MyVisionTest News Archive
May 13, 2010
Baby boomers less likely to have AMD than previous generations
Today's aging baby boomers might be less likely to have age-related macular degeneration (AMD) than their forebears, according to a new study presented at the Association for Research in Vision and Ophthalmology 2010 Annual Meeting.
"This rapid decline in age-related macular degeneration, which was 68% lower for each generation, suggests that modifiable factors play important roles in the etiology of AMD," said Karen J. Cruickshanks, MD. "Childhood exposure to environment contaminants — for instance, growing up in houses that used wood, coal, or kerosene for cooking — may contribute to the risk of AMD."
Birth cohort effects have been reported in the risk for AMD. In their study, Dr. Cruickshanks and her colleagues sought to determine whether this trend continued for people born in the United States from 1946 to 1964 — the baby boom years.
The study looked at data on participants 45 years or older from the Beaver Dam Offspring Study and at data from the parental cohort of the Beaver Dam Eye Study and the Epidemiology of Hearing Loss Study. AMD was graded using digital-based images in the boomer cohort and film-based images in the parental cohort.
Both studies included extensive information derived from questionnaires about behaviors — such as smoking and alcohol consumption — environmental factors, medical history, and measures of blood pressure, diabetes, and cholesterol.
A total of 9930 observations for participants born between 1905 and 1962 were included in the data analysis.
The study found that the prevalence of AMD declined with birth year, and was lower for recent generations. The age- and sex-adjusted odds ratio (OR) was 0.75 for every 5 years (P < .001), and this birth cohort effect (OR, 0.77; P < .001) remained after adjustment for independent risk factors for AMD, such as obesity, education, and heavy drinking. However, cigarette smoking, which is considered a risk factor, was not significantly associated with AMD in these models, she said.
"For example, for individuals born between 1935 and 1939, the prevalence was 12%, but for individuals born between 1950 and 1954, it was 4%," Dr. Cruickshanks said.
The reduced prevalence found by the researchers might simply be because the boomers haven't gotten old enough, said Johanna Seddon, MD.
"Age is a factor in AMD, and we know that the magnitude is going up, so these kinds of cohort studies can be difficult to interpret. It will be interesting to see if these results are borne out in longitudinal studies," she said.
Emily Chew, MD, agreed with Dr. Seddon's view. "It is very hard to adjust for age. We will have to look at these data for longer," Dr. Chew, who moderated the session at which the study was presented. "Also, all studies show that smoking is important in the development of age-related macular degeneration, but they did not find this was true here. It is hard to impute a cause-and-effect relationship in a birth cohort study such as this."
WHAT IT MEANS TO YOU: This study suggests that the incidence of AMD is falling due to changes in behavior and environmental exposures. While these results are in line with prior research, it remains possible that the boomer generation hasn't aged enough for AMD to become very prevalent. It is very hard for researchers to adjust for age differences, and hence may underestimate the effect growing older may have on the incidence of AMD among baby boomers. It is of some significance that this study failed to find that smoking was related to AMD, something that is now widely accepted. This might suggest that there were methodological or other problems with this study that may have lead to flawed results.
Read more...
Medscape
Tags: AMD, tobacco, risk factors
Today's aging baby boomers might be less likely to have age-related macular degeneration (AMD) than their forebears, according to a new study presented at the Association for Research in Vision and Ophthalmology 2010 Annual Meeting."This rapid decline in age-related macular degeneration, which was 68% lower for each generation, suggests that modifiable factors play important roles in the etiology of AMD," said Karen J. Cruickshanks, MD. "Childhood exposure to environment contaminants — for instance, growing up in houses that used wood, coal, or kerosene for cooking — may contribute to the risk of AMD."
The study looked at data on participants 45 years or older from the Beaver Dam Offspring Study and at data from the parental cohort of the Beaver Dam Eye Study and the Epidemiology of Hearing Loss Study. AMD was graded using digital-based images in the boomer cohort and film-based images in the parental cohort.
Both studies included extensive information derived from questionnaires about behaviors — such as smoking and alcohol consumption — environmental factors, medical history, and measures of blood pressure, diabetes, and cholesterol.
A total of 9930 observations for participants born between 1905 and 1962 were included in the data analysis.
The study found that the prevalence of AMD declined with birth year, and was lower for recent generations. The age- and sex-adjusted odds ratio (OR) was 0.75 for every 5 years (P < .001), and this birth cohort effect (OR, 0.77; P < .001) remained after adjustment for independent risk factors for AMD, such as obesity, education, and heavy drinking. However, cigarette smoking, which is considered a risk factor, was not significantly associated with AMD in these models, she said.
"For example, for individuals born between 1935 and 1939, the prevalence was 12%, but for individuals born between 1950 and 1954, it was 4%," Dr. Cruickshanks said.
The reduced prevalence found by the researchers might simply be because the boomers haven't gotten old enough, said Johanna Seddon, MD.
"Age is a factor in AMD, and we know that the magnitude is going up, so these kinds of cohort studies can be difficult to interpret. It will be interesting to see if these results are borne out in longitudinal studies," she said.
Emily Chew, MD, agreed with Dr. Seddon's view. "It is very hard to adjust for age. We will have to look at these data for longer," Dr. Chew, who moderated the session at which the study was presented. "Also, all studies show that smoking is important in the development of age-related macular degeneration, but they did not find this was true here. It is hard to impute a cause-and-effect relationship in a birth cohort study such as this."
WHAT IT MEANS TO YOU: This study suggests that the incidence of AMD is falling due to changes in behavior and environmental exposures. While these results are in line with prior research, it remains possible that the boomer generation hasn't aged enough for AMD to become very prevalent. It is very hard for researchers to adjust for age differences, and hence may underestimate the effect growing older may have on the incidence of AMD among baby boomers. It is of some significance that this study failed to find that smoking was related to AMD, something that is now widely accepted. This might suggest that there were methodological or other problems with this study that may have lead to flawed results.
Read more...
Medscape
