(6) Research into antimicrobial stewardship
The following provides a summary of the progress of studies of antimicrobial stewardship in Japan. It
covers only studies using medical insurance claims data for outpatient consultations across the whole of
Japan and excludes studies limited to a specific region and studies that analyzed only the amount of
antimicrobials used. The medical insurance claims data used includes the NDB2,3,6 developed by the
Ministry of Health, Labour and Welfare, the National Health Insurance database, 4 and commercial
databases created by combining medical insurance claims data from multiple health insurance societies
(JMDC Inc.’s JMDC Claims Database1,7,9-15 and IQVIA Inc.’s IQVIA Claims5). Unless otherwise
indicated, figures in square brackets ([]) in the text show the 95% or 99% confidence interval.
1. Overview of antimicrobial stewardship
[Review of past reports]
Yoshida et al. used the JMDC Claims Database to examine antimicrobials prescribed to pre-school
children aged from birth to six years at outpatient consultations between January 2005 and September
2014.1 Analysis of 1,492,548 consultations for 155,556 children revealed that antimicrobials were most
commonly prescribed for acute bronchitis (11.9%), acute upper respiratory tract infection (10.1%), and
asthma (7.5%). This study found that risk factors for the prescription of antimicrobials by physicians for
nonbacterial upper respiratory tract infections were increasing age, male gender, facility scale (clinic),
specialism in a field other than pediatrics, and out-of-hours consultations. Uda et al. conducted a similar
study of pediatric patients (aged 15 and under) using the NDB.2 Analysis of 297,197,328 consultations for
infectious diseases between 2013 and 2016 was carried out and the DOT investigated. The results showed
that DOT per consultation in 2016 was highest in the case of third-generation cephalosporins (0.545),
followed by macrolides (0.517) and penicillins without beta-lactamase inhibitors (0.182). Upper respiratory
tract infection (54.6% of the total) and lower respiratory tract infection (26.2%) accounted for about 80%
of all conditions for which they were prescribed, followed by otitis media (4.2%), skin infections (4.2%),
and gastroenteritis (4.0%). Fosfomycin (41.6%) was the most frequently prescribed antimicrobial for
gastroenteritis, with fluoroquinolone (12.7%) the most common choice for otitis media and third-generation
cephalosporins (74.1%) for skin infections.
[Information updated in FY2020]
Hashimoto et al. used the NDB to analyze the classes of oral antimicrobial agents prescribed at outpatient
consultations in Japan and the conditions for which they were prescribed.3 This study found that
266,470,173 antimicrobial agents were prescribed at 659,333,605 consultations for infectious diseases
between April 1, 2012 and March 31, 2015, and that they were prescribed to 89,600,000 people per year
(704 per 1,000 population). The conditions for which antimicrobials were most frequently prescribed were
acute bronchitis (184 per 1,000 population), acute upper respiratory tract infection (166), tonsillitis (104),
gastroenteritis (41), urinary tract infection (33), and skin and soft tissue infections (31). About 70% of
antimicrobials were used for respiratory tract infections and acute diarrhea. The antimicrobials most
commonly used were third-generation cephalosporins (36.9%), macrolides (28.8%), and fluoroquinolones
(20.3%), together accounting for around 85% of the total, while 56% of all prescriptions for antimicrobials
related to infectious diseases for which antimicrobials are not usually used (Table 84). These results did not
differ greatly from those of a similar study that the same authors conducted using National Health Insurance
data.4

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