MyVisionTest News Archive
Jan 16, 2012
AMD risk factors in Latinos
The Latino Eye Study identified older age and higher pulse pressure as risk factors for 4-year incidence of age-related macular degeneration (AMD) in adult Latinos.
Latinos constitute the largest and fastest-growing minority segment of the US population. If recent trends continue, the US Latino population is estimated to increase to 102.6 million in 2050, or 24.4% of the total population. But there is a relative lack of population-based data regarding ocular health in Latinos, and the factors associated with AMD incidence and progression among Latinos remain largely unexplored. Data from the Los Angeles Latino Eye Study (LALES) demonstrate a lower prevalence and incidence of early and late AMD compared to other populations. Therefore, it is important to understand whether different and modifiable factors are operative in Latinos that influence disease risk and progression and may explain the differences in rates.
In the LALES, examination of baseline data revealed several demographic (age, male gender, Native American ancestry, family history), behavioral (smoking, alcohol consumption), clinical (higher diastolic blood pressure [DBP], uncontrolled diastolic hypertension, pulse pressure), and ocular (presence of cataract, cataract surgery, and myopic refractive error) factors to be associated cross-sectionally with the prevalence of different AMD lesions in Latinos.
In the current analysis, the researchers examine the relationships between these factors and the 4-year incidence and progression of AMD in the cohort to tease out factors that are associated with disease development vs those associated with disease duration. While cross-sectional studies can identify associations between risk factors and existing AMD, longitudinal incidence studies are required to determine the indicators that may be associated with the development of future AMD.
Methods & Results
Latinos (Hispanics, Hispanic Americans, and Latino Americans) are individuals who are born into or have descended from a Spanish-speaking community, regardless of race. In the United States, Latinos are a heterogeneous group, with the majority being of Mexican ancestry (66%). The Los Angeles Latino Eye Study is a population-based longitudinal study of eye disease in self-identified Latinos, aged 40 years and older, living in 6 census tracts in the city of La Puente, Los Angeles County, California. Baseline examination was performed from 2000 to 2003, with 4-year follow-up examination from 2004 to 2008.
Participants, aged 40 or older, from The Los Angeles Latino Eye Study (LALES) underwent standardized comprehensive ophthalmologic examinations at baseline and at 4 years of follow-up. Age-related macular degeneration was detected by grading 30-degree stereoscopic fundus photographs using the modified Wisconsin Age-Related Maculopathy Grading System. Multivariate stepwise logistic regression was used to examine the independent association of incidence and progression of AMD and baseline sociodemographic, behavioral, clinical, and ocular characteristics.
Multivariate analyses revealed that older age (OR per decade of age: 1.52; 95% CI: 1.29, 1.85) and higher pulse pressure (OR per 10 mm Hg: 2.54; 95% CI: 1.36, 4.76) were independently associated with the incidence of any AMD. The same factors were associated with early AMD, soft indistinct drusen, and retinal pigmentary abnormalities. Additionally, presence of clinically diagnosed diabetes mellitus was independently associated with increased retinal pigment (OR: 1.66; 95% CI: 1.01, 2.85), and male gender was associated with retinal pigment epithelial depigmentation (OR 2.50; 95% CI: 1.48, 4.23). Older age (OR per decade of age: 2.20; 95% CI: 1.82, 2.67) and current smoking (OR: 2.85; 95% CI: 1.66, 4.90) were independently associated with progression of AMD. (see TABLE)
Discussion & Conclusions
In this longitudinal study, over a 4-year period we found older age, increased pulse pressure, diabetes mellitus, and male gender to be associated with incident early AMD in Latinos. Older age and current smoking were associated with increased risk of progression of AMD. Some of these findings are consistent with data from other population-based longitudinal studies, including the Beaver Dam Eye Study and the Blue Mountains Eye Study, which have used similar methodologies to detect and define AMD. However, we have found several novel associations, especially when the outcomes were defined as early AMD and soft drusen, that were not reported in earlier studies.
Sociodemographic Risk Factors
Numerous studies have demonstrated older age as the strongest risk factor of AMD prevalence, incidence, and progression. The relationship between age and prevalence of AMD was demonstrated previously with the LALES prevalence data. The present analyses demonstrated the increased risk of AMD incidence and progression with increasing age. It has been suggested that the ongoing subclinical pathogenetic processes, such as deposition of lipofuscin and thickening and loss of elasticity of the Bruch membrane, begin earlier in life. These changes are likely to manifest as clinical signs of early AMD as people age, due in part to the inability of the RPE in some individuals to process these degenerative products.
Gender difference in incident or prevalent AMD has been an inconsistent finding in most population-based studies. The previous report from LALES prevalence data was suggestive of an increased risk of all and early AMD prevalence. In the present report we found an increased risk in male participants for RPE depigmentation only.
The reasons for increased risk of RPE depigmentation in Latino men are not known, although several other known risk factors of AMD (eg, smoking, alcohol use, and cardiovascular disease) are found to be more prevalent in male subjects. Indeed, in LALES we noted that Latino men were more likely to smoke (19% vs 9%, P < .001) and drink alcohol regularly compared to Latino women (22% vs 3%). But even after adjusting for these variables, men were more likely than women to develop RPE depigmentation (OR 2.73; 95% CI: 1.52, 4.94).
Behavioral Risk Factors
The results of this study suggest an almost 3-fold increased risk of progression of AMD in current smokers (P = .0004). There was no such significant association in former smokers.
Smoking has been the most consistent modifiable behavioral risk factor in most population-based ocular epidemiologic studies. It has been found to be associated with all stages of AMD. In particular, the risk has been found strongest in those who are current smokers. Some investigators have suggested the effect of cigarette smoking on AMD may be attributable to its negative effect on antioxidants. In this report we found smoking to be associated with progression but not with incidence of AMD in Latinos.
Clinical Risk Factors
The association of blood pressure and AMD has been inconsistent in epidemiologic population-based studies. Our results suggest increased risks of all measures of AMD incidence with increased pulse pressure (see FIGURE). The BDES found a positive association of pulse pressure with prevalence of RPE depigmentation and increased retinal pigmentation in male subjects only. However, in the 5-year cumulative incidence in BDES, higher pulse pressure was significantly associated with increased incidence of RPE depigmentation (OR per 10 mm Hg: 1.27; 95% CI: 1.14, 1.42) and exudative macular degeneration (OR per 10 mm Hg: 1.29; 95% CI: 1.02, 1.65), irrespective of gender. However, a number of other studies did not report this association. Pulse pressure emerged as the most important modifiable risk factor in this cohort.
To further evaluate whether the effect of pulse pressure was independent of hypertension, we restricted the analysis to normotensive participants and found a similar age-adjusted independent relationship (OR for AMD: 2.6; 95% CI: 1.4, 4.9). The underlying mechanism of increased pulse pressure on AMD risk may be attributable to age-related degenerative changes in collagen and elastin, resulting in a decrease in distensibility of blood vessels. This in turn results in higher systolic and lower diastolic blood pressure and widening of pulse pressure.
Diabetes is a disparate finding as a risk factor for AMD. In this study, presence of clinically diagnosed diabetes mellitus was independently associated with incidence of increased retinal pigmentation. The Blue Mountains Eye Study found an association of diabetes with geographic atrophy but not with increased retinal pigment or any other measure of early AMD. In BDES, diabetes was not associated with early AMD but was associated with neovascular AMD in persons 75 or older. A large number of studies found no association. The paucity of literature suggests caution in drawing any inference. However, diabetes as a risk factor of any disease in Latinos requires more attention, as diagnosed diabetes is 1.7 times more likely in Latinos than in non-Hispanic whites. Therefore, timely prevention, diagnosis, and proper control of diabetes will likely have a positive impact on the burden of ocular disease in Latinos.
In LALES, there was a relative low rate of AMD progression. In this analysis we could not identify any protective factors that may affect AMD progression in Latinos. However, a previous analysis from LALES was suggestive of a low prevalence of the genetic risk factor of CFH Tyr402 polymorphism in Latinos. Further analysis of distributions of genetic risk factors, both protective and deleterious, and their relationship to AMD may shed more light on factors that are likely to play a role in progression, or relative lack of it, in this population.
In conclusion, in Latinos, increasing age, increased pulse pressure, and diabetes mellitus were associated with higher risks of incidence of early AMD, and increasing age and current smoking were associated with the progression of AMD. Some of the findings are similar to those reported by studies in non-Hispanic whites, suggesting some similarities in the pathogenesis of the disease between the 2 ethnic groups. Studies of genetic risk factors may explain the differences in risk factors for incidence of some early maculopathies like soft drusen. Because Latinos represent the largest minority group in the United States and exhibit different patterns of AMD incidence and progression than other ethnic groups, it is empirical to address the unique risk factors of AMD in Latinos. The fact that easily modifiable factors like pulse pressure were associated with Latinos may provide clinicians with important guidelines for preventive interventions. Further longitudinal studies of AMD progression in Latinos are needed for conclusive inferences. It remains to be seen whether interventions aimed at reducing pulse pressure or stopping smoking would affect the incidence and progression of AMD in Latinos.
Read more...
Am J Ophthalmol. 2011 Sep;152(3):385-95
Tags: AMD, racial differences, cardiovascular disease, genetics, diabetes
The Latino Eye Study identified older age and higher pulse pressure as risk factors for 4-year incidence of age-related macular degeneration (AMD) in adult Latinos.Latinos constitute the largest and fastest-growing minority segment of the US population. If recent trends continue, the US Latino population is estimated to increase to 102.6 million in 2050, or 24.4% of the total population. But there is a relative lack of population-based data regarding ocular health in Latinos, and the factors associated with AMD incidence and progression among Latinos remain largely unexplored. Data from the Los Angeles Latino Eye Study (LALES) demonstrate a lower prevalence and incidence of early and late AMD compared to other populations. Therefore, it is important to understand whether different and modifiable factors are operative in Latinos that influence disease risk and progression and may explain the differences in rates.
In the current analysis, the researchers examine the relationships between these factors and the 4-year incidence and progression of AMD in the cohort to tease out factors that are associated with disease development vs those associated with disease duration. While cross-sectional studies can identify associations between risk factors and existing AMD, longitudinal incidence studies are required to determine the indicators that may be associated with the development of future AMD.
Methods & Results
Latinos (Hispanics, Hispanic Americans, and Latino Americans) are individuals who are born into or have descended from a Spanish-speaking community, regardless of race. In the United States, Latinos are a heterogeneous group, with the majority being of Mexican ancestry (66%). The Los Angeles Latino Eye Study is a population-based longitudinal study of eye disease in self-identified Latinos, aged 40 years and older, living in 6 census tracts in the city of La Puente, Los Angeles County, California. Baseline examination was performed from 2000 to 2003, with 4-year follow-up examination from 2004 to 2008.
Participants, aged 40 or older, from The Los Angeles Latino Eye Study (LALES) underwent standardized comprehensive ophthalmologic examinations at baseline and at 4 years of follow-up. Age-related macular degeneration was detected by grading 30-degree stereoscopic fundus photographs using the modified Wisconsin Age-Related Maculopathy Grading System. Multivariate stepwise logistic regression was used to examine the independent association of incidence and progression of AMD and baseline sociodemographic, behavioral, clinical, and ocular characteristics.
Multivariate analyses revealed that older age (OR per decade of age: 1.52; 95% CI: 1.29, 1.85) and higher pulse pressure (OR per 10 mm Hg: 2.54; 95% CI: 1.36, 4.76) were independently associated with the incidence of any AMD. The same factors were associated with early AMD, soft indistinct drusen, and retinal pigmentary abnormalities. Additionally, presence of clinically diagnosed diabetes mellitus was independently associated with increased retinal pigment (OR: 1.66; 95% CI: 1.01, 2.85), and male gender was associated with retinal pigment epithelial depigmentation (OR 2.50; 95% CI: 1.48, 4.23). Older age (OR per decade of age: 2.20; 95% CI: 1.82, 2.67) and current smoking (OR: 2.85; 95% CI: 1.66, 4.90) were independently associated with progression of AMD. (see TABLE)
Discussion & Conclusions
In this longitudinal study, over a 4-year period we found older age, increased pulse pressure, diabetes mellitus, and male gender to be associated with incident early AMD in Latinos. Older age and current smoking were associated with increased risk of progression of AMD. Some of these findings are consistent with data from other population-based longitudinal studies, including the Beaver Dam Eye Study and the Blue Mountains Eye Study, which have used similar methodologies to detect and define AMD. However, we have found several novel associations, especially when the outcomes were defined as early AMD and soft drusen, that were not reported in earlier studies.Sociodemographic Risk Factors
Numerous studies have demonstrated older age as the strongest risk factor of AMD prevalence, incidence, and progression. The relationship between age and prevalence of AMD was demonstrated previously with the LALES prevalence data. The present analyses demonstrated the increased risk of AMD incidence and progression with increasing age. It has been suggested that the ongoing subclinical pathogenetic processes, such as deposition of lipofuscin and thickening and loss of elasticity of the Bruch membrane, begin earlier in life. These changes are likely to manifest as clinical signs of early AMD as people age, due in part to the inability of the RPE in some individuals to process these degenerative products.
Gender difference in incident or prevalent AMD has been an inconsistent finding in most population-based studies. The previous report from LALES prevalence data was suggestive of an increased risk of all and early AMD prevalence. In the present report we found an increased risk in male participants for RPE depigmentation only.
The reasons for increased risk of RPE depigmentation in Latino men are not known, although several other known risk factors of AMD (eg, smoking, alcohol use, and cardiovascular disease) are found to be more prevalent in male subjects. Indeed, in LALES we noted that Latino men were more likely to smoke (19% vs 9%, P < .001) and drink alcohol regularly compared to Latino women (22% vs 3%). But even after adjusting for these variables, men were more likely than women to develop RPE depigmentation (OR 2.73; 95% CI: 1.52, 4.94).
Behavioral Risk Factors
The results of this study suggest an almost 3-fold increased risk of progression of AMD in current smokers (P = .0004). There was no such significant association in former smokers.
Smoking has been the most consistent modifiable behavioral risk factor in most population-based ocular epidemiologic studies. It has been found to be associated with all stages of AMD. In particular, the risk has been found strongest in those who are current smokers. Some investigators have suggested the effect of cigarette smoking on AMD may be attributable to its negative effect on antioxidants. In this report we found smoking to be associated with progression but not with incidence of AMD in Latinos.
Clinical Risk Factors
The association of blood pressure and AMD has been inconsistent in epidemiologic population-based studies. Our results suggest increased risks of all measures of AMD incidence with increased pulse pressure (see FIGURE). The BDES found a positive association of pulse pressure with prevalence of RPE depigmentation and increased retinal pigmentation in male subjects only. However, in the 5-year cumulative incidence in BDES, higher pulse pressure was significantly associated with increased incidence of RPE depigmentation (OR per 10 mm Hg: 1.27; 95% CI: 1.14, 1.42) and exudative macular degeneration (OR per 10 mm Hg: 1.29; 95% CI: 1.02, 1.65), irrespective of gender. However, a number of other studies did not report this association. Pulse pressure emerged as the most important modifiable risk factor in this cohort.To further evaluate whether the effect of pulse pressure was independent of hypertension, we restricted the analysis to normotensive participants and found a similar age-adjusted independent relationship (OR for AMD: 2.6; 95% CI: 1.4, 4.9). The underlying mechanism of increased pulse pressure on AMD risk may be attributable to age-related degenerative changes in collagen and elastin, resulting in a decrease in distensibility of blood vessels. This in turn results in higher systolic and lower diastolic blood pressure and widening of pulse pressure.
Diabetes is a disparate finding as a risk factor for AMD. In this study, presence of clinically diagnosed diabetes mellitus was independently associated with incidence of increased retinal pigmentation. The Blue Mountains Eye Study found an association of diabetes with geographic atrophy but not with increased retinal pigment or any other measure of early AMD. In BDES, diabetes was not associated with early AMD but was associated with neovascular AMD in persons 75 or older. A large number of studies found no association. The paucity of literature suggests caution in drawing any inference. However, diabetes as a risk factor of any disease in Latinos requires more attention, as diagnosed diabetes is 1.7 times more likely in Latinos than in non-Hispanic whites. Therefore, timely prevention, diagnosis, and proper control of diabetes will likely have a positive impact on the burden of ocular disease in Latinos.
In LALES, there was a relative low rate of AMD progression. In this analysis we could not identify any protective factors that may affect AMD progression in Latinos. However, a previous analysis from LALES was suggestive of a low prevalence of the genetic risk factor of CFH Tyr402 polymorphism in Latinos. Further analysis of distributions of genetic risk factors, both protective and deleterious, and their relationship to AMD may shed more light on factors that are likely to play a role in progression, or relative lack of it, in this population.
In conclusion, in Latinos, increasing age, increased pulse pressure, and diabetes mellitus were associated with higher risks of incidence of early AMD, and increasing age and current smoking were associated with the progression of AMD. Some of the findings are similar to those reported by studies in non-Hispanic whites, suggesting some similarities in the pathogenesis of the disease between the 2 ethnic groups. Studies of genetic risk factors may explain the differences in risk factors for incidence of some early maculopathies like soft drusen. Because Latinos represent the largest minority group in the United States and exhibit different patterns of AMD incidence and progression than other ethnic groups, it is empirical to address the unique risk factors of AMD in Latinos. The fact that easily modifiable factors like pulse pressure were associated with Latinos may provide clinicians with important guidelines for preventive interventions. Further longitudinal studies of AMD progression in Latinos are needed for conclusive inferences. It remains to be seen whether interventions aimed at reducing pulse pressure or stopping smoking would affect the incidence and progression of AMD in Latinos.
Read more...
Am J Ophthalmol. 2011 Sep;152(3):385-95
