Disease burden of main bacterial infections in Japan, 2015-2020: A population-level study.

INTRODUCTION: Comprehensive evidence about the burden of infectious diseases in the Western Pacific Region is scarce. We thus examined the disease burden of infectious diseases in Japan in terms of disability-adjusted life years (DALYs). METHODS: We extracted national claims data from Japan's universal health insurance system to estimate the burden of disease for selected infections between 2015 and 2020 using DALYs. The mortality rate, disability duration and severity weight of each disease were estimated based on national data and literature reviews. RESULTS: Disease burden per 100,000 population was 1307.0 in 2015 and 972.1 in 2020 for bloodstream infections (BSI), 796.5 DALYs in 2015 and 498.9 DALYs in 2020 for pneumonia, 171.5 in 2015 and 149.4 in 2020 for meningitis and 11.6 in 2015 and 11.4 in 2020 for urinary tract infections (UTI). Only surgical site infections (SSI) showed a slightly increasing trend over the 5-year period, from 2.2 in 2015 to 2.8 in 2020. CONCLUSIONS: Our results showed that the disease burden of the five major infectious diseases was higher in Japan than in other countries. However, while the burden of SSI increased, the burden of pneumonia, meningitis, BSI and UTI gradually decreased year on year. The possible causes of the decreased morbidity should be examined in future work.

Literature Review of Studies Using the National Database of the Health Insurance Claims of Japan (NDB): Limitations and Strategies in Using the NDB for Research.

The use of the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) for research has increased over time. Researchers need to understand the characteristics of the data to generate quality-assured evidence from the NDB. In this review, we mapped and characterized the limitations and related strategies using the NDB for research based on the descriptions of published NDB studies. To find studies that used Japanese healthcare claims data, we searched MEDLINE, EMBASE, and Ichushi-Web up to June 2023. Additionally, we hand-searched the NDB data publication list from the Ministry of Health, Labour and Welfare (2017-2023). We abstracted data based on the NDB data type, research themes, age of the study sample or population, targeted disease, and the limitations and strategies in the NDB studies. Ultimately, 267 studies were included. Overall, the most common research theme was describing and estimating the prescriptions and treatment patterns (125 studies, 46.8%). There was a variation in the frequency of themes according to the type of NDB data. We identified the following categories of limitations: (1) lack of information on confounders/covariates, outcomes, and other clinical content, (2) limitations regarding patients not included in the NDB, (3) misclassification of data, (4) lack of unique identifiers and register of beneficiaries, and (5) others. Although the included studies noted several limitations of using the NDB for research, they also provided some strategies to address them. Organizing the limitations of NDB in research and the related strategies across research fields can help support high-quality NDB studies.

Factors Associated with Geographical Variability of Antimicrobial Use in Japan.

INTRODUCTION: Evidence regarding the factors affecting the geographical variation of antimicrobial use (AMU) is relatively scarce. This study aimed to evaluate factors potentially associated with geographical variability of AMU per day per 1000 habitants in the 47 prefectures of Japan. METHODS: This is an observational ecological study using the Japanese national database in 2019. The outcome was the defined daily doses per 1000 inhabitants per day by prefecture. Multivariable negative binomial regression analysis was conducted using patient- and physician-level variables. RESULTS: The study included 605,391,054 defined daily doses of AMU in 2019 from the 47 prefectures. In the multivariable negative binomial regression analyses for the outcome of total AMU, the proportion of female individuals (adjusted rate ratio [aRR] 1.04 [1.01-1.08] per 1% increase, p = 0.021), the proportion of upper secondary graduates going to further education (aRR 1.01 [1.00-1.01] per 1% increase, p = 0.005), and the annual number of diagnoses related to upper respiratory infections (URIs) per 1000 inhabitants per day (aRR 1.21 [1.10-1.34], p < 0.001) were significantly correlated with total AMU. CONCLUSIONS: In this ecological study, the variability of total AMU by Japanese prefecture was associated with the proportion of female individuals, education level, and the number of URI diagnoses per population. The results suggest the potential need for additional stewardship efforts to reduce unnecessary antimicrobial prescriptions for URI.

Trends in teicoplanin loading dose implementation from 2010 to 2019 and evaluation of safety and efficacy factors: a retrospective cohort study based on a Japanese administrative claims database.

BACKGROUND: The loading dose of teicoplanin (TEIC) is recommended for implementation. However, there is significant discrepancy between the dose settings in the package insert and, in the guidelines, and the actual status of loading doses in Japan is unclear. Furthermore, TEIC causes liver injury as side effect. Although the risk of developing liver injury has not been reported to be increased following a loading dose based on the guidelines, there is a lack of reports in large populations. Therefore, we evaluated the trend in the loading dose and factors affecting the efficacy and safety of TEIC administration. METHODS: A Japanese administrative claims database was used in this study. Trends in loading doses were evaluated in target populations administered TEIC between 2010 and 2019. Patient characteristics were adjusted by propensity score matching based on the guideline group (total dose of 3 days > 1,600 mg) and non-guideline group (≤ 1,600 mg) of the loading dose. Finally, univariable and multivariable conditional logistic regression analysis was performed to evaluate factors affecting 30-day mortality and liver injury. RESULTS: A total of 10,030 patients were selected based on these criteria. The proportion of loading doses based on the recommended guidelines showed an increase over time, regardless of the implementation of therapeutic drug monitoring (TDM), but especially so in cases where TDM was implemented, the loading doses were administered in accordance with the recommendations of the guidelines. Conditional logistic regression analysis showed a relationship between drug management and guidance fees (odds ratio [OR]: 0.45, 95% confidence interval [CI]: 0.36‒0.55), a reimbursement indicating pharmacist intervention, and a reduction in 30-day mortality. In addition, loading doses based on the recommended guidelines had no influence on liver injury, and other factors were not significantly associated with increased incidence of liver injury. CONCLUSION: Thus, this study implies the benefits of pharmacological management as indicated by drug management and guidance fee and supports the implementation of loading doses based on the guideline on TEIC administration.

Association between seasonal influenza vaccination and antimicrobial use in Japan from the 2015-16 to 2020-21 seasons: from the VENUS study.

BACKGROUND: Seasonal influenza vaccination might be considered an antimicrobial resistance (AMR) countermeasure because it can reduce unnecessary antimicrobial use for acute respiratory infection by mitigating the burden of such diseases. OBJECTIVES: To examine the association between seasonal influenza vaccination and antimicrobial use (AMU) in Japan at the community level and to examine the impact of influenza vaccination on the frequency of unnecessary antimicrobial prescription for upper respiratory infection. METHODS: For patients who visited any healthcare facility in one of the 23 wards of Tokyo, Japan, due to upper respiratory infection and who were aged 65 years or older, we extracted data from the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study database, which includes all claims data and vaccination records from the 2015-16 to 2020-21 seasons. We used the average treatment effect (ATE) with 1:1 propensity score matching to examine the association of vaccination status with frequency of antibiotic prescription, frequency of healthcare facility consultation, risk of admission and risk of death in the follow-up period of the same season (from 1 January to 31 March). RESULTS: In total, 244 642 people were enrolled. Matched data included 101 734 people in each of the unvaccinated and vaccinated groups. The ATE of vaccination was -0.004 (95% CI -0.006 to -0.002) for the frequency of antibiotic prescription, -0.005 (-0.007 to -0.004) for the frequency of healthcare facility consultation, -0.001 (-0.002 to -0.001) for the risk of admission and 0.00 (0.00 to 0.00) for the risk of death. CONCLUSIONS: Our results suggest that seasonal influenza vaccination is associated with lower frequencies of unnecessary antibiotic prescription and of healthcare facility consultation.

Necessity for a System Implementing Therapeutic Drug Monitoring in Outpatient Settings Based on the Actual Use of Voriconazole Using the National Database of Health Insurance Claims and Specific Health Checkups of Japan: A Descriptive Epidemiological Study.

Voriconazole (VRCZ) is an antifungal drug that necessitates therapeutic monitoring (TDM). Typically, TDM is recommended for patients undergoing long-term outpatient treatment. However, in Japan, insurance reimbursement for TDM is only permitted for inpatients. There is a concern that VRCZ use is growing among outpatients, although information regarding this issue remains unavailable. Therefore, we aimed to clarify the use of VRCZ by utilizing data from the National Database of Health Insurance Claims and Specific Health Checkups in Japan. The use of branded and generic oral VRCZ from 2013 to 2019 was calculated using the defined daily doses/1000 inhabitants/d (DID) for each receipt type. Oral VRCZ was used more frequently in the outpatient setting than that in the inpatient setting, with use increasing over time. The use of generic drugs began in 2016 and accounted for 52.5% of the use in 2019 among outpatients. Considering outpatient prescriptions, 76.4-81.0% were dispensed at insurance pharmacies, indicating the need for community pharmacist involvement. Accordingly, the appropriate use of VRCZ in ambulatory care should be promoted in collaboration with community pharmacists, and a reimbursement system should be established to implement TDM in ambulatory care.

Studies of Health Insurance Claims Data in Japan: A Scoping Review.

Background: Health insurance claims data are used in various research fields; however, an overview on how they are used in healthcare research is scarce in Japan. Therefore, we conducted a scoping review to systematically map the relevant studies using Japanese claims data. Methods: MEDLINE, EMBASE, and Ichushi-Web were searched up to April 2021 for studies using Japanese healthcare claims data. We abstracted the data on study characteristics and summarized target diseases and research themes by the types of claims database. Moreover, we described the results of studies that aimed to compare health insurance claims data with other data sources narratively. Results: A total of 1,493 studies were included. Overall, the most common disease classifications were "Diseases of the circulatory system" (18.8%, n = 281), "Endocrine, nutritional, and metabolic diseases" (11.5%, n = 171; mostly diabetes), and "Neoplasms" (10.9%, n = 162), and the most common research themes were "medical treatment status" (30.0%, n = 448), "intervention effect" (29.9%, n = 447), and "clinical epidemiology, course of diseases" (27.9%, n = 417). Frequent diseases and themes varied by type of claims databases. A total of 19 studies aimed to assess the validity of the claims-based definition, and 21 aimed to compare the results of claims data with other data sources. Most studies that assessed the validity of claims data compared to medical records were hospital-based, with a small number of institutions. Conclusions: Claims data are used in various research areas and will increasingly provide important evidence for healthcare policy in Japan. It is important to use previous claims database studies and share information on methodology among researchers, including validation studies, while informing policymakers about the applicability of claims data for healthcare planning and management.

Decline in Antimicrobial Consumption and Stagnation in Reducing Disease Burden due to Antimicrobial Resistance in Japan.

INTRODUCTION: Antimicrobial resistance (AMR) is a major global health threat. While antimicrobial consumption (AMC) in Japan substantially decreased after implementation of the AMR National Action Plan, the disease burden due to AMR seems to be unchanged. The main objective of this study is to examine the relationship between AMC and the disease burden due to AMR in Japan. METHODS: We estimated the annual population-standardized AMC from 2015 to 2021 using defined daily doses (DDDs) per 1000 inhabitants per day (DIDs) and the disease burden due to bloodstream infections caused by nine major antimicrobial-resistant bacteria (AMR-BSIs) from 2015 to 2021 using disability-adjusted life years (DALYs). We then examined the correlation between AMC and DALYs using Spearman's rank correlation coefficient and cross-correlation function. Spearman's [Formula: see text] > 0.7 was considered to indicate a strong correlation. RESULTS: The sales amounts of third-generation cephalosporins, fluoroquinolones, and macrolides were 3.82 DIDs, 2.71 DIDs, and 4.59 DIDs, respectively, in 2015, but 2.11, 1.48, and 2.72 in 2021. This corresponded to reductions of 44.8%, 45.4%, and 40.7% during the study period. DALYs due to AMR-BSIs were 164.7 per 100,000 population in 2015 but 195.2 per 100,000 in 2021. Spearman's rank correlation coefficients between AMC and DALYs were - 0.37 (total antibiotics), - 0.50 (oral antibiotics), - 0.43 (third-generation cephalosporins), - 0.5 (fluoroquin,olones) and - 0.5 (macrolides). No obvious cross-correlations were found. CONCLUSIONS: Our results reveal that changes in AMC are not associated with DALYs caused by AMR-BSIs. AMR countermeasures besides efforts to reduce inappropriate AMC might be necessary to mitigate the disease burden due to AMR.

Effects of population age structure on parenteral antimicrobial use estimations.

Antimicrobial use (AMU) is conventionally reported as unadjusted defined daily doses (DDDs) or population-adjusted DDDs per 1000 inhabitants per day (DID). DID is frequently used to monitor national AMU trends, this metric does not intrinsically take temporal changes in population age structure into account. We examined the effects of population age structure on DID estimates of parenteral AMU in Japan, and predicted future trends in DDDs based on population projections. Parenteral AMU data from 2013 to 2018 were acquired from a national claims database. We assessed temporal trends in parenteral AMU by age group (children aged < 15 years, working-age persons aged 15-64 years, and older persons aged ≥ 65 years) using both DID and DDDs. In addition, we modeled DDD predictions based on age-specific population projections from 2019 to 2030. DID values for older persons were 8.08-10.15 times and 5.43-5.63 times higher than in children and working-age persons, respectively. DID was stable, but DDDs increased in older persons. The prediction models showed that DDDs will continue to increase until 2030 if DID remains steady or decreases. DID estimates were skewed by the older population. More rigorous antimicrobial stewardship efforts targeting geriatric care are needed to counter the aging-associated increase in AMU.

Influence of pharmacists and infection control teams or antimicrobial stewardship teams on the safety and efficacy of vancomycin: A Japanese administrative claims database study.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) has a high mortality and requires effective treatment with anti-MRSA agents such as vancomycin (VCM). Management of the efficacy and safety of VCM has been implemented with the assignment of pharmacists in hospital wards and the establishment of teams related to infectious diseases. However, there are no reports evaluating the association between these factors and the efficacy and safety of VCM in large populations. METHODS: This study used the Japanese administrative claims database accumulated from 2010 to 2019. The population was divided into two groups, therapeutic drug monitoring (TDM) group and non-TDM group, and adjusted by propensity score matching. We performed multivariate logistic regression analysis to determine the influence of pharmacists and infection control teams or antimicrobial stewardship teams on acute kidney injury (AKI) and 30-day mortality. RESULTS: The total number of patients was 73 478 (TDM group, n = 55 269; non-TDM group, n = 18 209). After propensity score matching, 18 196 patients were matched in each group. Multivariate logistic regression analysis showed that pharmacological management for each patient contributed to the reduction of AKI (odds ratio [OR]: 0.812, 95% confidence interval [CI]: 0.723‒0.912) and 30-day mortality (OR: 0.538, 95% CI: 0.503‒0.575). However, the establishment of infectious disease associated team in facilities and the assignment of pharmacists in the hospital wards had no effect on AKI and 30-day mortality. In addition, TDM did not affect the reduction in AKI (OR: 1.061, 95% CI: 0.948‒1.187), but reduced 30-day mortality (OR: 0.873, 95% CI: 0.821‒0.929). CONCLUSION: Pharmacologic management for individual patients, rather than assignment systems at facilities, is effective to reduce AKI and 30-day mortality with VCM administration.

Search for Indexes to Evaluate Trends in Antibiotic Use in the Sub-Prefectural Regions Using the National Database of Health Insurance Claims and Specific Health Checkups of Japan.

The evaluation indexes of antimicrobial use (AMU) in sub-prefectural regions have not been established because these regional units are susceptible to the effects of population inflows and outflows. We defined the difference in AMU calculated each year as a new evaluation index and compared the AMU of secondary medical areas with those already reported for Japan and each prefecture. Patients/1000 inhabitants/day (PID) for oral antibiotics in 2013 and 2016 were calculated using the National Database of Health Insurance Claims and Specific Health Checkups. ΔPID was defined as the difference between the PIDs in 2013 and 2016. Differences in AMUs for Japan and prefectures that have already been published were also calculated, and the concordance rate with ΔPID in each secondary medical area was evaluated. Antibiotics and age groups with less than 50% concordance between secondary medical area and previously reported AMU changes were observed. This revealed that even at the secondary medical area level, which is more detailed than the prefectural level, the AMU changes were not consistent. Therefore, in order to appropriately promote measures against antimicrobial resistance, we suggest the necessity of not only surveying AMU at the national or prefectural levels but also examining sub-prefectural trends in AMU.

A study of trends and factors associated with therapeutic drug monitoring (TDM) implementation for arbekacin treatment using a large Japanese medical claims database.

INTRODUCTION: Reimbursements for pharmacist interventions and infectious disease teams have recently been introduced in Japan. Arbekacin (ABK) is used to treat pneumonia and sepsis caused by methicillin-resistant Staphylococcus aureus, and therapeutic drug monitoring (TDM) is recommended. This study aimed to clarify the trend in TDM implementation for ABK over time and the factors associated with TDM implementation using a claims database. METHODS: Data of patients aged ≥15 years who received ABK for ≥3 consecutive days between 2010 and 2019 were extracted from a large Japanese medical claims database. The proportion of reimbursements claimed for TDM, pharmacist interventions, and the setup of infectious disease teams for each year were calculated. The factors associated with TDM implementation were identified using multivariate logistic regression analysis. RESULTS: The proportion of TDM implementation for ABK increased by 9.1% from 2010 to 2019, but it remained less than 40% throughout this period. The proportion of TDM implementation was higher in patients who claimed reimbursements for pharmacist interventions than in patients who did not. Logistic regression analysis showed that the stationing of pharmacists in wards and long-term ABK treatment were significantly associated with TDM implementation. CONCLUSIONS: From 2010 to 2019, the proportion of TDM implementation for ABK was significantly low. Moreover, the factors associated with TDM implementation were clarified. An environment wherein pharmacists can help implement TDM for patients receiving ABK would be beneficial.

Evaluation of the Correspondence between the Concentration of Antimicrobials Entering Sewage Treatment Plant Influent and the Predicted Concentration of Antimicrobials Using Annual Sales, Shipping, and Prescriptions Data.

The accuracy and correspondence between the measured concentrations from the survey and predicted concentrations on the basis of the three types of statistical antimicrobial use in Japan was evaluated. A monitoring survey of ten representative antimicrobials: ampicillin (APL), cefdinir (CDN), cefpodoxime proxetil (CPXP), ciprofloxacin (CFX), clarithromycin (CTM), doxycycline (DCL), levofloxacin (LFX), minocycline (MCL), tetracycline (TCL), and vancomycin (VMC), in the influent of sewage treatment plant (STP) located in urban areas of Japan, was conducted. Then, the measured values were verified in comparison with the predicted values estimated from the shipping volumes, sales volumes, and prescription volumes based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB). The results indicate that the correspondence ratios between the predicted concentrations calculated on the basis of shipping and NDB volumes and the measured concentrations (predicted concentration/measured concentration) generally agreed for the detected concentration of antimicrobials in the STP influent. The correspondence ratio on the basis of shipping volume was, for CFX, 0.1; CTM, 2.9; LFX, 0.5; MCL, 1.9; and VMC, 1.7, and on the basis of NDB volume the measured concentration was CFX, 0.1; CTM, 3.7; DCL, 0.4; LFX, 0.7; MCL, 1.9; TCL, 0.6; and VMC, 1.6. To our knowledge, this is the first report to evaluate the accuracy of predicted concentrations based on sales, shipping, NDB statistics and measured concentrations for antimicrobials in the STP influent.

Antimicrobial Use Fell Substantially in Japan in 2020-The COVID-19 Pandemic May Have Played a Role.

This study investigated the impact of the COVID-19 pandemic on antimicrobial use (AU) trends in Japan in 2020 and explored its potential effects on appropriate AU. Using nationwide antimicrobial sales data, we examined the annual and monthly trends in AU from 2016-2020 according to the AWaRe classification (Access and Watch categories) and administration route (oral and injectable). To analyze the possible impact of the COVID-19 pandemic on AU, seasonal autoregressive integrated moving average (SARIMA) models were used to predict AU in 2020 (based on the trends from 2016-2019) under the assumption that the pandemic did not occur. We observed a substantial reduction in AU in 2020 compared with preceding years. In addition, the reductions in AU for total antimicrobials and Watch category antimicrobials were greater than predicted regardless of administration route. These results suggest that the COVID-19 pandemic contributed to the observed reductions in AU, but it is also possible that the changes reflect recent efforts to improve AU. Continued AU surveillance and research are needed to optimize prescribing practices through appropriate antimicrobial stewardship.

The intended purpose and regional patterns of use of antibiotics for managing Clostridioides (Clostridium) difficile infections: An analysis of the National Database of Health Insurance Claims and Specific Health Checkups data of Japan.

INTRODUCTION: We previously showed the trend of antimicrobial use (AMU) for Clostridioides (Clostridium) difficile infection (CDI) using sales data. However, the details of the prescribing medical institutions and regional characteristics are unknown. Therefore, the purpose of this study was to clarify the details of the medical institutions where antibiotics for CDI were prescribed, and evaluate the AMU for CDI and the regional characteristics. METHODS: Antibiotics for CDI, including oral vancomycin (VCM), oral metronidazole (MNZ), and intravenous (IV) MNZ, were collected from the National Database of Health Insurance Claims and Specific Health Checkups (NDB) between 2013 and 2016. The PID (patients/1000 inhabitants/day) was used as an evaluation index for AMU. The PID was calculated using the claim types: inpatient, outpatient, dental, and pharmacy. The PID of each prefecture was calculated for inpatient claims in 2016. RESULTS: The AMU of oral VCM and IV MNZ were observed mainly in the inpatient claims. For oral MNZ, the total AMU in the outpatient and pharmacy claims accounted for approximately 80% per year throughout the study period. For inpatient claims of each prefecture in 2016, the PID of the antibiotics used for CDIs was approximately 3.5 times the difference between the highest and lowest prefectures. CONCLUSIONS: The AMU for CDI that takes into account the purpose of use was clarified by using the information of the prescribed medical institutions that were included in the NDB. Oral MNZ was used frequently in outpatients, and attention should be paid to the acquisition of resistance.

Effects of the cefazolin shortage on the sales, cost, and appropriate use of other antimicrobials.

BACKGROUND: Shortages of antimicrobials lead to treatment failures, increase medical costs, and accelerate the development of antimicrobial resistance. We evaluated the effects of the serious cefazolin shortage in 2019 in Japan on the sales, costs, and appropriate use of other antimicrobials. METHODS: We evaluated monthly defined daily doses/1000 inhabitants/day (DID) values of antimicrobial sales from January 2016 to December 2019 using wholesaler's sales databases. Using 2016-2018 sales data, we generated a prediction model of DID in 2019 under the assumption that the cefazolin shortage did not occur. We then compared the predicted DID and actual DID. Cefazolin, government-recommended alternatives, and government-not-recommended broad-spectrum alternatives were assessed. Antimicrobial groups according to the AWaRe classification were also assessed to evaluate the effect on appropriate antimicrobial use. In addition, we evaluated changes in costs between 9 months before and after the cefazolin shortage. RESULTS: DID values of total antimicrobials increased sharply 1 month before the decrease in cefazolin. Actual DIDs were higher than predicted DIDs for ceftriaxone, flomoxef, clindamycin, cefotiam, piperacillin/tazobactam, and meropenem. Actual DID values were higher than the predicted DID values in the Watch group. The costs of antimicrobials between pre- and post- cefazolin shortage were unchanged. CONCLUSION: The cefazolin shortage brought confusion to the antimicrobial market and led to a setback in the appropriate use of antimicrobials. Early recognition and structures for prompt reactions to antimicrobial shortages are needed. Moreover, development of a system to secure the supply of essential antimicrobials is required.

Trends in healthcare visits and antimicrobial prescriptions for acute infectious diarrhea in individuals aged 65 years or younger in Japan from 2013 to 2018 based on administrative claims database: a retrospective observational study.

BACKGROUND: The inappropriate use of antimicrobials for acute infectious diarrhea is widespread and leads to the problem of antimicrobial resistance. To improve the use of antimicrobials, it is first necessary to understand the actual situation of diarrheal disease and to identify potential targets for intervention. This study aimed to investigate the recent epidemiological characteristics of and antimicrobial prescriptions for acute infectious diarrhea in Japan. METHODS: This was a retrospective observational study of outpatients aged 0-65 years, separated into children (age 0-17 years) and adults (age 18-65 years), diagnosed with acute infectious diarrhea, using the administrative claims database of the Japan Medical Data Center from 2013 to 2018. We evaluated the number of eligible visits/number of database registrants (defined as the visit rate). The analysis of the antimicrobial prescription rate was restricted to otherwise healthy individuals diagnosed with acute infectious diarrhea alone by excluding patients with multiple disease diagnoses and with medical backgrounds of chronic bowel diseases or immunocompromised conditions. We further classified them by diagnosis of bacterial or nonbacterial acute infectious diarrhea. RESULTS: The total number of eligible visits for acute infectious diarrhea was 2,600,065. The visit rate, calculated based on the number of eligible visits by database registrants, was higher in children (boys, 0.264; girls, 0.229) than in adults (men, 0.070; women, 0.079), with peaks in early summer and winter. The peaks for visits in adults lagged those of children. In total, 482,484 visits were analyzed to determine the antimicrobial prescription rate; 456,655 (94.6%) were diagnosed with nonbacterial acute infectious diarrhea. Compared with children (boys, 0.305; girls, 0.304), the antimicrobial prescription rate was higher in adults, and there were differences between sexes in adults (men, 0.465; women, 0.408). Fosfomycin and fluoroquinolone were most frequently used for nonbacterial acute infectious diarrhea in children (44.1%) and adults (50.3%), respectively. CONCLUSIONS: These results revealed overprescription of antimicrobials for acute infectious diarrhea in this administrative claims database in Japan and contribute to the development of antimicrobial stewardship strategies and the identification of targets for efficiently reducing inappropriate antimicrobial use.

Trends in Antipseudomonal Agent Use Based on the 2006 to 2015 Sales Data in Japan.

Pseudomonas aeruginosa resistance is a major issue worldwide. Drug resistance is related to inappropriate antibiotic use. Because antipseudomonal agents have a wide spectrum, they must be used appropriately. The purpose of this study was to clarify the trends in antipseudomonal agent use in Japan based on sales data from 2006 to 2015. The total antipseudomonal agent use was increased significantly (r = 0.10, Pfor trend = 0.00040). The proportion of fluoroquinolones use was the highest throughout the year, accounting for 88.6-91.4%. The use of piperacillin/tazobactam significantly increased. The increased use of these drugs may be due to the launch of higher doses and additional indications. On the other hand, for antipseudomonal agents, parenteral carbapenems use was 2.7-3.7%, but it has remained unchanged over the years. In Japan, permit and notification systems have been introduced to prevent the inappropriate use of parenteral carbapenems in medical institutions. It was speculated that these efforts suppressed the inappropriate use of parenteral carbapenems. This study clarified the trend of antipseudomonal agent use in Japan from 2006 to 2015. It is important to continue monitoring antipseudomonal agents use to conduct appropriate antimicrobial resistance measures.

Characteristics and limitations of national antimicrobial surveillance according to sales and claims data.

PURPOSE: Antimicrobial use (AMU) is estimated at the national level by using sales data (S-AMU) or insurance claims data (C-AMU). However, these data might be biased by generic drugs that are not sold through wholesalers (direct sales) and therefore not recorded in sales databases, or by claims that are not submitted electronically and therefore not stored in claims databases. We evaluated these effects by comparing S-AMU and C-AMU to ascertain the characteristics and limitations of each kind of data. We also evaluated the interchangeability of these data by assessing their relationship. METHODS: We calculated monthly defined daily doses per 1,000 inhabitants per day (DID) using sales and claims data from 2013 to 2017. To assess the effects of non-electronic claim submissions on C-AMU, we evaluated trends in the S-AMU/C-AMU ratio (SCR). To assess the effects of direct sales of S-AMU, we divided AMU into generic and branded drugs and evaluated each SCR in terms of oral versus parenteral drugs. To assess the relationship between S-AMU and C-AMU, we created a linear regression and evaluated its coefficient. RESULTS: Median annual SCRs from 2013 to 2017 were 1.046, 0.993, 0.980, 0.987, and 0.967, respectively. SCRs dropped from 2013 to 2015, and then stabilized. Differences in SCRs between branded and generic drugs were significant for oral drugs (0.820 vs 1.079) but not parenteral drugs (1.200 vs 1.165), suggesting that direct sales of oral generic drugs were omitted in S-AMU. Coefficients of DID between S-AMU and C-AMU were high (generic, 0.90; branded, 0.84) in oral drugs but relatively low (generic, 0.32; branded, 0.52) in parenteral drugs. CONCLUSIONS: The omission of direct sales information and non-electronically submitted claims have influenced S-AMU and C-AMU information, respectively. However, these data were well-correlated, and it is considered that both kinds of data are useful depending on the situation.

Effect of population inflow and outflow between rural and urban areas on regional antimicrobial use surveillance.

PURPOSE: Regional-level measures can complement national antimicrobial stewardship programs. In Japan, sub-prefectural regions called secondary medical areas (SMAs) provide general inpatient care within their borders, and regional antimicrobial stewardship measures are frequently implemented at this level. There is therefore a need to conduct antimicrobial use (AMU) surveillance at this level to ascertain antimicrobial consumption. However, AMU estimates are generally standardized to residence-based nighttime populations, which do not account for population mobility across regional borders. We examined the impact of population in/outflow on SMA-level AMU estimates by comparing the differences between standardization using daytime and nighttime populations. METHODS: We obtained AMU information from the National Database of Health Insurance Claims and Specific Health Checkups of Japan. AMU was quantified at the prefectural and SMA levels using the number of defined daily doses (DDDs) divided by (a) 1,000 nighttime population per day or (b) 1,000 daytime population per day. We identified and characterized the discrepancies between the two types of estimates at the prefectural and SMA levels. RESULTS: The national AMU was 17.21 DDDs per 1,000 population per day. The mean (95% confidence interval) prefectural-level DDDs per 1,000 nighttime and daytime population per day were 17.27 (14.10, 20.44) and 17.41 (14.30, 20.53), respectively. The mean (95% confidence interval) SMA-level DDDs per 1,000 nighttime and daytime population per day were 16.12 (9.84, 22.41) and 16.41 (10.57, 22.26), respectively. The nighttime population-standardized estimates were generally higher than the daytime population-standardized estimates in urban areas, but lower in the adjacent suburbs. Large differences were observed in the main metropolitan hubs in eastern and western Japan. CONCLUSION: Regional-level AMU estimates, especially of smaller regions such as SMAs, are susceptible to the use of different populations for standardization. This finding indicates that AMU standardization based on population values is not suitable for AMU estimates in small regions.