Journal of Epidemiology Vol. 25(2015) No. 3

Background: Uncoded diagnoses in health insurance claims (HICs) may introduce bias into Japanese health statistics dependent on computerized HICs. This study’s aim was to identify the causes and characteristics of uncoded diagnoses.
Methods: Uncoded diagnoses from computerized HICs (outpatient, inpatient, and the diagnosis procedure-combination per-diem payment system [DPC/PDPS]) submitted to the National Health Insurance Organization of Kumamoto Prefecture in May 2010 were analyzed. The text documentation accompanying the uncoded diagnoses was used to classify diagnoses in accordance with the International Classification of Diseases-10 (ICD-10). The text documentation was also classified into four categories using the standard descriptions of diagnoses defined in the master files of the computerized HIC system: 1) standard descriptions of diagnoses, 2) standard descriptions with a modifier, 3) non-standard descriptions of diagnoses, and 4) unclassifiable text documentation. Using these classifications, the proportions of uncoded diagnoses by ICD-10 disease category were calculated.
Results: Of the uncoded diagnoses analyzed (n = 363 753), non-standard descriptions of diagnoses for outpatient, inpatient, and DPC/PDPS HICs comprised 12.1%, 14.6%, and 1.0% of uncoded diagnoses, respectively. The proportion of uncoded diagnoses with standard descriptions with a modifier for Diseases of the eye and adnexa was significantly higher than the overall proportion of uncoded diagnoses among every HIC type.
Conclusions: The pattern of uncoded diagnoses differed by HIC type and disease category. Evaluating the proportion of uncoded diagnoses in all medical facilities and developing effective coding methods for diagnoses with modifiers, prefixes, and suffixes should reduce number of uncoded diagnoses in computerized HICs and improve the quality of HIC databases.

Background: Cardiac lesions, such as coronary dilatation, aneurysms, narrowing, myocardial infarction, and valvular lesions, sometimes occur in Kawasaki disease, but most studies have only evaluated cardiac lesions in the later phase of the disease. This study was undertaken to clarify the related factors between cardiac lesions and laboratory data in the initial phase of Kawasaki disease.
Methods: We conducted a cross-sectional study using data for 26 691 patients from the 22nd nationwide survey of Kawasaki disease in Japan, the observation period of which was from January 2011 through December 2012. We excluded patients with recurrent Kawasaki disease and who were more than seven days from the start of symptoms at admission. We analyzed 23 155 cases (13 353 boys; mean age: 923 ± 734 days) with available laboratory data for white blood cell count, platelet count, serum albumin, and C-reactive protein (CRP).
Results: Cardiac lesions were detected in 984 cases (656 boys and 328 girls); lesions were classified as coronary dilatation (764 cases), coronary aneurysm (40), giant coronary aneurysm (6), coronary narrowing (3), and valvular lesions (204). The significant related factors of initial coronary dilatation were male sex (odds ratio [OR] 1.73), older age (OR per 100 days increase 1.03), higher platelet count (OR per 10 000 cells/µL increase 1.006), lower albumin (OR per 1 g/dL increase 0.66), and higher CRP (OR per 1 mg/dL increase 1.02). The factors related to coronary aneurysm were higher platelet count (OR 1.01) and lower albumin (OR 0.34). No factors were significantly related to giant coronary aneurysm. The related factors of valvular lesions were age (OR 0.98), and higher CRP (OR 1.05).
Conclusions: Clinicians should consider male sex, older age, higher platelet count, lower albumin levels, and higher CRP levels when assessing risk of cardiac lesions in the initial phase of Kawasaki disease.

Background: The prevalence and risk factors for endometriosis may differ according to diagnosis methodologies, such as study populations and diagnostic accuracy. We examined risk profiles in imaging-diagnosed endometriosis with and without surgical confirmation in a large population of Japanese women, as well as the differences in risk profiles of endometriosis based on history of infertility.
Methods: Questionnaires that included items on sites of endometriosis determined by imaging techniques and surgical procedure were mailed to 1025 women who self-reported endometriosis in a baseline survey of the Japan Nurses’ Health Study (n = 15 019).
Results: Two hundred and ten women had surgically confirmed endometriosis (Group A), 120 had imaging-diagnosed endometriosis without a surgical procedure (Group B), and 264 had adenomyosis (Group C). A short menstrual cycle at 18–22 years of age and cigarette smoking at 30 years of age were associated with significantly increased risk of endometriosis (Group A plus Group B), while older age was associated with risk of adenomyosis (Group C). In women with a history of infertility, a short menstrual cycle was associated with a significantly increased risk of endometriosis in both Group A and Group B, but risk profiles of endometriosis were different between Group A and Group B in women without a history of infertility.
Conclusions: Women with surgically confirmed endometriosis and those with imaging-diagnosed endometriosis without surgery have basically common risk profiles, but these risk profiles are different from those with adenomyosis. The presence of a history of infertility should be taken into consideration for evaluation of risk profiles.

Background: Epidemiological findings regarding the relationship between decayed teeth (DT) and metabolic syndrome (MetS) are scarce. We evaluated the relationship of DT with MetS, obesity, and MetS components in early middle-aged male Japanese employees.
Methods: We cross-sectionally analyzed dental and medical health checkup results from a total of 4716 participants aged 42 or 46 years. Logistic regression models were employed to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) after adjustment for age, breakfast consumption frequency, drinking habits, smoking status, and physical activity.
Results: Significant differences in the prevalence of MetS, obesity determined by body mass index, and the components of MetS between participating men with and without DT were detected (all P < 0.01). The adjusted OR of MetS was 1.41 (95% CI, 1.14–1.74) for those with 1 or 2 DT, and 1.66 (95% CI, 1.28–2.16) for those with ≥3 DT (P for trend = 0.01), and this significant relationship was observed even in those without periodontal pocket formation (P for trend = 0.03) or missing teeth (P for trend = 0.02). DT was significantly related to overweight/obesity and the MetS components of hypertension, dyslipidemia, and hyperglycemia, with adjusted ORs of 1.35 (95% CI, 1.19–1.53), 1.22 (95% CI, 1.07–1.39), 1.18 (95% CI, 1.03–1.34), and 1.33 (95% CI, 1.13–1.56), respectively. In addition, even in non-overweight/non-obese men, DT was found to be related to dyslipidemia and hyperglycemia, though with marginal significance (P < 0.05).
Conclusions: Our findings suggest that having DT is related to MetS in early middle-aged Japanese men directly and through obesity and is independent of health behaviors, periodontal condition, and tooth loss.

Background: The present study aimed to investigate the prevalence of scoliosis and to analyze the factors associated with scoliosis in schoolchildren aged between 7 and 17 years.
Methods: This is a cross-sectional and quantitative study with stratified random selection of public school students in the city of Santa Cruz, Brazil. The presence of scoliosis was examined, as well as the flexibility of the posterior muscle chain, socioeconomic characteristics, anthropometry, lifestyle habits, sexual maturation, and ergonomics of school furniture. In order to identify factors associated with scoliosis, the variables were divided in biological, socioeconomic, lifestyle, and ergonomic factors, and crude and adjusted prevalence ratios (PRs) were estimated by means of Poisson regression analysis.
Results: Two hundred and twelve pupils participated in this study (mean age 11.61 years, 58% female). The prevalence of scoliosis was 58.1% (n = 123) and associated with female sex (PR 2.54; 95% CI, 1.33–4.86) and age between 13 and 15 years (PR 5.35; 95% CI, 2.17–13.21). Sleeping in a hammock was inversely associated with scoliosis (PR 0.44; 95% CI, 0.23–0.81).
Conclusions: Scoliosis seems to be positively associated with female sex and age between 13 and 15 years, whereas the habit of sleeping in a hammock is negatively associated with the onset of scoliosis.

Background: Season of birth (SoB) has been linked with various health outcomes. This study aimed to examine the associations between month of birth (MoB) and adult measures of leg length (LL), body mass index (BMI), and waist circumference (WC).
Methods: We analysed survey data from 10 geographically diverse areas of China obtained through the China Kadoorie Biobank. Analysis included 487 529 adults with BMI ≥ 18.5 kg/m². A general linear model was used to examine the associations between MoB and adult measures of LL, BMI, and WC, adjusted for survey site, sex, age, education level, smoking habit, alcohol consumption, physical activity level, sedentary leisure time, height (only for WC and LL), and hip circumference (only for LL).
Results: MoB was independently associated with both BMI and WC. Birth months in which participants had higher measures of adiposity were March–July for BMI and March–June for WC. The peak differences were 0.14 kg/m² for BMI and 0.47 cm for WC. The association between MoB and LL depended on survey site. Participants who were born in February–August in four sites (Harbin, Henan, Gansu, and Hunan) had the shortest LL (all P < 0.01). The peak difference in mean LL was 0.21 cm. No statistically significant association between MoB and LL was noted in the other sites (Qingdao, Suzhou, Sichuan, Zhejiang, Liuzhou, and Haikou).
Conclusions: These findings suggest that MoB is associated with variations in adult adiposity measures and LL among Chinese adults. Low exposure to ultraviolet B radiation and subsequent reduced levels of vitamin D during the late second and early third trimesters may be involved in these phenomena.

Background: To determine the clinical course, follow-up strategies, and survival of oesophageal cancer patients using a competing risks survival analysis.
Methods: We conducted a retrospective and prospective follow-up study. The study included 180 patients with a pathological diagnosis of oesophageal cancer in A Coruña, Spain, between 2003 and 2008. The Kaplan-Meier methodology and competing risks survival analysis were used to calculate the specific survival rate. The study was approved by the Ethics Review Board (code 2011/372, CEIC Galicia).
Results: The specific survival rate at the first, third, and fifth years was 40.2%, 18.1%, and 12.4%, respectively. Using the Kaplan-Meier methodology, the survival rate was slightly higher after the third year of follow-up. In the multivariate analysis, poor prognosis factors were female sex (hazard ratio [HR] 1.94; 95% confidence interval [CI], 1.24–3.03), Charlson’s comorbidity index (HR 1.17; 95% CI, 1.02–1.33), and stage IV tumours (HR 1.70; 95% CI, 1.11–2.59). The probability of dying decreased with surgical and oncological treatment (chemotherapy and/or radiotherapy) (HR 0.23; 95% CI, 0.12–0.45). The number of hospital consultations per year during the follow-up period, from diagnosis to the appearance of a new event (local recurrences, newly appeared metastasis, and newly appeared neoplasias) did not affect the probability of survival (HR 1.03; 95% CI, 0.92–1.15).
Conclusions: The Kaplan-Meier methodology overestimates the survival rate in comparison to competing risks analysis. The variables associated with a poor prognosis are female sex, Charlson’s comorbidity score and extensive tumour invasion. Type of follow-up strategy employed after diagnosis does not affect the prognosis of the disease.

Background: The number of patients and incidence rate of Kawasaki disease (KD) are increasing in Japan. We have therefore characterized the latest epidemiological information on KD.
Methods: The 22nd nationwide survey of KD, which targeted patients diagnosed with KD in 2011 and 2012, was conducted in 2013 and included a total of 1983 departments and hospitals. In order to report on all patients with KD during the 2 survey years, we targeted hospitals of 100 beds or more with pediatric departments, or specialized pediatric hospitals.
Results: From a total of 1420 hospitals and departments (71.6% response rate), 26 691 KD patients were reported (12 774 in 2011 and 13 917 in 2012; 15 442 males and 11 249 females). The annual incidence rates were 243.1 per 100 000 population aged 0 to 4 years in 2011 and 264.8 in 2012. The number of cases of KD recorded in 2012 was the highest ever reported in Japan. The incidence rate of complete cases was also the highest ever reported in Japan and contributed to the increase in the rate of total cases in recent years. The number of patients diagnosed per month peaked in January, and additional peaks were noted during summer months, although these peaks were lower than those seen in winter. Age-specific incidence rate showed a monomodal distribution with a peak in the latter half of the year in which patients were born.
Conclusions: The number of patients and the incidence rate of KD in Japan continue to increase. A similar trend has also been seen for patients with complete KD.

Background: The aim of this study was to explore whether there is a relationship between pyogenic liver abscess (PLA) and subsequent risk of acute pancreatitis in Taiwan.
Methods: Using inpatients claims data from the Taiwan National Health Insurance Program, we identified 30 866 subjects aged 20–84 years with the first-attack of PLA from 2000 to 2010 as the PLA group and randomly selected 123 464 subjects without PLA as the non-PLA group. The incidence of the first attack of acute pancreatitis at the end of 2010 and the risk associated with PLA and other comorbidities were measured.
Results: The overall incidence of acute pancreatitis was 3.84-fold greater in the PLA group than in the non-PLA group (4.61 vs 1.19 events per 1000 person-years; 95% CI, 3.43–4.29). After controlling for potential confounding factors, the adjusted hazard ratio of acute pancreatitis was 3.00 (95% CI, 2.62–3.43) for the PLA group, as compared to the non-PLA group. Further analysis showed that compared to subjects with neither PLA nor comorbidities, patients with PLA and hypertriglyceridemia, biliary stones, alcoholism, or hepatitis C had greater risk of acute pancreatitis than those with PLA alone.
Conclusions: PLA correlates with increased risk of subsequent acute pancreatitis. Comorbidities, including hypertriglyceridemia, biliary stones, alcoholism, and hepatitis C, may enhance the risk of developing acute pancreatitis.

Background: Neighborhood deprivation has been shown in many studies to be an influential factor in cardiovascular disease risk. However, no previous studies have examined the effect of neighborhood socioeconomic conditions on the risk of stroke in Asian countries.
Methods: This study investigated whether neighborhood deprivation was associated with the risk of stroke and stroke death using data from the Japan Public Health Center-based Prospective Study. We calculated the adjusted hazard ratios of stroke mortality (mean follow-up, 16.4 years) and stroke incidence (mean follow-up, 15.4 years) according to the area deprivation index (ADI) among 90 843 Japanese men and women aged 40–69 years. A Cox proportional-hazard regression model using a shared frailty model was applied.
Results: The adjusted hazard ratios of stroke incidence, in order of increasing deprivation with reference to the least deprived area, were 1.16 (95% CI, 1.04–1.29), 1.12 (95% CI, 1.00–1.26), 1.18 (95% CI, 1.02–1.35), and 1.19 (95% CI, 1.01–1.41), after adjustment for individual socioeconomic conditions. Behavioral and psychosocial factors attenuated the association, but the association remained significant. The associations were explained by adjusting for biological cardiovascular risk factors. No significant association with stroke mortality was identified.
Conclusions: Our results indicate that the neighborhood deprivation level influences stroke incidence in Japan, suggesting that area socioeconomic conditions could be a potential target for public health intervention to reduce the risk of stroke.