Abstract
From the group of men (ages 30-76) who received physical examinations in 1979 and 1980 which used the Automatic Multiphasic Test System to Diagnose Adult Disease at the Kyoto Red Cross Hospital, 390 were selected as completely healthy based on their physical examinations. The various physiological variables measured for these subjects were used as the data in this study.
The physical examination which the subjects had received involved more than 60 tests of physical proportions, respiratory functions, circulatory functions and physical and chemical properties of blood and urine. The correlation matrices of the various physiological variables were submitted to cluster analysis and factor analysis, and age differences for each physiological variable was examined. Nine variables were then chosen as adequate to represent human physical condition accurately and concisely and which can be used to follow the chang in physiological function as the body ages.
The following multiple regression equation was obtained using chronological age as a dependent variable and the nine physiological variables as independent variables:
Age=93.3-1.48X1-5.22X2+0.04X3+0.40X4-0.09X5+0.03X6-2.02X7-0.08X8+0.18X9 (R=0.711). Where X1 stands for hemoglobin, X2 albumin, X3 serum total cholesterol, X4 urea nitrogen, X5 GPT, X6 OGTT(1hr), X7 vision (left), X8 forced vital capacity, X9 systolic blood pressure.
Biological ages were calculated by the above equation. The mean biological age agreed with mean chronological age, but individually the discrepancies between chronological and biological ages were rather great. The standard deviation (SD) of the difference between an individual's chronological (X) and biological age was 7.3 years, and biological ages of about 68% of subjects fell between X±1.0 SD. The biological age thus obtained reflects physical condition well because it is estimated from various physiological variables. Therefore, biological age or the difference between biological and chronological age is considered an accurate means to evaluate the progress of aging.
Biological ages of 63 hypertensive and 65 diabetic patients were calculated by the above multiple regression equation. For both these two groups, the average biological age was significantly higher than the average chronological age, suggesting the validity of using the multiple regression equation to estimate biological age.
