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Inter-observer variation in image interpretation and prognostic importance of non-expansile lung in malignant pleural effusion

Research output: Contribution to journalArticle

Original languageEnglish
Article number13681
Number of pages7
Early online date21 Aug 2019
DateAccepted/In press - 30 Jul 2019
DateE-pub ahead of print (current) - 21 Aug 2019


Background and objective: Non-expansile lung (NEL) frequently complicates management of malignant pleural effusion (MPE) and is an important factor in clinical practice and trials. NEL is frequently diagnosed on a single radiographic observation, but neither the inter-observer agreement of this approach nor the prognostic importance of NEL in MPE have been reported. Methods: A multicentre retrospective cohort study was performed in 2 UK pleural centres. NEL was defined as <50% pleural re-apposition on post-drainage radiographs by primary and secondary assessors at each site. Inter-observer agreement was assessed by Cohen’s Kappa (). Kaplan-Meier methodology and multivariate Cox models were used to assess the prognostic impact of NEL vs no NEL and ‘Complete NEL’ vs ‘Complete expansion’, based on a single assessor’s results from each site. Results: NEL was identified by the primary assessor in 33/97 (34%) in Cohort 1 and 15/86 (17%) in Cohort 2. Inter-observer agreement between assessors was only fair-to-moderate (Cohort 1 0.38 (95% CI:0.21–0.55), Cohort 2 0.51 (95% CI:0.30–0.72)). In both cohorts, NEL was associated with shorter median overall survival (Cohort 1: 188 vs 371 days, Cohort 2: 192 vs 412 days). This prognostic association was independent in Cohort 1 (HR 2.19, 95% CI:1.31–3.66) but not Cohort 2 (HR 1.42, 95% CI:0.71–2.87). Survival was inferior in both cohorts in cases of ‘Complete NEL’ vs ‘Complete Expansion’. Conclusion: Radiographic NEL is common but inter-observer agreement is only fair-to-moderate. NEL is associated with adverse survival. These data do not support use of single radiographic assessments to classify NEL.

    Research areas

  • malignant pleural effusion, non-expansile lung, prognosis, trapped lung, unexpandable lung



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