Diagnostic Value of Anti-Nuclear Antibodies: Results From Korean University-Affiliated Hospitals.

BACKGROUND: Unnecessary and inappropriate laboratory testing accounts for a significant portion of waste in health care utilization. The aim of this study was to examine the diagnostic value of the anti-nuclear antibody (ANA) test by examining the rate of ANA associated rheumatic disease (AARD) diagnosis among ANA tested and ANA positive subjects and positive predictive value (PPV) of ANA test leading to AARD diagnosis in different ANA titers and different subsets of patients in 5 hospitals affiliated with a university. METHODS: We retrospectively extracted data from all subjects who were tested for ANA from year 2010 to 2019. Those who were first evaluated at or referred to rheumatology were further evaluated with extraction of data including ANA titer and ultimate diagnosis. PPVs for ANA test were evaluated after stratification according to clinically relevant key parameters, such as patient age (younger < 65 years vs. older), sex, and requesting department. RESULTS: From 2010 to 2019, A total of 94,153 patients were tested for ANA, of which 13,600 (14.4% of the total) were positive. AARD was diagnosed in only 0.69% among all ANA tested patients and 4.74% among ANA positive patients. The AARD diagnosis rate of ANA positive patients varied widely from 0.1% to 8.7% by requesting department. Using cutoff values above 1:320 yielded PPVs of 15.6 and 7.8% for all AARs and systemic lupus erythematosus. The PPV was significantly higher in young age (< 65 years) and in women, and when it was requested from internal medicine vs other departments. CONCLUSION: AARD was diagnosed in less than 1% of all ANA tested patients in university-affiliated hospitals. This result shows that careful consideration before ordering the screening ANA is needed to improve the utility of the test for providers and patients and to reduce health costs spurred by unnecessary testing and its consequences.

Estimation of Cavities beneath Plate Structures Using a Microphone: Laboratory Model Tests.

The objective of this study is to detect a cavity and estimate its size using sound waves in a laboratory model chamber filled with dry sand. One side of the chamber is covered with an acrylic plate, and a cavity is placed between the plate and sand. Sound waves are generated by impacting the plate with an instrumented hammer, and are measured using a microphone. The measured sound waves are analyzed with four comprehensive analyses including the measured area under the rectified signal envelope (MARSE) energy, flexibility, peak magnitude of wavelet transform, and frequency corresponding to the peak magnitude. The test results show that the accuracy of cavity detection using the MARSE energy is higher for thicker plates, whereas that using flexibility is higher for thinner plates. The accuracies of cavity detection using the peak magnitude of wavelet transform, and frequency corresponding to the peak magnitude are consistently high regardless of the plate thickness. Moreover, the cavity size may be under- or overestimated depending on the plate thickness and the selected analysis method. The average of the cavity sizes estimated by these methods, however, is slightly larger than the actual cavity size regardless of the plate thickness. This study demonstrates that microphones may be effectively used for the identification of a cavity and the estimation of its size.

Estimation of Soil-Water Characteristic Curves in Multiple-Cycles Using Membrane and TDR System.

The objective of this study is to estimate multiple-cycles of the soil-water characteristic curve (SWCC) using an innovative volumetric pressure plate extractor (VPPE), which is incorporated with a membrane and time domain reflectometry (TDR). The pressure cell includes the membrane to reduce the experimental time and the TDR probe to automatically estimate the volumetric water content. For the estimation of SWCC using the VPPE system, four specimens with different grain size and void ratio are prepared. The volumetric water contents of the specimens according to the matric suction are measured by the burette system and are estimated in the TDR system during five cycles of SWCC tests. The volumetric water contents estimated by the TDR system are almost identical to those determined by the burette system. The experimental time significantly decreases with the new VPPE. The hysteresis in the SWCC is largest in the first cycle and is nearly identical after 1.5 cycles. As the initial void ratio decreases, the air entry value increases. This study suggests that the new VPPE may effectively estimate multiple-cycles of the SWCC of unsaturated soils.