Comparative effectiveness and healthcare utilization for ambulatory cardiac monitoring strategies in Medicare beneficiaries.

BACKGROUND: Objective data comparing the diagnostic performance of different ambulatory cardiac monitors (ACMs) are lacking. OBJECTIVES: To assess variation in monitoring strategy, clinical outcomes and healthcare utilization in patients undergoing ambulatory monitoring without a pre-existing arrhythmia diagnosis. METHODS: Using the full sample (100%) of Medicare claims data, we performed a retrospective cohort study of diagnostic-naïve patients who received first-time ACM in 2017 to 2018 and evaluated arrhythmia encounter diagnosis at 3-months, repeat ACM testing at 6 months, all-cause 90-day emergency department (ED) and inpatient utilization, and cost of different strategies: Holter; long-term continuous monitor (LTCM); non-continuous, event-based external ambulatory event monitor (AEM); and mobile cardiac telemetry (MCT). We secondarily performed a device-specific analysis by manufacturer, identified from unique claim modifier codes. RESULTS: ACMs were used in 287,789 patients (AEM = 10.3%; Holter = 53.8%; LTCM = 13.3%; MCT = 22.5%). Device-specific analysis showed that compared to Holter, AEM, MCT, or other LTCM manufacturers, a specific LTCM (ZioⓇ XT 14-day patch, iRhythm Technologies, San Francisco, CA) had the highest adjusted odds of diagnosis and lowest adjusted odds of ACM retesting. Findings were consistent for specific arrhythmia diagnoses of ventricular tachycardia, atrioventricular block, and paroxysmal atrial fibrillation. As a category, LTCM was associated with the lowest 1-year incremental health care expenditures (mean Δ$10,159), followed by Holter ($10,755), AEM ($11,462), and MCT ($12,532). CONCLUSIONS: There was large variation in diagnostic monitoring strategy. A specific LTCM was associated with the highest adjusted odds of a new arrhythmia diagnosis and lowest adjusted odds of repeat ACM testing. LTCM as a category had the lowest incremental acute care utilization. Different monitoring strategies may produce different results with respect to diagnosis and care.

Comparison of three-dimensional motion of bacteria with and without wall accumulation.

A comparison of the movement characteristics between bacteria with and without wall accumulation could potentially elucidate the mechanisms of biofilm formation. However, authors of previous studies have mostly focused on the motion of bacteria that exhibit wall accumulation. Here, we applied digital holographic microscopy to compare the three-dimensional (3D) motions of two bacterial strains (Shewanella japonica UMDC19 and Shewanella sp. UMDC1): one exhibiting higher concentrations near the solid surfaces, and the other showing similar concentrations in near-wall and bulk regions. We found that the movement characteristics of the two strains are similar in the near-wall region but are distinct in the bulk region. Near the wall, both strains have small velocities and mostly perform subdiffusive motions. In the bulk, however, the bacteria exhibiting wall accumulation have significantly higher motility (including faster swimming speeds and longer movement trajectories) than the one showing no wall accumulation. Furthermore, we found that bacteria exhibiting wall accumulation slowly migrate from the bulk region to the near-wall region, and the hydrodynamic effect alone is insufficient to generate this migration speed. Future studies are required to test if the current findings apply to other bacterial species and strains.