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A systematic review of the quality and reporting standards of longitudinal biomarker studies in dementia and recommendations . C.W.Ritchie, L.Flicker, A. Noel-Storr, R.McShane. Background. Reporting standards drive better methodology
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A systematic review of the quality and reporting standards of longitudinal biomarker studies in dementia and recommendations C.W.Ritchie, L.Flicker, A. Noel-Storr, R.McShane
Background • Reporting standards drive better methodology • Claims about a diagnostic test should be based on body of data describing • Validation of new test against a gold standard • New prodromal criteria emphasise biomarker abnormality in patients with memory impairment to aid specificity to conversion.
Why ‘conversion’ as Gold Standard? • This is the critical clinical question. • Does my patient have Alzheimer’s disease causing their MCI? • Gold standards • Pathology in situ years before symptoms/dementia develops. Conversion to Alzheimer’s dementia verifies Alzheimer’s pathology. • Longitudinal – delayed verification.
General Aims: • To develop a series of DTA systematic reviews • Biomarkers (imaging and plasma/CSF proteins) • Neuropsychological tests • Specific aims of today: • Restricting to biomarkers: • To systematically review the weight of evidence: total numbers converting • The quality of the methodology and reporting
Methods • Stage 1 – Sensitive MEDLINE search from 2000 to June 2011 • 19,104 published abstracts/references • Stage 2 - Abstract review • Inclusion criteria • Biomarker of interest (Ab, tau, PET, or structural MRI) • Longitudinal design • Team of 9 medical students • ~2,250 references each • All students had a batch of 100 abstracts: kappa=0.62 (moderate to good) • Overlapping pairs of 100: kappa=0.62-0.75 (moderate to good)
Results: search MEDLINE (Ovid SP) 19104 500 Longitudinal 1032 Cross-sectional 17572 Not relevant (background/animal/review) 77 Ab 64 tau 44 PET 124 MRI Inter-assessor agreement Kappa: 0.62-0.7 202 references to studies for inclusion Accounts for multiple publications from same cohort 142 primary papers
Results: study size (1) 8 (6%) 79 (56%) 20 (14%) 35 (25%)
Results: STARD • CONSORT: consolidated standards for reporting trials • QUORUM: quality of reporting of meta-analyses • MOOSE: meta-analysis of observational studies in epidemiology • STARD: standards for reporting of diagnostic accuracy (2003)
STARD Item 17: Appropriate Time Interval Item 11: Blinding
Item 11: Blinding Describe whether or not the readers of the index tests and reference standard were blind (masked) to the results of the other test and describe any other clinical information available to the readers
Item 11: Blinding 32% 23%
Item 17: Time between tests Report time interval from the index tests to the reference standard, and any treatment administered between
STARDdem Phase 2 Phase 1 Phase 3 Discussion, collation, re-drafting Evaluation Delivery Complete
STARDdem Phase 2 Phase 1 Phase 3 Discussion, collation, re-drafting Evaluation Delivery
Phase 2: Delphi method (n=10) Discussion and item generation Discussion and item generation Round 1 Round 2 Round 3 Round 4 Round 5 2 papers Original STARD 3 papers Methods Original 2 papers STARDdem 3 papers Results 3 papers Methods Discussion and item generation Discussion and item generation Wider web-based development of consensus of extended STARD Criteria
STARDdem Phase 1 Phase 3 Phase 2 Evaluation Delivery Discussion