The validity of the fatigue and risk index for predicting impairments of health and safety under different shift schedules in the context of risk assessments.

In Germany, risk assessment of the working time arrangement is legally required, and within this context the authors assessed the usefulness of the fatigue and risk index (FRI) to predict any detrimental effects to health and safety. This assessment was made using data from two different surveys. Each contained records of working hours over a 4-wk period plus information on occupational accidents and health complaints. The independent variables drawn from the FRI parameters included the maxima, means, variances, and index factor scores. Phi-correlations between the FRI (dichotomized to the index of the reference system) and the incidence of an occupational accident were rather moderate, with a maximum correlation of .22 using the mean fatigue index (FI). Correlations between the two index factor scores and health complaints (sleep problems, stomach pain, eructation/heartburn) revealed the FI component, but not the risk index (RI) component, was related to those health complaints. Forward stepwise logistic regression analysis indicated the FI (but not the RI) predicted occupational accidents (FI(factor) odds ratio [OR] = 1.90, confidence interval [CI] 1.23-2.93). When using multiple regression analyses, the FI was able to predict sleep problems and other circadian related-problems, but the regression coefficients were moderate. In general, the results were not considered sufficient to justify a mandatory use of the FRI.