A System to Determine Risk of Osteoporosis in Patients With Autoimmune Hepatitis

Osteoporosis is a feared complication of autoimmune hepatitis (AIH), but bone disease has not been well studied in these patients. We aimed to identify specific risk factors for osteoporosis in patients with AIH and to develop a scoring system that could be used to identify patients with increased risk of osteoporosis.

We performed a retrospective cross-sectional study of 211 patients (mean age, 56.8 years; 79.1% women) in Germany with a diagnosis of AIH from 2012 through 2017 and an indication for assessment of bone mineral status. The patients underwent bone mineral density measurements by dual energy X-ray absorptiometry. A subgroup of 99 patients underwent a second measurement. We used logistic regression to identify patient and clinical factors associated with the presence of osteoporosis. We developed a weighted sum score for estimating risk of osteoporosis and tested it in development (n = 141) and validation (n = 70) sets of patients.

According to dual energy X-ray absorptiometry measurements, 15.6% of patients had osteoporosis 42.9% were in the range for osteopenia. The prevalence of osteoporosis in patients 50 years or older was 19.2%. Univariate and logistic regression analyses showed that age older than 54 years, duration of glucocorticoid use >90 months, body mass index <23 kg/m² and transient elastography values >8 kPA increased risk of osteoporosis 13.8-fold, 6.2-fold, 5.9-fold, and 3.0-fold, respectively. Based on these factors, we developed an index that identified patients at low-, moderate-, and high-risk of osteoporosis with an area under the curve of 0.811. Of the patients with a second osteodensitometry measurement, the rate of bone loss progression ranged from 2.7% after 1 year to 8.4% after 7 years (mean bone loss, 1.2% per year).

Almost 20% of patients with AIH older than 50 years have osteoporosis. Older age, duration of corticosteroid use, low body mass index, and liver fibrosis are independent risk factors for bone loss.