Median starting doses of infliximab in psoriatic arthritis patients in two nationwide registries were below the recommended dose of 5 mg/kg every 8 weeks, but outcomes suggest that a low starting dose with subsequent step-up is an effective treatment strategy, according to an observational cohort study based on the registries.
In 376 Danish patients in the Danish Rheumatologic Database (DANBIO) registry and 86 Icelandic patients in the Center for Rheumatology Research (ICEBIO) registry, starting infliximab doses were less than 3 mg/kg in 29% and 74%, respectively, 3-5 mg/kg in 42% and 27%, respectively, and greater than 5 mg/kg in 10% and 0%, respectively (starting doses in the remaining patients were not registered). In those cohorts, median starting doses were 3.1 mg/kg and 2.3 mg/kg, respectively, Dr. Bente Glintborg of the Copenhagen Center for Arthritis Research and Glostrup (Denmark) Hospital and her colleagues reported (Rheumatology 2014 June 17 [doi:10.1093/rheumatology/keu252]).
Treatment was maintained after 12 months in 58% and 66% of the Danish and Icelandic patients, respectively (and was highest in those taking concomitant methotrexate). At 12 months, the median doses were 3.3 and 2.9 mg/kg, respectively, and time until dose escalation, response rates, drug survival, and disease activity at 12 months did not differ based on starting dose. Dosing was sustained at below the recommended level in more than 70% of the patients, the investigators found.
Recommended starting doses of infliximab are higher for psoriatic arthritis than for rheumatoid arthritis (5 mg/kg vs. 3 mg/kg) based on randomized trial data, but data on the effectiveness of lower doses are lacking. The current findings suggest that the approach often used in RA – a lower starting dose with gradual escalation – is also effective in psoriatic arthritis, they concluded.
Dr. Glintborg reported having no disclosures. Other study authors reported receiving research grants, serving on a speakers’ bureau, providing consultancy, or serving as an adviser or investigator to a variety of manufacturers of biologic drugs.