Financial incentives for infection prevention and antimicrobial stewardship to reduce antibiotic use: Japan's nationwide observational study

BACKGROUND

The Japanese government introduced financial incentives to reduce nationwide antibiotic use in hospital settings.

AIM

This study aimed to determine whether the nationwide financial incentives for creating infection prevention and control (IPC) teams introduced in 2012 and antimicrobial stewardship (ASP) teams introduced in 2018 were associated with changes in antibiotic use and health resource utilization at a national level.

METHODS

We conducted time-series analyses and a difference-in-differences study consisting of 3,057,517 inpatients with infectious diseases from 472 medical facilities during fiscal years 2011-2018 using a nationally representative inpatient database in Japan. The primary outcome was the days of therapy (DOT) of antibiotic use per 100 patient-days (PDs). The secondary outcomes consisted of types of antibiotic used, health resource utilization, and mortality.

RESULTS

A total of 5,201,304 financial incentives were observed during 2012-2018, which resulted in a total of 12.1 billion JPY (≈110 million USD). Time-series analyses found decreasing trends in total antibiotic use (79.3-72.5 DOTs/100 PDs (8.6% reduction)) and carbapenem use (9.0-7.0 DOTs/100 PDs (7.8% reduction)) from 2011 to 2018 without adversely affecting other healthcare outcomes (e.g., mortality). In the difference-in-differences analyses, we did not observe meaningful changes in total antibiotic use between the incentivized and unincentivized hospitals for ASP teams, except for the northern part of Japan. No dose-response relationships were observed between the amount of financial incentives and reductions in antibiotic use during 2011-2019.

CONCLUSIONS

Further research and efforts are needed to accelerate antimicrobial stewardship in hospital settings in Japan.

The observation of nonlinear ion cyclotron wave excitation during high-harmonic fast wave heating in the large helical device

A wave detector, a newly designed magnetic probe, is installed in the large helical device (LHD). This wave detector is a 100-turn loop coil with electrostatic shield. Comparing a one-loop coil to this detector, this detector has roughly constant power coupling in the lower frequency range of 40 MHz, and it can easily detect magnetic wave in the frequency of a few megahertz. During high-harmonic fast wave heating, lower frequency waves (<10 MHz) were observed in the LHD for the first time, and for the power density threshold of lower frequency wave excitation (7.5 MHz) the power density of excited pumped wave (38.47 MHz) was approximately -46 dBmHz. These lower frequencies are kept constant for electron density and high energy particle distribution, and these lower frequency waves seem to be ion cyclotron waves caused by nonlinear wave-particle interaction, for example, parametric decay instability.

Sawtooth oscillation in current-carrying plasma in the large helical device

Sawtooth oscillations have been observed in current-carrying helical plasmas by using electron-cyclotron-emission diagnostics in the Large Helical Device. The plasma current, which is driven by neutral beam injection, reduces the beta threshold of the sawtooth oscillation. When the central q value is increased due to the plasma current, the core region crashes, and, when it is decreased, the edge region crashes annularly. Observed rapid mixture of the plasma in the limited region suggests that these sawtooth crashes are reconnection phenomena. Unlike previous experiments, no precursor oscillation has been observed.

Island dynamics in the large-helical-device plasmas

In the Large Helical Device plasma discharges, the size of an externally imposed island with mode number ( n/m = 1/1) decreases substantially when the plasma is collisionless ( nu(*)< approximately 1) and the beta is finite ( > approximately 0.1%) at the island location. For the collisional plasmas with finite beta, on the other hand, the size of the island increases. However, there is a threshold in terms of the vacuum island size below which the island enlargement is not seen.

Observation of the "self-healing" of an error field island in the large helical device

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced.

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.

Ion heating and high-energy-particle production by ion-cyclotron heating in the large helical device

Ion-cyclotron heating was applied to the Large Helical Device. When the proton-cyclotron resonance was near the saddle point of the magnetic field-strength plane, strong ion-cyclotron damping occurred. Under these conditions efficient plasma heating was achieved for more than one minute. A high-energy ion tail was observed, and the effective tail temperature was determined by a balance between the wave acceleration and the electron-drag relaxation. There was no apparent sign of particle orbit loss effect in the investigated density range of 0.8-1.3x10(19) m(-3).

Edge thermal transport barrier In LHD discharges

In LHD discharges a significant enhancement of the global energy confinement has been achieved for the first time in a helical device with an edge thermal barrier, which exhibits a sharp gradient at the edge of the temperature profile. Key features associated with the barrier are quite different from those seen in tokamaks: (i) almost no change in particle (including impurity) transport, (ii) a gradual formation of the barrier, (iii) a very high ratio of the edge temperature to the average temperature, and (iv) no edge relaxation phenomenon. These features are very attractive in applying the thermal barrier to future reactor grade devices.