SINBAD Classification System for Diabetic Foot Ulcers
Primary Recommendation
Use the SINBAD system as your primary tool for documenting and communicating diabetic foot ulcer characteristics among healthcare professionals in routine clinical practice. 1
What SINBAD Stands For
The SINBAD acronym represents six independent variables that comprehensively characterize diabetic foot ulcers 2, 3:
- Site (location on the foot)
- Ischemia (presence of peripheral artery disease)
- Neuropathy (loss of protective sensation)
- Bacterial infection (presence of infection)
- Area (wound size)
- Depth (tissue layers involved)
Each parameter is scored, creating a quantitative assessment that facilitates rapid clinical decision-making 2.
When and How to Use SINBAD
For Routine Clinical Communication
Document each individual SINBAD variable separately rather than reporting only a total score when communicating with other healthcare professionals 1. This approach provides more clinically useful information than a single number and has been validated in 12 studies with substantial-to-good reliability 4.
For Clinical Audit and Population Comparisons
Use the SINBAD total score for regional, national, or international audits to enable meaningful comparisons between institutions on diabetic foot ulcer outcomes 1. The system's simplicity makes it practical for busy clinicians while maintaining adequate data capture 1.
For Prognostic Information
Higher SINBAD scores predict lower probability of being alive and ulcer-free at 12 weeks and higher risk of major amputation within 6 months 4. However, do not use SINBAD (or any currently available classification system) to offer individual outcome prognosis for a specific patient, as the evidence quality for this purpose is weak 1.
Comparison with Other Systems
SINBAD vs. University of Texas Classification
A large independent observational study of 1,645 ulcer outcomes demonstrated that SINBAD and the University of Texas system had similar prognostic ability, with c-statistics of 0.72 and 0.71 respectively 5. SINBAD is preferred for routine use because it is simpler to apply and includes more comprehensive parameters (specifically neuropathy and ulcer area, which the UT system lacks) 4, 6.
SINBAD vs. WIfI System
The WIfI (Wound, Ischemia, foot Infection) system may be considered as an alternative when specialized vascular assessment equipment and expertise are available 1. However, SINBAD remains the first-line choice for general communication because it requires less specialized resources and expertise 1, 4.
Special Clinical Scenarios
When Infection is Present
Switch to the IDSA/IWGDF infection classification system (grades 1-4) when assessing infected diabetic foot ulcers, as this system specifically guides antibiotic selection and hospitalization decisions 1, 4. The SINBAD system's binary infection variable (present/absent) lacks the granularity needed for infection management 1.
When Peripheral Artery Disease is Prominent
Consider using the WIfI system in patients with significant peripheral artery disease and foot ulcers to stratify healing likelihood and amputation risk, provided you have access to ankle-brachial index, toe-brachial index, and pedal Doppler waveform assessment 1, 7.
Critical Assessment Components
When applying SINBAD, ensure you properly evaluate each component 1:
- Ischemia: Palpate foot pulses, measure ankle-brachial index (normal 0.9-1.3), assess pedal waveforms, and consider toe-brachial index (≥0.75 excludes significant PAD) 1
- Depth: Debride neuropathic ulcers with callus and necrosis before assessment (avoid debridement in non-infected ulcers with severe ischemia) 1
- Infection: Diagnose by presence of at least two signs of inflammation (redness, warmth, induration, pain/tenderness) or purulent secretions, recognizing these may be blunted by neuropathy or ischemia 1
Common Pitfalls to Avoid
- Do not report only the total SINBAD score without describing individual variables—this loses critical clinical information 1
- Do not use SINBAD to predict individual patient outcomes—the evidence quality is insufficient for this purpose despite its utility for population-level assessment 1, 4
- Do not rely on SINBAD's binary infection classification for managing infected ulcers—use the IDSA/IWGDF system instead 1
Practical Implementation
The SINBAD system's strength lies in its balance between comprehensiveness and ease of use 1, 2. It captures the multifaceted characteristics of diabetic foot ulcers while remaining simple enough to memorize and apply consistently in busy clinical settings 1. This makes it superior to more complex systems like Wagner (which inadequately addresses infection) or overly simplified systems that miss critical variables 1, 4.