on glycosaminoglycan replenishment agents (RA-GAG) available on the market in Spain.

Material and methods: A bibliographic analysis was made of the studies published in Medline from 1996 to 2012 on RA-GAG of application in the bladder, placing emphasis on the clinical results. A post-hoc comparison was made of the efficacy of this treatment in the studies conducted in patients with interstitial cystitis in different conditions by calculating the effect sizes to analyze improvement on the pain visual analogue scale (VAS) and clinical response rate. The number of patients needed to treat (NNT) for the different agents was calculated based on the odds ratio and associated economic implications.

Results: The globally available evidence is scarce. There are 38 articles about RA-GAGs in different indications, 71 of them in interstitial cystitis and only 8 may assist in establishing a comparison between the results presented. The treatments used were placebo, 0.8% high molecular weight hyaluronic acid (Cystistat(®)), 2% chondroitin sulfate sodium (Uracyst(®)) and a combination of 1.6% low molecular weight hyaluronic acid plus 2% chondroitin sulfate (Ialuril(®)), between 6 and 12 instillations. Another low molecular weight hyaluronic acid preparation (Uromac(®)) lacks any scientific evidence. All the therapeutic elements studied show a mean score decrease on the pain VAS and increase in the rate of post-treatment response. The NNT for the treatments that are statistically more beneficial over placebo ranges from 1.6 and 4.1. The post-hoc comparison of the response rates has established that Cystistat(®) 12 instillations (OR 18.8; 95% CI 6.4-57.2; P=.001) or 10 instillations (OR 19.2; 95% CI 5.3-75.3; P=.001) are the treatment regimes that obtain maximum effectiveness. In both cases, the NNT was 1.6.

Conclusions: This study has multiple limitations inherent to the nature of the design. However, although the available literature is scarce, it shows that there are differences regarding the clinical effectiveness of the different agents and regimes used for endovesical treatment of interstitial cystitis. These differences also entail economic type implications.