Systemic Comorbidities and Screening Tools for Rheumatoid Arthritis

Inflammatory arthritis is systemic. About 1 in 4 people with psoriasis develop a related arthritis, with higher risk when the skin disease is severe or affects the nails. People with Crohn's disease have about a 1 in 4 chance of arthritis within six years, and roughly 50% of people attending emergency eye clinics with uveitis have undiagnosed spondyloarthritis. These conditions link to HLA-B27, so first-degree relatives with them add weight. Lupus can affect the nervous and reproductive systems, and antiphospholipid syndrome can show as two or more miscarriages. Jack stresses timeframes and whether the history fits: an ankle sprain in someone with Crohn's disease is just a sprain at two days, but not at twelve weeks. The Clinically Suspected Arthralgia criteria are sensitive but not specific and need three or more positives, including MCPJ involvement, morning stiffness over 60 minutes and a positive squeeze test. The Leiden rule adds age, sex, joint spread, stiffness, CRP, anti-CCP and rheumatoid factor, with a score of 8 or more predicting rheumatoid arthritis.