Effectiveness of diagnostic tests

Systematic review 1

Highly sensitive systematic electronic searches for this systematic review were undertaken by December 2005. The diagnostic accuracy review of diagnostics and screening tests included 40 studies totaling more than 48 000 participants' ≥ 40 years. The primary reference standard was confirmation of OAG at follow-up examination. Also considered was diagnosis of OAG requiring treatment. No studies were at low risk of bias. A small subset of eight studies was judged to have higher quality. Most potential screening tests reviewed had an estimated specificity of 85% or higher. No test was clearly most accurate, with only a few, heterogeneous studies for each test «Burr JM, Mowatt G, Hernández R ym. The clinical ef...»1.

Systematic review 2

A systematic review through October 6, 2011 was conducted from MEDLINE®, Embase, LILACS, and CENTRAL through October 6, 2011, and MEDLINE and CENTRAL (March 2, 2011) and screening of an existing database to identify relevant systematic review.

After the Burr et al. 2007 systematic review (above), 4,960 studies were identified, of which 83 studies addressing the accuracy of screening and diagnostic tests were eligible. The sensitivity of standard automated perimetry (SAP) was higher than Goldmann tonometry, similar to the Heidelberg retina tomograph (HRT), and lower than disc photos or frequency doubling technology (FDT) visual field testing. The specificity of SAP was higher than disc photos and FDT, similar to HRT, and lower than Goldmann tonometry. Some comparisons of tests could not be performed due to variability in populations and reported thresholds. No other studies were identified.

68% of studies were at high risk of spectrum bias (not representative of those who would receive the test in practice). 6% had differential verification bias (different reference standards). The candidate tests were interpreted without knowledge of reference standard in only 29% of studies. 48% of the studies did not include an explanation of withdrawals from the study, and 46% of the studies reported the number of uninterpretable test results. Only 3 of 83 studies included a population-based sample «Ervin AE, Boland MV, Myrowitz EH . Screening for G...»2.

Systematic review 3

A systematic search for this systematic review was conducted up to April 2010 to identify studies evaluating 5 new technologies (confocal scanning laser opthalmoscopy by Heidelberg Retina Tomography, optical coherence tomography [OCT], scanning laser polarimetry using GDx-VCC, frequency doubling technology, and blue-on-yellow automated perimetry). The reference standards were optic disc assessment or standard achromaticwhite-on-white perimetry. The review included cost analyses or full economic evaluation studies comparing both costs and consequences associated with these technologies.

Of the 410 unique citations retrieved by the search, 6 articles either presented a cost analysis of tests for glaucoma diagnosis or included a review of published economic studies. Of those, 3 studies presented a cost analysis of scanning lasers and OCT, mostly in terms of costs associated with the diagnostic equipment. However, differences in settings or methods made comparisons between these 3 studies difficult. One study indicated that time required to conduct the test may be an important element to consider in economic evaluations. Other reviews of economic studies of glaucoma screening identified in the search did not cite any published studies evaluating these new technologies.

Despite our extensive search, and in line with previous findings, no cost-effectiveness studies of the newer diagnostic tests could be identified «Tarride JE, Burke N, Hopkins RB ym. New glaucoma d...»3.

Review 4

A non-systematic review of the literature was conducted in PubMed by October 2010 with key words Glaucoma and cost. No randomized screening, diagnostic and follow-up trials were found of the clinical effectiveness nor cost-effectiveness of the optimum test set preventing visual disability «Tuulonen A. Economic considerations of the diagnos...»4.

On-going Finnish randomized screening trial

The on-going randomised prospective cohort study - Northern Finland Birth Cohort (NFBC) Eye Study – trial is designed to address the following questions: what is the best combination of diagnostic tests for detecting glaucoma in an unscreened population, what are the benefits and disadvantages of the screening to the individual and the society and is glaucoma screening both effective and cost-effective. The prevalence, incidence and risk factors of glaucoma and other eye diseases will be evaluated, as well as their impact on quality of life. A postal questionnaire covering extensively the medical and socioeconomical background was sent to the 10 300 subjects. The effectiveness and the cost-effectiveness of glaucoma screening will be calculated. The response rate of the questionnaire was 67% (n = 6 855). For the Eye Study the subjects were randomised to the screening group (50%) and the control group (50%). 871 randomised subjects had undergone the eye screening protocol by the end of April 2013. In the future, both groups (100%) will be examined. The screening protocol includes automated and manifest refraction, best corrected visual acuity, central corneal thickness, intraocular pressure, Humphrey 24-2 perimetry, stereoscopic optic nerve head (ONH) photography, retinal nerve fibre layer (RNFL) photography and imaging with Scanning Laser Ophthalmoscopy (HRT), Scanning Laser Polarimetry (GDx) and Optical Coherence Tomography (OCT).Two ophthalmologists evaluate the ONH and RNFL photographs and the visual fields independently. All suspected glaucoma cases are re-evaluated by two independent glaucoma experts. HRT, GDx and OCT findings are assessed separately.