Estimate of a trend of incidence of pulmonary tuberculosis after abolition of mass miniature radiography
Nakamura, T.
Kekkaku 62(10): 497-501
1987
ISSN/ISBN: 0022-9776 PMID: 3444193 Document Number: 305038
On the assumption that the annual indiscriminate mass miniature radiography (MMR) is abolished, the author tried to estimate changes in a trend of incidence of pulmonary tuberculosis mathematically in an occupational group. Among the subject group, eighty percent of the pulmonary tuberculosis have been detected by MMR annually in the past thirty years. The new cases are classified into the three groups by extent of their roentgenological lesions at detection. According to the natural dynamics of tuberculosis, each case is divided into five stages at the present socio-medical settings; healed, improved, unchanged, deteriorated, and detected at clinics. With these categories, an epidemiological model was built, and a prospective yearly change was presumed by the use of Markovian chain model. The transition probabilities among each category were estimated from the data of the subject group in the past ten years, referring to some relevant studies. The results shows that, as far as the incidence of tuberculosis continues to decrease, the number of the new cases detected at clinics after abolition of MMR will not exceed those detected by MMR. On the other hand, some of the new cases detected at clinics will be more serious and infectious than they would be detected by MMR which may affect a decrease of tuberculosis incidence.