Rapid pain response following intra-articular steroid injections in rheumatoid arthritis finger joints: a prospective study with daily patient self-assessment

Intraarticular corticosteroid injections (ISA) are frequently used in rheumatoid arthritis (RA). In spite of this there are few studies on ISA in finger joints in RA. We set out to identify patient-experienced effect of ISA in RA patients regarding pain and mobility of injected arthritic joints, predictors thereof, time span to symptom relief and effect duration. RA patients, ≥ 18 years, were asked to participate just after having received an ISA, with methylprednisolone (MP), in a metacarpophalangeal (MCP) or proximal interphalangeal (PIP) joint, due to arthritis. Patient characteristics, degree of arthritis, CRP and ESR were collected at inclusion. Pain and mobility in the injected joint were reported by the patient on day of inclusion and the following 14 days. Primary outcome was defined as Numerical Rating Scale (NRS) pain ≤ 2 (NRS-scale 0-10) in the injected joint at day 14. Secondary outcomes were NRS mobility, time span and predictors of fulfilling the primary outcome and effect duration. Three-quarters of RA patients responded to ISA regarding pain, most within four days. Mobility improved in two-thirds after 14 days. PIP joints responded better than MCP joints. The only significant predictor was injected MP volume. Among responders, effect persisted for at least three months. ISA is an effective therapy with 75% of RA patients responding over 14 days. PIP joints tend to respond better than MCP joints and the only other predictor for good outcome is volume MP injected, where response increased with volume.