Characteristics of participants in multiphasic health examination, II

Abstract

The characteristics of two groups classified as participants and nonpartieipants (>30 years of age) in a multiphasic health examination (MHE) conducted in a rural town in Kyoto Prefecture (1983-87) were compared. The purposes of this study were (a) to clarify whether there was a bias towards self-selection in the participant group and (b) to determine whether the participants did indeed represent persons who needed to be screened by MHE.The participants (592 males, 839 females) examined at least once (1983-87) tended to be older than the nonparticipants (1282 males, 1222 females). In 1985, 526 male (88%) and 755 female (89%) participants, and 987 male (76%) and 960 (78%) female nonparticipants responded to a questionnaire that included the following: social factors, past history of diseases and present illnesses, and smoking, drinking, and dietary habits. Selected from among those respondents were 472 male and 580 female participants who were subsequently matched with a corresponding number of nonparticipants according to sex, age in 1985 (within a range of 3 years) and location in the town. Analyses using McNemar's test and the multivariate analysis of the quantification method of Hayashi were performed.Firstly, the factors which included occupation, e. g., farmer or lumberjack, workplace (in the town), participation in the town health service system, family members, and the number of rooms in the house were the most important predictors for participation. Secondly, the participants tended to have a past history of diseases, a higher incidence of present illnesses, and they frequently visited medical facilities. This showed that they perceived the efficacy of MHE because of their previous contact with diseases. Thirdly, participants showed a more positive behavior pattern for health, including better dietary habits, e. g., limited salt intake, and eating more fish, vegetables, beans, fruit and seaweed. This behavior seemed to decrease the risk for chronic diseases.Fewer white-collar workers in the prime of life were examined, but it seemed to he difficult to increase their participation because of their occupations and workplaces. Therefore, the occupation seemed to be a major confounding factor in the understanding of the role of the other predictors for participation.