[Preventive therapy in middle-aged and elderly persons selected from the population-based screening by mass miniature radiography--methodological aspect and adverse reactions].

The notification rate of tuberculosis in Japan was 31.0 per 100,000 in 2000. The rate was especially high among the elderly population, reaching 85.5 per 100,000 among those over 65 years of age. We conducted a study of preventive therapy in middle-aged and elderly persons selected from the population-based screening by the mass miniature radiography. The eligible criteria were 50-79 years of age, fibrous lesion which were compatible with healed tuberculosis and showed no change for at least one year, no previous treatment for tuberculosis, normal liver function tests, and no serious disease at the time of study. The eligible criteria for liver function tests in this study was less than 50 IU/L of AST and ALT value, and less than 1.5 mg/dl of T-bil level. A total of 13,219 people underwent TB screening in 4 cities in 1997 and 2 cities in 1998. Among them, 440 persons fulfilled the above criteria based on the screening records and chest X-ray films. The municipal offices sent letters to 418 people, except 22 whose addresses were unknown, to obtain permission to use their addresses and results of screening in our study. Permission was obtained from 137 persons and we sent them invitation letters for cost-free physical checkup service. Ninety-five persons visited us, and we offered them physical checkup and explained about our study. After obtaining the informed consent, we performed chest X-ray and sputum examination for 3 consecutive days. Finally 29 people were enrolled in the study. They were divided into 4 groups by sex and age, and were randomly assigned to one of two treatment groups. One group took 300 mg of INH per day for 6 months and the other group was only followed up by chest X-ray. Fourteen out of 29 persons began to take INH and received monthly liver function test. All the subjects were scheduled to follow by medical checkup every 6 months for 5 years. The proportion of taking INH tablets was estimated to range from 94% to 100%, based on the calendar for record of taking medication and the number of remaining tablets each month. Six (42.9%) of 14 persons reported adverse reactions. Two of 6 persons complained some of diarrhea, vomiting and gastrointestinal disturbance within 2 weeks, and discontinued taking INH, although none of them showed abnormal liver function tests. Two of 6 persons who reported some kinds of symptoms and 2 of 8 persons who did not complain of any symptoms showed abnormal liver function tests. The abnormal liver function tests had developed from 2 months after the beginning of INH taking in most of the persons and the abnormality improved after the completion of 6-month treatment. We have followed them for a maximum duration of 2.5 years, and 3 cases dropped out from the study. These defaulted cases had completed 6 months of INH. One person (69 y.o. male) was diagnosed as active TB by his chest X-ray film at the 6th month medical checkup, although it was not confirmed bacteriologically. One person (62 y.o. female) had the mastectomy for breast cancer 7 months before the entry to this study and relapsed at the 8th month after the entry. One person (73 y.o. female) was diagnosed as lung cancer at the medical checkup on 2.5 years. Besides them, 4 persons were suspected of worsening the abnormal shadows on chest X-ray films; one was from the INH group and three were from the follow-up group. However none of them was diagnosed clinically and bacteriologically as active tuberculosis.