The frequency at which unruptured cerebral aneurysms are detected has increased due to advances in low- or non-invasive diagnostic techniques. Despite the recent improvements in sur- gical and medical management of aneurysmal subarachnoid hemorrhages, however, the overall case- fatality rate of this disease is still high. To reduce it, the natural history of unruptured cerebral aneurysms should be better understood. METHODS: The subjects consisted of 156 patients with unruptured cerebral aneurysms who had been admitted to the Department of Surgical Neurology, Jichi Medical School Hospital or Jichi Medical School Ohmiya Medical Center, Japan, between January 1989 and December 1998. All of the patients were classified according to the process by which aneurysms had been detected. The expected num- ber of deaths was calculated by using age- and sex-specific mortality rates obtained from the vital sta- tistics. A standardized mortality ratio and 95% confidence interval were calculated by using the expect- ed and observed numbers of deaths. RESULTS: The standardized mortality ratios differed among the groups according to the process of detecting aneurysms. The incidence rate of rupture of unruptured cerebral aneurysms was 1.3 per 100 person-years. The annual rupture rate of unruptured cerebral aneurysms was higher than previously reported. The survival rate of the group that underwent surgical treatment for unruptured cerebral aneurysms was higher than that of the untreated group. CONCLUSIONS: The annual rupture rate of unruptured cerebral aneurysms may be higher than pre- viously reported. J Epidemiol 2003;13:289-295.
BACKGROUND: The increase in the smoking rate among young women is a worldwide problem. However, few reports have focused on female students, in particular, with detailed accounts of their smoking behavior. The aim of this study was to clarify the smoking patterns of Japanese women of approximately 20 years of age. METHODS: Smoking behavior, age at initiation, favorite brand and related attitudes were examined using a cross-sectional anonymous questionnaire administered to students at a women's university in Miyagi, Japan in 2000. RESULTS: Of 2, 984 subjects (response rate: 96%), 16% said that they smoke (95% confidence interval 15-18%): 7% of freshmen, 16% of sophomores, 22% of juniors and 20% of seniors. While music majors were most likely to smoke (21%), domestic science majors had the lowest rate of smoking (10%). Among the smokers, 27% started the habit at age 20 years, the legal age in Japan, and 25% started at age 18. The favorite brand was Marlboro (39%), followed by Mild Seven (16%), a domestic brand. One-third of the smokers had no plans to quit. CONCLUSIONS: Reaching the legal age and entering university may prompt young women to start smoking habitually. In contrast to its overall market share in Japan, a US brand is now favored by current young female smokers. J Epidemiol 2003;13:296-302.
Little is known about the relationship between a patient's personality and smoking behavior. METHODS: We assessed the smoking status of 262 male smokers who had been diagnosed with cancer and admitted to a teaching hospital, using a self-administered questionnaire that was mailed to the patients 6 months after discharge. The personality of the patients was assessed with the Kyushu University Egogram at admission, and the patients were categorized into five groups according to the ego state with the highest value among the five ego states, namely "Critical Parent" dominant, "Nurturing Parent" dominant, "Adult" dominant, "Free Child" dominant and "Adapted Child" dominant. Multivariate logistic regression analyses were used to assess the influence of the type of personality on smoking behavior after hospital discharge with adjustment for considerable predictive variables. RESULTS: The smoking cessation rate at 6 months after hospital discharge was 63% (164/262). Multivariate analyses revealed that after adjustment for age, cancer site, length of hospital stay, time elapsed since last cigarette, self-confidence to quit smoking and strength of nicotine dependence, and being an Adult dominant personality were positively (p<0.01), and being a Free Child dominant person- ality was negatively (p<0.05) associated with post-discharge abstinence. These findings did not change when the non-responders (n=50) of the questionnaire were included in the analysis as post-discharge smokers. CONCLUSIONS: These findings indicate that a male cancer patient's personality as assessed by the egogram has predictive significance for whether the patient will have a smoking habit after discharge. J Epidemiol 2003;13:303-313.
In recent years, numerous reports demonstrating the relationship between an increase in the concentration of fine particulate matter (PM2.5) and daily mortality have been released in the United States and Europe. There have been few studies that clearly characterize the short-term effects of particulate matter on the mortality in Japan. We conducted data analysis to investigate the short-term effects of suspended particulate matter (SPM) on mortality in Japan. METHODS: In this study, we used data sets from the 13 largest cities containing data on the daily mortality of residents aged 65 years or older, concentrations of air pollutants including SPM, temperature, and humidity. Risk ratios for mortality resulting from respiratory diseases, cardiovascular diseases, and all causes other than accidents, from 1990 through 1994, were summarized using a generalized additive model (GAM) and a meta-analysis of random effect model. RESULTS: The risk ratios for an increase of 10 ug/m3 in SPM concentrations adjusted for SO2, NO2, CO, Ox, temperature, and humidity were 1.0077 for all causes of mortality, 1.0109 for respiratory diseases, and 1.0091 for cardiovascular diseases, and the lower limits of the 95% confidence intervals for the risk ratios were greater than one for all cases. With regards to the effects of time lag, risk ratios were higher for the SPM concentrations on the day when the mortality was recorded, and the preceding day. CONCLUSIONS: These results suggest a positive relationship between SPM concentrations and daily mortality in Japan. J Epidemiol 2003;13:314-322.
The risk of colorectal cancer in relation to smoking habits has been examined mostly in Caucasians, and evidence for other ethnic groups is still scarce. METHODS: Our data came from the Japan Collaborative Cohort (JACC) Study. From 1988 through 1990, 25, 260 men and 34, 619 women aged 40-79 years completed a questionnaire on cigarette smoking and other lifestyle factors. Hazard ratios (HR) were estimated by fitting proportional hazards models. RESULTS: During the mean follow-up of 7.6 years through December 1997, we documented 408 incident colon cancers and 204 rectal cancers. We found a non-significant increase in colon cancer risk in male current smokers compared with never smokers. The multivariate-adjusted hazard ratios were 1.07 (95% confidence interval [CI]: 0.72-1.59) for ex-smokers and 1.23 (95% Cl: 0.85-1.78) for current smokers. We however failed to observe a clear dose-response relationship between smoking intensity or duration and colon cancer risk. The adjusted hazard ratio was 1.07 (95% Cl: 0.71-1.61) even for 40+ years of smoking. Almost no increase in colon cancer risk was detected for female smokers, and male smokers were not at an enhanced risk of rectal cancer. CONCLUSIONS: Cigarette smoking was not a strong risk factor for colorectal cancer even after a long-term exposure, although a weak association remains open to discussion. J Epidemiol 2003;13:323-332.
Numerous birth weight standards for twins have been reported in western countries, whereas little is in Japan. The aim of this study is to present birth weight, birth length, chest circumfer- ence, and head circumference references, clarifying features related to these body size parameters, and to compare our birth weight references with recent report of birth weight norms of Japanese twins using the vital statistics. METHODS: The subjects consisted of 1, 061 twin pairs in total, with birth years ranging from 1968 through 1990. Data was obtained from the Twins Protocol Questionnaire, which asked for information about twins' growth and development in infancy, and the "Maternal and Child Health Handbook, " which was presented by Ministry of Health and Welfare. Statistical means, standard deviations, and selected percentiles by gestational age were calculated and smoothed using data that contained at least gesta- tional age and one of the four items. RESULTS: Birth weight was significantly lighter than that of singletons when three additional parame- ters, especially chest and head circumference, were not measured. Gestational age was correlated with weight, length, chest circumference, and head circumference, in that order, for both sexes. Compared with singletons, birth weight difference in twins was marked and slight difference was observed as to length, whereas no difference was observed as to chest and head circumference. The present results as to birth weight were consistently similar to the birth weight norms of twins using vital statistics in Japan. CONCLUSION: Growth standards for twins, especially as to birth weight, are essential to understand and evaluate intrauterine growth of twins. J Epidemiol 2003;13:333-341.