BACKGROUND: Excessive daytime sleepiness is one of the principal symptoms of sleep disturbances,and is often associated with serious consequences including traffic and industrial accidents, decreased productivity, and interpersonal problems. However, there are few epidemiologic studies on excessive daytime sleepiness in a large scale sample targeting Japanese general population. METHODS: The survey was performed using a self-administered questionnaire in June 2000, targeting a population randomly selected from among 300 communities throughout Japan. This questionnaire included information about sleep habits and sleep problems. Excessive daytime sleepiness measured according to a question "Do you fall asleep when you must not sleep (for example when you are driving a car)?" RESULTS: A total of 28,714 subjects completed the questionnaire. The prevalence of excessive daytime sleepiness was 2.5% (male=2.8% and female=2.2%). Backward elimination analysis showed that the following were associated with excessive daytime sleepiness: male sex, young age, short sleep duration, subjective insufficient sleep, loss of deep sleep, disagreeable sensations in the legs, interruption of sleep by snoring or dyspnea, and feeling psychological stress. Interruption of sleep by snoring or dyspnea was the strongest associated factor (adjusted odds ratio=2.46, 95% confidence interval=1.76-3.43) of excessive daytime sleepiness. CONCLUSIONS: These results suggest that excessive daytime sleepiness in Japanese is associated with several sleep problems. These findings may be useful in attempts to prevent excessive daytime sleepiness in the general population of Japan. J Epidemiol 2005;15:1-8.
BACKGROUND: Keeping hamsters as pets has been increasing markedly. Clinical reports have suggested that hamster or other pet ownership is associated with respiratory symptoms. However, this association has not been fully investigated by population-based studies in Japan. The aim of the present study was to investigate the relationship between hamster ownership and respiratory symptoms by using a questionnaire. METHODS: During the period of August 1 to 20, 2002, we conducted a cross-sectional survey in Saitama Prefecture, which has a total population of approximately 7 million. First, we selected, proportionally to the population size, 100 areas from 5 administration districts of Saitama Prefecture. From each area, 30 households were chosen: 15 living in detached houses and 15 living in other types of dwelling, such as apartment houses. In this way, 2 groups based on type of dwelling (detached house versus other types) could be studied. A lay away plan was carried out. For the survey, 2 questionnaires were developed. One was a questionnaire dealing with household conditions, including pet keeping. The other sought details regarding individual health and lifestyle conditions. The questionnaire dealing with respiratory symptoms asked "whether the respondents had experienced respiratory symptoms (wheezing and/or breathlessness and/or bad cough) in the last 12 months." RESULTS: The response rate was 78.9%. There were 7,395 respondents in 2,368 households. There was no association between either dog or cat ownership and respiratory symptoms. In contrast, hamsters kept in the home were positively associated with respiratory symptoms. In a multivariate logistic regression analysis, hamster ownership increased the odds ratio for respiratory symptoms (odds ratio: 1.57; 95% confidence interval: 1.18-2.10). CONCLUSION: This large size population-survey indicated that hamster ownership is associated with respiratory symptoms. J Epidemiol 2005;15:9-14.
BACKGROUND: Although a household questionnaire survey is important for estimating vaccination coverage, it raises several problematic issues. METHODS: A household survey was conducted on 900 subjects aged 2, 4, and 6 years living in Obu City, Japan, and a second survey for non-respondents to the first survey was then conducted. Questionnaires bearing a subject's name were used for half of the subjects, while the others were anonymous (the named and nameless groups, respectively). The vaccination dates of six kinds of vaccines, including poliovirus and measles vaccine, for those in the named group were reviewed using the administrative records at the Obu City Health Center. RESULTS: The response rate was 70.1% in the first survey and 84.1% in the first and second surveys combined. The response rate for both groups was nearly equal. Based on administrative records in the named group, the vaccination coverage in the respondents was 0.9-2.9% higher than that in total subjects, and that in the respondents to the first survey was 0.8-4.9% higher. There were very few inconsistencies in the vaccination status between responses to the questionnaire and data of administrative records among respondents in the named group. CONCLUSIONS: These results suggested that vaccination coverage from a household questionnaire survey in Japan might not be extremely biased by either non-responses or incorrect answers. J Epidemiol 2005;15:15-19.
BACKGROUND: This study was conducted to describe the epidemiologic features of amyotrophic lateral sclerosis (ALS) in Japan by examining annual trends in mortality (1995-2001), and to discuss the background factors possibly responsible for the recent variations in the mortality rate. METHODS: Trends in both the age-adjusted and age-specific mortality rates of ALS were examined by using the data obtained from the vital statistics of Japan between 1995 and 2001. RESULTS: There were small increases in the number of ALS deaths (from 1249 to 1400 per year) and the crude mortality rates (from 1.00 to 1.10 per 100,000 population) between 1995 and 2001. The ageadjusted mortality rate of ALS (adjusted using the 1985 model population of Japan) has decreased (from 0.84 per 100,000 population in 1995 to 0.74 in 2001). Age-specific mortality rates have been increasing particularly in the population older than 70 years of age, with the peak in mortality in the 70- to 80- year old age group. CONCLUSIONS: ALS mortality rates increased proportionally more for elderly population during the study period. Further epidemiologic studies will be needed to clarify the possible background factors contributing to the increase in ALS mortality in the elderly. J Epidemiol 2005;15:20-23.
BACKGROUND: There have not been many reports regarding primary biliary cirrhosis (PBC) in Asia. We conducted a cross-sectional study of PBC in Japan. METHODS: In fiscal year 1999, 9,761 patients with symptomatic PBC were registered to receive public financial aid from the Ministry of Health, Labour and Welfare of Japan. For our cross-sectional study we chose 5,805 patients whose clinical data had been written between 1999 and 2000, and statistically analyzed the data, including sex, age, major symptoms, and laboratory data. RESULTS: Our study estimated that the male-to-female ratio was 1:8.0. The median ages of male and female patients were 59 and 60 years, respectively. The major symptoms and physical findings were as follows: pruritus 53.3%, jaundice 11.3%, xanthomas 5.8%, splenomegaly 38.1%, and esophageal varices 19.1%. Antimitochondrial antibody (AMA) was positive in 86.6%, but its positive rate was lower among Japanese patients than among those in western countries. IgM levels were higher among AMApositive patients than among AMA-negative patients. Regarding Sjogren's syndrome, rheumatoid arthritis, chronic thyroiditis, and scleroderma, patients had lower frequencies of complicated autoimmune diseases than those in western countries. CONCLUSIONS: The male-to-female ratio, frequencies by age group, symptoms and physical findings among patients with PBC were consistent with previous reports in Japan and from other countries. However, positivity of AMA and the frequency of complicated autoimmune diseases were lower among patients in Japan than among those in western countries. J Epidemiol2005; 15: 24-28.