Study objectives: To assess the accuracy of pleural
fluid (PF) pH in predicting duration of survival of patients with
malignant pleural effusions.
Design: Analysis of
patient-level data from nine sources retrieved from a MEDLINE search
and correspondence with primary investigators.
selection: Published and unpublished studies that report PF pH
values and duration of survival of patients with malignant pleural
Data collection and analysis: Primary
investigators supplied patient-level data (n = 417), which was
examined by receiver operating characteristic (ROC) analysis, logistic
regression, and survival time modeling to determine the utility of PF
pH for predicting survival compared with other clinical factors. The
primary investigations were graded for study design.
Measurements and results: Median survival (n = 417) was
4.0 months: PF pH (p < 0.0039) was an independent predictor of
survival duration. A PF pH test threshold ≤ 7.28 had the highest
accuracy for identifying poor 1-, 2-, and 3-month survivals. The
predictive accuracies of PF pH (area under the ROC curve range, 0.571
to 0.662) and a PF pH–high-risk tumor (lung, soft tissues, renal,
ovary, gastrointestinal, prostate, and oropharynx) model (odds ratio
range, 2.91 to 6.67), however, were modest for predicting 1-, 2-, and
3-month survival. Only 54.4% and 62.7% of patients identified by PF
pH ≤ 7.28 or the PF pH–high-risk tumor model to die within 3 months
were correctly classified. Weaknesses of the primary data were
Conclusions: PF pH has insufficient
predictive accuracy for selecting patients for pleurodesis on the basis
of estimated survival.