Epidemiologic analysis of the clinical features of Japanese patients with polymyositis and dermatomyositis.

OBJECTIVES: This study aimed to investigate the clinical characteristics of polymyositis/dermatomyositis (PM/DM) in Japan by analyzing data from the nationwide registration system. METHODS: The data of the registration system in 2009 were analyzed to investigate patient numbers, sex, clinical symptoms, therapies, complications, and prognosis of PM/DM. RESULTS: The total number of PM/DM cases was approximately 17,000, and the female/male sex ratio was 2.7:1. Almost all patients improved as a result of therapy, but many suffered from sequelae such as muscle weakness. CONCLUSIONS: The results characterize significant aspects of Japanese PM/DM patients. However, a further prospective survey is required to clarify the true epidemiology and natural history of PM/DM.

Prevalence and incidence of polymyositis and dermatomyositis in Japan.

OBJECTIVES: To estimate the number of patients with polymyositis/dermatomyositis (PM/DM) in Japan and the prevalence rate and incidence rate of the disease. METHODS: The electronic database in the nationwide registration system on intractable diseases from 2003 to 2010 was utilized to identify the number of prevalent and incident cases of PM/DM. The electronic data entry rate was used to establish the total number of registered cases. RESULTS: The estimated total number of patients with PM/DM and the prevalence rate in Japan in 2010 were 17,000 and 13.2 per 100,000 population, respectively. The prevalence of PM/DM ranged from 10 to 13 per 100,000 population with a trend toward increasing over time. The incidence of PM/DM was estimated within the range 10-13 per 1,000,000 person-years, except for 2003. CONCLUSIONS: We report the prevalence and incidence of PM/DM recently in Japan for the first time at the nationwide population level. Because the prevalence seems to be increasing recently, continued monitoring of these epidemiologic features is required.

[The effect of determining birthdays by social factors such as maternal preference on the distribution in the number of daily live births].

OBJECTIVES: To investigate the effect of determining birthdays by social factors on the distribution of daily live births. METHODS: We obtained data on live births tabulated by date and birthplace (hospitals, clinics, and maternity homes) between 1981 and 2010 in Japan from the National Vital Statistics System. This study analyzed the variations in live births for each day of the week, as well as for several specific days observed to have a systematic variation in the number of live births. We determined the ratio of the mean daily live births on those specific days to the overall daily average each month (the birth number ratio). The standardized deviation (the ratio of the deviation to the standard deviation for the day of week) regarding the birth number ratio of each specific day was also determined. RESULTS: The birth number ratio in hospitals and clinics was highest on Tuesdays and lowest on Sundays. Hospitals showed a large difference in the birth number ratio between weekdays and weekends, although the difference in the birth number ratio between weekdays and Saturdays was smaller in clinics than in hospitals. The birth number ratio during the first three days of the New Year was lower than that on Sundays. Until approximately 1995, the standardized deviation on February 29th and April 1st (the end of the Japanese school year) showed abnormally low values, while those on March 1st and April 2nd showed significantly high values. Following that time period, the significant variations on February 29th (only on Sundays), April 1st (only on Sundays), March 1st, and April 2nd almost completely disappeared. Maternity homes showed equivalent results until the 1980s or the middle of the 1990s. CONCLUSION: The variations in the days of the week were inconsistent with nationwide policies for consultation in each setting. These results indicate that some birth dates were set for institutional reasons or maternal preferences (i.e., the day after the leap day or the next school year) by using or avoiding obstetric intervention. The abnormal variation on leap days and on April 1st might be related to fictitious reporting. More recent variations in the birth number ratio on specific days suggest that some individuals may avoid obstetric intervention. The results of this study indicate that determining birthdays by social factors may have been practiced in maternity homes until approximately 1990.

Age at onset and gender distribution of systemic lupus erythematosus, polymyositis/dermatomyositis, and systemic sclerosis in Japan.

OBJECTIVES: The aim of this study was to describe age, gender distribution, and age at onset of systemic lupus erythematosus (SLE), polymyositis/dermatomyositis (PM/DM), and systemic sclerosis (SSc) in Japan. METHODS: We used epidemiological information on 21,405, 6,327, and 10,058 patients with SLE, PM/DM, and SSc, respectively, in a Japanese nationwide registration database of patients with intractable diseases. RESULTS: All three diseases occur predominantly in women, with the female-to-male ratio being 8.2:1, 2.6:1, and 7.7:1 for SLE, PM/DM, and SSc, respectively. The most susceptible age for SLE is 15-44 and 20-39 years for males and females, respectively. For PM/DM it is 45-64 and 40-64 years and for SSc, 50-69 and 40-59 for men and women, respectively. CONCLUSIONS: The basic descriptive epidemiological characteristics of SLE, PM/DM, and SSc in Japan, such as gender distribution, present age, and age at onset, were surveyed nationwide for fiscal 2007. It was found that these characteristics were similar to those in Western populations. Our finding provides new information on the natural history of disease development.

[Age at the onset of intractable disease: based on a clinical database for patients receiving financial aid for treatment].

OBJECTIVE: We examined a clinical database for patients receiving financial aid for treatment to elucidate age at onset of intractable disease. METHODS: Data were obtained from the clinical database of patients receiving financial aid for treatment in 2003. Age at onset of disease was calculated by subtracting the year of birth from the year of onset as registered in the database. Percentiles for age at onset and peak onset age were evaluated for each intractable disease. Peak onset ages for primary immune-deficiency syndrome, subacute sclerosing panencephalitis, lysosomal diseases, epidermolysis bullosa and neurofibromatosis I and II were under 20 years. RESULTS: Peak onset ages for aortitis syndrome, systemic lupus erythematosus, Behcet's disease, adrenoleukodystrophy, multiple sclerosis, ulcerative colitis and Crohn's disease were between 20 and 50. Distributions of age at onset for aplastic anemia, idiopathic thrombocytopenic purpura, myasthenia gravis, moyamoya disease and sarcoidosis were bimodal. Peak onset age for many other diseases were > or = 40 years. CONCLUSIONS: Using a clinical database for patients receiving financial aid for treatment, the distribution of ages at onset and peak onset ages could be systematically clarified for individual intractable diseases. Our study provides new information on the natural history of disease development.

[Chronological analysis of individually linked data for patients with intractable disease receiving public financial aid for treatment].

PURPOSE: Nationwide surveys of intractable disease patients receiving public financial aid for treatment were performed by Research Committee for Epidemiology of Intractable Disease (Ministry of Health and Welfare, Japan) 4 times in the past, in 1984, 1988, 1992 and 1997. The purpose of the present study was to clarify the features of continuance with intractable disease patients receiving public financial aid for treatment. METHODS: Individual information collected by each nationwide survey was linked using the disease, the residence, the sex, and the birth date. The proportion of intractable disease patients according to receipt duration, kind of medical insurance, sex and age was calculated with reference to the disease and an estimation of the receipt persistence rate was calculated for every year. Moreover, in consideration of variation in the data, average receipt persistence rates over years were also calculated. RESULTS: According to observation on individual patient's follow up, the proportion for which financial aid was discontinued within four years was 25%, while 70% continued receiving aid for at least four years and some 55% for eight or nine years. The proportion of those who continue receiving support long-term is high about the so-called autoimmune diseases, such as systemic lupus erythematosus, Behçet's disease, and the aortic syndrome. In contrast, with diseases having a poor prognosis, such as fulminant hepatitis, amyloidosis, and amyotrophic lateral sclerosis, periods of continuance are short. The proportion needing long-term continuation is higher in women than in men, especially with diseases which have long been eligible for support. However, with diseases for which receipt was started recently, there is a tendency for persistence to be higher in men than in women. CONCLUSION: With reform of insurance systems, including the medical system for intractable diseases, it is predicted that receipt continuation will change with alteration of social factors, and it is necessary to monitor receipt continuation carefully from now on.

[Characteristics of patients with intractable diseases receiving public financial aid for treatment--results of a nationwide survey, 1997].

OBJECTIVES: In order to clarify the characteristics of medical institutions visited by patients with selected intractable diseases, we analyzed data from the fourth nationwide survey in 1997. METHODS: We asked 47 prefectural governments to provide data concerning every patient receiving financial aid for treatment of 39 selected intractable diseases from April 1997 to March 1998. Out of 399,719 whose information was reported by prefectural governments, we analysed data of 370,232 patients whose medical institutions were reported. We performed detailed analysis on the relation between patients' residences and locations of medical institution which the patients visited, and on the characteristics of medical institutions. These analyses were respectively compared by sex and age, the beginning year of the financial aid, whether the patients were inpatients or outpatients, type of insurance, and clinical division where the patient was treated. RESULTS: 1. Analysis showed that 7.4% of all patients were treated in medical institutions outside the prefectures where they lived. Patients who lived in the neighboring prefectures of huge cities like Tokyo, tended to be treated in the medical institutions there. 2. We found that 23.5% of patients were treated in university hospitals, and 11.9% were seen in clinics. 3. There was a difference between patients with SMON and patients with myastenia gravis, pemphigus, epidermolysis bullosa or primary pulmonary hypertension. Of the two groups, the former preferred to visit clinics and be treated in medical institutions located in the same cities, towns, and villages where they lived. On the contrary, patients with the latter 4 diseases tended to visit large hospitals and be treated in those outside their prefectures. 4. Elderly patients over 70 years old tended to be treated in clinics or hospitals located in their neighborhoods. 5. Compared with past surveys, the percentage of patients treated in university hospitals had decreased, and that of patients treated in clinics had increased year by year. No change was found in the proportion of patients treated in medical institutions outside their prefectures. CONCLUSIONS: By the present analysis of a nationwide survey taken in fiscal year 1997, we were able to clarify the characteristics of medical institutions visited by patients with selected intractable diseases. This kind of analysis should be continued to obtain important information on the epidemiology of intractable diseases.

[Nationwide survey of intractable disease patients. Analyses of patients receiving public financial aid for treatment in fiscal year 1997].

OBJECTIVE: In order to clarify epidemiologic features of selected intractable diseases, an investigation of the fourth nationwide survey, in 1998, was performed. METHODS: We asked 47 prefectural governments to provide data concerning every patient receiving financial aid for treatment of 39 selected intractable diseases from April 1997 to March 1998. The items for each patient required were the beginning year of the financial aid, the disease code, sex, date of birth, residence, type of insurance, whether an in-patient or outpatient, medical institution and the clinical division where the patient was treated. We performed a detailed analysis regarding the age distribution, the prefecture, in-patient or outpatient, the clinical division, the insurance, and the disease, for both males and females. RESULTS: 1. The total number of patients who received financial aid for treatment was 399, 719 with a sex ratio of 0.66 (males 158, 766, or female 240, 953), 60.7% being between 45 and 74 years of age. Of 214, 173 patients whose status could be confirmed regarding outpatient or inpatient. 14.7% were the latter. Of 129, 685 cases, 56, 471 (43.6%) were treated in departments of internal medicine. Of 396, 187 patients, 65, 841 (16.6%) were covered by the health and medical services law for the aged. The greatest number of patients resided in Tokyo, and the least was in Yamanashi Prefecture. 2. With regard to specific intractable diseases, the largest number of patients receiving aid for treatment were suffering from ulcerative colitis at 52, 261, while the least number was for primary pulmonary hypertension at 96. The numbers for each group had increased within the 13 years from 1984 to 1997, except for SMON. As the patients' age increased, the percentage of those receiving treatment also increased and the numbers of aged individuals were especially elevated. 3. The proportion of in-patients for the Creutzfelde-Jakob disease was 76.4 percent, which was remarkably higher than for other diseases. CONCLUSION: By the present analysis of the nationwide survey in fiscal year 1997, we could clarify changes in epidemiologic features of patients receiving financial aid for treatment. This kind of analysis should be continued to obtain important information on the epidemiology of intractable diseases.