Musculoskeletal Hospital Admission and Surgical Procedure Rates among Patients Treated for Rheumatoid Arthritis in the Netherlands 1999-2012

Objectives: To assess trends in hospitalizations among patients receiving rheumatoid arthritis (RA)-treatment in a 14-year period compared with population references. Methods: Patients treated for RA with any disease-modifying antirheumatic drug (DMARD) between 1999 and 2012 were identified in the PHARMO Database Network. Population controls were randomly matched 2:1 by age, gender and pharmacy. Occurrence rates of musculoskeletal hospitalizations, surgical procedures and mortality were assessed and compared between patients and controls using Poisson regression. Results: Among 32,829 RA patients, the rate of musculoskeletal surgical procedures decreased from 7.3 (95% CI 6.5-8.2) per 100 person-years (py) in 1999 to 2.1 (95% CI 1.9-2.3) per 100 py in 2012, while the rate among matched reference subjects did not change. The relative rates were 5.6 (95% CI 4.5-7.1) and 2.4 (95% CI 2.0-2.7). In a subcohort of 2,832 RA patients who received a biological DMARD, the relative rate decreased from 18 (95% CI 7-44) in 2003 to 3.9 (95% CI 2.6- 5.8) in 2012. Musculoskeletal admission rates among RA patients were similar in 2012 compared to 1999 but temporarily increased around 2003, while the rate among reference subjects remained stable. Conclusion: Rates of musculoskeletal surgical procedures among patients treated for RA in the Netherlands decreased from 1999 to 2012. The largest reduction occurred among users of biological DMARDs. Surgical procedure rates in 2012 remained over twice as high for patients with RA as compared to reference subjects and almost four times higher in patients receiving bio-DMARDs.