The predictive validity of the Newcastle Independence Assessment Form Research (NIAF-R): Further development of an alternative measure

Earlier papers have detailed the conceptualization, development, and testing of the Newcastle Independence Assessment Form (NIAF-R), an alternative global outcome measure. This article establishes the predictive validity of the measure. Predictive validity was examined by applying two different prediction models, using functional status and return to work (RTW) as the two outcome variables. Multiple linear and logistic regression analyses indicated that the NIAF-R, when incorporated in equations with age and injury severity, the latter determined by length of coma, was consistently predicting functional status from as early as 8 weeks and return to work from as early as 12 weeks post-injury. Prediction of functional status was especially significant, with the NIAF-R accounting for up to 90 percent of the variance. Prediction of return to work, although consistent, was less powerful. Implications for the validity of the NIAF-R, with particular reference to prognosis and rehabilitation planning, are presented.