title: Observer variability in RECIST-based tumour burden measurements: a meta-analysis.
abstract: BACKGROUND
  Response Evaluation Criteria in Solid Tumours (RECIST)-based tumour burden measurements involve observer variability, the extent of which ought to be determined.
  
  
  METHODS
  A literature search identified studies on observer variability during manual measurements of tumour burdens via computed tomography according to the RECIST guideline. The 95% limit of agreement (LOA) values of relative measurement difference (RMD) were pooled using a random-effects model.
  
  
  RESULTS
  Twelve studies were included. Pooled 95% LOAs of RMD in measuring unidimensional longest diameters of single lesions ranged from -22.1% (95% confidence interval [CI], -30.3% to -14.0%) to 25.4% (95% CI, 17.2% to 33.5%) between observers and -17.8% (95% CI, -23.6% to -11.9%) to 16.1% (95% CI, 10.1% to 21.8%) for a single observer. Pooled 95% LOAs of RMD in measuring the sum of multiple lesions ranged from -19.2% (95% CI, -23.7% to -14.9%) to 19.5% (95% CI, 15.2% to 23.9%) between observers, and -9.8% (95% CI, -19.0% to -0.3%) to 13.1% (95% CI, 3.6% to 22.6%) for a single observer. Pooled 95% LOA of RMD in calculating the interval change of tumour burden with a single lesion ranged from -31.3% (95% CI, -46.0% to -16.5%) to 30.3% (95% CI, 15.3% to 44.8%) between observers. Studies on calculating the interval change of tumour burden for a single observer or with multiple lesions were lacking.
  
  
  CONCLUSIONS
  Interobserver RMD in measuring single tumour burden and calculating its interval change may exceed the 20% cut-off for progression. Variability decreased when tumour burden was measured by a single observer or assessed by the sum of multiple lesions.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, South Korea.
authors.forename: Soon Ho
authors.initials: SH
authors.lastname: Yoon
authors.affiliation: Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
authors.forename: Kyung Won
authors.initials: KW
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, South Korea; Cancer Research Institute, Seoul National University, South Korea.
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Goo
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Dong-Wan
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Medicine, Seoul National University College of Medicine, Seoul, South Korea. Electronic address: hahns@snu.ac.kr.
authors.forename: Seokyung
authors.initials: S
authors.lastname: Hahn
mesh_terms: D006801:Humans; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D015588:Observer Variation; D066066:Response Evaluation Criteria in Solid Tumors; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: Measurement; Meta-analysis; Observer variation; Response Evaluation Criteria in Solid Tumours; Tumour burden