Dataset Information

Prevalence of age-related macular degeneration in Nakuru, Kenya: a cross-sectional population-based study.

ABSTRACT:

Background

Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population.

Methods and findings

In a population-based cross-sectional survey in the Nakuru District of Kenya, 100 clusters of 50 people 50 y of age or older were selected by probability-proportional-to-size sampling between 26 January 2007 and 11 November 2008. Households within clusters were selected through compact segment sampling. All participants underwent a standardised interview and comprehensive eye examination, including dilated slit lamp examination by an ophthalmologist and digital retinal photography. Images were graded for the presence and severity of AMD lesions following a modified version of the International Classification and Grading System for Age-Related Maculopathy. Comparison was made between slit lamp biomicroscopy (SLB) and photographic grading. Of 4,381 participants, fundus photographs were gradable for 3,304 persons (75.4%), and SLB was completed for 4,312 (98%). Early and late AMD prevalence were 11.2% and 1.2%, respectively, among participants graded on images. Prevalence of AMD by SLB was 6.7% and 0.7% for early and late AMD, respectively. SLB underdiagnosed AMD relative to photographic grading by a factor of 1.7. After controlling for age, women had a higher prevalence of early AMD than men (odds ratio 1.5; 95% CI, 1.2-1.9). Overall prevalence rose significantly with each decade of age. We estimate that, in Kenya, 283,900 to 362,800 people 50 y and older have early AMD and 25,200 to 50,500 have late AMD, based on population estimates in 2007.

Conclusions

AMD is an important cause of visual impairment and blindness in Kenya. Greater availability of low vision services and ophthalmologist training in diagnosis and treatment of AMD would be appropriate next steps. Please see later in the article for the Editors' Summary.

SUBMITTER: Mathenge W

PROVIDER: S-EPMC3576379 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Publications

Prevalence of age-related macular degeneration in Nakuru, Kenya: a cross-sectional population-based study.

Mathenge Wanjiku W Bastawrous Andrew A Peto Tunde T Leung Irene I Foster Allen A Kuper Hannah H

PLoS medicine 20130219 2

<h4>Background</h4>Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population.<h4>M ...[more]

PMID: 23431274

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Project description:ImportanceThe incidence of age-related macular degeneration (AMD) is unknown in Africa.ObjectiveTo estimate the 6-year cumulative incidence and progression of AMD in older adults (≥50 years old) in Nakuru, Kenya.Design, setting, and participantsThis study assessed a population-based cohort with 6-year follow-up of 4414 participants who had a complete assessment. Random cluster sampling with probability proportionate to size procedures was used to select a representative, cross-sectional sample of adults 50 years and older from January 26, 2007, through November 11, 2008. A 6-year follow-up was undertaken from January 7, 2013, through March 12, 2014. On both occasions, a comprehensive ophthalmic examination was performed that included logMAR visual acuity, digital retinal photography, and grading of images at Moorfields Eye Hospital Reading Centre. Data were collected on general health and risk factors.Main outcomes and measuresIncident AMD in participants with no AMD at baseline and progression from early to late AMD.ResultsA total of 1453 of the 2900 individuals (50.1%) at risk for AMD were followed up after 6 years (mean [SD] age, 60.7 [8.2] years; 635 female [49.5%]; 799 Kikuyu [62.3%], 324 Kalenjin [25.3%], and 159 other [12.4%]); 1282 had data on AMD status at follow-up. Of these, 202 developed early AMD, and no participants developed late AMD. The 6-year weighted (for loss to follow-up) cumulative incidence of early AMD was 164.2 per 1000 persons (95% CI, 136.7-195.9 per 1000 persons). Two individuals with baseline early AMD from the 142 at risk had developed late AMD at follow-up, with a 6-year cumulative incidence of progression from early to late AMD of 24.5 per 1000 persons (95% CI, 5.0-111.7 per 1000 persons). Cumulative incidence of AMD increased with age (≥80 years old vs 50-59 years old: 1.8; 95% CI, 0.9-3.5) and was higher in women (female vs male: 1.6; 95% CI, 1.2-2.1) and persons with diabetes (diabetes vs no diabetes: 1.7; 95% CI, 1.0-2.8).Conclusions and relevanceIn Kenya, more than 100 000 estimated new cases of AMD, mainly early AMD, will develop every year in individuals 50 years or older, although a 50% loss to follow-up and wide CIs for progression to late AMD limit definitive conclusions from these findings.

Project description:BackgroundOCT-A is a recent imaging technique allowing a non-invasive assessment of the retinal and choroidal microvasculature, providing valuable data for the diagnosis and monitoring of wet AMD. We aim to determine the diagnosis accuracy, describe the morphological features, and assess the clinical activity of MNV in wet AMD using OCT-A.Materials and methodsWe conducted a descriptive cross-sectional study over a 15-month period. We enrolled patients with treatment-naive and treated MNV secondary to wet AMD. Macular OCT-A images were obtained using a swept-source OCT-A device (Triton SS-OCT, Topcon, Tokyo, Japan). Morphologic characteristics and semi-automated measurements were analyzed on the en face projection OCT-Angiograms. For the qualitative analysis, determined the sensitivity of detection of the MNV using OCTA. When detected, we described its shape, branching pattern, anastomoses and loops, and vessel termination. We looked for the halo sign and the feeder vessel. We then defined the lesion's "pattern" reflecting its exudative activity. For the quantitative analysis, we measured the lesion's area in square millimeters, when its borders were clearly defined.Results70 eyes from 55 patients were enrolled in this study. Type 1 MNV was identified in 57,1% eyes, type 2 in 21,4%, mixed type 1 and2 in 1,4%, type 3 in 1,4% and unclassified fibrotic MNV in 18,6%. 55,7% were active and 44,3% were inactive. Sensitivity of detection was 85% for type 1 lesions, 100% for type 2, mixed and type 3 lesions, and 92% for unclassified fibrotic lesions. It was 84,6% for active lesions and 96,8% for inactive lesions. For each detected lesion, shape was well-defined (medusa, glomerulus, seafan), long liner vessels or ill-defined. Branching pattern was dense or loose. Anastomoses and vascular loops were numerous or few. Termination was in an anastomotic arcade or in a dead-tree aspect. Halo sign was present or absent and feeder vessel was detected or not. All types combined, 41,3% of the lesions were "pattern I" and 58,7% were pattern II. We reported a correlation rate of 84,8% between the lesion's activity on MI and « pattern I » on OCT-A, and of 96,6% between absence of activity signs on MI and « pattern II » on OCT-A The mean area of inactive lesions was slightly larger than that of active lesions with respective values of 3.86 mm2 and 2.92 mm2.ConclusionOCT-A is a non-invasive, safe, and reproducible retinal imaging technique with a high sensitivity of detection of MNV in AMD. It provides useful qualitative and quantitative data. The involvement of OCT-A in the treatment decision for MNV in AMD is linked to identifying the "pattern" of the lesion reflecting its active or inactive status.

Project description:ImportanceAge-related macular degeneration (AMD) is a leading cause of vision loss and blindness. AMD prevalence has not been estimated for the US in over a decade and early-stage AMD prevalence estimates are scarce and inconsistently measured.ObjectiveTo produce estimates of early- and late-stage AMD prevalence overall and by age, gender, race and ethnicity, county, and state.Design, setting, and participantsThe study team conducted a bayesian meta-regression analysis of relevant data sources containing information on the prevalence of AMD among different population groups in the US.Data sourcesWe included data from the American Community Survey (2019), the National Health and Nutrition Examination Survey (2005-2008), US Centers for Medicare & Medicaid Services claims for fee-for-service beneficiaries (2018), and population-based studies (2004-2016).Study selectionWe included all relevant data from the US Centers for Disease Control and Prevention's Vision and Eye Health Surveillance System.Data extraction and synthesisThe prevalence of early- and late-stage AMD was estimated and stratified when possible by factors including county, age group, gender, and race and ethnicity. Data analysis occurred from June 2021 to April 2022.Main outcomes or measuresThe prevalence of early- (defined as retinal pigment epithelium abnormalities or the presence of drusen 125 or more microns in diameter in either eye) and late-stage (defined as choroidal neovascularization and/or geographic atrophy in either eye) manifestations of AMD.ResultsThis study used data from nationally representative and local population-based studies that represent the populations in which they were conducted. For 2019, we estimated that there were 18.34 million people 40 years and older (95% uncertainty interval [UI], 15.30-22.03) living with early-stage AMD, corresponding to a crude prevalence rate of 11.64% (95% UI, 9.71-13.98). We estimated there were 1.49 million people 40 years and older (95% UI, 0.97-2.15) living with late-stage AMD, corresponding to a crude prevalence rate of 0.94% (95% UI, 0.62-1.36). Prevalence rates of early- and late-stage AMD varied by demographic characteristics and geography.Conclusions and relevanceWe estimated a higher prevalence of early-stage AMD and a similar prevalence of late-stage AMD as compared with earlier studies. State-level and county-level AMD estimates may help guide public health practice.

Dataset Information

Prevalence of age-related macular degeneration in Nakuru, Kenya: a cross-sectional population-based study.

Background

Methods and findings

Conclusions

Publications

Prevalence of age-related macular degeneration in Nakuru, Kenya: a cross-sectional population-based study.

Similar Datasets

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