Objective: To assess the reliability of 6 gait performance tests in individuals with chronic mild to moderate post-stroke hemiparesis. Design: An intra-rater (between occasions) test-retest reliability study. Subjects: Fifty men and women (mean age 58 6.4 years) 6–46 months post-stroke. Methods: The Timed “Up & Go” test, the Comfortable and the Fast Gait Speed tests, the Stair Climbing ascend and descend tests and the 6-Minute Walk test were assessed 7 days apart. Reliability was evaluated with the intraclass correlation coefficient (ICC 2,1), the Bland & Altman analysis, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%). Results: Test-retest agreements were high (ICC2,1 0.94–0.99) with no discernible systematic differences between the tests. The standard error of measurement (SEM%), representing the smallest change that indicates a real (clinical) improvement for a group of individuals, was small (9%). The smallest real difference (SRD%), representing the smallest change that indicates a real (clinical) improvement for a single individual, was also small (13–23%). Conclusion: These commonly used gait performance tests are highly reliable and can be recommended to evaluate improvements in various aspects of gait performance in individuals with chronic mild to moderate hemiparesis after stroke.

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Reliability of gait performance tests in men and women with hemiparesis after stroke

The aim of this study is to show the relationship between test-retest reproducibility and responsiveness and to introduce the smallest real difference (SRD) approach, using the sickness impact profile (SIP) in chronic stroke patients as an example. Forty chronic stroke patients were interviewed twice by the same examiner, with a 1-week interval. All patients were interviewed during the qualification period preceding a randomized clinical trial. Test-retest reproducibility has been quantified by the intraclass correlation coefficient (ICC), the standard error of measurement (SEM) and the related smallest real difference (SRD). Responsiveness was defined as the ratio of the clinically relevant change to the SD of the within-stable-subject test-retest differences. The ICC for the total SIP was 0.92, whereas the ICCs for the specified SIP categories varied from 0.63 for the category 'recreation and pastime' to 0.88 for the category 'work'. However, both the SEM and the SRD far more capture the essence of the reproducibility of a measurement instrument. For instance, a total SIP score of an individual patient of 28.3% (which is taken as an example, being the mean score in the study population) should decrease by at least 9.26% or approximately 13 items, before any improvement beyond reproducibility noise can be detected. The responsiveness to change of a health status measurement instrument is closely related to its test-retest reproducibility. This relationship becomes more evident when the SEM and the SRD are used to quantify reproducibility, than when ICC or other correlation coefficients are used.

Smallest real difference, a link between reproducibility and responsiveness.

Reliability: What is it, and how is it measured?

Background: Accurate measurement of physical activity patterns can be used to identify sedentary behaviour and may facilitate interventions aimed at reducing inactivity. Objective: To evaluate the activ PAL physical activity monitor as a measure of posture and motion in everyday activities using observational analysis as the criterion standard. Methods: Wearing three activ PAL monitors, 10 healthy participants performed a range of randomly assigned everyday tasks incorporating walking, standing and sitting. Each trial was captured on a digital camera and the recordings were synchronised with the activ PAL. The time spent in different postures was visually classified and this was compared with the activ PAL output. Results: Intraclass correlation coefficients (ICC 2,1) for interdevice reliability ranged from 0.79 to 0.99. Using the Bland and Altman method, the mean percentage difference between the activ PAL monitor and observation for total time spent sitting was 0.19% (limits of agreement −0.68% to 1.06%) and for total time spent upright was −0.27% (limits of agreement −1.38% to 0.84%). The mean difference for total time spent standing was 1.4% (limits of agreement −6.2% to 9.1%) and for total time spent walking was −2.0% (limits of agreement −16.1% to 12.1%). A second-by-second analysis between observer and monitor found an overall agreement of 95.9%. Conclusion: The activ PAL activity monitor is a valid and reliable measure of posture and motion during everyday physical activities.

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The validation of a novel activity monitor in the measurement of posture and motion during everyday activities

Objective: To evaluate interrater reliability using 5 newly trained observers in the assessment of pressure pain threshold (PPT) using a fixed-angle algometer. Methods: The study design comprised 2 phases. Phase 1: 5 undergraduate physical therapists were trained in algometry at a predefined angle, at a rate of 5 Newtons (N)/s, to the first dorsal interosseous muscle. Each observer then underwent a competency test of the application speed. The aim was to achieve repeated applications at 5 N/s without visual feedback from the algometer. Phase 2: the 5 observers measured PPT of 13 healthy volunteers, at the first dorsal interosseous muscle. The sequence of observer measurements for each participant was randomized. Mean PPT values for each observer were analyzed using repeated measures analysis of variance, intraclass correlation coefficient (ICC2,1), and standard error of measurement, with 95% confidence intervals (CIs). Results: No significant differences between observers’ mean values were found (P = 0.094), suggesting no bias. The ICC was 0.91 (95% CI 0.82, 0.97). The standard error of measurement value was 6.27 N/cm 2 (95% CI 5.35, 7.59). Differences in PPT measurements of more than 17.39 N/cm 2 (1.77 kg/cm 2 ) are likely to exceed the magnitude of measurement error, and could be used to indicate true change. This margin of error is, however, somewhat larger than a previously proposed minimum clinically important difference in PPT of 14.71 N/cm 2 (1.5 kg/cm 2 ). Discussion: This study provides new evidence that trained observers can apply an algometer at a consistent rate and provide highly reliable measures of PPT in healthy humans, when PPT is calculated as the mean of 3 trials.

Interrater reliability of algometry in measuring pressure pain thresholds in healthy humans, using multiple raters

Objective: To provide a practical guide to appropriate statistical analysis of a reliability study using real-time ultrasound for measuring muscle size as an example.Design: Inter-rater and intra-rater (between-scans and between-days) reliability.Subjects: Ten normal subjects (five male) aged 22–58 years.Method: The cross-sectional area (CSA) of the anterior tibial muscle group was measured using real-time ultrasonography.Main outcome measures: Intraclass correlation coefficients (ICCs) and the 95% confidence interval (CI) for the ICCs, and Bland and Altman method for assessing agreement, which includes calculation of the mean difference between measures (d), the 95% CI for d, the standard deviation of the differences (SD diff), the 95% limits of agreement and a reliability coefficient.Results: Inter-rater reliability was high, ICC (3,1) was 0.92 with a 95% CI of 0.72 → 0.98. There was reasonable agreement between measures on the Bland and Altman test, as d was -0.63 cm2, the 95% CI for d was -1.4 → 0.14 ...

Reliability of assessment tools in rehabilitation: an illustration of appropriate statistical analyses

This study was undertaken to establish normal reference ranges for abdominal muscle size and symmetry and to examine the effects on these of gender and age. We studied 123 subjects, consisting of 55 men (aged 21-72 years) and 68 women (aged 20-64 years). Real-time ultrasound imaging of the abdominal muscles was performed. Thickness of internal and external oblique (IO, EO), transversus abdominis (TA), and rectus abdominis (RA), and cross-sectional area (CSA) of RA were measured, and absolute and relative muscle thickness (percent total muscle thickness), order of thickness, and symmetry (percent difference between sides) were determined. Males had significantly larger muscles than females and size was poorly correlated with age. The pattern of relative muscle thickness was RA > IO > EO > TA. Symmetry for total absolute thickness of all three lateral muscles was 8%-9% (mean) but for individual muscles there was asymmetry of absolute size (13%-24%), whereas relative thickness was symmetrical for all muscles. These findings provide robust reference data for the abdominal muscles in normal males and females in order to enable comparison with clinical groups to assess abnormalities and establish sensitivity for evaluating the effectiveness of interventions.

G. Rankin

Papers

Reliability of assessment tools in rehabilitation: an illustration of appropriate statistical analyses

Abdominal muscle size and symmetry in normal subjects

Ultrasound imaging of lumbar multifidus muscle: normal reference ranges for measurements and practical guidance on the technique.

Size and shape of the posterior neck muscles measured by ultrasound imaging: normal values in males and females of different ages