MedWire News: The Bacillus Calmette-Guerin (BCG) vaccine should not be used as a routine treatment for interstitial cystitis (IC), the Interstitial Cystitis Clinical Trials group says.
In a follow-up study of IC patients who responded to BCG or placebo in an initial double-blind trial, the researchers found that BCG responders showed a durable response to the vaccine that was "essentially the same" as that seen for placebo responders.
The etiology of IC, a chronic condition characterized by bladder pain and storage symptoms in association with cystoscopic findings, is unknown and treatment remains suboptimal, the researchers explain.
The group, which was set up by the National Institutes of Health, conducted an initial 34-week randomized, double-blind, placebo-controlled trial of intravesical BCG, and reported a similar response in each treatment arm.
The current trial involved a subset of the participants who responded to BCG or placebo in the former trial. In all, 38 patients were followed-up for a further 34 weeks.
At week 68, 12 (75%) of the 16 participants who responded to placebo and 19 (86%) of the 22 who responded to BCG said they were still "moderately or markedly improved."
Scores for symptoms, including pain, urgency, and 24-hour frequency, were also "generally maintained" after follow-up in both groups.
Reporting in the Journal of Urology, Kathleen Propert (University of Pennsylvania, Philadelphia, USA) and colleagues say they were "interested" to find that a high proportion of patients who responded to intravesical saline administration maintained the response at follow-up.
"Although spontaneous symptom remission is frequently mentioned in IC cases, this result is provocative," they say.
"It is distinctly unusual to see long-lasting dramatic symptom improvement in such refractory cases in the absence of specific therapy.
"It suggests that the placebo response in IC may also be long term, especially for invasive modes of administration of blinded treatment."
The authors also say that the study, which was an observational study of just a subgroup of the original set of patients, may have involved selection bias.
They conclude: "These longer term results provide more evidence that BCG should not be routinely used for IC."
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