12-phase flow (12)

1. 1FRAME
   Confirmed/suspected idiopathic inflammatory myopathy in an adult. Pure rhabdomyolysis routes elsewhere; isolated CK without weakness/skin is screened for mimics first
   inputs: weakness_distribution
   advance: IIM scope confirmed; not a pure metabolic/toxic rhabdomyolysis presentation
2. 2ENTRY
   Recognise subacute symmetric proximal weakness + elevated muscle enzymes, OR DM skin signs, OR myositis-antibody positivity, OR ILD/dysphagia + weakness
   inputs: weakness_distribution, skin_findings
   advance: IIM trigger captured (weakness pattern / enzymes / skin / antibody / ILD)
3. 3CONTEXT
   Age, statin/drug exposure (anti-HMGCR IMNM), prior cancer, smoking, exertional pattern (metabolic mimic), family history (dystrophy), thyroid status, immunosuppression already on board
   inputs: age, statin_or_drug_exposure
   advance: mimic context + drug history + cancer history captured
4. 4RED_FLAGS
   Rapidly progressive ILD / hypoxemia (esp anti-MDA5, antisynthetase), respiratory-muscle weakness (declining FVC, paradoxical breathing), severe dysphagia/aspiration, myocarditis/arrhythmia — escalate to ICU + pulse methylprednisolone
   inputs: dysphagia_aspiration, ecg_echo_troponin
   actions: workup.acute_weakness, calc.qsofa
   advance: respiratory + cardiac + airway red flags screened and acted on
5. 5INITIAL_WORKUP
   CK, aldolase, AST/ALT/LDH, CBC, CMP, TSH, myositis-specific/associated antibody panel (ANA, anti-Jo1/PL7/PL12, anti-MDA5, anti-SRP, anti-HMGCR, anti-Mi2, anti-TIF1γ, anti-NXP2, anti-Ro52), ESR/CRP; baseline troponin + ECG
   inputs: creatine_kinase, ast_alt_ldh, myositis_antibody_panel, aldolase
   actions: workup.acute_weakness, panel.inflammation, panel.cbc, panel.cmp, panel.metabolic, panel.cardiac
   advance: enzyme panel + MSA/MAA panel + cardiac baseline sent
6. 6BRANCHING_WORKUP
   EMG (irritable myopathy), MRI muscle (edema → biopsy target), muscle biopsy (perifascicular atrophy DM / endomysial CD8 PM / necrosis IMNM / rimmed vacuoles IBM), HRCT chest + PFTs (FVC/DLCO) for ILD, swallow evaluation, echo, age-appropriate + antibody-targeted cancer screen (CT chest/abd/pelvis ± mammography/pelvic US/colonoscopy/PSA)
   inputs: hrct_chest, pft_fvc_dlco, cancer_screen_status
   actions: workup.acute_weakness, workup.polyarthritis
   advance: EMG/MRI/biopsy + ILD workup + swallow + cancer screen booked or resulted
7. 7DIFFERENTIAL
   Assign subtype (DM incl. amyopathic/anti-MDA5; PM by exclusion; IMNM anti-SRP/HMGCR; antisynthetase anti-Jo1/PL7/PL12; IBM). Exclude mimics: statin/drug/toxic myopathy, hypothyroid myopathy, metabolic/mitochondrial myopathy, muscular dystrophy, motor neuron disease, myasthenia gravis, rhabdomyolysis, overlap/MCTD
   inputs: skin_findings, myositis_antibody_panel
   advance: IIM subtype assigned and non-inflammatory mimics excluded or co-managed
8. 8RISK_STRATIFICATION
   Severity by organ threat: rapidly progressive anti-MDA5 ILD / hypoxemic respiratory failure (life-threatening), respiratory-muscle weakness / declining FVC, severe dysphagia/aspiration, myocarditis/arrhythmia, paraneoplastic malignancy. IBM flagged as immunotherapy-refractory
   inputs: pft_fvc_dlco, dysphagia_aspiration
   actions: calc.qsofa, calc.news2
   advance: severity tier set; ICU vs ward vs outpatient disposition decided
9. 9TREATMENT
   High-dose glucocorticoid backbone (prednisone 1 mg/kg/d; pulse methylprednisolone 0.5–1 g IV × 3 for severe/ILD/dysphagia/myocarditis) + EARLY steroid-sparing agent (methotrexate or azathioprine; mycophenolate preferred when ILD). IVIG strong in DM (ProDERM), dysphagia, refractory, pregnancy. Rituximab for refractory, antisynthetase, anti-SRP. Rapidly progressive anti-MDA5 ILD → aggressive early triple therapy (high-dose GC + calcineurin inhibitor + cyclophosphamide or rituximab ± JAK inhibitor) + ICU/lung-transplant pathway. IBM → no effective immunotherapy: supportive + exercise. Supportive: PJP prophylaxis, bone protection, swallow/aspiration precautions, PT, vaccination. Cancer-directed therapy if paraneoplastic
   inputs: myositis_antibody_panel, pft_fvc_dlco, creatine_kinase
   advance: GC backbone + steroid-sparer (± IVIG/rituximab/triple therapy) + supportive bundle documented; IBM diverted to supportive
10. 10DISPOSITION
    Rapidly progressive ILD / hypoxemia / respiratory-muscle failure / severe aspiration / myocarditis → ICU. Moderate (new ILD, dysphagia, severe weakness) → admit. Mild without organ threat → expedited rheumatology outpatient. Paraneoplastic → oncology co-management
    advance: level of care + subspecialty consults (rheum, pulm, neuromuscular, ± onc) set
11. 11MONITORING
    CK + manual muscle testing (MMT-8) trend, serial PFTs (FVC/DLCO) + HRCT for ILD, repeat swallow eval, ECG/troponin if cardiac involvement, infection surveillance on immunosuppression, anti-MDA5 ferritin/CRP trend, ongoing cancer surveillance (esp DM anti-TIF1γ/NXP2, first 3 years)
    inputs: creatine_kinase, pft_fvc_dlco
    actions: panel.cmp, panel.cbc, panel.cardiac
    advance: objective strength + enzyme + pulmonary response demonstrated; relapse surveillance plan set
12. 12FOLLOWUP
    Lifelong rheumatology/neuromuscular continuity; steroid minimisation + bone/PJP protection; pulmonary follow-up for ILD; cancer surveillance schedule; PT/OT + speech therapy; vaccination (non-live on immunosuppression); pregnancy planning on compatible agents; IBM disability/assistive-device planning
    advance: long-term immunosuppression, surveillance, and rehabilitation plan documented