Wen-Shian Lu

Minimal Detectable Change of the Timed “Up & Go” Test and the Dynamic Gait Index in People With Parkinson Disease

Background The minimal detectable change (MDC) is the smallest amount of difference in individual scores that represents true change (beyond random measurement error). The MDCs of the Timed “Up & Go” Test (TUG) and the Dynamic Gait Index (DGI) in people with Parkinson disease (PD) are largely unknown, limiting the interpretability of the change scores of both measures. Objective The purpose of this study was to estimate the MDCs of the TUG and the DGI in people with PD. Design This investigation was a prospective cohort study. Methods Seventy-two participants were recruited from special clinics for movement disorders at a university hospital. Their mean age was 67.5 years, and 61% were men. All participants completed the TUG and the DGI assessments twice, about 14 days apart. The MDC was calculated from the standard error of measurement. The percentage MDC (MDC%) was calculated as the MDC divided by the mean of all scores for the sample. Furthermore, the intraclass correlation coefficient was used to examine the reproducibility between testing sessions (test-retest reliability). Results The respective MDC and MDC% of the TUG were 3.5 seconds and 29.8, and those of the DGI were 2.9 points and 13.3. The test-retest reliability values for the TUG and the DGI were high; the intraclass correlation coefficients were .80 and .84, respectively. Limitations The study sample was a convenience sample, and the participants had mild to moderately severe PD. Conclusions The results showed that the TUG and the DGI have generally acceptable random measurement error and test-retest reliability. These findings should help clinicians and researchers determine whether a change in an individual patient with PD is a true change.

A controlled pilot trial of two commercial video games for rehabilitation of arm function after stroke

Objectives: To investigate the acceptability and potential efficacy of two commercial video games for improving upper extremity function after stroke in order to inform future sample size and study design. Design: A controlled clinical trial design using sequential allocation into groups. Setting: A clinical occupational therapy department. Subjects: Twenty-four first-stroke patients. Interventions: Patients were assigned to one of three groups: conventional group, Wii group, and XaviX group. In addition to regular one-hour conventional rehabilitation, each group received an additional half-hour of upper extremity exercises via conventional devices, Wii games, or XaviX games, for eight weeks. Main measures: The Fugl-Meyer Assessment of motor function, Box and Block Test of Manual Dexterity, Functional Independence Measure, and upper extremity range of motion were used at baseline and postintervention. Also, a questionnaire was used to assess motivation and enjoyment. Results: The effect size of differences in change scores between the Wii and conventional groups ranged from 0.71 (SD 0.59) to 0.28 (SD 0.58), on the Fugl-Meyer Assessment of motor function (d = 0.74) was larger than that between the XaviX and conventional groups, ranged from 0.44 (SD 0.49) to 0.28 (SD 0.58) (d = 0.30). Patient enjoyment was significantly greater in the video game groups (Wii mean 4.25, SD 0.89; XaviX mean 4.38, SD 0.52) than in the conventional group (mean 2.25, SD 0.89, F = 18.55, p < 0.001), but motivation was not significantly different across groups. Conclusion: Patients were positive to using video games in rehabilitation. A sample size of 72 patients (24 per group) would be appropriate for a full study.

Smallest Real Difference of 2 Instrumental Activities of Daily Living Measures in Patients With Chronic Stroke

OBJECTIVE To estimate the smallest real difference (SRD) values of 2 instrumental activities of daily living measures (the Nottingham Extended Activities of Daily Living [NEADL] and the Frenchay Activities Index [FAI]) in patients with chronic stroke. DESIGN Test-retest reliability study. SETTING Physical rehabilitation units of 5 hospitals. PARTICIPANTS Chronic stroke patients (N=52; 37 men, 15 women) who were discharged from the hospital for more than 6 months. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Both measures were administered twice about 2 weeks apart to participants. The SRD was calculated on the basis of standard error of measurement: SRD = 1.96 × √2 × Standard error of measurement. SRD% (the value of SRD divided by total score of a measure) was used to compare measurement errors across both measures. Reproducibility between successive measurements of the measures was investigated with intraclass correlation coefficients (ICCs). RESULTS The SRD (SRD%) values of the NEADL and the FAI were 12.0 (21.1%) and 6.7 (14.9%), respectively. Test-retest reproducibility of both measures was high (ICC: NEADL=.89, FAI=.89). CONCLUSIONS Because of substantial SRD values of the NEADL and the FAI, prospective users should be cautious in using both measures to detect real change for a single subject.

Practice effects and test-re-test reliability of the Five Digit Test in patients with stroke over four serial assessments

Abstract Objectives: To investigate practice effect and test–re-test reliability of the Five Digit Test (FDT) over four serial assessments in patients with stroke. Design: Single-group repeated measures design. Methods: Twenty-five patients with stroke were administered the FDT in four consecutive assessments every 2 weeks. The FDT contains four parts with five indices: ‘basic measures of attention and processing speed’, ‘selective attention’, ‘alternating attention’, ‘ability of inhibition’ and ‘ability of switching’. Results: The five indices of the FDT showed trivial-to-small practice effects (Cohen’s d = 0.03–0.47) and moderate-to-excellent test–re-test reliability (intra-class correlation coefficient = 0.59–0.97). Practice effects of the five indices all appeared cumulative, but one index, ‘basic measures of attention and processing speed’, reached a plateau after the second assessment. The minimum and maximum values of the 90% confidence interval (CI) of reliable change index modified for practice (RCIp) for this index were [−17.6, 11.2]. Conclusions: One of five indices of the FDT reached a plateau, whose minimum and maximum values of the 90% CI RCIp are useful to determine whether the change in an individual’s score is real. However, clinicians and researchers should be cautious when interpreting the test results of these four indices over repeated assessments.

Test-retest reliability and minimal detectable change of the Beck Depression Inventory and the Taiwan Geriatric Depression Scale in patients with Parkinson's disease

Background The Beck Depression Inventory II (BDI-II) and the Taiwan Geriatric Depression Scale (TGDS) are self-report scales used for assessing depression in patients with Parkinson’s disease (PD) and geriatric people. The minimal detectable change (MDC) represents the least amount of change that indicates real difference (i.e., beyond random measurement error) for a single subject. Our aim was to investigate the test-retest reliability and MDC of the BDI-II and the TGDS in people with PD. Methods Seventy patients were recruited from special clinics for movement disorders at a medical center. The patients’ mean age was 67.7 years, and 63.0% of the patients were male. All patients were assessed with the BDI-II and the TGDS twice, 2 weeks apart. We used the intraclass correlation coefficient (ICC) to determine the reliability between test and retest. We calculated the MDC based on standard error of measurement. The MDC% was calculated (i.e., by dividing the MDC by the possible maximal score of the measure). Results The test-retest reliabilities of the BDI-II/TGDS were high (ICC = 0.86/0.89). The MDCs (MDC%s) of the BDI-II and TGDS were 8.7 (13.8%) and 5.4 points (18.0%), respectively. Both measures had acceptable to nearly excellent random measurement errors. Conclusions The test-retest reliabilities of the BDI-II and the TGDS are high. The MDCs of both measures are acceptable to nearly excellent in people with PD. These findings imply that the BDI-II and the TGDS are suitable for use in a research context and in clinical settings to detect real change in a single subject.

Minimal detectable change of the Personal and Social Performance scale in individuals with schizophrenia

The minimal detectable change (MDC) of the Personal and Social Performance scale (PSP) has not yet been investigated, limiting its utility in data interpretation. The purpose of this study was to determine the MDCs of the PSP administered by the same rater or different raters in individuals with schizophrenia. Participants with schizophrenia were recruited from two psychiatric community rehabilitation centers to complete the PSP assessments twice, 2 weeks apart, by the same rater or 2 different raters. MDC values were calculated from the coefficients of intra- and inter-rater reliability (i.e., intraclass correlation coefficients). Forty patients (mean age 36.9 years, SD 9.7) from one center participated in the intra-rater reliability study. Another 40 patients (mean age 44.3 years, SD 11.1) from the other center participated in the inter-rater study. The MDCs (MDC%) of the PSP were 10.7 (17.1%) for the same rater and 16.2 (24.1%) for different raters. The MDCs of the PSP appeared appropriate for clinical trials aiming to determine whether a real change in social functioning has occurred in people with schizophrenia.

Interrater and Intrarater Reliability of the Balance Computerized Adaptive Test in Patients With Stroke

OBJECTIVE To examine the interrater and intrarater reliability of the Balance Computerized Adaptive Test (Balance CAT) in patients with chronic stroke having a wide range of balance functions. DESIGN Repeated assessments design (1wk apart). SETTING Seven teaching hospitals. PARTICIPANTS A pooled sample (N=102) including 2 independent groups of outpatients (n=50 for the interrater reliability study; n=52 for the intrarater reliability study) with chronic stroke. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Balance CAT. RESULTS For the interrater reliability study, the values of intraclass correlation coefficient, minimal detectable change (MDC), and percentage of MDC (MDC%) for the Balance CAT were .84, 1.90, and 31.0%, respectively. For the intrarater reliability study, the values of intraclass correlation coefficient, MDC, and MDC% ranged from .89 to .91, from 1.14 to 1.26, and from 17.1% to 18.6%, respectively. CONCLUSIONS The Balance CAT showed sufficient intrarater reliability in patients with chronic stroke having balance functions ranging from sitting with support to independent walking. Although the Balance CAT may have good interrater reliability, we found substantial random measurement error between different raters. Accordingly, if the Balance CAT is used as an outcome measure in clinical or research settings, same raters are suggested over different time points to ensure reliable assessments.

Test–Retest Reliability and Minimal Detectable Change of the D2 Test of Attention in Patients with Schizophrenia

Objective The d2 Test of Attention (D2) is a commonly used measure of selective attention for patients with schizophrenia. However, its test-retest reliability and minimal detectable change (MDC) are unknown in patients with schizophrenia, limiting its utility in both clinical and research settings. The aim of the present study was to examine the test-retest reliability and MDC of the D2 in patients with schizophrenia. Method A rater administered the D2 on 108 patients with schizophrenia twice at a 1-month interval. Test-retest reliability was determined through the calculation of the intra-class correlation coefficient (ICC). We also carried out Bland-Altman analysis, which included a scatter plot of the differences between test and retest against their mean. Systematic biases were evaluated by use of a paired t-test. Results The ICCs for the D2 ranged from 0.78 to 0.94. The MDCs (MDC%) of the seven subscores were 102.3 (29.7), 19.4 (85.0), 7.2 (94.6), 21.0 (69.0), 104.0 (33.1), 105.0 (35.8), and 7.8 (47.8), which represented limited-to-acceptable random measurement error. Trends in the Bland-Altman plots of the omissions (E1), commissions (E2), and errors (E) were noted, presenting that the data had heteroscedasticity. Conclusions According to the results, the D2 had good test-retest reliability, especially in the scores of TN, TN-E, and CP. For the further research, finding a way to improve the administration procedure to reduce random measurement error would be important for the E1, E2, E, and FR subscores.