Epidemiology provides extremely valid information and evidence regarding human health. Epidemiologic findings with regard to major illnesses must be amassed, enhanced, and expanded further into related areas as a foundation for evidence-based medicine that is based on clinical practice, as well as for evidence-based healthcare that includes public health-related issues. Epidemiology should be recognized not only by epidemiologists but also by a variety of people, including specialists in other areas for healthcare and medicine, people in law and media, policy makers, and the general public. A system is needed that can create information for facilitating appropriate decision-making with issues related to clinical medicine and public health. The principles and methodology of epidemiology are used as a base for developing a field of health informatics. The objective of health informatics is to establish a system for facilitating the flow and circulation of health and medical information. Health informatics has potential applications for the creation, communication, and use of information, and the discipline is being expanded as a practical applied science in search of solutions. This report represents an effort to expand the scope of health informatics and extend the applications of epidemiology by working with individuals in other disciplines and the public. J Epidemiol 2006; 16: 93-100.
BACKGROUND: It is important to examine progression to acquired immunodeficiency syndrome (AIDS) or death and its predictors among human immunodeficiency virus (HIV) infected persons before and after the introduction of the highly active antiretroviral therapy (HAART) available in Japan since 1997. METHODS: The data used were from a survey of persons with HIV infected through blood coagulation factor products in Japan. Progression to AIDS or death during two periods, between January 1994 and March 1997, and between April 1997 and March 2002, were observed. RESULTS: The AIDS-free proportion after 3 years was 74% among 417 participants for the earlier period and 94% among 605 participants in the later one. The hazard ratio of low CD4 cell count (less than 200 cells/μL) was 50.8 for the earlier period and 4.7 for the later one compared with that of 500 cells/μL or more. After adjustment by plasma HIV RNA levels and use of antiretroviral therapy, the hazard ratios of the low CD4 cell count for the later period were still significant. CONCLUSION: The AIDS-free proportion among people with HIV infected through blood products in Japan largely increased after the introduction of HAART. The CD4 cell count remains an important predictor of future progression, but its importance might be less because of HAART. J Epidemiol 2006; 16: 101-106.
BACKGROUND: Revision of the national nutrient database in 2000 had a strong impact on the absolute level of estimated nutrient intake in dietary assessments. However, whether it influenced the ranking of individuals by estimated intake, a more important function in epidemiologic studies, has not been investigated. Here, we investigated the effect of this revision of the nutrient database on the validity of a food frequency questionnaire (FFQ) used to estimate nutrient intake in the Japan Public Health Center-based prospective Study (JPHC Study). METHODS: Subjects were a subsample of the JPHC Study who volunteered to participate in the validation study of the FFQ. Validity of the FFQ was evaluated by reference to the 28-day weighed dietary records as a gold standard. Nutrient intake according to the FFQ was recalculated using the revised database, and the results were compared to those using the previous database. Spearman's rank correlation coefficients (CCs) between intakes estimated by the FFQ and dietary records were computed using the revised database, and were compared to CCs computed using the previous database. RESULTS: For most of the nutrients, mean intake increased or decreased significantly using the revised database. However, no notable change was seen for the CC between estimated intake according to dietary records and FFQ when the revised database was used for calculation. Differences in the point estimates of the CCs ranged from -0.14 to 0.15. Likewise, CCs between biomarkers and estimated intake according to FFQ were similar for the two databases. CONCLUSION: Despite changes in intake levels for many nutrients, the validity of our FFQ using rank correlation by nutrient intake was not influenced by revision of the nutrient database in Japan. J Epidemiol 2006; 16: 107-116.
BACKGROUND: Few epidemiologic studies have examined the association between the rate of eating and obesity. In this study, we cross-sectionally examined the association of the self-reported rate of eating with current Body Mass Index (BMI), and BMI-change from 20 years of age to the current age. METHODS: Subjects were 3737 male (mean age ± standard deviation and mean BMI ± standard deviation: 48.2 ± 7.1 years and 23.3 ± 2.7 kg/m2) and 1005 female (46.3 ± 7.0 years and 21.8 ± 2.8 kg/m2) Japanese civil servants. We measured self-reported categorical rate of eating, current BMI, BMI at age 20, and BMI-change from age 20. Energy intake was assessed over a 1-month period with a brief-type diet history questionnaire. RESULTS: The multiple regression analysis in which the current BMI was regressed by categorical rate of eating, energy intake, age, and lifestyle factors showed that current BMI steadily increased by -0.99, -0.67, 0.81, and 1.47 kg/m2 along with the progress of categorical rate of eating from the 'medium' group to 'very slow', 'relatively slow', 'relatively fast', and 'very fast' groups, respectively, in men. In women, the corresponding values were -1.06, -0.35, 0.50, and 1.34 kg/m2. When the BMI increment from age 20 to current age was regressed in the same manner, the increment was -0.63, -0.34, 0.57, and 1.05 kg/m2 in men and -0.71, -0.32, 0.34, and 1.14 kg/m2 in women, respectively. Additionally, both BMI at age 20 and current height were positively associated with rate of eating. CONCLUSIONS: Our results among middle-aged men and women suggest that eating fast would lead to obesity. J Epidemiol 2006; 16: 117-124.
BACKGROUND: In Japan, the incidence rate of colon cancer has more rapidly increased than that of rectal cancer. The differential secular trends may be due to different dietary factors in the development of colon and rectal cancers. METHODS: To compare dietary risk factors between colon and rectal cancers, we undertook a casecontrol study at Aichi Cancer Center Hospital, Japan. Subjects were 507 patients with newly diagnosed colon (n = 265) and rectal (n = 242) cancers, and 2,535 cancer-free outpatients (controls). Intakes of nutrients and food groups were assessed with a food frequency questionnaire, and multivariate-adjusted odds ratios (ORs) were estimated using unconditional logistic models. RESULTS: We found a decreasing risk of colon cancer with increasing intakes of calcium and insoluble dietary fiber; the multivariate ORs across quartiles of intake were 1.00, 0.90, 0.80, and 0.67 (trend p = 0.040), and 1.00, 0.69, 0.64, and 0.65 (trend p = 0.027), respectively. For rectal cancer, a higher consumption of carotene and meat was associated with a reduced risk; the corresponding ORs were 1.00, 1.10, 0.71, and 0.70 for carotene (trend p = 0.028), and 1.00, 0.99, 0.68, and 0.72 for meat (trend p = 0.036). Carbohydrate intake was positively correlated with the risk of rectal cancer (ORs over quartiles: 1.00, 1.14, 1.42, and 1.54; trend p = 0.048). This association was stronger in women, while fat consumption was inversely correlated with the risk of female colon and rectal cancers. CONCLUSIONS: Dietary risk factors appear to considerably differ between colon and rectal cancers. J Epidemiol 2006; 16: 125-135.