Research Trends and Impact Factor on PubMed Among General Medicine Physicians in Japan: A Cross-Sectional Bibliometric Analysis

Background: Japan created a specialty system for general medicine in 2018. However, Japanese academic generalists' contribution to research remains unclear. This study examines the popularity of Japanese general medicine research, the characteristics of journal publications, annual trends, and the characteristics/differences among publications in journals with an impact factor (IF).Methods: This bibliometric analysis extracted international, English-language, journal articles published on PubMed between January 1, 2015, and December 31, 2020. Analysis included articles with either the first, second, or last author in general medicine. We classified articles according to publication or article type and field of research. We obtained standard descriptive statistics for each publication type. Chi-squared test or Fisher's exact test was used to compare nominal variables. For continuous variables, t-tests or Wilcoxon rank-sum tests were used, as appropriate.Results: Of the 2372 articles analyzed, original articles were most common (56.3%), followed by case reports (30.1%), reviews (7.63%), and letters/others (5.9%). Publication volume increased 2.64-fold annually over 5 years. Clinical research (60.5%) was most common among original articles, followed by basic experimental research (17.5%) and public health/epidemiology (12.7%). Medical quality and safety (4.1%), medical and clinical education (3.1%), and health services (1.42%) received comparatively little attention. Eighty percent of articles were published in journals with IF; however, these journals rarely published case reports. Among original articles, the likelihood of publishing in journals with IF was high for basic laboratory medicine articles with higher IF (median IF 3.83, OR 1.71, 95% CI 2.20-5.95, p=0.044) and lower for clinical education research with the lowest IF (median IF 1.83, OR 0.56, 95% CI 01.8-0.75, p<0.001).Discussion: General medicine physicians' international research output is increasing in Japan; however, research achievements have not been generalized, but rather much influenced by clinical subspecialty backgrounds. This will likely continue unless an academic generalist discipline is established.