Minimal detectable change of gait and balance measures in older neurological patients: estimating the standard error of the measurement from before-after rehabilitation data thanks to the linear mixed-effects models

BACKGROUND

Tracking gait and balance impairment in time is paramount in the care of older neurological patients. The Minimal Detectable Change (MDC), built upon the Standard Error of the Measurement (SEM), is the smallest modification of a measure exceeding the measurement error. Here, a novel method based on linear mixed-effects models (LMMs) is applied to estimate the standard error of the measurement from data collected before and after rehabilitation and calculate the MDC of gait and balance measures.

METHODS

One hundred nine older adults with a gait impairment due to neurological disease (66 stroke patients) completed two assessment sessions before and after inpatient rehabilitation. In each session, two trials of the 10-meter walking test and the Timed Up and Go (TUG) test, instrumented with inertial sensors, have been collected. The 95% MDC was calculated for the gait speed, TUG test duration (TTD) and other measures from the TUG test, including the angular velocity peak (ωpeak) in the TUG test's turning phase. Random intercepts and slopes LMMs with sessions as fixed effects were used to estimate SEM. LMMs assumptions (residuals normality and homoscedasticity) were checked, and the predictor variable ln-transformed if needed.

RESULTS

The MDC of gait speed was 0.13 m/s. The TTD MDC, ln-transformed and then expressed as a percentage of the baseline value to meet LMMs' assumptions, was 15%, i.e. TTD should be < 85% of the baseline value to conclude the patient's improvement. ωpeak MDC, also ln-transformed and expressed as the baseline percentage change, was 25%.

CONCLUSIONS

LMMs allowed calculating the MDC of gait and balance measures even if the test-retest steady-state assumption did not hold. The MDC of gait speed, TTD and ωpeak from the TUG test with an inertial sensor have been provided. These indices allow monitoring of the gait and balance impairment, which is central for patients with an increased falling risk, such as neurological old persons.

TRIAL REGISTRATION

NA.

Reliability of the transcranial Doppler ultrasound-derived mean flow index for assessing dynamic cerebral autoregulation in healthy volunteers

The transcranial Doppler ultrasound-derived mean flow index (Mxa) is widely used for assessing dynamic cerebral autoregulation (dCA) in different clinical populations. This study aimed at estimating the relative and absolute reliability of Mxa in healthy participants in the supine position and during head-up tilt (HUT). Fourteen healthy participants were examined on two separate occasions during which, mean middle cerebral artery blood flow velocity (MCAv), non-invasive blood pressure, and heart rate were continuously recorded in the supine position and during HUT. Mxa was calculated as the correlation coefficient between mean arterial blood pressure and MCAv using either 3-, 5-, or 10-second averages collected over a 300 second period. Intraclass correlation coefficient (ICC_1.1) was calculated to assess relative reliability, while the standard error of measurement (SEM), and limits of agreement (LOA) were used to assess absolute reliability. Mxa-based 3-second averages yielded a similar relative and absolute reliability in both positions. When Mxa was calculated from 5-second averages, the most reliable values were obtained during HUT. The poorest reliability was achieved using 10-second averages, regardless of posture. The Mxa shows fair reliability with acceptable LOA in healthy volunteers when based on 3-second averages, both in the supine position and during HUT.

Self-efficacy in adolescents with inflammatory bowel disease: a pilot study of the "IBD-yourself", a disease-specific questionnaire

BACKGROUND AND AIMS

Successful transfer of adolescent IBD patients to an adult gastroenterologist requires anticipation of a changing role for patients and their parents. Self-efficacy has been demonstrated to be important for transfer readiness. We therefore developed an IBD-specific questionnaire (the "IBD-yourself") to assess self-efficacy in adolescent IBD patients visiting a transition clinic. Our aim was to evaluate the reliability of this questionnaire, and to describe the self-efficacy level of adolescent IBD patients, and the perceived self-efficacy level according to their parents.

METHODS

In a cross-sectional design, 50 IBD patients (aged 14-18 years) and 40 parents completed the "IBD-yourself" questionnaire. Internal reliability was assessed by standardised Cronbach's α. Median self-efficacy scores per domain were calculated.

RESULTS

The domains of the questionnaire for adolescents showed good to excellent internal consistency, with Cronbach's α ranging from 0.64 to 0.93. The domains of the parental questionnaire had Cronbach's α ranging from 0.47 to 0.93. Median self-efficacy scores of adolescents varied from 70 to 100%. In comparison with patient's self-assessment, parents thought that their child was more self-efficacious in knowledge of IBD and diagnostic tests, self-management of medication use, and transfer readiness. Length of time since first visit to the transition clinic was positively correlated with several domains of the questionnaire, such as independent behaviour at the outpatient clinic, and transfer readiness.

CONCLUSION

The "IBD-yourself" questionnaire is a first step toward evaluating quality and efficacy of IBD transition programmes. Paediatric gastroenterologists should be aware that parents do not always accurately assess the self-efficacy of their child.