Clinical effectiveness of screening for age-related macular degeneration: A systematic review
Estimated Read Time: 8 minutes, 40 seconds
Originally Published: 16 November 2023
Source: PLOS ONE
Type of article: Clinical Research Summary
MedED Catalogue Reference: MOCT07
Category: Ophthalmology
Cross-reference: Gerontology
Keywords: AMD, Retinal Disease, OCT, CFP, blindness, burden of disease, public health
This is a summary of an original research article, reproduced under CC BY 4.0 DEED. Attribution 4.0 License. Links to the original study can be found below.
Key Take Aways
1. Globally, 200 million people are affected by AMD, resulting in significant individual, social and economic burdens.
2. Low- and middle-income countries are disproportionately impacted by the disease burden primarily due to a lack of resources and public health measures to diagnose and manage the condition.
3. Early detection of AMD is not always possible due to a lack of symptoms in the early stages. Screening for the disease is an essential step in managing its impacts.
4. While OCT is deemed the gold standard for AMD screening with superior results, its cost is a consideration compared to alternatives.
4. Telemedicine-based screening for AMD via remote testing may be a viable solution for early detection, particularly in moving forward, but research to date has been limited.
Overview | Objectives | Study Design | Findings | Summary | Limitations | Conclusion | Original Research | References
This is a summary of an original research article, reproduced under CC BY 4.0 DEED. Attribution 4.0 License. It does not replace the original work, which has been linked below.
Overview
An estimated 200 million people are affected by AMD globally. This figure is set to rise to 300 million by 2040, making the condition one of the most common causes of blindness. Recent research conducted in 2019 indicated that developing or low-income countries bear a higher burden of the disease, significantly impacting the individual's quality of life and the societies in which they function.2,3
It is important to note that there are currently no early or intermediate AMD treatments. Early detection is key to effectively managing the disease trajectory. However, the asymptomatic nature of the condition in its nascent state makes detection challenging. Screening in specific contexts could assist in this early detection, reducing the clinical and social impact of the disease.
Objectives
The researchers of this study review, Gomes & Curado et al., set out to assess the effectiveness of screening methods for early detection of AMD in adults aged 50 years or older.
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Study Design & Methods
Study Design
The study was a systematic review of existing clinical trials and comparative observational studies that reviewed AMD screening methods in individuals aged 50 years or older who presented at primary care, outpatient or hospital settings. It compared the study results of those who had received screening to individuals where no screening or other strategies had been implemented.
The study was registered on the PROSPERO (International Prospective Register of Systematic Reviews) platform under CRD42022315907
Eligible studies included randomized clinical trials (RCTs) and various comparative observational studies, such as quasi-experimental, cohort, cross-sectional, and case-control studies. The primary focus was analyzing the effectiveness of screening in the eligible population, the screening method used, and the outcomes assessed. Various screening methods were considered, including biomicroscopy, angiography, ophthalmoscopy, retinography, optical coherence tomography (OCT), and telemedicine-based screening.
Investigations that assessed participants with a confirmed diagnosis of AMD or other ocular diseases like glaucoma and diabetic retinopathy were excluded. Studies that investigated artificial intelligence techniques as a screening method and those lacking a control group were also excluded.
Intervention
The initial literature search resulted in 5,290 articles. After analysis, fifty-two of these were considered potentially eligible for the study. Three met the study criteria and were included in this systematic review.
Findings
The first trial under discussion was conducted by researchers Midena and Frizziero et al. in 2020.4 It was a retrospective observational study that compared OCT to CFP and the complementary use of both via population-based screening.
- They found that OCT provided a higher rate of gradable images ( 97.7%) when compared to CFP ( 524%). Clinical signs of AMD were identified in 10.4% of the OCT eyes compared to 7.4% of the eyes CPF, whereas the detection rate was higher in the CFP eyes (10.8%) compared to 8.7% of the OCT eyes.
- Concerning the complementary use of both screening methods, this study indicated that OCT could be considered complementary to CFP as it could classify gradable images compared to CPF.
- Overall, "..AMD was detected in 7.4% of eyes assessed by CFP, with 3.9% graded as early AMD (grade 2), 2.3% intermediate (grade 3) and 1.2% late AMD (grade 4). In comparison, the disease was detected in 1,615 (10.4%) of the gradable OCT images, with 282 (1.8%) classified as late AMD (grade 20)." 1
The second trial reviewed was a prospective observational study by researchers Fidalgo and Dabasia et al.5 Their analysis was conducted on a cohort of older subjects recruited from primary care, who underwent a series of tests aimed at the detection of life-threatening diseases, including analysed glaucoma, AMD and diabetic retinopathy.
- Regarding AMD screening, they found that OCT, which enables examination of the macula and optic nerve, exhibited a high level of sensitivity of 50% and specificity 73.4%.
- Sensitivity and specificity for visual acuity assessment (< 6/12) were 37.5% and 89.1%, respectively, and 60.4% and 64.3% for visual field analysis
- The study's findings were of limited value owing to the lack of information regarding the research tester.
The final study under investigation considered the viability of telemedicine-based screening for AMD via remote testing. Hadziahmetovic et al. conducted a prospective study comparing remote diagnostic imaging with in-person examinations for detecting AMD.6
- Results, analyzed by trained non-expert imagers remotely or by retinal specialists in person, suggested equivalent diagnostic performance.
- Sensitivity was high for individual or combined tests (94%), with OCT showing greater specificity (93%) than CFP (63%).
- A high rate of uninterpretable images in CFP remeant the tests had a lower positive predictive value than OCT (56% vs. 87%).
- When combined, OCT and CFP positive predictive values improved to 89%
- Both techniques demonstrated high negative predictive values: CFP was 95% versus OCT at 97%. The combined value for CFP and OCT was 97%
Summary
- The OCT data indicates effective disease detection, with telemedicine-based tests showing promising results comparable to conventional screening methods. However, caution is advised due to methodological issues and low supporting evidence, highlighting the need for careful interpretation of the data.
- The systematic review suggests that effective AMD screening involves using at least two imaging exam formats, with OCT being complementary to CFP due to its high yield. The recommendation is to employ a sequence of tests, starting with the least expensive and invasive and progressing to more sensitive and specific tests. This approach aims to enhance the screening and diagnosis of AMD, providing a set of imaging tests for comprehensive evaluation.
- The research highlights the utility of tests like OCT and OCT angiography (OCT-A) in detecting abnormalities not visible in CFP or fluorescein angiography. While OCT is deemed the gold standard for AMD screening with superior results, its cost is a consideration compared to alternatives. The suggestion is potentially recommending tests like CFP in the initial screening stage. Further primary studies with improved methodological design would be required to validate such recommendations.
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Limitations
Limitations of this study included the low quality of the available study data concerning evidence regarding outcomes of interest and the heterogeneity of the studies, which impacted accurate comparison.
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Conclusion
The researchers concluded that the data obtained from this systematic review did not allow them to draw any reliable inference regarding the efficiacy of early screening for AMD. The reasons included methodological problems and the low evidence of required outcomes in the studies reviewed.
While the evidence did not support a definitive conclusion, there is no doubt that screening for diseases such as AMD is of value, particularly in low-middle income countries, which carry a significant disease burden, including significant social and economic impacts. More research is required to understand the efficacy of such treatments concerning their costs and delivery schedule.
Reproduced under CC BY 4.0 DEED. Attribution 4.0 License
References
1.Gomes, D. F., Curado, D. D. S. P., Gomes, R. M., Leite, B. F., Ramos, M. C., & Silva, E. N. D. (2023). Clinical effectiveness of screening for age-related macular degeneration: A systematic review. PloS one, 18(11), e0294398. https://doi.org/10.1371/journal.pone.0294398
2. Vyawahare, H., & Shinde, P. (2022). Age-Related Macular Degeneration: Epidemiology, Pathophysiology, Diagnosis, and Treatment. Cureus, 14(9), e29583. https://doi.org/10.7759/cureus.29583
3. Jiang, B., Jiang, C., Li, J., & Lu, P. (2023). Trends and disparities in disease burden of age-related macular degeneration from 1990 to 2019: Results from the global burden of disease study 2019. Frontiers in public health, 11, 1138428. https://doi.org/10.3389/fpubh.2023.1138428
4. Midena E, Frizziero L, Torresin T, Todaro PB, Miglionico G, Pilotto E (2020) Optical coherence tomography and color fundus photography in the screening of age-related macular degeneration: A comparative, population-based study. PLoS One. pmid:3279708
5. Fidalgo BR, Dabasia P, Jindal A, Edgar DF, Ctori I, Peto T, et al (2019) Role of advanced technology in the detection of sight-threatening eye disease in a UK community setting. BMJ Open Ophthalmol 4:e000347. pmid:3190919
6. Hadziahmetovic M, Nicholas P, Jindal S, Mettu PS, Cousins SW (2019) Evaluation of a Remote Diagnosis Imaging Model vs Dilated Eye Examination in Referable Macular Degeneration. JAMA Ophthalmol 137:802–808. pmid:31095245
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