Patients with RA: Registered in DANBIO with a diagnosis of M05.9, M06.0 or M06.9.

Patients with SpA: Registered in DANBIO with a diagnosis of M45.9, M46.1, M46.8+M02.9, M46.8+M07.4, M46.8+M07.5 or M46.9.

Patients with PsA: Registered in DANBIO with a diagnosis of M07.3 or M46.8+M07.2.

First bDMARD treatment course.

Start of treatment with first bDMARD in the period January 1, 2006 to December 31, 2016.

Age at start of treatment with first bDMARD ≥ 18 years.

Predicting Hospitalized Infection in Patients With Chronic Inflammatory Arthritis Treated With Biological Drugs