Factors associated with treatment outcomes after intravesical hyaluronic acid therapy in women with refractory interstitial cystitis

Background: Bladder instillation of hyaluronic acid (HA) is an acceptable treatment for bladder pain syndrome/interstitial cystitis (BPS/IC). The treatment is limited by a high proportion of non-responders (~30%–40%). Here, we aimed to evaluate predisposing factors associated with treatment outcomes. Methods: This is a prospective multicenter study. We enrolled a total of 137 (out of 140) women with refractory IC. They all underwent a standard protocol of 6-month intravesical HA therapy (initial 4 weeks, once weekly, followed by once monthly). To assess the outcomes, we used the pain Visual Analog Scale (Pain-VAS), Interstitial Cystitis Symptom and Problem Index (ICSI & ICPI), and a scaled Global Response Assessment (GRA). Results: The age of patients was 47.6 ± 27.5 (range 24–77) years. We found statistically significant improvement (p < 0.001) in the Pain-VAS and the ICSI & ICPI scores both after the initial 4-weekly instillations and at the end of 6-month treatment. Those who reported moderate/marked improvement on GRA at the 2 follow-up visits were considered responders: 39.4% (n = 54) at the first follow-up, and 59.9% (n = 82) at the second follow-up. No remarkable side effect was noted. After statistical analyses, treatment outcomes on GRA were positively associated with baseline functional bladder capacity and with Pain-VAS scores. The initial treatment responses optimally (p < 0.001) predicted final treatment outcomes (McNemar). Conclusion: Intravesical HA therapy is safe and effective for most (~60%) of our patients with refractory IC. Functional bladder capacity and Pain-VAS scores before treatment, and the early treatment responses are helpful predictors of treatment outcomes.