システム分析による過去の有病率の推定

抄録

It is inappropriate to compare the prevalence of active tuberculosis in the 1953 nationwide tuberculosis survey with that of 1958 or 1963, as the criteria for active cases in 1953 were different from that in 1958 or 1963.
The authors tried to estimate the prevalence of active cases in 1953 provided that the criteria in 1953 were the same as that in 1958 or 1963, by moving the system of our epidemetric model of tuberculosis backward, which we have reported in 1970.
Various parameters during 1953 to 1958 were estimated as the same procedure during 1958 to 1968, and the other parameters are the same as before.
The initial situation was set at 1968. The output which the model generated has been examined comparing the results of nationwide tuberculosis prevalence survey in 1963 and 1958, and about the same figures could be obtained.
Then, the prevalence of active cases of tuberculosis estimated in 1953 was computed, and the results are as follows: Active cases with cavity were 632, 400 and those without cavity 3, 898, 600, totalled 4, 530, 000 cases, that is 5.2% of general population. Comparing the above results with the figures in 1953 nationwide tuberculosis survey, the marked differences were obtained in the age groups 30 to 69. It may be caused by the difference of the criteria.
If the figures of prevalence during 1953. to 1968 are comparable, the reduction rates for the cases without cavity are 35% during 1953 to 1958, 30% during 1958 to 1963 and 25% during 1963 to 1968, and for the cases with cavity, they are 35%, 30% and 11%, respectively.
The other estimations were carried out under the conditions that the prevalence of active cases were the highest in 1955 during the study period, or the real prevalence in 1953 were 5, 350, 000, which were the sum of active and inactive cases in the 1953 nationwide tuberculosis surve
Comparing various figures of prevalence estimated in 1953, the trend of prevalence in Japan was discussed.