Comparison between specified percentage and fifth percentile criteria for spirometry interpretation in Thai patients.
ABSTRACT The present study was conducted to determine the degree of agreement between the interpretation of spirometry using a specified percentage of predicted value (SPC) and the fifth percentile (FPC) as the cut off between normal and abnormal.
Spirometric values were collected for 1754 subjects attending the respiratory service at Siriraj Hospital between February 2000 and April 2001. These values included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, maximal mid-expiratory flow (FEF25-75%) and peak expiratory flow (PEF). A comparison of results between SPC and FPC was performed. The SPC cut-off values for FVC, FEV1, FEV1/FVC, FEF25-75% and PEF were 80% predicted, 80% predicted, 70%, 65% predicted and 80% predicted, respectively. The FPC cut-off values were calculated from reference equations for the Thai population. Inter-rater agreement was calculated as the kappa score.
High kappa scores were obtained for FVC (0.84), FEV1 (0.88) and FEF25-75% (0.80). However, poor agreement was found for FEV1/FVC (0.72) and PEF (0.61). When the cut-off values for SPC were modified to 90% of predicted values for FEV1/FVC and to 65% of predicted values for PEF, agreement was substantially improved to 0.92 and 0.89, respectively.
Interpretation by SPC using cut-off values of 80% predicted for FVC and FEV1 and 65% predicted for FEF25-75% resulted in good agreement with FPC. However, the SPC cut-off values for FEV1/FVC and PEF should be modified to 90% predicted and 65% predicted, respectively.
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ABSTRACT: There are limited studies directly comparing correlation and agreement between peak expiratory flow rate (PEFR) and forced expiratory volume in 1 second (FEV1) for severity classification of COPD. However, clarifying the role of PEFR as a surrogate of COPD severity classification instead of FEV1 is essential in situations and areas where spirometry is not routinely available. To evaluate the agreement between FEV1 and PEFR using Global initiative for chronic Obstructive Lung Disease (GOLD) severity classification criteria. This cross-sectional study included stable COPD patients. Both absolute values and % predicted FEV1 and % predicted PEFR were obtained from the same patients at a single visit. The severity of COPD was classified according to GOLD criteria. Pearson's correlation coefficient was used to examine the relationship between FEV1 and PEFR. The agreement of % predicted FEV1 and % predicted PEFR in assigning severity categories was calculated using Kappa statistic, and identification of the limits of agreement was by Bland-Altman analysis. Statistical significance was set at P-value <0.05. Three hundred stable COPD patients were enrolled; 195 (65.0%) male, mean age 70.4±9.4 years, and mean % predicted FEV1 51.4±20.1. Both correlations between the % predicted FEV1 and PEFR as well as the absolute values were strongly significant (r=0.76, P<0.001 and r=0.87, P<0.001, respectively). However, severity categories of airflow limitation based on % predicted FEV1 or PEFR intervals were concordant in only 179 patients (59.7%). The Kappa statistic for agreement was 0.41 (95% confidence interval, 0.34-0.48), suggesting unsatisfied agreement. The calculated limits of agreement were wide (+27.1% to -28.9%). Although the correlation between FEV1 and PEFR measurements were strongly significant, the agreement between the two tests was unsatisfied and may influence inappropriate clinical decision making in diagnosis, severity classification, and management of COPD.International Journal of COPD 06/2015; 10:1213-1218. DOI:10.2147/COPD.S85166
Conference Paper: Dual gate MOS thyristor (DGMOT)[Show abstract] [Hide abstract]
ABSTRACT: A novel MOS-gated thyristor structure called the dual-gate MOS thyristor (DGMOT) is proposed. In this device the insulated-gate bipolar transistor (IGBT) mode turn-off is attained due to the integration of a lateral n-MOSFET with the thyristor structure, while the thyristor mode operation is achieved in the on-state. Consequently, the on-state voltage of the DGMOT is much lower than that of the IGBT with almost the same turn-off time. This result suggests that the DGMOT could be a superior alternative to the IGBT for a low-frequency circuitPower Semiconductor Devices and ICs, 1993. ISPSD '93., Proceedings of the 5th International Symposium on; 06/1993
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ABSTRACT: Silicosis is the most common occupational lung disease in Thailand. Determinants of pulmonary function impairment in Thai silicotic patients have not been mentioned before. The present study was conducted in silicotic patients who attended the Siriraj Occupational Lung Clinic in the year 2006. Patients were classified according to the forced expiratory volume in one second (FEV1) into the severe impairment group (< 50% predicted) and the non-severe group (FEV1 > 50% predicted) which includes normal FEV1. Comparison between the two groups in terms of demographic characteristics, smoking history, history of pulmonary tuberculosis, and radiographic features were assessed. Thirty-four patients of which 24 were female (70.6%) had an overall mean age of 53.7 years. Seven patients (20.6%) had severe impairment, four were female, three were smokers, and two had a history of pulmonary tuberculosis. All of the severe impairment patients had nodule profusion in category 2 and had large opacity. Only the presence of large opacity was significantly associated with the severity of pulmonary function impairment (p = 0.002). Only the presence of large opacity in a chest radiograph can determine the severity of pulmonary function impairment in Thai silicotic patients.Journal of the Medical Association of Thailand = Chotmaihet thangphaet 12/2007; 90 Suppl 2:54-8.