SUMMARY
SETTING
Conventional approaches to tuberculosis (TB) diagnosis and resistance
testing are slow. The Xpert® MTB/RIF assay is an emerging molecular
diagnostic assay for rapid TB diagnosis, offering results within 2 hours.
However, the cost-effectiveness of implementing Xpert in settings with low
TB prevalence, such as the United States, is unknown.
OBJECTIVE
We evaluated the cost-effectiveness of incorporating Xpert into TB
diagnostic algorithms in the United States compared to existing
diagnostics.
DESIGN
A decision-analysis model compared current TB diagnostic algorithms
in the United States to algorithms incorporating Xpert. Primary outcomes
were the costs and quality-adjusted life years (QALYs) accrued with each
strategy; cost-effectiveness was represented using incremental
cost-effectiveness ratios (ICER).
RESULTS
Xpert testing of a single sputum sample from TB suspects is expected
to result in lower total health care costs per patient (US$2673) compared to
diagnostic algorithms using only sputum microscopy and culture (US$2728) and
improved health outcomes (6.32 QALYs gained per 1000 TB suspects). Compared
to existing molecular assays, implementation of Xpert in the United States
would be considered highly cost-effective (ICER US$39 992 per QALY
gained).
CONCLUSION
TB diagnostic algorithms incorporating Xpert in the United States are
highly cost-effective.
A single-step printable platform for ultraviolet (UV) metasurfaces is introduced to overcome both the scarcity of low-loss UV materials and manufacturing limitations of high cost and low throughput. By dispersing zirconium dioxide (ZrO2) nanoparticles in a UV-curable resin, ZrO2 nanoparticle-embedded-resin (nano-PER) is developed as a printable material which has a high refractive index and low extinction coefficient from near-UV to deep-UV. In ZrO2 nano-PER, the UV-curable resin enables direct pattern transfer and ZrO2 nanoparticles increase the refractive index of the composite while maintaining a large bandgap. With this concept, UV metasurfaces can be fabricated in a single step by nanoimprint lithography. As a proof of concept, UV metaholograms operating in near-UV and deep-UV are experimentally demonstrated with vivid and clear holographic images. The proposed method enables repeat and rapid manufacturing of UV metasurfaces, and thus will bring UV metasurfaces more close to real life.
Background
Self-selected speed is an important functional index of walking. A self-pacing controller that reliably matches walking speed without additional hardware can be useful for measuring self-selected speed in a treadmill-based laboratory.
Methods
We adapted a previously proposed self-pacing controller for force-instrumented treadmills and validated its use for measuring self-selected speeds. We first evaluated the controller’s estimation of subject speed and position from the force-plates by comparing it to those from motion capture data. We then compared five tests of self-selected speed. Ten healthy adults completed a standard 10-meter walk test, a 150-meter walk test, a commonly used manual treadmill speed selection test, a two-minute self-paced treadmill test, and a 150-meter self-paced treadmill test. In each case, subjects were instructed to walk at or select their comfortable speed. We also assessed the time taken for a trial and a survey on comfort and ease of choosing a speed in all the tests.
Results
The self-pacing algorithm estimated subject speed and position accurately, with root mean square differences compared to motion capture of 0.023 m s −1 and 0.014 m, respectively. Self-selected speeds from both self-paced treadmill tests correlated well with those from the 10-meter walk test (R>0.93,p<1×10−13). Subjects walked slower on average in the self-paced treadmill tests (1.23±0.27 ms−1) than in the 10-meter walk test (1.32±0.18 ms−1) but the speed differences within subjects were consistent. These correlations and walking speeds are comparable to those from the manual treadmill speed selection test (R=0.89,p=3×10−11;1.18±0.24 ms−1). Comfort and ease of speed selection were similar in the self-paced tests and the manual speed selection test, but the self-paced tests required only about a third of the time to complete. Our results demonstrate that these self-paced treadmill tests can be a strong alternative to the commonly used manual treadmill speed selection test.
Conclusions
The self-paced force-instrumented treadmill well adapts to subject walking speed and reliably measures self-selected walking speeds. We provide the self-pacing software to facilitate use by gait researchers and clinicians.
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