Consistency between three different ways of administering the Short Form 6 Dimension version 2

Background The Short Form 6 Dimension (SF-6D) is a multi-attribute utility instrument derived from the Short-Form 36 Health Survey Version 2 (SF-36v2) quality of life questionnaire and is used to calculate quality-adjusted life years (QALYs) on a scale 0 to 1. The SF-6Dv2 is a new version of the SF-6D. Objective The aim of this study was to assess the consistency of respondents’ answers to 3 different methods to administer this new version. Methods SF-6Dv2 utility values were generated from the SF-36v2 using the following: (1) full questionnaire with 36 items (SF-6Dv2SF-36); (2) subset questionnaire with 10 items (SF-6Dv2ind-10); (3) SF-6Dv2 administered as an independent instrument (rephrased questionnaire with only 6 items [SF-6Dv2ind-6]). The order of the 3 instruments was randomly allocated between respondents. Results A total of 782 respondents from Quebec, Canada, were interviewed, out of whom 697 fully completed the survey. Very few deviations in respondents’ answers were observed between the 3 instruments, with mean weighted kappa of 0.79 (range 0.61-0.91) and mean global consistency index of 70% (range 54-83). Maximal difference in utility values generated was found between SF-6Dv2ind-10 and SF-6Dv2ind-6 (mean difference 0.016, P < .01), whereas minimal difference was found between SF-6Dv2SF-36 and SF-6Dv2ind-10 (0.002, P = .38). No ceiling effect was observed. Conclusions The SF-6Dv2 was designed to derive utilities from the SF-36v2, and our results indicate that it is still preferable to use the full questionnaire, although the difference with other variants of the questionnaire is very small. To use the SF-6Dv2 as an independent instrument will thus introduce minimal bias in utility values generated

The equivocal appendix at CT: prevalence in a control population

The purpose of the study was to determine the prevalence of appendices with an equivocal appearance at computed tomography (CT) in a control population. We retrospectively identified a control population of 150 patients who underwent CT of the abdomen and pelvis for evaluation of hematuria (without abdominal pain, fever, or colonic disease). One reader measured the diameter of the appendix and noted if the appendix was either isodense in appearance or airless and fluid filled. Sixty-seven of 150 cases (44.6%) demonstrated appendiceal diameter greater than 6 mm. The appendix was collapsed or isodense in 34/150 cases (22.7%). Only ten of 150 or 6.6% of cases were isodense in combination with diameter greater than 6 mm, and none had diameter greater than 10 mm. Only one of 150 cases (0.67%) demonstrated airless fluid within the lumen, and the appendix measured less than 6 mm. While the diameter of the normal appendix is frequently greater than 6 mm, none measured greater than 10 mm in combination with ambiguous morphology. Furthermore, in the normal appendix, airless fluid filling the lumen is a rare appearance with a prevalence of less than 1%. While appendicitis could undoubtedly occur in an isodense appendix between 6 and 10 mm in diameter, such an appearance can occur in up to 6.6% of the normal populatio

Reliability Study of GaN-on-SiC HEMT RF Power Amplifiers

The RF power amplifier demonstrators containing each one GaN-on-SiC, HEMT, CHZ015A-QEG, from UMS in SMD quad-flat no-leads package (QFN) were subjected to thermal cycles (TC) and power cycles (PC) and evaluated electrically, thermally and structurally. Two types of solders, Sn63Pb36Ag2 and lead-free SnAgCu (SAC305), and two types of TIM materials, NanoTIM and TgonTM 805, for PCB attachment to the liquid cold plate were tested for thermo-mechanical reliability. Changes in the electrical performance of the devices, namely the reduction of the current saturation value, threshold voltage shift, increase of the leakage current and degradation of the HF performance were observed as a result of an accumulated current stress during PC. No significant changes in the investigated solder or TIM materials were observed