The intra- and interrater reliability of the action research arm test: A practical test of upper extremity function in patients with stroke

Objectives: To determine the intra- and interrater reliability of the Action Research Arm (ARA) test, to assess its ability to detect a minimal clinically important difference (MCID) of 5.7 points, and to identify less reliable test items. Design: Intrarater reliability of the sum scores and of individual items was assessed by comparing (1) the ratings of the laboratory measurements of 20 patients with the ratings of the same measurements recorded on videotape by the original rater, and (2) the repeated ratings of videotaped measurements by the same rater. Interrater reliability was assessed by comparing the ratings of the videotaped measurements of 2 raters. The resulting limits of agreement were compared with the MCID. Patients: Stratified sample, based on the intake ARA score, of 20 chronic stroke patients (median age, 62yr; median time since stroke onset, 3.6yr; mean intake ARA score, 29.2). Main Outcome Measures: Spearman's rank-order correlation coefficient (Spearman's rho); intraclass correlation coefficient (ICC); mean difference and limits of agreement, based on ARA sum scores; and weighted kappa, based on individual items. Results: All intra- and interrater Spearman's rho and ICC values were higher than .98. The mean difference between ratings was highest for the interrater pair (.75; 95% confidence interval, .02-1.48), suggesting a small systematic difference between raters. Intrarater limits of agreement were -1.66 to 2.26; interrater limits of agreement were -2.35 to 3.85. Median weighted kappas exceeded .92. Conclusion: The high intra- and interrater reliability of the ARA test was confirmed, as was its ability to detect a clinically relevant difference of 5.7 points

The influence of physical activity and fractures on ultrasound parameters in elderly people

In this cross-sectional study we investigated the relationship between ultrasound measurements in the calcaneus versus daily physical activity and fractures sustained in the past in elderly subjects. Ultrasound measurements were performed at both heels, which enabled us to examine determinants of differences between contralateral heels. Participants were 132 men and 578 women, aged 70 years and over (mean age and standard deviation (SD): 83 ± 6 years), living in homes for the elderly (n = 343) or apartment houses for the elderly (n = 367). Broadband ultrasound attenuation (BUA) and speed of sound (SOS) were measured in the right and left calcaneus. The median difference (and interquartile range) between the two heels for BUA and SOS, expressed as a percentage of the mean value for each individual, was 9.6% (4.2-15.7%) and 1.0% (0.4-1.7%), corresponding to 25% and 40% of the study population SDI respectively. Greater differences in BUA between the two heels were associated with variables indicating poorer functional status, such as past fractures at the lower extremities. The level of daily physical activity was obtained by means of a questionnaire regarding household and leisure activities. Subsequently sumscores were calculated for daily physical activity and a subscore indicating weight-bearing physical activity. After adjustment for age, gender, residence, and body weight, physical activity scores were positively linearly related to both BUA and SOS. Each 5 point increase on the weight-bearing physical activity score, corresponding to, for example, walking for 2.5 h per week, was associated with a difference in BUA of 4.7 dB/MHz and in SOS of 5.1 m/s, which is similar to the differences associated with 10 kg higher body weight, or 10 years younger age. After the age of 50 years 47 subjects had fractured a hip, 61 subjects had sustained another lower extremity fracture, 104 subjects a wrist fracture, and 62 subjects another upper extremity fracture. After adjusting for age, gender and residence, odds ratios for all fracture types in the lowest terciles of BUA and SOS versus the highest terciles ranged from 1.9 to 3.8. This study showed significant differences in ultrasound measurements between the left and the right heel, indicating that measurements at both sides are necessary for optimal evaluation of bone strength. Furthermore, after careful adjustments, ultrasound parameters had higher values with higher daily physical activity in elderly subjects and discriminated subjects with a history of fracture from those without

The relation between the permeability of structured dispersions and the viscoelastic properties of the dispersed phase

It is shown that not only the average particle size and compression modulus, but also the viscoelastic properties of the network affect the rate of liquid removal out of a concentrated disperse system that is unilaterally compressed. A Maxwell-like constitutive equation is introduced to express these viscoelastic properties. The rate of liquid removal is calculated for a set of values of the elastic modulus and the time constant that appear in the constitutive equation. It is shown that permeability measurements on concentrated fat dispersions can be interpreted in terms of network properties also when the network is viscoelastic, i.e., it is assumed that processes take place inside the network that involve energy dissipation

Reproducibility and responsiveness of evaluative outcome measures - Theoretical considerations illustrated by an empirical example

Objective: This article outlines basic methods for quantifying reproducibility and responsiveness of evaluative outcome measures. Methods: The background noise in stable patients provides the desired information to quantify the reproducibility. From this, the smallest real difference (SRD) for longitudinal differences can be derived. We propose to use the SRD to define responsiveness: from all patients who change according to an external criterion, we take the percentage that changes at least SRD on the outcome measure. A more complete picture of the responsiveness of the outcome measure arises when the receiver operating characteristic (ROC) is constructed, corresponding to all possible cut-off change scores. The proposed methods are illustrated with an empirical example. Results: In the illustration the methods appeared to be very useful and complemented each other. We could evaluate whether the observed change score was larger than that expected due to chance. With the methods it was possible to evaluate both the ability of an instrument to detect change if there is a real change in health status (sensitivity to change) and the ability to detect absence of change if there is no real change (specificity to change). Conclusion: We presented the use of SRDs and ROC curves for quantifying reproducibility and responsiveness. We started with the basic notions and arrived at methods that are both understandable and useful

Endothelial LRP1 transports amyloid-β1-42 across the blood-brain barrier

According to the neurovascular hypothesis, impairment of low-density lipoprotein receptor-related protein-1 (LRP1) in brain capillaries of the blood-brain barrier (BBB) contributes to neurotoxic amyloid-beta (A beta) brain accumulation and drives Alzheimer's disease (AD) pathology. However, due to conflicting reports on the involvement of LRP1 in A beta transport and the expression of LRP1 in brain endothelium, the role of LRP1 at the BBB is uncertain. As global Lrp1 deletion in mice is lethal, appropriate models to study the function of LRP1 are lacking. Moreover, the relevance of systemic A beta clearance to AD pathology remains unclear, as no BBB-specific knockout models have been available. Here, we developed transgenic mouse strains that allow for tamoxifen-inducible deletion of Lrp1 specifically within brain endothelial cells (Slo1c1-CreER(Tz) Lrp1(fl/fl) mice) and used these mice to accurately evaluate LRP1-mediated A beta BBB clearance in vivo. Selective deletion of Lrp1 in the brain endothelium of C57BL/6 mice strongly reduced brain efflux of injected [I-125] A beta(1-42). Additionally, in the 5xFAD mouse model of AD, brain endothelial-specific Lrp1 deletion reduced plasma A beta levels and elevated soluble brain A beta, leading to aggravated spatial learning and memory deficits, thus emphasizing the importance of systemic AD elimination via the BBB. Together, our results suggest that receptor-mediated A beta BBB clearance may be a potential target for treatment and prevention of A beta brain accumulation in AD