[An evaluation of the case-holding index in pulmonary tuberculosis]

The morbidity rate of pulmonary tuberculosis has been used as index to calculate the level of case-holding in recent years. As the methods used are different, the results will not be similar. Therefore, the morbidity rate, its varibility in different years and the number of cases registered are considered as three main factors of which the accuracy of case-holding rate might be influenced. The index has been evaluated. A formula applied for calculation is as following: Pt = P1(1 + r)tP t:predictive value of morbidity in t year, P1:morbidity rate of the first prevalence survey, r:average annual variation rate, t:the interval years between the first prevalence survey and its year to be predicated.