TY - JOUR T1 - When is baseline adjustment useful in analyses of change? An example with education and cognitive change. JF - Am J Epidemiol Y1 - 2005 A1 - M. Maria Glymour A1 - Weuve, Jennifer A1 - Lisa F Berkman A1 - Ichiro Kawachi A1 - Robins, James M. KW - Age Factors KW - Aged KW - Bias KW - Cognition Disorders KW - Educational Status KW - Epidemiologic Methods KW - Female KW - Health Status KW - Humans KW - Longitudinal Studies KW - Male KW - Models, Statistical KW - Neuropsychological tests KW - Regression Analysis KW - United States AB -

In research on the determinants of change in health status, a crucial analytic decision is whether to adjust for baseline health status. In this paper, the authors examine the consequences of baseline adjustment, using for illustration the question of the effect of educational attainment on change in cognitive function in old age. With data from the US-based Assets and Health Dynamics Among the Oldest Old survey (n = 5,726; born before 1924), they show that adjustment for baseline cognitive test score substantially inflates regression coefficient estimates for the effect of schooling on change in cognitive test scores compared with models without baseline adjustment. To explain this finding, they consider various plausible assumptions about relations among variables. Each set of assumptions is represented by a causal diagram. The authors apply simple rules for assessing causal diagrams to demonstrate that, in many plausible situations, baseline adjustment induces a spurious statistical association between education and change in cognitive score. More generally, when exposures are associated with baseline health status, this bias can arise if change in health status preceded baseline assessment or if the dependent variable measurement is unreliable or unstable. In some cases, change-score analyses without baseline adjustment provide unbiased causal effect estimates when baseline-adjusted estimates are biased.

PB - 162 VL - 162 IS - 3 U1 - http://www.ncbi.nlm.nih.gov/pubmed/15987729?dopt=Abstract U4 - Methodology/EDUCATION/Health-cognitive ability ER - TY - RPRT T1 - Does Childhood Schooling Affect Old Age Cognitive Function? Evidence from Natural Experiments Y1 - 2004 A1 - M. Maria Glymour A1 - Lisa F Berkman A1 - Robins, James M. A1 - Ichiro Kawachi KW - Adult children KW - Demographics KW - Health Conditions and Status PB - Harvard University U4 - Childhood/Education/Cognitive Function ER -