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19/71 OCT-angiography for the detection of neovascular age-related macular degeneration
The aim of the HTA Programme is to ensure that high quality research information on the effectiveness, costs and broader impact of health technology is produced in the most efficient way for those who use, manage, provide care in or develop policy for the NHS. Topics for research are identified and prioritised to meet the needs of the NHS. Health technology assessment forms a substantial portfolio of work within the National Institute for Health Research and each year about fifty new studies are commissioned to help answer questions of direct importance to the NHS. The studies include both primary research and evidence synthesis.
Research Question: What is the diagnostic accuracy of optical coherence tomography angiography for the detection of neovascular age related macular degeneration?
1.Technology: Optical coherence tomography angiography (OCT-angiography). Applicants should specify and justify the OCT-angiography technology of their choice, which should be of high standard and available in the NHS.
2.Patient group: Patients presenting with suspected neovascular age-related macular degeneration (AMD) in the first or second eye.
Applications are encouraged which include recruitment from geographic populations with high disease burden which have been historically underserved by research activity in this field.
3.Setting: Secondary care.
4.Comparators: Optical coherence tomography (OCT); fundus angiography (fluorescein and/or indocyanine green as required).
5.Study design: A prospective diagnostic accuracy study with an internal pilot phase to test the ability to recruit and the availability of a sufficient number of trained OCT-angiography image readers. Clear stop/go criteria should be provided to inform progression from pilot to full study. Participants should undergo OCT-angiography, OCT, and fundus angiography. The study should include an assessment and validation of currently used criteria in the interpretation of OCT-angiography images.
6.Important outcomes: A comprehensive assessment of measures of diagnostic accuracy of OCT, OCT-angiography and fundus angiography, both alone and in combinations; false positive and false negative results; intra- and interrater agreement.
Other outcomes and outputs: Validation of criteria for the OCT-angiography based diagnosis of neovascular AMD; limitations of OCT-angiography use; adverse events; a simple economic evaluation of the tests and test combinations (e.g. cost per case identified).
Age-related macular degeneration (AMD) is described as ageing changes without any other obvious cause that occur in the central area of the retina (macula), sometimes with new blood vessel formation (wet AMD). It is a painless condition that generally leads to the gradual impairment of vision, but can sometimes cause a rapid reduction in vision. The condition predominantly affects the central vision, which is used for reading and recognising faces.
AMD is the most common cause of visual impairment in the developed world, and the most common cause of certification for vision impairment in the UK. Due to its very high prevalence, the need for monitoring and treatment of patients with late/advanced disease causes a significant burden to patients and the NHS.
Currently there is no treatment available for the most common type of AMD ('dry' AMD), but various treatments are available for the less common 'wet' form of AMD (also called neovascular or exudative AMD), which is characterised by the formation of new vessels inside the eye and leakage from these vessels. Damage caused by AMD is irreversible, but disease progression in wet AMD can be slowed or delayed. Therefore, early diagnosis and treatment of wet AMD is paramount.
Fundus angiography (FA) is currently considered the 'gold standard' for the diagnosis of wet AMD. This test requires intravenous application of dye in order to visualise vessel formation and leakage. Alternatively, optical coherence tomography (OCT) may be used. This non-invasive technology provides high-resolution images of the retinal layers revealing their separation when there is exudation (leakage). However, the technology does not visualise the abnormal vascular complexes present in wet AMD. Hence, additional confirmatory FA may still be required.
More recently, non-invasive OCT-angiography technology has become available that enables clinicians to inspect blood vessels within the eye without the use of intravenous dye. Images can be acquired within a few minutes by a trained imaging technician, and, unlike FA, OCT-angiography has no side effects. In addition, routine use of OCT-angiography instead of FA is thought to save staff time, although some of this may be outweighed by the time required to read and analyse the images acquired through OCT-angiography.
OCT-angiography technology is available in many NHS centres and is rapidly being adopted by clinicians. However, to date, there is only a small body of moderate quality evidence to suggest OCT-angiography is sufficiently accurate in the detection of neovascular AMD and has the potential to replace FA. Most studies do not fully report measures of diagnostic accuracy, data on the accuracy of OCT-angiography in combination with OCT compared to the current multimodal OCT+FA strategy are scarce, and image readers were often not masked.
Research is therefore needed to provide high quality evidence to inform future guidelines and clinical practice.