Asbestos exposure as a risk factor for retroperitoneal fibrosis

Retroperitoneal fibrosis (RPF) is an uncommon disease with unknown causation in most cases. The pathognomonic finding is a fibrous mass covering the abdominal aorta and the ureters. Our aim was to clarify the possible role of asbestos exposure in the development of RPF. The hypothesis was based on the ability of asbestos to cause fibrosis in pulmonary and pleural tissue. We undertook a case-control study of 43 patients with the disease (86% of eligible cases) treated in three university hospital districts of Finland in 1990–2001. For every patient, five population-based controls were selected, matched by age, sex, and central hospital district. We assessed asbestos exposure and medical history using a postal questionnaire and a personal interview. Of the 215 eligible controls, 179 (83%) participated in the study. The age-standardised incidence of RPF was 0·10 (95% CI 0·07–0·14) per 100 000 person-years. The disease was strongly associated with asbestos exposure. The odds ratio (OR) was 5·54 (1·64–18·65) for less than 10 fibre-years of asbestos exposure and 8·84 (2·03–38·50) for 10 or more fibre-years, the attributable fraction being 82% and 89%, respectively. Other risk factors were previous use of ergot derivates (OR 9·92 [1·63–60·26]), abdominal aortic aneurysm (OR 6·73 [0·81–56·08]), and smoking for more than 20 pack-years (OR 4·73 [1·28–17·41]). Our results show that occupational asbestos exposure is an important causal factor for RPF. For patients with work-related asbestos exposure, RPF should be considered an occupational disease.