Covariates included in the final adjusted models were examiner; child age at examination, sex, birth year, school grade, prenatal smoke and alcohol exposure; household income; parental education; and maternal age at birth, IQ, birth place, and pregnancy omega-3 intake.
In addition to weight at the time of examination, basic models for young children included age at examination and a variable indicating the examiner.
Five HAU patients were female, and five were male, mean age at examination was 50.3 years (range 15 to 70 years).
Since there was a significant age difference between cases and controls in this initial analysis, we extended the study by selecting Caucasian pairs matched at the exact age at examination.
From the 1547 individuals in the Vanderbilt/Duke AMD population association study (including 157 in the preliminary study), we were able to match 560 (280 cases and 280 unaffected) on exact age at examination.
In the remainder analyses, age at examination was included as covariate.
However, the previous analysis only adjusted for age at examination without considering the effect of the year at examination.
As PLS penalizes variables with small variances (e.g. age at examination), covariates are scaled to have unit variance [37] [39].
The aim is to investigate the secular trends in blood pressure over 1925 and 1950 while taking into account the year of examination and age at examination.
We observed some baseline differences for the ratio of males to females and mean age at examination in cases and controls.
