Small Minimal Detectable Change Research Articles

Reliability of Spatiotemporal Characteristics During Single-Legged Hop and Bilateral Drop Jump Tasks Using an Instrumented Pressure Walkway.

Single-legged hop tests have been widely used to assess performance-based outcomes after anterior cruciate ligament (ACL) reconstruction. Traditional single, triple, or 6-meter (6m) timed hop tests only measure distance or time as the principal variables, neglecting other variables, such as individual hop distances within a series of hops, flight time, and stance time. The development of portable instrumented pressure walkways has made it possible to collect parameters such as hop velocity, flight time, stance time, distance, and pressure outside of a laboratory setting. However, the reliability of instrumented pressure walkways in measuring spatial and temporal variables during single-legged hop tests is unknown. This study aimed to determine if the Zeno walkway can reliably measure spatiotemporal (ST) characteristics of hop tests. Cross-Sectional Study. Individuals (n=38) in this cross-sectional study performed single, triple, and 6m hop tests on a pressure-sensitive Zeno walkway. Twenty-one participants completed follow-up testing between one and 14 days later. Intraclass correlation coefficients (ICC(3,k)) were used to assess test-retest reliability of ST variables. The accuracy of vertical jump height and 6m hop timing were also measured. All ST variables demonstrated excellent test-retest reliability (ICC > 0.86) with small minimal detectable change (MDC) values during single-legged hop tests. Six-meter hop time and jump height during a bilateral drop jump were also accurately measured by the walkway. An instrumented pressure walkway is a novel tool to reliably assess non-traditional parameters of clinically relevant hop and jump tests such as flight time, stance time, and jump height after lower extremity injury, surgery, and rehabilitation. 3b.

Development and Intertester Reliability of a Novel Device to Measure Nonweightbearing Ankle Joint Dorsiflexion Range of Motion.

Ankle joint dorsiflexion range of motion is essential to normal gait. Ankle equinus has been implicated in a number of foot and ankle pathologies included Achilles tendonitis, plantar fasciitis, ankle injury, forefoot pain, and foot ulceration. Reliable measurement of ankle joint dorsiflexion range of motion, both clinically and in a research setting, is important. The primary aim of this study was to investigate the intertester reliability of an innovative device for measuring ankle joint dorsiflexion range of motion. A total of 31 (n = 31) participants volunteered to take part in this study. A paired t-test was performed to assess for systematic differences between the mean measures of each rater. Intertester reliability was evaluated using the intraclass correlation coefficient (ICC) and their 95% confidence intervals. A paired t-test demonstrated that the mean ankle joint dorsiflexion range of motion did not significantly differ between raters. The ankle joint ROM mean for rater 1 was 4.65 SD (3.71) and rater 2 was 4.67 SD (3.91). Intertester reliability for the use of the Dorsi-Meter was excellent and demonstrated a very narrow range of error. The ICC (95%CI) was 0.991 (0.980 to 0.995) the SEM (in degrees) was 0.07, the MDC95, in degrees was 0.19 and 95% LOA, degrees was -1.49 to 1.46. We found the intertester reliability of the Dorsi-Meter to demonstrate higher levels of intertester reliability compared to previous studies investigating other devices. We reported the MDC values to provide an estimate of the smallest amount of change in the ankle joint dorsiflexion range of motion that must be achieved to reflect a true change, outside the error of the test. The Dorsi-Meter has been established as an appropriate reliable device to measure ankle joint dorsiflexion for clinicians and researchers with very small minimal detectable change and limits of agreement.

The McNemar Change Index worked better than the Minimal Detectable Change in demonstrating the change at a single subject level

Background and ObjectiveTo assess the agreement between the Rasch Change Index (RCI), minimal detectable change (MDC), and McNemar Change Index (McCI), three statistics for demonstrating the patient's improvement/deterioration. MethodsThe Mini-Balance Evaluation Systems Test (Mini-BESTest (MB)) (a balance scale developed with the Rasch analysis) was administered before and after rehabilitation to 315 neurological patients. The MB RCI was chosen as the criterion standard for detecting the patient's improvement. Positive likelihood ratios and negative likelihood ratios (PLRs and NLRs, respectively) were used to evaluate the MDC and McCI accuracy in identifying the patient's improvement. Three different MB MDCs were assessed. ResultsOne-hundred patients improved their MB in accordance with the RCI. All three MDCs and the McCI were solid in ruling out the patient's improvement (NLR <0.2). The McCI and the largest MDC were also good in detecting the patient's improvement (PLR>5), whereas the smaller MDCs were not. Of the four indices, McCI was the most robust in case of missing items. ConclusionA patient stable in accordance with the MDCs or McCI is actually stable as per the criterion standard. To be reasonably sure that the patient is actually improved, larger MDC values or the McCI should be preferred, and the McCI is preferable if there are missing items.

A comparison of test–retest reliability and random measurement error of the Barthel Index and modified Barthel Index in patients with chronic stroke

Objective To compare the test–retest reliability and random measurement errors of the Barthel Index (BI) and modified Barthel Index (MBI) in patients with chronic stroke. Method The intraclass correlation coefficient (ICC) and the minimal detectable change (MDC) were applied respectively to examine the test–retest reliability (about 2 weeks apart) and the random measurement errors. The MDC% was used to adjust the cut-off score for determining whether a real change had been achieved, if heteroscedasticity existed. Results A total of 60 patients participated. The BI and MBI both had high ICCs (0.94 and 0.94, respectively) with small MDCs (16.2 and 15.4, respectively) and MDC%s (21.2% and 19.0%, respectively), indicating that both measures have comparable reliability in repeated assessments. However, moderate associations (r = −0.47 for the BI and −0.59 for the MBI) were found between the means of tests and retests and the absolute values of change scores, indicating heteroscedasticity. These findings suggest that a fixed MDC value is not appropriate for determining the real change in both measures because the amount of random measurement error varies with the patients’ ADL function. Conclusion The MBI, which showed excellent test–retest reliability and relatively lower random measurement error than the BI, appears to be a better ADL measure. The MDC% adjusted value is recommended to determine whether the change scores are beyond random measurement error. IMPLICATIONS FOR REHABILITATION The MBI is recommended for clinical and research applications because it has better test–retest reliability and relatively lower random measurement error than those of the original BI. The MDC% adjusted value is recommended to determine whether the change scores are beyond random measurement error when the MBI or the BI is used.

Minimal Detectable Change in Dual-Task Cost for Older Adults With and Without Cognitive Impairment.

Dual-task (DT) training has become a common intervention for older adults with balance and mobility limitations. Minimal detectable change (MDC) of an outcome measure is used to distinguish true change from measurement error. Few studies reporting on reliability of DT outcomes have reported MDCs. In addition, there has been limited methodological DT research on persons with cognitive impairment (CI), who have relatively more difficulty with DTs than persons without CI. The purpose of this study was to describe test-retest reliability and MDC for dual-task cost (DTC) in older adults with and without CI and for DTs of varying difficulty. Fifty participants 65 years and older attended 2 test sessions within 7 to 19 days. Participants were in a high cognitive group (n = 27) with a Montreal Cognitive Assessment (MoCA) score of 26 or more, or a low cognitive group (n = 23) with a MoCA score of less than 26. During both sessions, we used a pressure-sensing walkway to collect gait data from participants. We calculated motor DTC (the percent decline in motor performance under DT relative to single-task conditions) for 4 DTs: the Timed Up and Go (TUG) while counting forward by ones (TUG1) and counting backward by threes (TUG3); and self-selected walking speed (SSWS) with the same secondary tasks (SSWS1 and SSWS3). Intraclass correlation coefficients (ICCs) and MDCs were calculated for DTC for the time to complete the TUG and spatiotemporal gait variables during SSWS. A 3-way analysis of variance was used to compare differences in mean DTC between groups, tasks, and sessions. ICCs varied across groups and tasks, ranging from 0.02 to 0.76. MDCs were larger for individuals with low cognition and for DTs involving counting backward by threes. For example, the largest MDC was 503.1% for stride width during SSWS3 for individuals with low cognition, and the smallest MDC was 5.6% for cadence during SSWS1 for individuals with high cognition. Individuals with low cognition demonstrated greater DTC than individuals with high cognition. SSWS3 and TUG3 resulted in greater DTC than SSWS1 and TUG1. There were no differences in DTC between sessions for any variable. Our study provides MDCs for DTC that physical therapists may use to assess change in older adults who engage in DT training. Persons with low cognition who are receiving DT training must exhibit greater change in DTC before one can be confident the change is real. Also, greater change must be observed for more challenging DTs. Thus, cognitive level and task difficulty should be considered when measuring change with DT training.

What Are the Minimal and Substantial Improvements in the HOOS and KOOS and JR Versions After Total Joint Replacement?

Patient-reported outcome measures (PROMs) are a gold standard for measuring therapeutic outcomes in research. Extending their use to inform clinical care decisions, determine the appropriateness of therapeutic choices, and assess healthcare quality is attractive but will require our professional community to establish valid estimates of minimal and substantial clinical improvements. The purposes of this study were (1) to assess the validity of estimates for the minimal clinically important difference (MCID) calculated using distribution- and anchor-based methods by determining whether they exceed the minimal detectable change (MDC) for the Hip Disability and Osteoarthritis Outcome Score (HOOS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) domains, the HOOS, joint replacement (JR) and the KOOS, JR among patients who underwent THA or TKA; (2) to determine substantial clinical benefit thresholds for the HOOS and KOOS domains, the HOOS, JR, and the KOOS, JR among patients who underwent THA or TKA; and (3) to assess the proportions of patients who underwent THA or TKA who achieved an MCID for the HOOS and KOOS domains, HOOS, JR, and KOOS, JR based on distribution-based and anchor-based methods as well as the percentages of patients who achieved substantial clinical benefit using the anchor-based method. Medicare patients enrolled in our institutional joint replacement registry who subsequently underwent THA (n = 2323) or TKA (n = 2630) between 2007 and 2012 completed HOOS or KOOS preoperatively and 2 years postoperatively. Short-form joint replacement (JR) versions of each PROM were derived from the full PROMs. Of all eligible patients, 78% (3161 of 4080) of THAs and 74% of TKAs (3815 of 5156) consented to join the registry and completed a baseline survey, 88% (2796 of 3161) of THAs and 85% (3230 of 3815) of TKAs were eligible for followup survey administration, and 83% of THAs (2323 of 2796) and 81% (2630 of 3230) of TKAs returned 2-year surveys. For each HOOS domain, KOOS domain, HOOS, JR, and KOOS, JR, we calculated the calibration variation of the instrument (MDC) with confidence intervals (CIs) reflecting 80% (MDC80), 90% (MDC90), and 95% (MDC95) certainty; we calculated the smallest difference joint health patients might detect (MCID) using distribution- and anchor-based approaches and the difference that can be considered a large improvement in joint health (substantial clinical benefit) using an anchor-based approach. Patients undergoing THA were 57% female with a mean (± SD) age of 73 ± 6 years, whereas patients undergoing TKA were 63% female with a mean age of 74 ± 6 years. Depending on the CI chosen for the MDC, values ranged from 7 to 16 for the HOOS and KOOS domains and the JRs. The MCIDs ranged from 6 to 9 for the distribution-based approach and 7 to 36 for the anchor-based approach. All HOOS and KOOS domains and all JR scores are scores from 0 (worst joint health) to 100 (best joint health). The MCIDs calculated using the distribution-based approach were not valid, because they were lower than the MDC for all HOOS/KOOS domains and both JRs at every confidence level. The anchor-based receiver operating characteristic approach, on the other hand, resulted in MCIDs exceeding MDC80 for seven of eight HOOS/KOOS domains and MDC95 for both JR scores. For all domains and JR versions, substantial clinical benefits ranged from 15 to 36, exceeding MDC95 in all domains and JR scores. Across HOOS and KOOS domains as well as the JR, the proportion of patients undergoing THA who achieved an MCID ranged from 77% to 95% with the distribution-based method and from 67% to 96% using the anchor-based method. The proportion achieving substantial clinical benefit ranged from 67% to 85%. The MDC and MCID differ greatly based on assumptions and methods used. The MCID anchor-based approach had superior construct and face validity compared with the MCID distribution-based approach, which never exceeded even small MDCs. Achieving consensus about standard definitions of meaningful improvement will be necessary to maximize utility of these PROMs to inform clinical care or performance measurement. Level III, diagnostic study.

Reliability and Minimal Detectable Change Values for Predictions of Knee Forces during Gait and Stair Ascent Derived from the FreeBody Musculoskeletal Model of the Lower Limb.

FreeBody is a musculoskeletal model of the lower limb used to calculate predictions of muscle and joint contact forces. The validation of FreeBody has been described in a number of publications; however, its reliability has yet to be established. The purpose of this study was, therefore, to establish the test–retest reliability of FreeBody in a population of healthy adults in order to add support to previous and future research using FreeBody that demonstrates differences between cohorts after an intervention. We hypothesized that test–retest estimations of knee contact forces from FreeBody would demonstrate a high intra-class correlation. Kinematic and kinetic data from nine older participants (4 men: mean age = 63 ± 11 years; 5 women: mean age = 49 ± 4 years) performing level walking and stair ascent was collected on consecutive days and then analyzed using FreeBody. There was a good level of intra-session agreement between the waveforms for the individual trials of each activity during testing session 1 (R = 0.79–0.97). Similarly, overall there was a good inter-session agreement within subjects (R = 0.69–0.97) although some subjects showed better agreement than others. There was a high level of agreement between the group mean waveforms of the two sessions for all variables (R = 0.882–0.997). The intra-class correlation coefficients (ICC) were very high for peak tibiofemoral joint contact forces (TFJ) and hamstring forces during gait, for peak patellofemoral joint contact forces and quadriceps forces during stair ascent and for peak lateral TFJ and the proportion of TFJ accounted for by the medial compartment during both tasks (ICC = 0.86–0.96). Minimal detectable change (MDC) of the peak knee forces during gait ranged between 0.43 and 1.53 × body weight (18–170% of the mean peak values). The smallest MDCs were found for medial TFJ share (4.1 and 5.8% for walking and stair ascent, respectively, or 4.8 and 6.7% of the mean peak values). In conclusion, the results of this study support the use of FreeBody to investigate the effect of interventions on muscle and joint contact forces at the cohort level, but care should be taken if using FreeBody at the subject level.

The CONFbal scale: a measure of balance confidence—a key outcome of rehabilitation

Objective Optimising balance confidence is the goal of rehabilitation among people with mobility problems. The aim of this study was to examine the measurement properties of the CONFbal scale of balance confidence, and comment on its importance in rehabilitation. The 10-item CONFbal scale can also be referred to as a ‘falls self-efficacy scale’. Study 1: Internal consistency and test–retest reliability Design CONFbal was administered on two occasions, 1 week apart, using a standardised procedure. Setting Three day centres in south-west London. Participants Older people ( n = 45, mean age 81 years, standard deviation 7) without any recent change in mobility. Results The 10 scale items were summed to give an index of balance confidence. Cronbach's alpha for the items was 0.91, with an intra-class correlation coefficient of 0.95. The within-subject standard deviation was 1.145, giving a minimal detectable change of three scale points. This suggests that a change in score of three points following treatment indicates a true difference. Study 2: Concurrent validity Setting Geriatric medical wards in three south-west London hospitals. Participants One hundred and fifty-three people (mean age 81 years, standard deviation 6) completed the test battery prior to discharge. Data CONFbal; postural instability; perceived unsteadiness; previous mobility; falls in the last 3 years. Results CONFbal scores (lower scores indicate greater balance confidence) were related to an index of postural instability [correlation coefficient ( r) = 0.75], previous mobility ( r = −0.76) and perceived unsteadiness ( r = 0.48), but demonstrated a weak relationship with experience of falling ( r = 0.26). Conclusions The CONFbal scale demonstrates excellent internal consistency, excellent test–retest reliability, and a small minimal detectable change which allows users to judge whether or not there has been a true clinical improvement. Relationships between the CONFbal scale and other relevant physical and psychological variables support its validity in this population.