Arthritis, autoimmune disease and geriatric care

Inflammatory Arthropathies & Crystal Diseases

Accurate differentiation between inflammatory synovitis, crystal-induced arthritis, and septic arthritis is essential to prevent permanent joint destruction.

Joint Fluid Aspiration Characteristics

• Normal: Macroscopic Appearance: Clear, straw, viscous; Leucocyte Count ($\text{cells/}\mu\text{L}$): $< 200$; Neutrophils: $< 25\%$; Polarized Light Microscopy: No crystals
• Osteoarthritis (Non-inflammatory): Macroscopic Appearance: Clear, yellow, viscous; Leucocyte Count ($\text{cells/}\mu\text{L}$): $200 - 2,000$; Neutrophils: $< 25\%$; Polarized Light Microscopy: No crystals
• Rheumatoid / Inflammatory Arthritis: Macroscopic Appearance: Translucent/turbid, yellow; Leucocyte Count ($\text{cells/}\mu\text{L}$): $2,000 - 50,000$; Neutrophils: $50 - 75\%$; Polarized Light Microscopy: No crystals
• Gout: Macroscopic Appearance: Turbid, milky; Leucocyte Count ($\text{cells/}\mu\text{L}$): $10,000 - 50,000+$; Neutrophils: $> 75\%$; Polarized Light Microscopy: Needle-shaped, strongly negatively birefringent crystals (bright yellow parallel to axis)
• Pseudogout (CPPD): Macroscopic Appearance: Turbid, cloudy; Leucocyte Count ($\text{cells/}\mu\text{L}$): $10,000 - 50,000+$; Neutrophils: $> 75\%$; Polarized Light Microscopy: Rhomboid-shaped, weakly positively birefringent crystals (bright blue parallel to axis)
• Septic Arthritis: Macroscopic Appearance: Opaque, purulent, thick; Leucocyte Count ($\text{cells/}\mu\text{L}$): $> 50,000$ (often $> 100,000$); Neutrophils: $> 90\%$; Polarized Light Microscopy: Gram stain/culture may identify infection; negative results do not exclude it, and crystals may coexist

Clinical Profiles of Arthropathies

1. Rheumatoid Arthritis (RA):

   • Chronic, systemic autoimmune polyarthritis with predilection for small joints of the hands and feet: metacarpophalangeal (MCP), proximal interphalangeal (PIP), and metatarsophalangeal (MTP) joints, alongside wrists. Distal interphalangeal (DIP) joints and the thoracolumbar spine are characteristically spared.
   • Symptoms: Symmetrical joint pain, swelling, and early morning stiffness $> 60\text{ minutes}$ that improves with physical activity.
   • Serology: Anti-cyclic citrullinated peptide (anti-CCP) antibodies are highly specific ($> 95-98\%$) and predict aggressive erosive disease. Rheumatoid Factor (RF) is sensitive ($70-80\%$) but less specific.
   • Pharmacotherapy: Early introduction of disease-modifying antirheumatic drugs (DMARDs) is mandatory to prevent irreversible erosive joint destruction:
     • First-Line csDMARD: Methotrexate ($10 - 25\text{ mg}$ once weekly) co-prescribed with folic acid ($5\text{ mg}$ once weekly on a different day to reduce GI toxicity, stomatitis, and hepatic transaminitis). Baseline tests: full blood count, liver function tests, renal function, and chest X-ray. Regular FBC and LFT monitoring every 4-8 weeks is mandatory.
     • Biologic DMARDs: TNF-alpha inhibitors (adalimumab, infliximab, etanercept). Pre-treatment screening for latent tuberculosis (QuantiFERON-TB Gold or Mantoux test), Hepatitis B, and Hepatitis C is mandatory prior to commencement to prevent fatal reactivation.

2. Gout:

   • Deposition of monosodium urate (MSU) crystals in joints following chronic hyperuricaemia. Characterized by sudden, excruciating monoarthritis, classically affecting the first metatarsophalangeal joint (podagra) in $> 50\%$.
   • Acute Treatment: High-dose NSAIDs (naproxen, indomethacin), low-dose oral colchicine ($1\text{ mg}$ stat, followed by $0.5\text{ mg}$ 1 hour later, then $0.5\text{ mg}$ bd; avoid old toxic regimens), or intra-articular/systemic corticosteroids.
   • Long-Term Urate-Lowering Therapy (ULT): Indicated for recurrent attacks ($\ge 2/\text{year}$), presence of tophi, radiological erosions, or renal calculi. First-line is allopurinol (xanthine oxidase inhibitor), started at $100\text{ mg}$ daily and titrated to target serum urate $< 0.36\text{ mmol/L}$ ($< 0.30\text{ mmol/L}$ if tophi present). Mandatory rule: Co-prescribe prophylactic colchicine ($0.5\text{ mg}$ daily) or an NSAID for the first 3 to 6 months of allopurinol initiation to prevent acute mobilization flares.

3. Pseudogout (Calcium Pyrophosphate Dihydrate [CPPD]):

   • Rhomboid, positively birefringent crystals in synovial fluid; predilection for large joints (knees, wrists). Plain radiographs demonstrate chondrocalcinosis (calcification of the articular cartilage or menisci). Associated with haemochromatosis, primary hyperparathyroidism, and hypomagnesaemia.

4. Septic Arthritis:

   • Medical and surgical emergency. Presents with an acutely warm, erythematous, swollen, exquisitely tender joint with severe restriction of both active and passive range of motion, accompanied by fever and systemic toxicity. Most commonly Staphylococcus aureus (including MRSA) or Neisseria gonorrhoeae in young adults.
   • Suspected septic arthritis: Aspirate and culture urgently, but do not delay antibiotics/resuscitation in sepsis or shock. A negative Gram stain, cell count below 50,000 or crystals cannot safely exclude infection. Obtain orthopaedic input and select antibiotics for the patient and local microbiology.

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Systemic Autoimmune Conditions: SLE & Giant Cell Arteritis

Systemic Lupus Erythematosus (SLE)

• Multisystem autoimmune disease driven by immune complex deposition affecting women of childbearing age ($9:1$ female-to-male ratio).
• Manifestations: Malar 'butterfly' rash (sparing nasolabial folds), discoid lupus, photosensitivity, non-scarring alopecia, painless oral ulcers, non-erosive polyarthritis, serositis (pleurisy, pericarditis), lupus nephritis, and haematological cytopenias.
• Serological Markers:
  • Anti-Nuclear Antibody (ANA): Sensitive ($> 95\%$); ideal initial screening test; negative ANA virtually excludes active SLE.
  • Anti-double-stranded DNA (anti-dsDNA): Highly specific ($> 95\%$); titres correlate with disease flares and active lupus nephritis.
  • Anti-Smith (anti-Sm): Highly specific for SLE.
  • Anti-Ro (SSA) and Anti-La (SSB): Associated with photosensitivity, secondary Sjögren syndrome, and neonatal lupus (causing congenital complete heart block in the infant).
  • Serum Complement (C3, C4): Depressed during active immune-complex consumption flares.
• SLE treatment: Hydroxychloroquine is recommended for most patients unless contraindicated, with dose/risk-aware retinal surveillance. Higher-risk patients need earlier monitoring. Nephritis and other organ disease require rheumatology/nephrology assessment and phenotype-specific immunosuppression.

Giant Cell Arteritis (GCA / Temporal Arteritis)

• Granulomatous large-vessel vasculitis affecting individuals $> 50\text{ years}$ of age, strongly associated with Polymyalgia Rheumatica (PMR) (bilateral aching and morning stiffness in the shoulder and pelvic girdles).
• Clinical Presentation:
  • New-onset localized headache (predominantly temporal)
  • Scalp tenderness (pain when combing hair or resting head on a pillow)
  • Jaw claudication (fatigue and cramping pain in masseter muscles while chewing food, highest specificity for GCA)
  • Visual symptoms: Amaurosis fugax, diplopia, or sudden painless unilateral visual loss caused by anterior ischaemic optic neuropathy (AION) due to posterior ciliary artery occlusion.
• GCA investigations: ESR and CRP are often raised, but normal results do not exclude disease. Urgent ultrasound in an experienced service and/or biopsy support diagnosis; visual threat warrants immediate glucocorticoids and specialist care without awaiting tests.
• Definitive Diagnosis: Temporal artery biopsy demonstrating transmural granulomatous inflammation with multinucleated giant cells and disruption of the internal elastic lamina. Because inflammation is segmental ('skip lesions'), a biopsy length of $\ge 1.5 - 2.0\text{ cm}$ is required. Temporal artery duplex ultrasound showing a non-compressible hypoechoic wall oedema ('halo sign') is an excellent non-invasive adjunct.
• Critical Emergency Rule: If Giant Cell Arteritis is suspected, commence immediate high-dose systemic corticosteroids (oral prednisolone 1 mg/kg/day, typically 50-60 mg daily, or intravenous methylprednisolone 500-1000 mg daily for 3 days if visual symptoms are present) prior to performing a temporal artery biopsy. Biopsy remains diagnostic for up to 1-2 weeks following steroid initiation, and delayed treatment risks permanent, irreversible bilateral blindness.

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Comprehensive Geriatric Assessment (CGA)

The Comprehensive Geriatric Assessment is a multidisciplinary diagnostic process evaluating medical, psychological, and functional capabilities of frail older adults to coordinate integrated treatment plans.

1. Delirium: Identification and Management

Delirium is an acute, fluctuating neurocognitive syndrome characterized by disturbances in attention, awareness, and baseline cognition. It is categorized into hyperactive, hypoactive (most common, characterized by lethargy, reduced motor activity, and withdrawal; associated with worse prognosis), and mixed subtypes.

• Delirium screening: 4AT at least 4 suggests delirium and requires clinical assessment for acute change and causes. CAM assesses acute/fluctuating course, inattention and either disorganised thinking or altered consciousness. Neither replaces a search for reversible illness.
  1. Acute onset and fluctuating course, AND
  2. Inattention, AND EITHER
  3. Disorganized thinking, OR
  4. Altered level of consciousness.
• Precipitating Factors: The 'PINCH ME' Mnemonic:
  • P — Pain (inadequately controlled)
  • I — Infection (urinary tract infection, pneumonia, cellulitis)
  • N — Nutrition / Starvation
  • C — Constipation / Urinary retention
  • H — Hydration (dehydration) / Hypoxia
  • M — Medication (anticholinergics, benzodiazepines, opioids, polypharmacy) / Metabolic (electrolyte derangements)
  • E — Environment (room changes, sensory deprivation, sleep cycle disruption)
• Delirium Management: First-line therapy is non-pharmacological and environmental: frequent verbal reorientation, presence of family members, ensuring sensory aids (glasses and hearing aids) are in place, single quiet room with natural daylight, visible clock/calendar, early mobilization, and avoiding physical restraints. Pharmacotherapy (low-dose oral haloperidol $0.25 - 0.5\text{ mg}$ or risperidone $0.25 - 0.5\text{ mg}$) is reserved strictly for severe distress or intractable agitation where the patient poses immediate danger to themselves or others, using the lowest effective dose for $< 48-72\text{ hours}$.

2. Falls Risk Assessment & Deprescribing

• Falls Assessment: Multidisciplinary assessment includes history of falls, mobility testing using the Timed Up and Go (TUG) test (time $> 12\text{ seconds}$ indicates heightened fall risk), environmental hazard inspection, vision screening, and targeted physical therapy.
• Deprescribing & Beers Criteria: Reviewing and ceasing potentially inappropriate medications in older adults:
  • Anticholinergics and sedating antihistamines (urinary retention, delirium, cognitive decline)
  • Benzodiazepines and Z-drugs (falls, hip fractures, motor vehicle accidents)
  • Tertiary tricyclic antidepressants (postural hypotension, cardiac conduction delay)
  • Non-steroidal anti-inflammatory drugs (gastric ulceration, worsening renal function, heart failure decompensation)
  • Antihypertensives in patients with severe orthostatic hypotension (fall risk)
• Frailty Syndrome: Characterized by diminished physiological reserve across multiple organ systems. Assessed using the Fried Frailty Phenotype (unintentional weight loss $> 4.5\text{ kg}$ in 1 year, exhaustion, weak grip strength, slow walking speed, low physical activity; $\ge 3$ criteria confirms frailty).

Primary references (checked 7 October 2026): RACGP thrombocytopenia assessment.