Renal Doppler was introduced in the 1980s to screen for renovascular disease and detect renal artery stenosis. 1It was also studied as a potential tool to improve the assessment of renal obstruction or transplant dysfunction. 2 The renal resistive index (RRI) obtained by the Doppler arterial waveform analysis is the most popular measure described in these pathologies. 3 It is a noninvasive and reproducible measure to investigate renal hemodynamics, 4 calculated from the peak systolic and end-diastolic velocities using the following equation: ([peak systolic velocity−end-diastolic velocity]/peak systolic velocity). RRI is based on the changes in flow velocity created by the pulsatile arterial perfusion and can be used as an estimate of renal arterial resistance. For instance, vasomotor stimuli such as sympathetic activation or fluid load can induce changes in the RRI that indirectly reflect changes in the renal vascular resistance.5 Drugs affecting arteriolar vasomotor properties, such as nitroglycerine or captopril, have also been reported to change RRI. 6,7 However, a preserved vascular compliance seems to be necessary for vascular resistance to affect RRI. 8 Hence, with increasing downstream resistance, the diastolic velocity falls relative to systolic value, and RRI increases. In contrast, in the presence of a significant (>70%) main artery stenosis, the diastolic blood flow is less affected, but a slower systole with a dampened waveform (called parvus tardus) is observed, resulting in a decreased RRI value. 9 Even with the widespread use of RRI, reference values and systematic factors influencing measurement values are not well known. Only small-sized studies have evaluated Abstract-Increased renal resistive index (RRI) has been recently associated with target organ damage and cardiovascular or renal outcomes in patients with hypertension and diabetes mellitus. However, reference values in the general population and information on familial aggregation are largely lacking. We determined the distribution of RRI, associated factors, and heritability in a population-based study. Families of European ancestry were randomly selected in 3 Swiss cities. Anthropometric parameters and cardiovascular risk factors were assessed. A renal Doppler ultrasound was performed, and RRI was measured in 3 segmental arteries of both kidneys. We used multilevel linear regression analysis to explore the factors associated with RRI, adjusting for center and family relationships. Sex-specific reference values for RRI were generated according to age. Heritability was estimated by variance components using the ASSOC program (SAGE software). Four hundred women (mean age±SD, 44.9±16.7 years) and 326 men (42.1±16.8 years) with normal renal ultrasound had mean RRI of 0.64±0.05 and 0.62±0.05, respectively (P<0.001). In multivariable analyses, RRI was positively associated with female sex, age, systolic blood pressure, and body mass index. We observed an inverse correlation with diastolic blood pressure and heart rate. Age had a nonli...

BackgroundWe examined the associations between substance use (cigarette smoking, alcohol drinking, and cannabis use) and psychosocial characteristics at the individual and family levels among adolescents of the Seychelles, a rapidly developing small island state in the African region.MethodsA school survey was conducted in a representative sample of 1432 students aged 11-17 years from all secondary schools. Data came from a self-administered anonymous questionnaire conducted along a standard methodology (Global School-based Health Survey, GSHS). Risk behaviors and psychosocial characteristics were dichotomized. Association analyses were adjusted for a possible classroom effect.ResultsThe prevalence of cigarette smoking, alcohol drinking and cannabis use was higher in boys than in girls and increased with age. Age-adjusted and multivariate analyses showed that several individual level characteristics (e.g. suicidal ideation and truancy) and family level characteristics (e.g. poor parental monitoring) were associated with substance use among students.ConclusionsOur results suggest that health promotion programs should simultaneously address multiple risk behaviors and take into account a wide range of psychosocial characteristics of the students at the individual and family levels.