Oblique direction reach test: evaluating psychometric properties in stroke population

Post-stroke individuals are observed to have reduced limits of stability (LOS) in all directions. Functional activities are rarely performed in pure cardinal planes; instead, they are most likely to be performed in an oblique direction. Existing tools are either expensive or sophisticated to assess the LOS in an oblique direction. Therefore, this study's primary objective is to evaluate the intra-rater, inter-rater reliability, and validity of the oblique direction reach test (ODRT) among stroke subjects.

A total of 96 first-time stroke patients with age, gender, height, and weight-matched healthy controls aged 18-80 years were recruited for the study. Oblique, forward, and lateral reach distances were assessed using the standard procedure of ODRT, Functional Reach Test (FRT), and Lateral Reach Test (LRT), respectively. Validity was tested by correlating the ODRT distance with the Berg Balance Scale (BBS) Score using Spearman's rank correlation coefficient. Intraclass correlation coefficients (ICCs) and Bland Altman analysis were used to establish inter-rater reliability. ICCs were used to find intra-rater reliability. The Mann-Whitney U test was used to establish the mean difference of the FRT, LRT, and ODRT. Spearman's rank correlation coefficient and linear regression were used to correlate the distance of FRT and LRT with ODRT.

A high concurrent validity was found between BBS and ODRT with an r-value of 0.905 (p < 0.001). Inter-rater reliability was high with an ICC of 0.997 (95% CI [0.996-0.998]), and intra-rater reliability was highly significant with an ICC of 0.996 (95% CI [0.994-0.998]). The stroke subjects reached a significantly shorter distance than healthy individuals in FRT, ODRT, and LRT. ODRT was highly correlated with FRT (r = 0.985) and LRT (r = 0.978) (p < 0.001) and had an R² = 0.987.

ODRT is a highly valid and reliable tool that can be used to evaluate balance in stroke patients. Individuals who reached less in the forward and lateral directions showed reduced reach distance in the oblique direction.