How should I differentiate between osteoarthritis and rheumatoid arthr

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

To differentiate between osteoarthritis (OA) and rheumatoid arthritis (RA) in primary care:

Osteoarthritis is typically diagnosed clinically in people aged 45 or over who have activity-related joint pain and either no morning stiffness or morning stiffness lasting no longer than 30 minutes. Imaging is not routinely required unless atypical features or alternative diagnoses are suspected .
Rheumatoid arthritis should be suspected in adults with persistent synovitis, especially if multiple small joints of the hands or feet are affected, or if symptoms have persisted for 3 months or longer before seeking advice. Referral for specialist opinion is recommended in these cases .
Blood tests such as rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies can support the diagnosis of RA but should not delay referral .
X-rays of hands and feet may be used in suspected RA to detect erosions but are not routinely used to diagnose OA ,.
OA symptoms are generally related to mechanical use and improve with rest, whereas RA symptoms often include prolonged morning stiffness and symmetrical joint involvement with systemic features ,.

How should I differentiate between osteoarthritis and rheumatoid arthritis in a primary care setting?