Association of common comorbidities with osteonecrosis: a nationwide population-based case-control study in Denmark

Objective To examine recent time trends in the incidence of osteonecrosis (ON) in Denmark and to investigate different common comorbidities association with ON in a population-based setting. Methods Using Danish medical databases, we included all patients with a first-time hospital diagnosis of ON during 1995-2012. Each ON case was matched with 10 randomly selected population control subjects from general population. For all participants, we obtained a complete hospital history of comorbidities included in the CharlsonComorbidity Index 5 years preceding the inclusion date. Results 4107 ON cases and 41 063 controls were included. The incidence of ON increased from 3.9 in 1995 to 5.5 in 2012 per 100 000 inhabitants. Solid cancer was the most common comorbidity, associated with an adjusted OR (aOR) for ON of 2.0 (95% CI 1.7 to 2.2). For advanced metastatic cancer, leukaemia and lymphoma, aORs of ON were 3.4 (95% CI 2.5 to 4.5), 4.3 (95% CI 2.7 to 7.0) and 5.8 (95% CI 4.3 to 7.8), respectively. Among other chronic conditions, aORs were 3.5 (95% CI 3.0 to 4.1) for connective tissue diseases and 2.3 (95% CI 2.0 to 2.7) for chronic pulmonary diseases. aORs were also increased at 2.8 (95% CI 1.9 to 4.1) and 4.5 (95% CI 2.5 to 8.2) for mild and moderate-to-severe liver disease, respectively, and 4.2 (95% CI 3.4 to 5.2) for renal disease. Conclusion This large population-based study provides evidence for an increasing ON incidence in the general population and documents an association between several common comorbid conditions and risk of ON.