Interstitial cystitis, also known as painful bladder syndrome or IC/PBS, is a chronic inflammatory disease of the bladder causing long-term pelvic pain, urinary frequency and urgency. It can have a significant impact on lifestyle, work, relationships and emotional health 1.
One of the leading hypotheses for the cause of IC/PBS is based on a urine-tissue barrier disorder – an imbalance in the protective lining of the bladder (the urothelium) causing permeation of toxic urinary compounds into the bladder wall, inducing urgency, frequency and pain 2. Glycosaminoglycans (GAGs) play an important role in the structure of the urothelium by reinforcing the surface and reducing direct contact with urine. Consequently, GAGs are involved in the pathophysiology, diagnosis and treatment for IC/PBS.
GAG replacement therapy is widely used to treat or manage IC/PBS – with considerable response rates. However, controlled studies on IC/PBS treatment are rare and often heterogeneous due to difficult diagnostic criteria, multifactorial aetiology and poorly-defined pathogenesis. In 2008, Riedl et al. conducted a study to evaluate the efficacy of intravesical therapeutic hyaluronic acid (hyaluronan) – a natural constituent of the GAG layer – in IC/PBS 2.
Patient selection and method
Patients were included in this study if:
- They had a positive modified potassium test to confirm they had a urine-tissue barrier disorder – i.e. they showed a >30% reduction in maximal bladder capacity 2
- They were able to retain the instillations for a minimum of 2h
Since 2000, 121 female patients with a diagnosis of IC/PBS were treated with weekly instillations of 50cm3phosphate-buffered saline solution containing 40mg hyaluronate. This means that patients with a very low functional capacity (<50cm3) were not candidates in this study.
Instillations were continued until patients were free of IC/PBS symptoms or they had significantly improved. If up to 10 instillations had been performed with no improvement, then treatment was stopped.
Symptoms were recorded using a questionnaire to assess global-bladder or IC-related symptoms. The questionnaire used a visual analogue scale (VAS) rating from 0 (no symptoms) to 10 (maximal symptoms). Data was collected before initiation of therapy (pre-treatment) and again at a mean of 6.5 months after their last instillation. The post-treatment questionnaire asked patients about their symptoms at the time of their last instillation and at time of completion of the questionnaire. It also asked about overall impact of the therapy on their quality of life and if they would have it again.
Results
A positive and long-lasting impact of hyaluronan therapy on IC/PBS symptoms was evident in the assessment of pre-treatment and post-treatment VAS scores (see table 1). Pre-treatment VAS scores had a mean of 8.5, indicating severe symptoms. Post treatment, the mean VAS score was 3.5 showing a significant decrease (p<0.0001). At time of completion of the questionnaire, the VAS score remained stable at an average of 3.5 showing a long-term benefits of the treatment regimen.
Other key findings include:
- 85% of patients reported an improvement of more than or equal to 2 VAS units following instillation therapy
- 15% reported a VAS score as 0 at the end of instillation therapy
- 55% remained with no or minimal bladder symptoms after treatment
- 84% reported that their quality of life had improved significantly
- 86% would repeat hyaluronan instillations in the future if needed
Conclusions
In patients who discontinued the instillation regimen because their symptoms had significantly improved or disappeared, only 34.5% had to be reinstituted to maintain the therapeutic effect. Of note, patients in this study were treatment-naïve, having not received IC/PBS-specific therapy before. It may therefore be hypothesised that early GAG substitution can restore the urothelial or GAG defect.
It is also interesting to note that the patients in this study all had a functional capacity of at least 50cm3, therefore excluding those with a low capacity. Given the results of this study and empirical data 2showing the potential of intravesical therapy, further research into instillation volume and dosing regimens aimed at these patients should be considered. The formulation of Solatum GAG replenisher as a standard 40mg dose in a lower 20cm3(20ml) volume makes it suitable for instillation and a potential treatment for those with a low functional capacity.
Table 1. VAS symptom scores
| PARAMETER | HYALURONAN-TREATED PATIENTS (n=121) |
| VAS scores (mean ± SD (minimum−maximum)) | |
| Pre-treatment | 8.5 ± 1.7 (4.0−10.0) |
| Post treatment | 3.5 ± 2.7 (0.0−10.0) |
| Follow-upa | 3.5 ± 2.7 (0.0−10.0) |
| Mean VAS score changes (mean ± SD (minimum−maximum)) | |
| Pre-treatment to posttreatment | −5.0 ± 2.8b(−10.0−0.0) |
| Posttreatment to follow-up | +0.0 ± 2.3 |
| Pre-treatment to follow-up | −5 ± 2.9 (−10.0−1.0) |
| Patient changes between pre-treatment and follow-up | |
| Improved ≥2 VAS units | 103 (85%) |
| Improved <2 VAS units | 6 (5%) |
| Unchanged | 12 (10%) |
VASVisual analogue scale, SDstandard deviation
aFollow-up assessment refers to the VAS score recorded at the time of completion of the questionnaire
bPre-treatment VAS score was significantly different (p<0.0001) from post treatment and follow-up scores; scores between posttreatment and follow-up were not significantly different (p=0.7036)
References
- NHS, “Interstitial cystitis,” 2018. [Online]. Available: https://www.nhs.uk/conditions/interstitial-cystitis/. [Accessed 20 August 2019].
- C. R. Riedl, P. F. Engelhardt and K. L. Daha, “Hyaluronan treatment of interstitial cystitis/painful bladder syndrome,” International Urogynecology Journal, no. 19, pp. 717-721, 2008.
- L. K. Daha, C. R. Riedl, G. Hohlbrugger, M. Knoll, P. F. Engelhardt and H. Pflüger, “Comparative Assessment of Maximal Bladder Capacity, 0.9% NaCl Versus 0.2 M Kcl, for the Diagnosis of Interstitial Cystitis: A Prospective Controlled Study,” The Journal of Urology, vol. 170, no. 3, pp. 807-809, 2003.
- G. Karsenty, W. AlTaweel, S. Hajebrahimi and J. Corcos, “Efficacy of Interstitial Cystitis Treatments: A Review,” European Association of Urology, vol. 4, pp. 47-61, 2006.