Canadian variation by province in rheumatoid arthritis initiating anti-tumor necrosis factor therapy: results from the optimization of adalimumab trial

Abstract

Objective: We compared variations among Canadian provinces in rheumatoid arthritis (RA) initiating anti-tumor necrosis factor (TNF) therapy.

Methods: Data were obtained from the Optimization of Humira trial (OH) and from the Ontario Biologics Research Initiative (OBRI). Baseline characteristics were compared between regions: Ontario (ON), Quebec (QC), and other provinces (OTH). We compared Ontario OH to OBRI patients who were initiating anti-TNF therapy.

Results: In 300 OH patients, mean age was 54.8 years (13.3). There were 151 (50.3%) ON patients, 57 from QC (19%), and 92 from OTH (30.7%). Regional differences were seen in the number of disease-modifying antirheumatic drugs (DMARD) ever taken (ON: 3.8 ± 1.4, QC: 3.1 ± 1.1, OTH: 3.3 ± 1.4; p < 0.001); swollen joint count (SJC; ON: 10.9 ± 5.9, QC: 9.0 ± 4.4, OTH: 11.3 ± 5.6; p = 0.033); tender joint count (TJC; ON: 12.2 ± 7.5, QC: 10.3 ± 5.7, OTH: 14.4 ± 7.6; p = 0.003); 28-joint Disease Activity Score (DAS28; ON: 5.8 ± 1.2, QC: 5.6 ± 1.0, OTH: 6.0 ± 1.1; p = 0.076); and Health Assessment Questionnaire (ON: 1.4 ± 0.7, QC: 1.7 ± 0.7, OTH: 1.5 ± 0.7; p = 0.060). DMARD-ever use differed: methotrexate (ON: 94.7%, QC: 93%, OTH: 84.8%; p = 0.025); leflunomide (ON: 74.8%, QC: 21.1%, OTH: 51.1%; p < 0.001); sulfasalazine (ON: 51%, QC: 38.6%, OTH: 25%; p < 0.001); myochrysine (ON: 9.3%, QC: 0%, OTH: 15.2%; p = 0.008); and hydroxychloroquine (ON: 67.5%, QC: 86%, OTH: 66.3%; p = 0.018). In comparison to ON OH patients, 95 OBRI patients initiating first anti-TNF had lower SJC (p = 0.017), TJC (p = 0.008), and DAS28 (p = 0.05).

Conclusion: In Quebec, where access to anti-TNF is less restrictive, patients had lower SJC and TJC. ON used more DMARD, especially leflunomide, as mandated by the provincial government. Both provincial funding criteria and prescribing habits may contribute to differences. Canadian rheumatologists may vary in treatment decisions, but patients generally have similar DAS28 when initiating anti-TNF therapy.