Associations of types of lens opacities between and within eyes of individuals: an application of second-order generalized estimating equations. The Framingham Eye Studies Group.
The lens opacity characteristics of individuals constitute multivariate data. Our goal was to estimate the associations between the three main types of age-related lens opacities (nuclear, cortical, posterior subcapsular) both between and within eyes of individuals using cross-sectional data from the Framingham (Massachusetts) Eye Studies. We describe use of a recently proposed extension of the generalized estimating equations approach to marginal logistic models (GEE2), and we demonstrate that a variety of research problems can be investigated with this methodology. For example, in our data, there were strong associations of the same opacity types between the two eyes of individuals and weak associations between different types of opacities. We also note that estimation of such associations may be limited in other epidemiologic settings.
Podgor
M J
MJ
Division of Biometry and Epidemiology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2510, USA.
Hiller
R
R
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D002386:Cataract / Q000145:classification* / Q000453:epidemiology / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D012107:Research Design