Journal of General Internal Medicine

, Volume 26, Issue 2, pp 148–153 | Cite as

Incidence of Adverse Drug Events and Medication Errors in Japan: the JADE Study

  • Takeshi Morimoto
  • Mio Sakuma
  • Kunihiko Matsui
  • Nobuo Kuramoto
  • Jinichi Toshiro
  • Junji Murakami
  • Tsuguya Fukui
  • Mayuko Saito
  • Atsushi Hiraide
  • David W. Bates
Original Research



The epidemiology of adverse drug events (ADEs) and medication errors has received little evaluation outside the U.S. and Europe, and extrapolating from these data might not be valid, especially regarding selecting and prioritizing solutions.


To assess the incidence and preventability of ADEs and medication errors in Japan.


The Japan Adverse Drug Events (JADE) study was a prospective cohort study.


A cohort of 3,459 adults admitted to a stratified random sample of seven medical and eight surgical wards and three intensive care units in three tertiary care hospitals over 6 months.


We measured ADE and medication error rates from daily reviews of charts, laboratories, incident reports, and prescription queries by on-site reviewers; presence of a signal was considered an incident. Two independent physicians reviewed incidents to determine whether they were ADEs or medication errors and to assess severity and preventability.


We identified 1,010 ADEs and 514 medication errors (incidence: 17.0 and 8.7 per 1,000 patient-days, respectively) during the study period. Among ADEs, 1.6%, 4.9% and 33% were fatal, life-threatening and serious, respectively. Among ADEs, 14% were preventable. The rate per admission was 29 per 100 admissions, higher than in U.S. studies because associated with of the long length of hospital stay in Japan (mean, 17 days).


The epidemiology and nature of ADEs and medication errors in Japan were similar to other countries, although more frequent per admission. Solutions that worked in these countries might thus improve medication safety in Japan, as could shortening hospital length of stay.


adverse drug events epidemiology medication errors patient safety 



We are indebted to Ms. Makiko Ohtorii, Ms. Ai Mizutani, Ms. Kimiko Sakamoto, Ms. Eri Miyake, Ms. Takako Yamaguchi, Ms. Yoko Oe, Ms. Kyoko Sakaguchi, Ms. Kumiko Matsunaga, Ms. Yoko Ishida, Ms. Kiyoko Hongo, Ms. Masae Ohtani, Ms. Yasuko Ito, Ms. Ayumi Samejima, and Ms. Shinobu Tanaka for their assistance.

This study was funded by grants 17689022 and 18659147 from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, and the Pfizer Health Research Foundation.

Presented in part at the 26th International Conference of the International Society for Quality in Health Care, Dublin, Ireland. October 13, 2009

Conflict of Interest

None disclosed.


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Copyright information

© Society of General Internal Medicine 2010

Authors and Affiliations

  • Takeshi Morimoto
    • 1
  • Mio Sakuma
    • 1
  • Kunihiko Matsui
    • 2
  • Nobuo Kuramoto
    • 1
  • Jinichi Toshiro
    • 3
  • Junji Murakami
    • 4
  • Tsuguya Fukui
    • 5
  • Mayuko Saito
    • 5
  • Atsushi Hiraide
    • 1
  • David W. Bates
    • 6
  1. 1.Center for Medical EducationKyoto University Graduate School of MedicineSakyo-kuJapan
  2. 2.Department of General MedicineYamaguchi University HospitalUbeJapan
  3. 3.Rakuwakai Otowa HospitalKyotoJapan
  4. 4.Aso Iizuka HospitalIizukaJapan
  5. 5.St. Luke’s International HospitalTokyoJapan
  6. 6.Division of General Internal Medicine and Primary CareBrigham and Women’s Hospital and Harvard Medical SchoolBostonUSA

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