[Accuracy of participation rate data for health examination research]

Each local government conducts health examinations based on the Health and Medical Law for the Aged. However, since some residents are able to take health examinations at their own work places, for example, and the local government are allowed to exclude such people from taking the law-mandated health examination, it is difficult to obtain an accurate picture of the examination rate in each area. We investigated the actual participation status for health examination services of all of the 6,080 persons 20 years and over in age in Sakuragawa-mura, Ibaraki Prefecture. A comparative investigation was made on 3,655 non-bedridden/non-hospitalized persons of 40 years and over to ascertain the reliability of responses to questions about participation in lung cancer and gastric cancer examination services given by the village. The rate of valid responses was extremely low in those who had not participated in health examinations (male 54%, female 55% for the lung cancer, and male 53%, female 56% for the gastric cancer). These discrepancies are assumed to be the result of confusing the current health examinations with: (1) the health examination given in the previous year, (2) other kinds of health examinations, or (3) the health examination given in the work place or the like. A comparative investigation through logistic regression analysis, between the responses to the questions in this investigation and the actual health examination participation records, for persons who had not yet taken either lung cancer examinations or gastric cancer examinations (908 males and 938 females for the former, and 1,038 males and 1,187 females for the latter). Results showed that the influence of (1) and (2) were more or less detected in every kind of cancer examination, and the influence of (1) on the gastric cancer examination was particularly clear. No definite result was obtained about (3), because the actual record of the health examination service at the work place, etc. was unavailable. The results of this study suggests the necessity of a careful examination of methods when conducting a comprehensive service investigation for the health examinations.