Predictors of attrition in a longitudinal cognitive aging study: the Maastricht Aging Study (MAAS).
A large sample of older participants of the Maastricht Aging Study (MAAS) were compared to drop-outs at the 3-year follow-up with respect to socio-demographic, health, and cognitive characteristics. In addition, the impact of selective drop-out on measures of cognitive change was examined. To this end, hypothetical scores were estimated for drop-outs by using single and multiple imputation methods. Of the initial sample of 539 subjects, aged 49 years and older at baseline, 116 (22 %) did not return for the follow-up (n = 32 had died, n = 84 refused participation). Drop-outs who refused to participate in the follow-up were more often women, had lower educational levels, and had lower baseline scores on neurocognitive tests. Follow-up drop-outs who had died were more often men, older, and had a poorer performance on cognitive tests than the follow-up participants. Although follow-up participants and drop-outs differed in terms of socio-demographic and cognitive characteristics, attrition appeared to have little effect on the estimates of cognitive change.
Van Beijsterveldt
C E M
CE
European Graduate School of Neuroscience (EURON), Universiteit Maastricht, Department of Psychiatry and Neuropsychology, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
van Boxtel
M P J
MP
Bosma
H
H
Houx
P J
PJ
Buntinx
F
F
Jolles
J
J
D000368:Aged / Q000523:psychology*; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003071:Cognition; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D010352:Patient Dropouts; D011159:Population Surveillance; D012044:Regression Analysis; D015983:Selection Bias