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

Geoffrey A Martin, Andrew C Kidd, Selina Tsim, Paul Halford, Anna Bibby, Nick A Maskell, Kevin G Blyth

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
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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.
Original languageEnglish
Article number13681
Number of pages7
Early online date21 Aug 2019
Publication statusE-pub ahead of print - 21 Aug 2019


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

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