The role of matching when adjusting for baseline differences in the outcome variable of comparative effectiveness studies.
OBJECTIVE
Evaluate performance of analytical strategies commonly used to adjust for baseline differences in continuous outcome variables for comparative effectiveness studies.


METHODS
Data simulations resembling a comparison of HbA1c values after initiation of antidiabetic treatments adjusting for baseline HbA1c. We evaluated change scores, analyses of covariance including linear, nonlinear with/without robust variance estimations, before and after optimal matching. We also evaluated the impact of measurement error.


RESULTS
With increasing HbA1c baseline differences between groups, bias in effect estimates and suboptimal CI coverage probabilities increased in all approaches. These issues were further compounded by measurement error. Matching on baseline HbA1c, substantially mitigated these issues.


CONCLUSIONS
In comparative studies with continuous outcomes, matching on baseline values of the outcome variable improves analytical performance.
Department of Health Policy, Vanderbilt University, Nashville, TN, 37232 USA.|VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.
Carlos G
CG
Grijalva
VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.|Department of Medicine, Vanderbilt University, Nashville, TN, 37232 USA.
Christianne L
CL
Roumie
VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.|Department of Medicine, Vanderbilt University, Nashville, TN, 37232 USA.
Harvey J
HJ
Murff
VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.|Department of Medicine, Vanderbilt University, Nashville, TN, 37232 USA.
Adriana M
AM
Hung
Department of Biostatistics, Vanderbilt University, Nashville, TN, 37203 USA.
Cole
C
Beck
VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.|Department of Biostatistics, Vanderbilt University, Nashville, TN, 37203 USA.
Xulei
X
Liu
Department of Health Policy, Vanderbilt University, Nashville, TN, 37232 USA.|VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.|Department of Medicine, Vanderbilt University, Nashville, TN, 37232 USA.
Marie R
MR
Griffin
VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC), Nashville, TN, 37212 USA.|Department of Biostatistics, Vanderbilt University, Nashville, TN, 37203 USA.
Robert A
RA
Greevy
D000704:Analysis of Variance; D015331:Cohort Studies; D057186:Comparative Effectiveness Research / Q000379:methods / Q000706:statistics & numerical data*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism*; D005260:Female; D006442:Glycated Hemoglobin / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents
baseline adjustment; comparative effectiveness; diabetes; glycated hemoglobin; matching