Rheumatoid Arthritis Flashcards
What is the epidemiology of rheumatoid arthritis ?
In NZ: affects 1-2% of none population
Predominantly female (3:1)
Occurs in all ethnic groups, climates and altitudes
Can develop at any age but most likely between 35-45 years
What is rheumatoid arthritis?
Chronic progressive systemic autoimmune disease characterised by inflammation of the synovial tissue in joints causing swelling, pain, stiffness be joint destruction.
It has symmetrical joint involvement.
Can result in deformity and disability if untreated.
Associated with increased risk of CBD and MI
What is juvenile rheumatoid arthritis?
Rheumatoid arthritis occurring at <16 years
What are the risk factors of rheumatoid arthritis?
Sex - women more likely to develop
Age- RA can occur at any age, but most commonly begins between 40-60 years of age
Genetics- presence of HLA-DR4 more common in patients with RA. PTPN22 and other genes also identified as risk factors
Smoking- quitting can reduce risk
Infections- by bacteria or virus
Hormones- explains why disease is more common in women than in men
What is the Pathogenesis of rheumatoid arthritis?
Environmental triggers such as smoking, microorganisms and stress, and/of genetic pre-dispositions such as HLA-DR4, PTPN22 can result in dysregulation of the humoural cell mediated components of the immune system which can cause autoimmunity.
B cells can produce RF and anti-CCP antibodies, directed at common antigens expressed widely outside of the joint. the presence of these antibodies can precede the synovial inflammation of RA by decades.
From whichever reason, an antigen is able to activate CD4+ T cells which in turn activate B plasma cells, macrophages and leukocytes.
B cells produce autoantibodies which activate and combine with complement activates neutrophils and stimulates an immune response. They also bind to and activate macrophages in the synovium. Neutrophils release cytotoxins, oxygen free radicals and OH radicals promoting cellular damage to synovial and bone.
Macrophages release cytokines causing fibroblasts, chrondrocytes and synovial cells to proliferate. They also increase collagenase, elastase, resulting in pannus formation and destruction of bone.
T cells also activate macrophages and fibroblasts resulting in tissue destruction.
What are the main clinical presentations of rheumatoid arthritis?
Pain in the joints Swelling at joints (warmth and redness) Stiffness in the mornings Fatigue Muscle pain Loss of appetite Anemia
What are the extra articular sites of rheumatoid arthritis?
Haematological Pulmonary Cardiac Neurological Vasculitis (inflammation of bloodvessels) Rheumatoid nodules (asymptomatic) Ocular
What are the implications of haematological RA?
Anemia
Leukopenia –> susceptibility to infection
What are the implications of pulmonary RA?
Pleuritis
Pneumonitis (pulmonary fibrosis)
What are the implications of cardiac RA?
Pericarditis/myocarditis
This is higher in those with a more active inflammation
What are the implications of neurological RA?
Carpal tunnel and nerve compression
What are the implications of ocular RA?
Scleritis
Uveitis
Sjögren’s syndrome (atrophy of the lacrimal duct causing decreased tear formation, dry and itchy eyes) artificial tears can be used to relieve symptoms
How is rheumatoid arthritis diagnosed?
Early morning stiffness >1 hours Arthritis of 3 or more joint areas Asymmetrical arthritis (70% of patients) Involvement of hand joints Rheumatoid nodules X-ray changes Positive RF
Patient is said to have RA if the exhibit 4/7 criteria for at least 6 weeks
What is seen in the lab tests in rheumatoid arthritis?
RF detectable in 60-70% of patients
Elevated ESR and CrP (markers for inflammation)
Anti CCP antibodies (present in 50-85% of patients)
Increased WBC
Anemia common
Thrombocytopenia (result of toxicity of MTX etc)
Synovial fluid usually turbid and less viscous
What is the DAS?
Disease activity score.
This is the measure of activity in RA
Used to ascertain whether treatment is effective based on the number of swollen and tender joints at specific locations.
What is the DAS based on?
The assessment of 28 joints routinely used in Clinical practice, to assess potential treatment with biologicals and to evaluate their effectiveness and whether they should be continued.
What parameters does the disease activity sore use?
Number of joints tender to touch
Number of swollen joints
Erythrocyte sedimentation rate
Patient assessment of disease activity
What are the diseases related to the differential diagnosis of RA?
Osteoarthritis Gout Systemic lupus erythematous Psoriatic arthritis Lyme disease
What are the desired outcomes / treatment goals of RA?
Reduce pain and inflammation Minimise and prevent joint damage Maximise joint movement Control of systemic involvment Remission Improvise quality of life
What are the drugs used for acute- mild to moderate RA disease for a patient NOTT pregnant and not planning to be?
Methotrexate
Sulphasalazine
Leflunomide
Hydroxychloroquine
Sodium arothiomalate injection gold
Azathioprine
+Corticosteroids like prednisolone, methyl prednisolone acetate, dexamethasone sodium phosphate
+NSAIDs
What is methotrexate?
Anticancer agent but also first line (gold standard) for RA with onset starting within 3-4 weeks and full effect achieved by 12 weeks
How does methotrexate work?
It is a dihydrofolate reductase inhibitor preventing tetrahydofolate synthesis.
Inhibits cytokine production and purine biosynthesis
May stimulate adenosine secretion which may be responsible for anti inflammatory properties.
What are the precautions with methotrexate ?
Take caution in prescription to alcoholics and patients with renal/hepatic disease
Do not start in patients with severe respiratory disease
Drug is teratogenic. Effective contraception should be used at least 3 months after treatment
What are the adverse effects of methotrexate?
Nausea, mouth ulcers, rash, transaminases elevation (stop treatment if AST or ALT is 2x normal) leucopoenia, alopecia
Why must methotrexate (given on Monday) be coadministered with folic acid?
Must give folic acid 5-30mg (on a Friday) as folic acid is still required by our normal day to day cells
What is sulphasalazine?
Amino salicylate used as a DMARD for RA with effects seen in 2 months.
However its use is limited due to side effects
How does sulphasalazine work?
It inhibits prostaglandin and Leukotriene synthesis resulting in the impairment of white cell adhesion and inhibition of cytokine synthesis
What is the adverse effects of sulphasalazine?
Nausea, vomiting (dose reduction) Rash (must stop due to risk of Steven Johnson syndrome which is toxic epidermal necrolysis) Reversible reduction in sperm count Abdominal pain Hepatotoxicity (stop if LFTs >2x normal) Leucopenia
What is leflunomide ?
A DMARD with therapeutic effects seen at 4-6 weeks and continuing to 4-6 months
How does leflunomide work?
Inhibits pyrimidime synthesis leading to decreased lymphocyte proliferation and modulation of inflammation