Dose escalation of infliximab therapy in arthritis patients is related to diagnosis and concomitant methotrexate treatment: observational results from the South Swedish Arthritis Treatment Group register.

OBJECTIVE: To study frequency of dose escalation in infliximab-treated patients and to identify possible predictors thereof.
METHODS: Patients with chronic arthritis initiating their first course of anti-TNF treatment with infliximab at Lund University Hospital were included in a structured clinical follow-up protocol. Information on diagnosis, drug dosage, disease duration, previous and ongoing DMARDs, treatment start and cessation were prospectively collected during the period March 1999 through February 2007. All patients were started on a dose of 3 mg/kg at time 0, week 2, week 6 and then every eighth week independent of diagnosis and were followed for a period of 2 yrs.
RESULTS: A total of 206 patients were included in the study. Thirty-two of the patients had PsA, 25 had AS and 149 patients had RA. A minor dose escalation, defined as less than doubling of the dosage, was observed for 53, 48 and 42% of the patients with PsA, AS and RA, respectively. The corresponding values for major dose escalation was observed for 19, 8 and 15% of the patients, respectively. Regression analysis showed that patients with a diagnosis of PsA (P = 0.03), longer follow-up period (P < 0.01), and lack of concomitant MTX treatment (P = 0.03) were significantly associated with risk of dose escalation.
CONCLUSION: Dose escalations were performed in 59% of all infliximab-treated patients during the first 2 yrs of treatment. Our data suggest that PsA patients might require higher dosages than RA and AS patients.