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IntroductionMultimorbidity, the co-occurrence of 2 or more disorders in a patient, can complicate treatment planning and affect health outcomes. Improvements in prevention and management strategies for patients with 3 or more or more co-occurring chronic diseases requires an understanding of the epidemiology of common 3-way disease patterns and their interactions. Our study aimed to describe these common 3-way disease patterns and examine the factors associated with the co-occurrence of 3 or more diseases in elderly Japanese patients.MethodsWe included all Japanese citizens aged 75 or older living in Tokyo who used medical care between September 2013 and August 2014 (N = 1,311,116) in our analysis. The 15 most common 3-way patterns of 22 target diseases according to sex and age were identified from among all possible combinations by using an anonymized medical claims database. We examined the associations of sociodemographic characteristics and health care use with the presence of 1 or 2 co-occurring diseases and 3 or more co-occurring diseases by using multinomial logistic regression.ResultsApproximately 65% of patients had 3 or more co-occurring diseases. The most common 3-way pattern was hypertension, coronary heart disease, and peptic ulcer disease in men (12.4%) and hypertension, dyslipidemia, and peptic ulcer disease in women (12.8%). The prevalence of 3 or more diseases was positively associated with men, patients aged 85 to 90, the use of home medical care services, the number of outpatient facilities visited, and hospital admissions.ConclusionThe common 3-way disease patterns and multimorbidity factors identified in our study may facilitate the recognition of high-risk patients and support the development of clinical guidelines for multimorbidity.

Periodontitis is a multifactorial disease in which bacterial, lifestyle, and genetic factors are involved. Although previous genetic association studies identified several susceptibility genes for periodontitis in European populations, there is little information for Asian populations. Here, we conducted a genome-wide association study and a replication study consisting of 2,760 Japanese periodontitis patients and 15,158 Japanese controls. Although single-nucleotide polymorphisms that surpassed a stringent genome-wide significance threshold (P < 5 × 10(-8)) were not identified, we found 2 suggestive loci for periodontitis: KCNQ5 on chromosome 6q13 (rs9446777, P = 4.83 × 10(-6), odds ratio = 0.82) and GPR141-NME8 at chromosome 7p14.1 (rs2392510, P = 4.17 × 10(-6), odds ratio = 0.87). A stratified analysis indicated that the GPR141-NME8 locus had a strong genetic effect on the susceptibility to generalized periodontitis in Japanese individuals with a history of smoking. In conclusion, this study identified 2 suggestive loci for periodontitis in a Japanese population. This study should contribute to a further understanding of genetic factors for enhanced susceptibility to periodontitis.

Adult-onset Still's disease (AOSD) is a rare disease, and large epidemiological studies of this disease are limited. Furthermore, it has been difficult to show the incidence and characteristics of severe AOSD complications due to the rarity of this disease. The aim of our study was to describe the demographics of AOSD and the incidence and characteristics of severe complications. Using a large Japanese administrative database, we identified hospitalized patients with AOSD and described the demographics. We also calculated the incidence of severe complications (i.e., macrophage activation syndrome [MAS] and disseminated intravascular coagulation [DIC]) and in-hospital mortality in AOSD patients, and then analyzed the age-controlled difference between men and women. We identified 513 patients with AOSD (mean age: 53.1 years; women 64.1 %). According to the age distribution, there was no distinct peak age. The thirties and the sixties were relatively large age groups. There were 76 patients of AOSD with MAS or DIC observed in this study. The incidence of severe complications was 14.8 %, 95 % CI [11.9, 18.2]. Women were more likely to have severe complications than men after controlling for age (odds ratio: 2.07; [1.14, 3.73]; p = 0.014). AOSD does not predominantly affect young adults in our study population. Elderly AOSD patients can be observed more than before due to global population aging. Severe complications are more likely to occur in women than in men.