title: Prognostic value of pleural fluid pH in malignant epithelial mesothelioma after talc poudrage.
abstract: BACKGROUND
  Current staging schemes for malignant mesothelioma are inadequate. The most accurate staging may require pneumonectomy - a procedure associated with many complications. The pH of pleural fluid (ppH) predicts survival in non-mesotheliomatous malignant pleural effusions, suggesting that this noninvasive test might be useful for prognostication in malignant mesothelioma.
  
  
  OBJECTIVE
  It was the aim of this study to determine whether baseline ppH correlates with survival in malignant epithelial pleural mesothelioma.
  
  
  METHODS
  We reviewed survival data in patients treated with thoracoscopic talc pleurodesis whose final diagnosis was epithelial malignant pleural mesothelioma and whose chart recorded a ppH determination performed just before thoracoscopy. We monitored 26 patients until April 2002 (25 of these patients died), identifying cutoff ppH values that discriminate best for survival; Cox proportional hazards models were recursively run by increasing the ppH cutoff value by 0.02 each time.
  
  
  RESULTS
  The mean follow-up time was 19+/-14 months. Mean ppH was 7.30+/-0.09, and median ppH was 7.32. Several cutoff points correlated with a statistically significant difference in survival, but ppH 7.32 was associated with the greatest value for the area under the curve. Patients with ppH>.32 lived a median of 21.2 months (95% confidence interval 16.5-30.0 months) after diagnosis compared with patients who had ppH <or=7.32 and lived a median of 13.4 months (95% confidence interval 4.5-16.2 months; p=0.0194).
  
  
  CONCLUSIONS
  Baseline ppH correlates with survival in epithelial mesothelioma patients treated palliatively with pleurodesis by thoracoscopic talc poudrage. This noninvasive test - ppH - should be included when staging patients with malignant mesothelioma.
authors: Department of Internal Medicine, Kaiser Permanente Medical Center, Harbor City, Calif. 90275, USA. y.aelony@cox.net
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