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The foundations of socioeconomic inequities and the educational outcomes of efforts to reduce gaps in socioeconomic status are of great interest to researchers around the world, and narrowing the achievement gap is a common goal for most education systems. This review of the literature focuses on socioeconomic status (SES) and its related constructs, the association between SES and educational achievement, and differences among educational systems, together with changes over time. Commonly-used proxy variables for SES in education research are identified and evaluated, as are the relevant components collected in IEA's Trends in International Mathematics and Science Study (TIMSS). Although the literature always presents a positive association between family SES and student achievement, the magnitude of this relationship is contingent on varying social contexts and education systems. TIMSS data can be used to assess the magnitude of such relationships across countries and explore them over time. Finally, the literature review focuses on two systematic and fundamental macro-level features: the extent of homogeneity between schools, and the degree of centralization of education standards and norms in a society.

International large-scale assessments may be used to understand differences in average student performance across countries over time. Differences in achievement are associated with students' background characteristics and, while the most salient background variables may differ across education systems, a substantial amount of the variance in student achievement is normally explained by family socioeconomic status (SES). Family SES is thus considered an important factor in education research, but there are still challenges regarding how to best measure SES operationally. In addition to measuring student achievement, the IEA's Trends in International Mathematics and Science Study (TIMSS) has been collecting background information from students, their teachers, and principals at four-year intervals since 1995. This study uses data from the IEA's TIMSS grade eight mathematics and science assessments to examine changes in the achievement gaps between high-and low-SES students between 1995 and 2015 for 13 education systems, as operationalized by a modified version of the TIMSS home educational resources index. The performance of disadvantaged students may also be tracked over time. These measures explain a sizeable amount of variation in the TIMSS achievement scores and, in conjunction with data on the countries' education systems and other macroeconomic indicators, can provide country-specific analyses and an across-country synthesis.

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ObjectiveTricuspid regurgitation (TR) is a common valvular heart disease with unsatisfactory medical therapeutics and high surgical mortality. The present study aims to evaluate the safety and effectiveness of transcatheter tricuspid valve replacement (TTVR) in high-risk patients with severe TR.MethodsThis was a compassionate multicentre study. Between September 2018 and November 2019, 46 patients with TR who were not suitable for surgery received compassionate TTVR under general anaesthesia and the guidance of trans-oesophageal echocardiography and fluoroscopy in four institutions. Access to the tricuspid valve was obtained via a minimally invasive thoracotomy and transatrial approach. Patients’ data at baseline, before discharge, 30 days and 6 months after the procedure were collected.ResultsAll patients had severe TR with vena contracta width of 12.6 (11.0, 14.5) mm. Procedural success (97.8%) was achieved in all but one case with right ventricle perforation. The procedural time was 150.0 (118.8, 180.0) min. Intensive care unit time was 2.0 (1.0, 4.0) days. 6-month mortality was 17.4%. Device migration occurred in one patient (2.4%) during follow-up. Transthoracic echocardiography at 6 months after operation showed TR was significantly reduced (none/trivial in 33, mild in 4 and moderate in 1) and the primary safety end point was achieved in 38 cases (82.6%). Patients suffered from peripheral oedema and ascites decreased from 100.0% and 47.8% at baseline to 2.6% and 0.0% at 6 months.ConclusionsThe present study showed TTVR was feasible, safe and with low complication rates in patients with severe TR.