Differences in higher-level functional capacity between participants and non-participants in health checkups among...

The present study was conducted to characterize the lifestyles and health status of non-participants and to investigate whether diminished higher-level functional capacity may cause selection bias in non-compulsory mass health screening for the elderly. Using a self-administered questionnaire for evaluating the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG Index of Competence) which consists of three sublevels, namely, instrumental self-maintenance, intellectual activity and social role, we conducted a survey of 1543 (mean age, 64.9+/-12.5 years, 677 males and 866 females) out of all the 1701 individuals over the age of 40 residing in a village where mass health screening is conducted annually. The mean TMIG Index of Competence score was the highest in Group V (composed of 434 individuals who participated in the mass health screening conducted by the village), followed, in that order, by the score in Group W (composed of 531 individuals who had undergone a health checkup organized at their workplaces or by their family physicians, but not the one conducted by the village, during the previous year) and that in Group N (composed of 578 individuals who had not undergone any health checkup during the previous year). Group N showed a significantly lower mean TMIG Index of Competence score than Groups V and W. In regard to the scores for the sublevels of the index, Group N had a significantly lower percentage of subjects, both men and women, with perfect scores than Group V for all the sublevels, and also a significantly lower percentage of subjects with a perfect score for the intellectual activity than Group W. However, there were no significant differences in the percentages of subjects habituated to exercise, drinking or smoking among the three groups. Thus, special attention may need to be paid to selection bias in mass health screenings caused by differences in the higher-level functional capacity.