HBI captures symptoms only — it does not reflect mucosal healing. Treat-to-target strategies now require endoscopic or biomarker confirmation (calprotectin, CRP) alongside clinical remission.
Section 4
Next Steps
Clinical Actions
01
HBI < 5: Maintain current therapy; annual monitoring; consider endoscopic assessment to confirm mucosal healing.
02
HBI 5–7: Optimise current drug therapy, check adherence; measure CRP, faecal calprotectin; endoscopy within 3–6 months.
03
HBI ≥ 8 (Moderate–Severe): Step-up or add biologics; check for infection (stool cultures, C. diff); GI specialist review; consider imaging for complications.
04
All patients: Nutritional review, smoking cessation counselling, vaccination update.
Section 5
Evidence Appraisal
Validation
Metric
Value
Correlation with CDAI
r = 0.93
Remission threshold
HBI < 5
Response definition
Decrease ≥ 3 points
Primary Reference
A simple index of Crohn's-disease activity
Harvey RF et al. • Lancet. 1980;1(8167): 514
Section 6
Literature
Development
Published by Robert Harvey and John Bradshaw in The Lancet in 1980 as a brief clinical letter, the HBI was proposed as a simplified alternative to the Crohn's Disease Activity Index (CDAI). The authors noted that the complex 7-day diary burden of CDAI was impractical for routine clinical use and designed the HBI as a same-day assessment using five domains that captured the core determinants of CDAI.
Correlation & Adoption
The high correlation with CDAI (r = 0.93) established credibility for the HBI as a practical surrogate. ECCO guidelines and BSG guidance have incorporated HBI as the preferred point-of-care Crohn's disease activity measure for clinical practice (as opposed to clinical trials, where CDAI or PRO-2 remain the regulatory standard). The conversion equation CDAI ≈ 68.9 + 43.9 × HBI enables retrospective comparison with trial datasets.
