Objectives: To assess the usefulness of color charts for the diagnosis of finger whiteness in vibration-exposed workers.
Methods: A group of 146 forestry and stone workers exposed to hand-transmitted vibration (HTV) were examined twice over 1 year follow up period. The anamnestic diagnosis of finger whiteness was made on the basis of (a) a medical history alone, and (b) the administration color charts which showed changes in the skin color of fingers and hands. The cold response of digital arteries was assessed by measuring the change in finger systolic blood pressure (FSBP) after local cooling from 30 to 10 degrees C (FSBP%(10 degrees )).
Results: Assuming the administration of color charts as the gold standard, the sensitivity and specificity of the medical history alone to diagnose finger whiteness was 88.2 and 93.8%, respectively, at the initial cross-sectional study and 94.4 and 97.7% at the end of the follow-up. Random-intercept linear regression analysis of follow up data showed that after adjustment for several covariates, FSBP%(10 degrees )was significantly associated with finger whiteness assessed by either medical history alone (P < 0.005) or the color charts (P < 0.001). However, a statistical measure of overall fit of regression models (Bayesian Information Criterion) suggested that the color chart method performed better than medical history alone for the prediction of the cold response of digital arteries.
Conclusion: The administration of color charts seems to reduce the proportion of false positive responses for finger whiteness in a population of vibration-exposed workers. The color chart method was a more significant predictor of digital arterial hyperresponsiveness to cold than medical history alone. These findings suggest that the use of color charts in clinical and epidemiological studies may be of help to assist in the diagnosis of finger whiteness in vibration-exposed workers.