Rheumatoid Arthritis Flashcards
what is rheumatoid factor
circulating antibody, usually IgM
binds to Fc of host IgG
first-line ab test for pt with ?RA (anti-CCP if RF-)
how to detect RF?
Rose-Waaler test - sheep red agglutination
Latex agglutination test - less specific
what conditions are a/w + RF?
RA (70-80%) - high titre levels a/w severe progressive disease but NOT MARKER OF DISEASE ACTIVITY
felty syndrome - 100%
sjogren’s - 50%
infective endocarditis - 50%
sle - 20-30%
systemic sclerosis - 30%
general population - 5%
rare - tb, hbv, ebv, leprosy
what is the most specific antibody for RF?
anti-cyclic citrullinated peptide ab (90-95% specificity)
maybe detectable ~10y before dev of RA
correlate w disease progression
ix for ?RA?
x-rays of hands and feet
RF (and anti-CCP if RF -ve)
what conditions is raised ESR important in?
pmr
temporal arteritis
multiple myeloma
what antibodies are a/w ra?
anti-ccp
anti-phospholipid (also + in sle, anti-phospholipid syndrome)
rf
initial mx of RA?
DMARD monotherapy (usually methotrexate) ± short-course bridging prednisolone
monitoring tx response using CRP + disease activity (composite score like DAS28)
mx of RA flares?
corticosteroids - oral, intra-articular injection, or IM
e.g. methylprednisolone acetate, triamcinolone acetonide
can use NSAIDs but only short-course - not as effective compared to steroids but useful in reducing pain and inflammation (+ PPI cover)
paracetamol for pain
what DMARDs may be used in RA mx?
methotrexate most common
sulfasalazine
leflunomide
hydroxychloroquine
when should TNF-inhibitors be started in RA mx?
if inadequate response to at least 2 DMARDs (incl methotrexate)
which TNF inhibitors are used in RA mx?
etanercept
infliximab
adalimumab
what is etanercept?
recombinant human protein
acts as decoy receptor for TNFa
sc administration
can cause demyelination, reactivation of TB
what is infliximab?
mAb
binds to TNFa, preventing binding with TNF receptors
IV administration
can cause reactivation of TB
what is adalimumab?
mAb
sc administration
what is rituximab?
anti-CD20 mAb, causing B-cell depletion
2 1g IV infusions 2 weeks apart
infusion reactions are common
what is abatacept?
fusion protein modulating key signal required for T cell activation
reduces T cell proliferation + cytokine production
given as infusion
not recommended for RA rn
how long do DMARDs take to become effective?
~2-3 months
so changing dose not useful for acute flares despite being helpful in long-term management
what should be prescribed with methotrexate?
folate to reduce risk of bone marrow suppression
methotrexate inhibits DHF which is an enzyme involved in folate metabolism; folic acid essential to DNA synthesis; so reduction can lead to myelosuppression where RBCs/WBCs/platelets are reduced in number -> can lead to severe infection/other comps
poor prognostic features of RA?
RF +
anti-CCP ab
poor functional status at presentation
hla dr4
extra-articular features e.g. nodules
insiduous onset
x-ray: early erosions e.g. after <2y
female?
joitn aspirate in RA?
high WBC (20-50k leucocytes), predominantly PMNs
appearance: yellow, cloudy, absent of crystals
variable neurophil count
negative gram stain
no crystals
joint aspirate in septic arthritis?
cloudy/obqque
>50k leucocytes per microlitre
>90% neutrophils
usually + gram stain
respiratory comps of rheumatoid arthritis?
pulmonary fibrosis
pleural effusion
pulmonary nodules
bronchiolitis obliterans
methotrexate pneumonitis
ocular comps of rheumatoid arthritis?
keratoconjunctivitis sicca
episcleritis
scleritis
corneal ulceration
keratitis
steroid-induced cataracts
chloroquine retinopathy
ortho comps of rheumatoid arthritis?
osteoporosis
atlantoaxial subluxation (can lead to cervical cord compression)
cardiac comps of rheumatoid arthritis?
ischaemic heart disease (similar risk to T2DM)
immuno comps of rheumatoid arthritis?
increased risk of infections
psychiatric comps of rheumatoid arthritis?
depression
what are less common comps of RA?
Felty’s syndrome
amyloidosis
what is the core triad in felty’s syndrome?
ra
splenomegaly (resulting in anaemia secondary to hyposplenism)
low WCC (neutropenia)
how do pt with felty’s syndrome present
recurrent, severe infections (which can lead to sepsis)
why does felty’s syndrome present with anaemia?
secondary to hyposplenism
why does felty’s syndrome present with neutropenia?
RA causes inflammatory splenomegaly
chronic activation of neutrophils leads to neutropenia
what imaging needs to be done preop for pt with RA?
ap and lateral cervical spine radiographs
to screen for atlantoaxial subluxation
ensure pt has c-spine collar during surgery + neck is not hyperextended on intubation
what score can be used to measure disease activity in rheumatoid arthritis?
disease activity score-28 (DAS-28)
includes tender joint count, swollen joint count, esr, global health
what must absolutely be monitored with methotrexate?
FBC & LFTs due to the risk of myelosuppression and liver cirrhosis
list some examples of dmards?
methotrexate
sulfasalazine
leflunomide
hydroxychloroquine
what is a/w good prognosis in ra?
rf negative
what results from bone subluxation in RA?
z-thumb appearance in hand
bone subluxation occurs due to erosion
