12-phase flow (12)

1. 1FRAME
   Frame as a CHRONIC outpatient engine: 12-week symptom + objective evidence (endoscopy or CT) to confirm CRS, then phenotype-by-polyp (CRSwNP vs CRSsNP), then run the EPOS 2020 / AAO-HNS 2015 stepped ladder. Recognise AERD, AFRS, secondary causes (CF/PCD/GPA/sarcoid), and the RED-FLAG mimics (orbital, intracranial, invasive fungal). Acute invasive complications, surgical FESS, and invasive fungal disease are routed OUT, not authored here.
   advance: chronic-CRS scope confirmed; orbital/intracranial/invasive-fungal mimics flagged for routing
2. 2ENTRY
   Apply the 12-week symptom-cluster gate at the door (EPOS 2020 / AAO-HNS 2015): ≥2 of nasal blockage, nasal discharge, facial pain/pressure, hyposmia/anosmia for ≥12 weeks, at least one of which must be blockage OR discharge. <12 weeks → acute or recurrent-acute pathway. SNOT-22 quantifies burden at entry.
   inputs: cardinal_symptom_count_and_duration
   advance: symptom-cluster + duration recorded; non-CRS / acute rerouted
3. 3CONTEXT
   Build the modifier set that will gate phenotyping and the biologic ladder: asthma + NSAID intolerance (AERD), atopy / allergic rhinitis, prior FESS, prior oral corticosteroid courses/year, smoking, occupational exposures, comorbid OSA. These are the EPOS 2020 / SINUS / POLYP / SYNAPSE eligibility variables.
   inputs: asthma_and_nsaid_hypersensitivity_history, allergic_rhinitis_atopy_history, prior_endoscopic_sinus_surgery_fess, prior_systemic_corticosteroid_courses_year, tobacco_smoking_exposure
   actions: panel.inflammation
   advance: AERD, atopy, prior-surgery / steroid burden, and modifiable-risk-factor profile captured
4. 4RED_FLAGS
   Recognise can't-miss complications and DO NOT manage them here: orbital extension (proptosis, ophthalmoplegia, vision change) — emergent IV abx + ENT/ophth; intracranial extension (severe headache, meningismus, focal neuro, Pott puffy tumour) — emergent neurosurg; invasive fungal sinusitis in immunocompromised (black eschar, palatal ulcer, rapid progression) — emergent debridement + amphotericin. Route to deep-neck-space / sepsis / surgical engines; do not delay on the CRS ladder.
   inputs: orbital_signs_proptosis_vision_change, intracranial_signs_severe_headache_meningismus_focal, immunocompromise_status_dm_neutropenia_transplant
   actions: workup.airway_distress, calc.qsofa, calc.news2
   advance: orbital / intracranial / invasive-fungal red flags screened and routed by engine_id if positive
5. 5INITIAL_WORKUP
   Obtain the OBJECTIVE diagnostic anchor: NASAL ENDOSCOPY with Lund-Kennedy scoring (polyps / mucopurulence / oedema). This both confirms CRS and SUBTYPES into CRSwNP vs CRSsNP — the central management pivot. Quantify burden with SNOT-22. EPOS 2020 / AAO-HNS 2015 endorse endoscopy as the office-based confirmatory step.
   inputs: snot22_patient_reported_outcome, nasal_endoscopy_lund_kennedy
   actions: panel.inflammation, panel.cbc
   advance: endoscopy completed; CRSwNP vs CRSsNP assigned; SNOT-22 baseline recorded
6. 6BRANCHING_WORKUP
   Branch on phenotype + endotype: CRSwNP → blood eosinophils + total IgE for type-2 endotype + biologic-selection cue (mepolizumab eos≥150; omalizumab IgE+weight nomogram; dupilumab broadly type-2). CRSsNP → consider mucociliary/CF/PCD/GPA when atypical (sweat chloride, nasal NO, ANCA). CT-PNS Lund-Mackay required pre-FESS and when endoscopy equivocal; AFRS = characteristic heterogeneous mucin + fungal hyphae + type-I hypersensitivity → reframe to AFRS pathway. Vasculitis (GPA — septal perforation, crusting), sarcoid, IgG4 are EPOS-2020 secondary-CRS causes — handle out.
   inputs: ct_paranasal_sinuses_lund_mackay, blood_eosinophil_count, total_serum_ige, cystic_fibrosis_or_primary_ciliary_dyskinesia
   actions: panel.cbc, panel.inflammation
   advance: phenotype (CRSwNP vs CRSsNP) confirmed; endotype (type-2 vs non-type-2) anchored; secondary-CRS causes excluded or routed
7. 7DIFFERENTIAL
   Terminal differential: PRIMARY-CRS CRSsNP (predominantly non-type-2/mixed) vs PRIMARY-CRS CRSwNP (predominantly type-2 eosinophilic) vs AERD (CRSwNP + asthma + NSAID-intolerance pivot) vs AFRS (allergic fungal — eosinophilic mucin + fungal hyphae + heterogeneous CT + type-I-hypersensitivity pivot) vs ODONTOGENIC sinusitis (unilateral maxillary + dental source pivot) vs SECONDARY-CRS (CF/PCD/GPA/sarcoid/IgG4 — systemic-feature pivot, reframe and route out) vs invasive fungal sinusitis (immunocompromised + necrosis pivot — emergency, route out). The choice of pathway flows from this branch.
   advance: single best CRS subtype assigned (CRSsNP / CRSwNP / AERD / AFRS / secondary / invasive-fungal-routed); biologic-endotype anchored
8. 8RISK_STRATIFICATION
   Stratify by EPOS 2020 uncontrolled-disease criteria: ongoing nasal blockage, nasal discharge, facial pain/pressure, hyposmia/anosmia, sleep disturbance / fatigue, asthma exacerbations, despite appropriate INCS + 1 prior surgery. Layer biologic-selection criteria: bilateral polyps + need for systemic CS ≥2/y OR significant QoL impairment OR loss of smell OR comorbid asthma. SNOT-22 and Lund-Mackay trend over time drive escalation.
   inputs: snot22_patient_reported_outcome, prior_systemic_corticosteroid_courses_year, prior_endoscopic_sinus_surgery_fess
   actions: panel.inflammation
   advance: controlled / partly-controlled / uncontrolled band assigned; biologic-candidacy explicitly evaluated for CRSwNP
9. 9TREATMENT
   Stepped EPOS 2020 / AAO-HNS 2015 ladder, phenotype-specific. ALL: high-volume saline irrigation BID + topical INCS (mometasone or fluticasone) BID — the foundation (Cochrane 2016 INCS for CRS). EXACERBATION / step-up: short-course oral corticosteroid (5-10 days). CRSwNP refractory to maximal medical: add off-label budesonide irrigation (1 mg in 240 mL saline BID) → FESS (functional endoscopic sinus surgery). UNCONTROLLED type-2 CRSwNP despite medical + 1 prior surgery, OR contraindication to surgery: BIOLOGIC LADDER — dupilumab 300 mg SC q2w (broadly type-2, dominant smell-recovery), omalizumab dose-by-IgE-and-weight (atopic / IgE-driven), mepolizumab 100 mg SC q4w (eos-high). AERD: aspirin desensitisation 650-1300 mg/day + dupilumab. AFRS: surgery + INCS + allergen immunotherapy.
   inputs: pregnancy, asthma_and_nsaid_hypersensitivity_history
   advance: phenotype-appropriate ladder step selected; biologic candidacy and choice documented; pregnancy modifier honoured
10. 10DISPOSITION
    CRS management is OUTPATIENT (rhinology + allergy/immunology co-management). Admit / route OUT for: orbital cellulitis or extension, intracranial extension, invasive fungal sinusitis, severe uncontrolled asthma flare in AERD. FESS is a scheduled outpatient procedure — not authored here. Biologic initiation requires payer authorisation + first-dose observation per label.
    inputs: orbital_signs_proptosis_vision_change, intracranial_signs_severe_headache_meningismus_focal
    advance: outpatient longitudinal plan documented; emergency complications routed OUT; biologic initiation logistics confirmed if applicable
11. 11MONITORING
    Track at every 3-6-month review: SNOT-22 trend, Lund-Kennedy endoscopy score, smell (UPSIT/Sniffin-Sticks), oral-corticosteroid usage in past year (key uncontrolled-disease metric), asthma control if comorbid (ACT, exacerbations). On biologics: response at 6 months by SNOT-22 + NPS + smell + asthma control + oral-CS use — non-responders (no improvement in ≥3 domains) should be reassessed for endotype / switch / continued surgery. Long-term INCS systemic absorption is minimal but monitor IOP and cataract risk in long-term high-dose users.
    inputs: snot22_patient_reported_outcome, prior_systemic_corticosteroid_courses_year
    actions: panel.inflammation
    advance: structured SNOT-22 + endoscopy + smell + oral-CS-usage review completed at each interval; biologic response assessed at 6 mo
12. 12FOLLOWUP
    Longitudinal chronic-disease arc: every 3-6 months stable, 4-6 weeks after biologic start / surgery, urgent if uncontrolled flare. Allergy testing + immunotherapy decision for atopic / AFRS. Asthma co-management (CRSwNP and asthma are united-airways; treat in parallel). Smoking cessation. Patient education on irrigation technique + INCS technique (head-tilt, contralateral hand) — adherence is the dominant determinant of medical-ladder success. Pregnancy planning conversation (biologic timing).
    inputs: tobacco_smoking_exposure
    advance: structured longitudinal plan + allergy / asthma co-management + adherence-coaching documented