Reliability and validity of the Acute Care Index of Function for patients with neurologic impairment.

The Acute Care Index of Function (ACIF), developed to standardize the assessment of functional status in patients with acute neurologic deficits, was tested for interrater reliability and concurrent validity. Interrater reliability was tested on 91 patients in a five-week study. After a two-week training period, six physical therapists were paired so that each therapist was paired with each other therapist for one week. All patients were rated weekly with the ACIF by a pair of physical therapists. A total of 166 assessments were conducted. Concurrent validity was tested using descriptions of function of 10 hypothetical patients. Each patient description was assigned a score based on the ACIF. Ten experienced therapists were then asked to rank order the functional status of each patient based on the patient's description. The average of the physical therapists' rankings was correlated with the ranking determined with the ACIF scores. Reliability data were analyzed using Cohen's weighted Kappa. The weighted Kappa values ranged from .60 to .98. Validity data were analyzed with the Spearman rank-order correlation coefficient (rs = .81, p less than .01). The results of this study indicate that the ACIF is reliable between raters and valid in its ability to rank order functional status for patients with acute neurologic deficits.