Chest
Volume 117, Issue 1, January 2000, Pages 79-86
Journal home page for Chest

Clinical Investigations
PLEURAL DISEASE
Pleural Fluid pH as a Predictor of Survival for Patients With Malignant Pleural Effusions

https://doi.org/10.1378/chest.117.1.79Get rights and content

Study objectives

To assess the accuracy of pleuralfluid (PF) pH in predicting duration of survival of patients withmalignant pleural effusions.

Design

Analysis ofpatient-level data from nine sources retrieved from a MEDLINE searchand correspondence with primary investigators.

Studyselection

Published and unpublished studies that report PF pH values and duration of survival of patients with malignant pleuraleffusions.

Data collection and analysis

Primaryinvestigators supplied patient-level data (n = 417), which wasexamined by receiver operating characteristic (ROC) analysis, logisticregression, and survival time modeling to determine the utility of PFpH for predicting survival compared with other clinical factors. Theprimary investigations were graded for study design.

Measurements and results

Median survival (n = 417) was4.0 months: PF pH (p < 0.0039) was an independent predictor ofsurvival duration. A PF pH test threshold ≤ 7.28 had the highestaccuracy for identifying poor 1-, 2-, and 3-month survivals. Thepredictive accuracies of PF pH (area under the ROC curve range, 0.571to 0.662) and a PF pH–high-risk tumor (lung, soft tissues, renal, ovary, gastrointestinal, prostate, and oropharynx) model (odds ratiorange, 2.91 to 6.67), however, were modest for predicting 1-, 2-, and3-month survival. Only 54.4% and 62.7% of patients identified by PFpH ≤ 7.28 or the PF pH–high-risk tumor model to die within 3 monthswere correctly classified. Weaknesses of the primary data wereidentified.

Conclusions

PF pH has insufficientpredictive accuracy for selecting patients for pleurodesis on the basisof estimated survival.

Section snippets

Materials and Methods

The study was approved by the Institutional Review Board for Human Research of the Medical University of South Carolina. Pertinent articles that contained data on pH and survival for patients with malignant pleural effusions were identified by a MEDLINE search that used the following search terms: pH, PF, pleural effusions, pleural malignancy, malignant effusions, and pleurodesis. Articles in the authors’ files and references of retrieved articles were also reviewed. Retrieved articles were

Data Sources

The search identified nine sources with available data 1, 47, 1516, 1718, 19, 20 reported by seven primary investigators and one unpublished data set (F. Rodriguez-Panadero, MD, personal communication). An additional study that reported PF pH and survival in 131 patients with malignant effusions was identified, but the primary investigator stated that the primary data were no longer available.21

The data sources contained information on PF pH collected from 417 patients. We previously reported

Discussion

Our analysis of individual patient-level data demonstrates that PF pH has limited clinical utility for selecting patients for pleurodesis on the basis of predicted survival. Among the patient characteristics available for analysis, only pH and tumor type were independent predictors of poor short-term survival. Patients with a pH ≤ 7.28 had a 3-month survival of 38.9% compared with 61.6% for patients with a pH > 7.28. Although pH was a significant predictor of duration of survival and calibrated

ACKNOWLEDGMENTS

The authors thank the investigators who performed the primary investigations for providing their patient-level data. We also thank Drs. Steven A. Sahn and Marc Silverstein for reviewing the manuscript.

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