12-phase flow (12)

1. 1FRAME
   Adult with suspected ANCA-associated small-vessel vasculitis. Define MPA: necrotizing pauci-immune small-vessel vasculitis WITHOUT granulomas; NO destructive ENT/granulomatous masses (key vs GPA). New-onset vs relapse vs ILD-predominant
   inputs: age
   advance: AAV scope confirmed; MPA phenotype suspected
2. 2ENTRY
   Recognize trigger — MPO-ANCA + renal involvement, pulmonary-renal syndrome, active sediment + rising Cr, constitutional + purpura + mononeuritis multiplex, or DAH/ILD on imaging
   inputs: mpo_anca
   advance: presenting syndrome captured
3. 3CONTEXT
   Capture drug-induced ANCA exposure (hydralazine, levamisole-cocaine, PTU, minocycline), prior immunosuppression, HBV/HCV/TB screen, active infection, fertility status pre-CYC, vaccination status
   inputs: drug_exposure_anca, baseline_immunosuppression_infection, age
   advance: drug-induced ANCA addressed; infection/fertility context captured
4. 4RED_FLAGS
   Diffuse alveolar hemorrhage (hypoxia + falling Hb + hemoptysis), dialysis-dependent RPGN, double-positive anti-GBM, rapidly progressive ILD with respiratory failure, mononeuritis multiplex with motor deficit → ICU + pulse methylprednisolone + organ-protective induction
   inputs: spo2, creatinine
   actions: calc.news2
   advance: organ/life-threatening features acted on
5. 5INITIAL_WORKUP
   MPO-ANCA + PR3-ANCA (ELISA), creatinine + trend, UA with micro (dysmorphic RBC / RBC casts), CBC, CMP, CRP/ESR, coagulation, CXR; urgent nephrology + biopsy planning when RPGN
   inputs: mpo_anca, pr3_anca, creatinine, urinalysis_with_micro, cbc_with_diff, crp_esr
   actions: workup.rpgn, panel.renal, panel.ua, panel.cbc, panel.inflammation, panel.cmp
   advance: ANCA serology + renal activity + baseline organ panels sent
6. 6BRANCHING_WORKUP
   Renal biopsy (pauci-immune necrotizing crescentic GN — distinguish from anti-GBM linear IgG and immune-complex GN); anti-GBM antibody (double-positive); HRCT for DAH vs fibrotic UIP-like MPA-ILD; nerve conduction / sural biopsy for mononeuritis multiplex; skin biopsy for leukocytoclastic vasculitis; bronchoscopy/BAL for serial bloody returns confirming DAH
   inputs: anti_gbm_antibody, chest_hrct
   actions: workup.acute_weakness, panel.coag, panel.cardiac
   advance: pauci-immune crescentic GN confirmed or organ-specific biopsy booked; anti-GBM excluded
7. 7DIFFERENTIAL
   Pivot MPA vs GPA (PR3/c-ANCA, granulomatous destructive ENT, more relapse) vs EGPA (asthma + eosinophilia); exclude anti-GBM disease (double-positive), immune-complex GN (IgA vasculitis, cryoglobulinemia, lupus nephritis, post-infectious), drug-induced ANCA (hydralazine, levamisole-cocaine, PTU, minocycline), infective endocarditis mimic, and idiopathic pulmonary fibrosis when ILD precedes vasculitis
   inputs: mpo_anca, pr3_anca
   advance: MPA phenotype assigned; mimics and double-positivity excluded
8. 8RISK_STRATIFICATION
   Organ/life-threatening (DAH, RPGN, dialysis-dependent AKI, severe mononeuritis multiplex) vs non-severe; BVAS disease activity, VDI damage, FFS prognosis; renal recovery potential (% normal glomeruli on biopsy) guides plasma-exchange and dialysis-dependence prognostication
   inputs: creatinine, spo2
   actions: calc.qsofa, calc.news2
   advance: severity tier set; PEXIVAS plasma-exchange eligibility decided
9. 9TREATMENT
   Induction (organ/life-threatening): glucocorticoid with reduced-dose PEXIVAS taper + rituximab OR cyclophosphamide; pulse methylprednisolone for severe/DAH; plasma exchange SELECTIVE per PEXIVAS (dialysis-dependent / severe AKI from GN, or DAH — not routine; consider for concomitant anti-GBM); avacopan steroid-sparing add-on (ADVOCATE). Supportive: PJP prophylaxis, bone protection, vaccination, fertility preservation pre-CYC. Maintenance: rituximab (preferred) or azathioprine, prolonged. Treat MPA-ILD with immunosuppression ± antifibrotic for progressive fibrosis. Manage relapse and ESKD/transplant; mitigate long-term CV/infection/malignancy risk
   inputs: creatinine, spo2, baseline_immunosuppression_infection
   advance: induction GC + RTX/CYC ± plasma exchange ± avacopan in flight; prophylaxis ordered
10. 10DISPOSITION
    DAH / respiratory failure / dialysis-dependent RPGN / double-positive → ICU; active RPGN or moderate organ involvement → inpatient with nephrology + rheumatology; non-severe limited disease → expedited outpatient induction
    inputs: spo2, creatinine
    advance: level of care set; nephrology/rheumatology/pulmonology consults secured
11. 11MONITORING
    Cr + UA for renal response; ANCA trend (rising titer + clinical features suggests relapse, not titer alone); CBC weekly during CYC (cytopenia nadir); CD19 B-cells + IgG before rituximab redosing; infection surveillance on immunosuppression; PFTs + HRCT if MPA-ILD; glucocorticoid taper adherence to PEXIVAS schedule
    inputs: creatinine, cbc_with_diff
    actions: panel.renal, panel.ua, panel.cbc
    advance: remission by 3-6 months; maintenance phase entered
12. 12FOLLOWUP
    Prolonged maintenance (rituximab or azathioprine) with relapse surveillance; ESKD pathway and kidney transplant timing (defer until sustained remission); MPA-ILD progression monitoring ± antifibrotic; long-term CV risk modification, infection prophylaxis, malignancy surveillance (CYC bladder/hematologic); vaccination (avoid live vaccines on immunosuppression); fertility/family planning
    advance: maintenance + long-term risk plan documented