Potassium sensitivity test (PST) as a measurement of treatment efficacy of painful bladder syndrome/interstitial cystitis: a prospective study with cyclosporine A and pentosan polysulfate sodium.

AIMS: Potassium sensitivity test (PST) has been used as an optional tool in diagnosing painful bladder syndrome/interstitial cystitis (PBS/IC). The role of PST in the follow-up of patients with PBS/IC is elusive. We performed PST before and after treatment of PBS/IC with cyclosporine A (CyA) or pentosan polysulfate sodium (PPS), to test whether the result of repeated PST correlates with alleviation of PBS/IC-related symptoms.

MATERIALS AND

METHODS

Sixty-four patients who participated in a randomized clinical study comparing CyA and PPS in the treatment of PBS/IC were recruited to the present study. Patients underwent 0.4 M PST before and after 6 months of treatment. The primary end point was a change from positive PST to negative among patients who responded to both treatments determined by global response assessment (GRA).

RESULTS

Potassium sensitivity test (PST) was more likely to change from positive to negative among patients who responded to their treatment according to GRA (P < 0.001). The PST change follows the clinical course (ICSI score, voiding frequency, VAS score), which was more beneficial in the CyA-treated patients.

CONCLUSIONS

Potassium sensitivity test (PST) reflects symptom severity of PBS/IC patients. Change of pre-treatment positive PST to negative correlates well with clinical alleviation of PBS/IC-related symptoms. In patients with persistent symptoms it may be painful and does not offer additional information. Thus, we do not recommend PST to be used as a routine clinical test in monitoring of PBS/IC treatment efficacy.