134/100,000 respectively. In accordance with the above prevalences, the estimated number of active pulmonary tuberculosis was about 5,930,000. Among them, 33.3% (about 2,000,000 patients) was bacteriological positive patients and 25.5% (about 1,510,000 patients) was smear positive patients. 76.5% of the bacteriological positive patients was also smear positive.
In comparison with the results of the first survey in 1979, the prevalence of active pulmonary tuberculosis showed a 27% decrease and the annual reduction rate was 2.8% within 11 years (1979-1990); the prevalence of smear positive pulmonary tuberculosis had reduced to 28.3% and the annual reduction rate was 3.0%. In comparison with the results of the second survey in 1984/85, the prevalence of active pulmonary tuberculosis showed only 4.9% decrease and the annual reduction rate was only 0.9% within 5 years; concerning smear positive pulmonary tuberculosis, the rate were 14.1 % and 2.7% respectively. The above results revealed that the decrease of the prevalence of pulmonary tuberculosis especially the active pulmonary tuberculosis cases in the later 5 years was slower than the previous 5 years.
Since the cultural examination of sputum was not recommended in the first survey (1979), the data of bacteriological prevalence was thus not available. The bacteriological prevalences of pulmonary tuberculosis in 1984/85 and 1990 were 205/100,000 and 177/100,000 respectively; showed a 13.7% decrease and the annual reduction rate was 2.6%
2. Morbidity of Pulmonary Tuberculosis Among Different Age Groups and Sex
(1) Prevalence of Pulmonary Tuberculosis Among Different Age Groups and Sex
The prevalence, bacteriological prevalence and smear positive prevalence gradually increased with age in both sexes. The bacteriological and smear positive prevalence significantly increased among the age groups before 20; the speed of increase then slowed down and reached a peak at 70 years of age. After that, the prevalence decreased slightly (Table 1).
The prevalence of active, bacteriological and smear positive pulmonary tuberculosis in female before 15 years of age were all higher than male. The curves crossed in the age group about 20 years of age. After that, the prevalence of male was gradually higher than female and the amplitude of variation was on the increase gradually (table 3).
The curves of prevalence and smear positive prevalence by age in three surveys were similar generally. The curve of smear positive prevalence in children under 5 years in 1990 was slightly higher than that in 1979 and lower than that in 1984/85; but it was slightly lower than that in 1979 and higher than that in 1984/85 in age group above 70 years of age.
(2) Proportion of Pulmonary Tuberculosis Patients by Age Group
The highest proportion of examined population was in the 15-29 age group (29.8%), and the 0-14 age group came next (27.5%). The proportions decreased with the increase in age in other age groups. The number of active pulmonary tuberculosis and the proportion of bacteriological positive and smear positive cases increased with the increase in age.
The examined population in the 0-29 age groups amounted to 57.3% of total examined population, 24.2% of the active patients, 19.7% of the bacteriological positive cases and 19.9%
of the smear positive cases. The examined population in the age groups above 45 accounted for 21.4% of the total examined population, but made up 56.7% of the active patients, 56.9% of the bacteriological positive patients and 55.4% of the smear positive cases . The above situation indicated that most of the patients were in the old age group. This situation was similar to the situation of prevalence.
3. Morbidity of Pulmonary Tuberculosis Among Provinces, Regions and Municipalities
(1) Prevalence of Pulmonary Tuberculosis Among Province, Regions and Municipalities
Prevalence of the active pulmonary tuberculosis: Xizang had the highest prevalence (1,203/100,000); Sichuan, Neimeng and Hainan followed - all above 800/100,000. Shanghai had the lowest (64.4/100,000) and Beijing followed (65.9/100,000). The highest prevalence was 18.7 times higher than that of the lowest. After standardization, Xizang still had the highest standardized prevalence (1,186/100,000). The rank of the standardized prevalence of the next eight provinces was similar to that of the prevalence without standardization. Beijing had the lowest standardized prevalence (38.6/100,000) and Shanghai followed (38.9/100,000). The highest standardized prevalence was 30.7 times higher than that of the lowest.
After standardization, there were nine provinces and regions whose standardized prevalence of active pulmonary tuberculosis was higher than that of the national weighted prevalence (average value). They were Xizang, Sichuan, Neimeng, Hainan, Jiangxi, Hunan, Xinjiang, Heilongjiang and Ningxia.
