Objectives: To determine whether occupational exposure to hand-transmitted
vibration is a risk factor for scleroderma (systemic sclerosis, SSc), two c
ase-control studies were conducted in the provinces of Trento and Verona, n
ortheastern Italy. Methods: In the Trento study, 21 patients with a diagnos
is of either systemic or localised scleroderma were recruited from those ad
mitted to all hospitals of the province from I January 1976 to 31 December
1991. For each case, two age- and gender-matched controls were selected. In
the Verona study, cases included 55 patients diagnosed with SSc and clinic
ally followed at the rheumatology clinic of the local university hospital b
etween I January 1997 and 30 June 1999. The controls included 171 subjects
frequency-matched by gender and age group. In both studies, all subjects we
re interviewed by structured questionnaire containing items on personal cha
racteristics, smoking and drinking habits, use of medicines, occupational h
istory and complete medical history. Women were also investigated about sil
icone implants and cosmetic surgery. Jobs and job tasks involving the use o
f vibratory tools, with or without concomitant exposure to silica dust in m
ining and non-mining occupations, were carefully investigated. A minimum cr
iterion of 6 months was required for exposure duration. Results: In the Tre
nto Study, men with scleroderma were more likely than controls to have had
exposure to hand-transmitted vibration (odds ratio (OR) 1.5, 95% confidence
interval (95% CI) 0.1-74.1) or silica dust (OR 5.2, 95% CI 0.5-74.1), but
the association was not significant. The scleroderma patients were miners o
r stone workers who had operated jackhammers and rock drills. In the Verona
study, a greater, although not statistically significant, odds of SSc was
observed in men exposed to hand-transmitted vibration (OR 2.4, 95% CI 0.4-1
4.0) and in women exposed to silica (OR 2.4, 95% CI 0.4-15.5). The SSc pati
ents with vibration exposure were machinery operators or metal workers who
had used grinders and impact wrenches. Conclusions: Our case-control studie
s did not show a significant association between scleroderma and hand-trans
mitted vibration, with or without concomitant exposure to silica dust. Owin
g to the rarity of the disease and the small number of cases in the present
studies, a genetic susceptibility to connective tissue disorders in SSc pa
tients with occupational exposure to hand-transmitted vibration and/or sili
ca cannot be ruled out.