Asbestos and Smoking as Risk Factors for Idiopathic Retroperitoneal Fibrosis

BACKGROUND: Idiopathic retroperitoneal fibrosis (RPF) is a rare disease. Asbestos exposure has been proposed as a risk factor for idiopathic RPF. OBJECTIVE: To investigate the role of asbestos and other occupational agents (such as silica, metals, and organic solvents), as well as environmental agents (such as smoking), and their interactions as potential risk factors for idiopathic RPF. DESIGN: Case-control study. SETTING: National referral hospital for idiopathic RPF. PATIENTS: 90 patients with idiopathic RPF and 270 control participants matched for age, sex, and region of residency. MEASUREMENTS: Occupational history was obtained using structured questionnaires administered by blinded specialists in occupational medicine. Exposure to nonoccupational agents and presence of diseases that were potentially predisposing to idiopathic RPF were assessed through patient interviews and examination of medical records. RESULTS: A history of asbestos exposure was associated with idiopathic RPF (odds ratio [OR], 4.22 [95% CI, 2.14 to 8.33]). Both current smoking (OR, 3.21 [CI, 1.46 to 7.07]) and former smoking (OR, 2.93 [CI, 1.39 to 6.14]) were more prevalent among patients than among those who never smoked. A multiplicative effect was found between tobacco smoke and both occupational asbestos exposure (OR, 12.04 [CI, 4.32 to 38.28]) and extraoccupational asbestos exposure (OR, 8.42 [CI, 2.77 to 30.58]). LIMITATION: Retrospective, questionnaire-based assessment of occupational exposure. CONCLUSION: Exposure to asbestos and tobacco smoke resulted in strong risk factors for idiopathic RPF. Coexposure to asbestos and smoke had a multiplicative effect on risk compared with single exposure.