A follow up study of vibration induced white finger in compensation claimants.

AIMS To follow up vibration induced white finger (VWF) in a selected group of 73 vibration exposed workers who claimed unsuccessfully for VWF compensation at a first examination. METHODS The VWF claimants were sent to our unit by the National Insurance Institute. The basic compensatory criteria included a positive history of VWF and abnormal cold response of the digital arteries. Following the first unsuccessful examination, over a mean time period of 4.1 (range 1-11) years the National Insurance Institute requested a second examination for all 73 claimants and a third examination for 29. During the follow up period, all subjects continued to work with vibratory tools. RESULTS There were 14 new cases who reported white finger during the follow up period. In the new VWF cases, finger blanching attacks became visible after about 3.5 years since the first examination. All incident cases of anamnestic VWF showed an abnormal cold response in the digital arteries and obtained compensation according to the basic compensatory criteria. In the entire sample of VWF claimants, there was a discrepancy between positive history of VWF symptoms at medical interview (55%) and abnormal cold provocation outcomes (19%). Digital arterial hyperresponsiveness to cold was associated with both VWF symptoms and the duration of vibration exposure since the first examination. Over the follow up period, a significant increase in the vasoconstrictor response to cold was observed in the vibration exposed workers with no symptoms of finger whiteness. Abnormal cold response was not associated with either age or smoking habit. CONCLUSIONS Cold test measuring finger systolic blood pressure may be considered a useful laboratory method to confirm objectively VWF symptoms and to disclose abnormal cold induced vasoconstrictor response in vibration exposed workers with a negative history of VWF. Medical interview outcomes should be interpreted with caution in medicolegal situations involving VWF claimants.