EFFICACY OF PENTOSAN POLYSULFATE IN THE TREATMENT OF INTERSTITIAL CYSTITIS - A METAANALYSIS

Objectives. To determine the efficacy of pentosan polysulfate (Elmiron ) compared to placebo in the treatment of interstitial cystitis. Metho ds. The data sources used were MEDLINE, Excerpta Medica, and Internati onal Pharmaceutical Abstracts databases, and the manufacturer. Bibliog raphies of articles obtained were reviewed. The keywords used were pen tosanpolysulfate, pentosanpolysulfate sodium, and pentosan. inclusion criteria were blinded selection of English language, prospective, rand omized, placebo-controlled comparative trials, greater than or equal t o 8 weeks' duration; greater than or equal to 300 mg daily; adult huma ns with greater than or equal to 1 symptoms including pain, urgency, f requency, and nocturia; symptoms for greater than or equal to 12 month s; normal urinalysis; negative findings for urine culture and cytology . Exclusion criteria were hemorrhagic cystitis; drug-, microbial-, or radiation-induced cystitis; carcinoma in situ; other influencing disea ses. The outcome of success was defined as a greater than or equal to 50% decrease in pain, urgency, frequency, and nocturia. The number of successes was extracted by blinded investigators, treating withdrawals as failures. The percentage difference in success rates of pentosan p olysulfate and placebo, and the number needed to treat (NNT) were dete rmined for each variable; P values and 95% confidence intervals (Cls) were determined for combined data. Homogeneity of effect was determine d by calculating Q (chi-squared). Article quality was assessed using t he Chalmers scale to determine if quality affected outcome. Effective inter-rater reliability was determined using Rosenthal's method. Signi ficance was set at P <0.05. Results. Four studies were included. Data were extracted from all four studies for pain (n = 398), three for urg ency (n = 306), two for frequency (n = 160), and one study for nocturi a (n = 106). The differences (95% confidence limits) were pain: 16.6% (95% CI 8%, 25%), NNT = 7; urgency: 13.0% (1.0%, 25%), NNT = 7.5; freq uency: 16.7% (2.3%, 31.1%), NNT = 6; nocturia: -1% (-19.8%, 21.8%). P values from homogeneity tests were not significant. Mean quality score s were 63.8%, 48.1%, 50.4%, and 65.6%, respectively, in the four studi es; the effective inter-rater reliability was 0.96. Results did not di ffer when weighted by quality score. Conclusions. Pentosan polysulfate is more efficacious than placebo in the treatment of pain, urgency, a nd frequency associated with interstitial cystitis. Pentosan polysulfa te is not significantly different from placebo in treating nocturia as sociated with interstitial cystitis. (C) 1997, Elsevier Science Inc. A ll rights reserved.