This has to be considered a pilot study from which obtain very initial data with omalizumab, a larger study with 10 patients, as suggested, would still be insufficient for a trial and  a larger population would be needed. It could even be argued that BPS/IC, a rare disease, perhaps is not so rare as it used to be regarded before, maybe 20 years ago.

In an experience similar to our study, montelukast, a leukotriene receptor antagonist commonly used in the treatment of allergic rhinitis and asthma, was initiated in a patient with IC, and a substantial improvement in urinary urgency and pain during therapy was noted (1). This improvement subsequently disappeared when montelukast was stopped. Currently this drug is FDA approved for use in the treatment and prevention of mild-to-moderate asthma and exercise-induced asthma, as well as treatment of seasonal and perennial allergic rhinitis.

 The author concludes that montelukast may be an effective treatment option in the management of interstitial cystitis and that further research is needed to substantiate this novel use.

A few observations can be made. In a survey study in the United States, 40.6 % of the patients with IC stated that they suffered from allergy and in a Swedish study 41-47% (2, 3). This is 2x more frequent than in the general population.

In a Japanese study (4), young IC patients (20-39 years) were compared with an older IC group (50-69 years). The study looked at the number of allergies, the type of IC symptoms ("painful type" or "frequency and urgency type"), skin tests, blood tests and the course of the IC following hydrodistension.  In two patients from the young group, IC was considered to be part of generalised allergic diseases. In 25 patients an association was assumed between IC and the allergy and in 15 of these the symptoms of allergy and IC alternated or ran parallel.

Eleven patients had multiple allergies. In the young patients, 86% had one or more allergies, in the older

patients this was 19%.

 In conclusion, I think  the hypothesis that allergy may play a role in the pathogenesis of BPS/IS remains to be proved, and research into this field should be encouraged.

DANIELE PORRU MD

1. Traut JL, Macdonald ES, Spangler ML, Saxena S. Montelukast for symptom control of interstitial cystitis. Ann Pharmacother. 2011 Sep;45(9):e49. Epub 2011 Aug 23.
2. Alagiri M, Chottiner S, Ratner V, et al. Interstitial cystitis: unexplained associations with other chronic disease and pain syndromes. Urology 1997;49:52-7.
3. Peeker R, Atanasiu L, et al. Intercurrent autoimmune conditions in classic and non-ulcer interstitial cystitis. Scand J Urol Nephrol 2003;37:60-3.
4. Yamada T. Significance of complications of allergic diseases in young patients with interstitial cystitis. Int J Urol 2003, 10 (suppl): 556-558.

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