Keio J. Med. 27: 69-88, 1978 PREVALENCE OF CHRONIC BRONCHITIS SYMPTOMS IN JAPAN -A review of the nation-wide surveys on prevalence of pulmonary symptoms using standard questionnaire TOSHIO TOYAMA* and JUN KAGAWA** * Department of Preventive Medicine and Public Health , School of Medicine, Keio University, Tokyo, Japan ** Department of Public Health , School of Medicine, Tokai University, Kanagawa, Japan (Received for Publication, October 28, 1978) ABSTRACT This paper reviewed prevalence rates of various pulmonary symptoms among 22,560 general population in 21 survey areas throughout Japan, 1965 1973, interviewed by health professions using standard questionnaire of Japa nese version of British Medical Research Council for chronic bronchits. Prime symptoms, persistent cough and phlegm were fairly low rates as compared to England and the U.S. studies. Their wide ranged rates may imply the pre valence of pumonary symptoms in Japan is not static, and cigarette smoking and rapid industrialization may be possible factors to altering the morbidity to comparable level of the Western countries in future. Sputum examination and pulmonary function tests were also discussed. INTRODUCTION The statistics of mortality and morbidity of the chronic non-specific lung diseases in Japan have been obscure because of lack their appropriate standard diagnostic criteria and being regarded as minor respiratory conditions, and until recently for chest physicians tuberculosis had been the greatest concern among other lung diseases. Furthermore in our National Health Insurance Scheme, chronic bronchitis is considered to be a low cost disease and thus reflected on doctors diagnostic habits. For instance the crude death rate for chronic bron chitis for all ages in 1963 in Japan was very low, 3.4, (Table 1) in contrast to 69 70 Toshio Toyama and Jun Kagawa Table 1 Respiratory Disease Crude Death-Rates/10,0000, Both Sexes in All Ages, by Specified Cause in Japan * WHO 1957 ** WHO 1968 *** not tabulated 119.0 for England Wales in the same year.1 Morbidity of chronic bronchitis had been almost unreliable until about 10 years ago because the disease was not re portable and there was no eligible epidemiological studies. The present study is reviewed excerpts from studies and surveys on pre valence of pulmonary symptoms among general population throughout Japan, carried out from 1965 to 1973 by individual researchers of university, local in stitutes of health and local health centers. All the surveys discussed here were done by interview techniques using the Japanese version of the British Medical Research Council's questionnaire of respiratory symptoms (1966). The inter views were made by physicians, epidemiologists and public health nurses. In a study abbreviated KI in this report, the 1960's version was used by author in 1965, which was first attempting of interview towards general population in a rural area in Japan. Because the interviews were carried out in different places (21 districts), by different interviewers, at different times (majority was done in winter and autumn seasons, and one in summer), and on different segment of general popu lation from farmers to white-collar employee in city, only a crude comparison without calculating any statistical significance is discussed here by merely dis playing mean prevalence rates and their ranges, minimum and maximum rates of various items of the pulmonary symptoms in the survey areas. Prevalence of Chronic Bronchitis Symptoms in Japan 71 OUTLINE OF THE SURVEYS AND THE SOURCES OF MATERIAL In 25 surveys in 21 survey areas, 22.590 subjects were interviewed with the standard questionnaire as shown in Table 2. Seven surveys were done by individual researchers of universities or research institutes and 18 were carried out under the national programme by local health agencies with the aid of local medical schools. The population density of each district is listed for the con venience of urban-rural comparison. The type of district was cited from "The minryoku" (Resources of public welfare) by the Asahi Press.2 In 7 surveys total population sampling was made for 40 to 59 years of age and in 18 districts random sampling was done from the residence registry of general populations of the same age groups. Interviews were taken place at local health centers, citizen's halls and community centers. Home visits and letter communications afterwards filled the blank of the reasons for those unable to come. The response rates in the table included those cases. Three serial surveys were made in Kashima town (abbreviated K1, K2 and K3 in Table 2) in 1965, 1969 and 1973. The first survey was done in the agricultural period with entirely clean air and the second was at the beginning of construction of a large scaled industrial com plex. The third (K3) was of two years after when some large plants began to work. The sources of the original reports are listed on the end of this paper. It is regrettable that many reports adopted here, with three exceptions, were un official government publications furnished basic data for the purpose of area designation of the environmental health hazard compensation act. PREVALENCE OF PULMONARY SYMPTOMS 1) Classification and definition of the respiratory symptoms The symptoms classified here were based on the report of the BMRC's com mittee on the aetiology of chronic bronchitis3 and its instruction for the use of the questionnaire (1966),4 and referred also to many important studies published in the past, mainly in U.K. and the U.S.5-17,19,20 The symptom or combination of symptoms selected, and the coding of ques tions and their symptomatic implications are as follows : Persistent cough: Grade 2 or "yes" to (Q 1.+3+5) and (Q 5), usually cough first thing in the morning, during the day or at night in the winter on most days for as much as three months each year. Table 2 Surveys of Prevalence of Pulmonary Symptoms in Japan, 1965-1978 Prevalence of Chronic Bronchitis Symptoms in Japan 93 Persitent phlegm : Grade 2 or "yes" to (Q 6+8+10) and (Q 10), usually bring up any phlegm from the chest first thing in the morning, during the day or at night in the winter or most days for as much as three months each year. Persistent cough and phlegm (PCP) : "yes" to (Q 1/3+5+6/8+10) and (Q 5+10) . Persistent cough and phlegm plus exacerbations or shortness of breath: "yes" to (Q 1/3+5+6/8+10+12bc and Q 5+10+12bc) or (Q 5+10+14b) , exacerbations of cough and phlegm lasting three weeks or more in the last three years, or CPC with dyspnoea. "Chronic bronchitis syndrome"4: "yes" to (Q 6+12b/c+4a ,b and "no" to Q 14c), winter morning phlegm, exacerbations of 3 weeks or more with more than one, and breathlessness grade 3. 2) Persistent cough, and persistent phlegm As shown in Table 3, both cough and phlegm in males are higher grade than in females in total, and age gradients exist. Prevalence of phlegm is much higher than cough in over all. In this table, rural and urban area was grouped by population density 1,000 per square kilometer. The difference of urban and rural mean prevalence of the symptoms is very remarkable, about twice in urban. Holland and Reid6 reported in their 1965's study in London that almost no rural urban difference as to these items of symptom was observed. Their U.K.'s rates (1965) seemed little higher than Japan. However, while the prevalence of phlegm grade 2 of male in U.K. country towns and London mail-van drivers ranged 15-19% for 40-49 years and 13.8-25.5% for 50-59 years, the present Japanese rates for males were 2.8-26.5% (40-49 years) and 3.3-30.2% (50-59 years) re spectively. These figures account for that there is no large difference in per sistent phlegm between Londoner and Japanese in some cities although the time of survey differs about 10 years. In the U.S. studies such as postal and transit workers in New York City,14 East coast telephone plants,18 and California telephone workers,16 the rates of persistent coughs and persistent phlegm"' were within the range of our present data. 3) Persistent cough and phlegm (PCP) Prevalence of PCP in the survey areas by sex and age, and rural-urban difference was shown in Figure 1. The difference of prevalences (Q 1/3+5+ 6/8+10) and (Q 5+10) is originated in persistency of symptoms in the morning or on the day (or at night), and in all the day, as described in MRC instruction Table 3 Prevalence (%) of Cough Grade 2 & Persistent Cough, and Phlegm Grade2 2 & Persistent Phlegm * Numbers are BMRC questionnaire items . ** District: K 1 , K 2, A, AK, M, S 1, F 1, F 2, *** District: I , KI, T, C, 0, YO, N, MI, S 2, OM, Y, SAK, YO, TOY, KA, Prevalence of Chronic Bronchitis Symptoms in Japan 75 * 1/3+5+6/8+10 8 5+10 Fig. 1 Prevaolence (%) of Persistent Cough & Phlegm, guide. Age gradient, higher rate in older age, and sex gradient, higher in male than female, were also observed. Regional difference of the PCP in terms of population density was also remarkable. A trend of higher prevalence was ob served in newly developing industrial regions. Overall rates of PCP (5+10) for males were considerably low ranging 1.7-17.9 (mean 7.7) for 40-49 years 76 Toshio Tovama and Jun Kagawa and 0.8-23.5 (mean 10.0) for 50-59 years. These figures are considerably lower than London (25.7% for 40-49 years and 38.7% for 50-59 years)' and U.K.