MSK (OA, RA, Gout) Flashcards
Pathophysiology of gout?
over-production of uric acid +/ under-excretion of uric acid -> increase uric acid -> deposit monosodium urate crystals in articular & periarticular tissues -> inflammation & pain
What kind of diet leads to gout?
Purine-rich food (guanine & adenine): red meat, seafood
What drugs lead to under-excretion of uric acid?
- diuretics (loop, thiazide)
- ethambutol
- pyrazinamide
Symptoms of gout:
- inflammation
- motion
- stiffness
- other characteristics
- onset
- symmetry
- time of occurrence
- inflammation: swelling, red, pain (very bad for hours), warmth
- motion: restricted
- stiffness: NA
- other characteristics: gout tophi
- onset: rapid
- symmetry: asymmetrical (usually MTP of big toe)
- time: night? (lower temp)
Symptoms of OA:
- inflammation
- motion
- stiffness
- other characteristics
- onset
- symmetry
- time occurrence
- pain (precipitating & relieving factors)
- inflammation: swelling, red, pain, warmth
- motion: restricted
- stiffness: morning <30min
- other characteristics: affected by weather, crepitus on movement
- onset: gradual
- symmetry: asymmetrical (weight-bearing)
- time: worse at the end of the day (rarely nocturnal)
- pain: on movement, relieved by rest
Symptoms of RA:
- inflammation
- motion
- stiffness
- other characteristics
- onset
- symmetry
- time of occurrence
- pain (precipitating & relieving factors)
- inflammation: swelling, red, pain, warmth
- motion: restricted
- stiffness: morning >30min
- other characteristics: fatigue, fever, weight loss, deformities, other systemic sx
- onset: gradual
- symmetry: symmetrical
- time: worse in morning (nocturnal pain)
- pain: on rest, relieved by movement
Is asymptomatic hyperuricaemia = gout?
No
First line for 1st attack of gout?
- colchicine
- NSAID
- corticosteroids (PO/intra-articular/IM)
First line for chronic gout (prevent next attack)?
- allopurinol
- febuxostat
- probenecid
Diff between crystals of gout and pseudo gout?
- gout: needle negative birefringent crystals
- pseudo gout: rhomboid positive birefringent crystals
How to determine gout is present?
joint aspiration (synovial fluid) -> detect presence of monosodium crystals
What is clinical remission of gout?
No flares for ≥1y & no tophi
When to treat acute flares of gout?
ASAP (within 24h)
If pt was already on ULT when the acute flare happens, does the pt continue ULT?
Yes
Colchicine MOA?
Leukocyte motility inhibitor (tubulin disruption)
DDI with colchicine?
macrolides, azoles, statin (colchicine is 3A4 substrate)
Nonpharm for gout?
- weight loss if overweight
- exercise (but rest affected joints during gout attack)
- avoid smoking
- healthy diet (low-fat dairy products, veg, water; avoid alcohol, sugary drinks, high-purine food)
Complications of gout (if left untreated)?
Tophi, kidney/bladder stones, joint damage
ULT treatment criteria?
- frequent acute gout flares (≥2/year)
- presence of tophi
- radiographic damage due to gouty arthritis
- history of urolithiasis
When to refer to specialist for gout?
- severe / refractory gout (e.g. recurrent flares despite reaching target serum urate levels with ULT)
- eGFR <30
- difficulty in achieving management goal with ULT
- serious adverse effects from ULT
Target urate levels for those with and without tophi?
Without: <6 mg/dL (360 µmol/L)
With: <5 mg/dL (300µmol/L)
Does allopurinol or febuxostat have a higher risk of causing CV death?
Febuxostat
Dose of allopurinol when initiating and titrating and max dose?
Start: 50-100mg/day (start low)
uptitrtte in 50-100mg Q4-8w (go slow)
max: 900mg/day (normal renal function)
MOA of allopurinol & febuxostat?
xanthine oxidase inhibitor -> inhibit uric acid synthesis
MOA of probenecid?
uricosuric agent -> increase uric acid excretion
SE of allopurinol & febuxostat?
SCAR (SJS, TEN, DRESS) in first 3m after therapy initiation
sx: flu-like sx (fever, body aches etc), mouth ulcers / sore throat, red / sore eyes, rash
Febuxostat dose?
start: 40mg
up to 80mg/day
CI for probenecid?
- urolithiasis
- CrCl <30 (not as effective)
Which ULT has risk of haemolytic anaemia in pts with G6PD deficiency?
Probenecid
What is the risk of using ULT esp during initial period of starting meds?
Precipitate acute flares
What can be used as prophylaxis against acute flares during initial period of ULT? (include dose & duration)
- Colchicine 0.5-0.6mg OD up to 6m
- NSAIDs / corticosteroid (if cannot use colchicine)
Colchicine SE?
- N/V/D
Risk factors for allopurinol-induced SCAR?
RASHES
- renal impairment
- agent (concomitant use of therapeutic agents e.g. diuretic)
- starting dose (high)
- HLA-B*58:01
- escalation (rapid increase in dose)
- seniority (old age)
Dose of colchicine for acute flares?
- one-off tx with 1mg or 1.2mg loading dose, then one dose of 0.5mg or 0.6mg 1h later
OR - 0.5mg or 0.6mg BD-TDS until acute flare resolves
What kind of joints does OA usually affect?
Weight-bearing joints
1st line for OA and other options for tx?
1st line: topical NSAIDs
Others: PO NSAIDs, paracetamol, tramadol, topical capsaicin, IA glucocorticoid injection, duloxetine
Nonpharm for OA?
- exercise (strengthening, aerobic, mind-body)
- weight management
- physical & occupational therapy
- surgery if all else fails
What is RA?
Autoimmune disease, attack articular cartilage & underlying bone
Examples of deformities of RA?
- swan neck
- boutonniere
Systemic sx of RA?
- fever
- fatigue
- weight loss
- extra-articular complications (affecting eye, heart, haem, lung, renal, skin, vascular)
Lab findings of RA?
- positive rheumatoid factor
- positive anti-CCP assays
- increase ESR & CRP
Diagnosis of RA?
≥4/6 of the following:
- early morning stiffness ≥1h for ≥6w
- swelling of ≥3 joints for ≥6w
- swelling of wrist / MCP/ PIP joints for ≥6w
- rheumatoid nodules
- +ve RF +/ anti-CCP tests
- radiographic changes
What is considered remission of RA?
≥6m of Boolean 2.0 criteria
- tender joint count ≤1
- swollen joint count ≤1
- CRP ≤ 1mg/dL
- patient global assessment using 10cm VAS ≤2cm
Nonpharm for RA?
- psychosocial interventions (e.g. CBT)
- rest inflamed joints
- exercise
- PT/OT
- weight management
- diet (decrease inflammation -> fish oil)
1st line for RA? Other possible options for tx?
1st line: DMARDs
Others: NSAIDs (short-term relief), corticosteroids (low-dose bridging therapy when initiating DMARDs)
How long should corticosteroids be used for RA?
taper & discontinue within 3m
Examples of csDMARDs? Which one is preferred for initial RA tx in DMARD-naive pts (depending on disease activity)?
- hydroxychloroquine
- sulfasalazine
- methotrexate
- leflunomide
Preferred:
- Low disease activity: hydroxychloroquine > sulfasalazine > MTX > leflunomide
- High disease activity: MTX
What should be given together with MTX?
Folic acid 5mg/week
Should steroids be used together with bDMARD/tsDMARD?
No
If pts with MTX are not at target, what else can be added for RA?
- bDMARD/tsDMARD
- hydroxychloroquine & sulfasalazine (triple therapy)
Rescue therapy for MTX?
- folate (high dose)
- folinic acid / folinate
Examples of bDMARD?
Anti-TNF mAbs (infliximab, adalimumab)
Examples of tsDMARD?
JAK inhibitors (-tinib)
What pre-treatment screening is required before starting bDMARD/tsDMARD?
- TB (if have, start tx after completing anti-TB tx)
- hep B & C
What vaccinations are required before starting bDMARD/tsDMARD?
- pneumococcal
- influenza
- hep B
- varicella zoster
Can use bDMARD and tsDMARD together?
No
