Smallest real difference of 2 instrumental activities of daily living measures in patients with chronic stroke

Abstract

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.