title: Automated imaging technologies for the diagnosis of glaucoma: a comparative diagnostic study for the evaluation of the diagnostic accuracy, performance as triage tests and cost-effectiveness (GATE study).
abstract: BACKGROUND
  Many glaucoma referrals from the community to hospital eye services are unnecessary. Imaging technologies can potentially be useful to triage this population.
  
  
  OBJECTIVE
  To assess the diagnostic performance and cost-effectiveness of imaging technologies as triage tests for identifying people with glaucoma.
  
  
  METHODS
  Within-patient comparative diagnostic accuracy study. Markov economic model comparing the cost-effectiveness of a triage test with usual care.
  
  
  METHODS
  Secondary care.
  
  
  METHODS
  Adults referred from the community to hospital eye services for possible glaucoma.
  
  
  METHODS
  Heidelberg Retinal Tomography (HRT), including two diagnostic algorithms, glaucoma probability score (HRT-GPS) and Moorfields regression analysis (HRT-MRA); scanning laser polarimetry [glaucoma diagnostics (GDx)]; and optical coherence tomography (OCT). The reference standard was clinical examination by a consultant ophthalmologist with glaucoma expertise including visual field testing and intraocular pressure (IOP) measurement.
  
  
  METHODS
  (1) Diagnostic performance of imaging, using data from the eye with most severe disease. (2) Composite triage test performance (imaging test, IOP measurement and visual acuity measurement), using data from both eyes, in correctly identifying clinical management decisions, that is 'discharge' or 'do not discharge'. Outcome measures were sensitivity, specificity and incremental cost per quality-adjusted life-year (QALY).
  
  
  RESULTS
  Data from 943 of 955 participants were included in the analysis. The average age was 60.5 years (standard deviation 13.8 years) and 51.1% were females. Glaucoma was diagnosed by the clinician in at least one eye in 16.8% of participants; 37.9% of participants were discharged after the first visit. Regarding diagnosing glaucoma, HRT-MRA had the highest sensitivity [87.0%, 95% confidence interval (CI) 80.2% to 92.1%] but the lowest specificity (63.9%, 95% CI 60.2% to 67.4%) and GDx had the lowest sensitivity (35.1%, 95% CI 27.0% to 43.8%) but the highest specificity (97.2%, 95% CI 95.6% to 98.3%). HRT-GPS had sensitivity of 81.5% (95% CI 73.9% to 87.6%) and specificity of 67.7% (95% CI 64.2% to 71.2%) and OCT had sensitivity of 76.9% (95% CI 69.2% to 83.4%) and specificity of 78.5% (95% CI 75.4% to 81.4%). Regarding triage accuracy, triage using HRT-GPS had the highest sensitivity (86.0%, 95% CI 82.8% to 88.7%) but the lowest specificity (39.1%, 95% CI 34.0% to 44.5%), GDx had the lowest sensitivity (64.7%, 95% CI 60.7% to 68.7%) but the highest specificity (53.6%, 95% CI 48.2% to 58.9%). Introducing a composite triage station into the referral pathway to identify appropriate referrals was cost-effective. All triage strategies resulted in a cost reduction compared with standard care (consultant-led diagnosis) but with an associated reduction in effectiveness. GDx was the least costly and least effective strategy. OCT and HRT-GPS were not cost-effective. Compared with GDx, the cost per QALY gained for HRT-MRA is £22,904. The cost per QALY gained with current practice is £156,985 compared with HRT-MRA. Large savings could be made by implementing HRT-MRA but some benefit to patients will be forgone. The results were sensitive to the triage costs.
  
  
  CONCLUSIONS
  Automated imaging can be effective to aid glaucoma diagnosis among individuals referred from the community to hospital eye services. A model of care using a triage composite test appears to be cost-effective.
  
  
  CONCLUSIONS
  There are uncertainties about glaucoma progression under routine care and the cost of providing health care. The acceptability of implementing a triage test needs to be explored.
  
  
  BACKGROUND
  The National Institute for Health Research Health Technology Assessment programme.
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK.
authors.forename: Augusto
authors.initials: A
authors.lastname: Azuara-Blanco
authors.affiliation: Health Services Research Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: Katie
authors.initials: K
authors.lastname: Banister
authors.affiliation: Robertson Centre for Biostatistics, University of Glasgow, Glasgow, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Boachie
authors.affiliation: Health Economics Group, Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: McMeekin
authors.affiliation: Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK.
authors.forename: Joanne
authors.initials: J
authors.lastname: Gray
authors.affiliation: School of Medicine, University of St Andrews, St Andrews, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Burr
authors.affiliation: Vision and Eye Research Unit, Postgraduate Institute, Anglia Ruskin University, Cambridge, UK.
authors.forename: Rupert
authors.initials: R
authors.lastname: Bourne
authors.affiliation: National Institute of Health Research Biomedical Research Centre, Moorfields Eye Hospital, London, UK.|University College London Institute of Ophthalmology, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Garway-Heath
authors.affiliation: St Paul's Eye Unit, Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Batterbury
authors.affiliation: Health Economics Research Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Hernández
authors.affiliation: Health Services Research Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: Gladys
authors.initials: G
authors.lastname: McPherson
authors.affiliation: Health Services Research Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: Ramsay
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cook
mesh_terms: D000368:Aged; D003362:Cost-Benefit Analysis; D003941:Diagnostic Techniques, Ophthalmological / Q000191:economics*; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D019057:Quality-Adjusted Life Years; D057109:Scanning Laser Polarimetry; D012680:Sensitivity and Specificity; D013673:Technology Assessment, Biomedical; D041623:Tomography, Optical Coherence / Q000379:methods*; D014218:Triage / Q000191:economics* / Q000379:methods; D058609:Visual Field Tests / Q000379:methods