Risk factors for idiopathic orbital inflammation: a case-control study.

Objective: To identify risk factors involved in the development of idiopathic orbital inflammation (IOI).

Methods: Case-control study of 69 adults who had had a first episode of IOI and 296 adult controls with rhegmatogenous retinal detachment (RD) selected from three orbital centres in The Netherlands between 2000 and 2006. Participants filled out a questionnaire on demographic factors, medical history, health status and exposures for the 2 years prior to disease presentation. In addition, women were questioned about previous or current pregnancies and their hormonal status. ORs and accompanying 95% CIs for IOI in relation to potential risk factors such as body mass index (BMI), bisphosphonates and autoimmune disease were estimated. ORs were adjusted for age, sex, socio-economic status, smoking and blunt orbital trauma using logistic regression. Analyses were carried out both with and without multiple imputation of missing values.

Results: The risk of IOI was increased in participants who had a higher BMI (third vs first tertile: OR, 2.88; 95% CI 1.32 to 6.32) and in participants who used bisphosphonates (OR 8.68; 95% CI 1.16 to 65.0). The risk was decreased in participants with a higher socio-economic status (third vs first tertile: OR 0.38; 95% CI 0.17 to 0.84) and in women who were older at first childbirth (third vs first tertile: OR 0.14; 95% CI 0.03 to 0.64). An almost significant association was found for IOI and autoimmune disease (OR 2.56; 95% CI 0.93 to 7.05).

Conclusions: IOI is associated with lower socio-economic status, higher BMI and use of oral bisphosphonates. In women, IOI is also associated with younger age at first childbirth.