Ryoko Sakai
About
Ryoko Sakai is a scholar working on Rheumatology, Genetics and Pathology and Forensic Medicine.
According to data from OpenAlex, Ryoko Sakai has authored 50 papers receiving a total of 794 indexed citations (citations by other indexed papers that have themselves been cited), including 38 papers in Rheumatology, 12 papers in Genetics and 9 papers in Pathology and Forensic Medicine. Recurrent topics in Ryoko Sakai's work include Rheumatoid Arthritis Research and Therapies (30 papers), Systemic Lupus Erythematosus Research (15 papers) and Chronic Lymphocytic Leukemia Research (11 papers). Ryoko Sakai is often cited by papers focused on Rheumatoid Arthritis Research and Therapies (30 papers), Systemic Lupus Erythematosus Research (15 papers) and Chronic Lymphocytic Leukemia Research (11 papers). Ryoko Sakai collaborates with scholars based in Japan, United States and South Korea. Ryoko Sakai's co-authors include Masayoshi Harigai, Naomi Ohshiro, Masayuki Ohbayashi, Yasuna Kobayashi, Noriko Kohyama, Toshinori Yamamoto, Eisuke Inoue, Takeshi Awasaki, Masaki Sone and Emiko Suzuki and has published in prestigious journals such as Neuron, International Journal of Radiation Oncology*Biology*Physics and Annals of the Rheumatic Diseases.
In The Last Decade
Ryoko Sakai
43 papers receiving 782 citations
Peers
Ryoko Sakai
Anja Vales Austria
Cinzia Melchiorri Italy
Donald L. Kimpel United States
Shoji Yamane Japan
Tomoyasu Isobe Japan
Takaaki Fukuda Japan
Jun‐Ichi Masuyama Japan
Erwin T. Waas Netherlands
Eileen T. Samy United States
Shan Li China
Citations per year, relative to Ryoko Sakai Ryoko Sakai (= 1×)
peers
Anja Vales
Countries citing papers authored by Ryoko Sakai
Since
Specialization
Citations
This map shows the geographic impact of Ryoko Sakai's research. It shows the number of citations coming from papers published by authors working in each country. You can also color the map by specialization and compare the number of citations received by Ryoko Sakai with the expected number of citations based on a country's size and research output (numbers larger than one mean the country cites Ryoko Sakai more than expected).
Fields of papers citing papers by Ryoko Sakai
Since
Specialization
Physical SciencesHealth SciencesLife SciencesSocial Sciences
This network shows the impact of papers produced by Ryoko Sakai. Nodes represent research fields, and links connect fields that are likely to share authors. Colored nodes show fields that tend to cite the papers produced by Ryoko Sakai. The network helps show where Ryoko Sakai may publish in the future.
Co-authorship network of co-authors of Ryoko Sakai
This figure shows the co-authorship network connecting the top 25 collaborators of Ryoko Sakai. A scholar is included among the top collaborators of Ryoko Sakai based on the total number of citations received by their joint publications. Widths of edges represent the number of papers authors have co-authored together. Node borders signify the number of papers an author published with Ryoko Sakai. Ryoko Sakai is excluded from the visualization to improve readability, since they are connected to all nodes in the network.
All Works
1.
Matsushita, Masakazu, Ryoko Sakai, Naoto Yokogawa, et al.. (2025). Prevalence of systemic lupus erythematosus and age-stratified treatment trends in the Japanese population: A cross-sectional study based on the National Database of Health Insurance Claims. Modern Rheumatology. 35(5). 850–858.
2.
Takahata, Kenichi, et al.. (2025). Comparison of the risk of hospitalized infections between self-injecting and non-self-injecting biologics in patients with rheumatoid arthritis. Modern Rheumatology. 36(2). 319–321.
3.
Shimizu, Masaki, Eisuke Inoue, Ryoko Sakai, et al.. (2025). Verification of unmet medical needs in patients with juvenile idiopathic arthritis in Japan. Modern Rheumatology. 35(5). 909–915.
4.
Takahata, Kenichi, et al.. (2025). Economic Impact of Self-Injected Biologics for Rheumatoid Arthritis in Japan: A Propensity Score-Matched Analysis From a Public Healthcare Payer Perspective. Value in Health Regional Issues. 53. 101511–101511.
5.
Harigai, Masayoshi, Eiichi Tanaka, Eisuke Inoue, et al.. (2024). Incidence of Malignancies and the Association with Biological Disease-Modifying Antirheumatic Drugs in Japanese Patients with Rheumatoid Arthritis: A Time-Dependent Analysis from the IORRA Patient Registry. Rheumatology and Therapy. 11(5). 1181–1195.
6.
Inoue, Yuzaburo, Ryoko Sakai, Eisuke Inoue, et al.. (2024). Nationwide epidemiological survey of juvenile idiopathic arthritis during transition to young adulthood in Japan using the National Database of Designated Incurable Diseases of Japan. Modern Rheumatology. 35(2). 359–365.
7.
Yokogawa, Naoto, Ryoko Sakai, Masakazu Matsushita, et al.. (2024). Delayed global standardization and prefectural disparities in systemic lupus erythematosus treatment in Japan: A nationwide study using the National Database of Health Insurance Claims and Specific Health Checkups of Japan. Modern Rheumatology. 35(2). 294–299.
8.
Harigai, Masayoshi, Ryoko Sakai, Ataru Igarashi, et al.. (2023). Risk of hospitalized infections in older elderly patients with rheumatoid arthritis treated with tocilizumab or other biological/targeted synthetic disease-modifying antirheumatic drugs: Evaluation of data from a Japanese claims database. Modern Rheumatology. 34(2). 287–296.
9.
Sakai, Ryoko, Eiichi Tanaka, Eisuke Inoue, et al.. (2022). Association between patient-reported outcomes and impairments in work and activity in patients with rheumatoid arthritis in clinical remission: A retrospective analysis using the IORRA database. Modern Rheumatology. 33(5). 899–905.
10.
Yamazaki, Hayato, Tsutomu Takeuchi, Koichi Amano, et al.. (2020). Identification of molecules associated with response to abatacept in patients with rheumatoid arthritis. Arthritis Research & Therapy. 22(1). 46–46.
11.
Honda, Suguru, et al.. (2020). Non-increased risk of thrombosis by steroid pulse therapy in patients with lupus nephritis from the Japanese health insurance database. Thrombosis Research. 190. 86–88.
12.
Nakajima, Ayako, Ryoko Sakai, Eisuke Inoue, & Masayoshi Harigai. (2020). Prevalence of patients with rheumatoid arthritis and age‐stratified trends in clinical characteristics and treatment, based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan. International Journal of Rheumatic Diseases. 23(12). 1676–1684.
13.
Sakai, Ryoko, Koichi Amano, Ryusuke Yoshimi, et al.. (2017). THU0170 Outcomes of the rapid dose escalation of methotrexate in japanese patients with early rheumatoid arthritis; results from a randomized controlled trial. Annals of the Rheumatic Diseases. 76. 265–266.
14.
Sakai, Ryoko, Fumio Hirano, Waka Yokoyama, et al.. (2016). FRI0146 Incidence Rate and The Risk of Herpes Zoster in Patients with Rheumatoid Arthritis Using Japanese Health Insurance Database. Annals of the Rheumatic Diseases. 75. 481–481.
15.
Sakai, Ryoko, Soo‐Kyung Cho, Toshihiro Nanki, et al.. (2014). The risk of serious infection in patients with rheumatoid arthritis treated with tumor necrosis factor inhibitors decreased over time: a report from the registry of Japanese rheumatoid arthritis patients on biologics for long-term safety (REAL) database. Rheumatology International. 34(12). 1729–1736.
16.
Sakai, Ryoko, Fumio Hirano, Waka Yokoyama, et al.. (2014). FRI0088 Prevalence of Comorbidities in Patients with Rheumatoid Arthritis Using Japanese Health Insurance Database. Annals of the Rheumatic Diseases. 73. 413–413.
17.
Kobayashi, Yasuna, Ryoko Sakai, Naomi Ohshiro, et al.. (2005). POSSIBLE INVOLVEMENT OF ORGANIC ANION TRANSPORTER 2 ON THE INTERACTION OF THEOPHYLLINE WITH ERYTHROMYCIN IN THE HUMAN LIVER. Drug Metabolism and Disposition. 33(5). 619–622.
18.
Saitoh, Hidetoshi, et al.. (2002). Dose distribution of narrow beam irradiation for small lung tumor. International Journal of Radiation Oncology*Biology*Physics. 53(5). 1380–1387.
19.
Awasaki, Takeshi, Masaki Sone, Emiko Suzuki, et al.. (2000). The Drosophila Trio Plays an Essential Role in Patterning of Axons by Regulating Their Directional Extension. Neuron. 26(1). 119–131.
20.
Estrada-Franco, José G., et al.. (1993). Evidence Through Crossmating Experiments of a Species Complex in Anopheles pseudopunctipennis Sensu Lato: A Primary Malaria Vector of the American Continent. American Journal of Tropical Medicine and Hygiene. 49(6). 746–755.
Rankless uses publication and citation data sourced from OpenAlex, an open and comprehensive bibliographic database. While OpenAlex provides broad and valuable coverage of the global research landscape, it—like all bibliographic datasets—has inherent limitations. These include incomplete records, variations in author disambiguation, differences in journal indexing, and delays in data updates. As a result, some metrics and network relationships displayed in Rankless may not fully capture the entirety of a scholar's output or impact.
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