Measurements of Large and Small Artery Elasticity Indexes in a Swedish Population: Are Repeated Measurements Needed?

Aim: The aim of this study was to investigate whether the repeated measurement of the pulse wave from the radial artery improve the precision of the estimated elasticity. Method: Between 2002 and 2005 a total of 2816 individuals (Men 1400) 35-74 years old, in the Skaraborg County in southern Sweden, were randomly selected for a health survey within the Skaraborg Project (the Vara-Skovde Cohort). All participants were examined with an oral glucose tolerance test (OGTT), blood pressure and anthropometric data. Pulse wave measurements were performed by two trained study nurses using the HDI/Pulse wave CR-2000 (Eagan, MN). Three repetitive measurements were performed within 5 minutes. Large and small artery elasticity indexes (LAEI and SAEI) from each measurement, as well as the mean value of the first two measurements and all three measurements were evaluated with intraclass correlation (ICC) and Pearsons correlation to investigate the precision of the test. Coefficient of variation (CV) was calculated for each measurement and for the variable of the mean of two first measurements and the mean of three measurements. Results: The measurements were successful in 2733 subjects (97%). The mean LAEI in 1st, 2nd and 3rd measurements were respectively 16.2±5.6ml/mmHg, 16.3±5.4 ml/mmHg and 16.5± 5.4 ml/mmHg and for SAEI the corresponding results were 7.4±3.6 ml/mmHg, 7.5±3.6 ml/mmHg and 7.4±3.5 ml/mmHg. A significant successive increase was observed in both the LAEI and the SAEI; comparing the third to the first examination LAEI-diff by 0.28 ml/mmHg CI 0.14-0.43 0 p Conclusion: Considering the high CV in both LAEI and SAEI repeated measurements are recommended. However, the high correlation between the mean of two and three measurements suggests only slight improvement in the precision is achieved with three examinations. As commonly recommended for blood pressure control we suggest using the mean of two measurements also for these indices of arterial elasticity.