Compute FDI-S (Safety), FDI-E (Efficiency), and FDI-C (Composite) from PAS and Yale Pharyngeal Residue ratings.
Enter scores only for consistencies that were tested. Switch to pre–post to read the change between two
examinations against the reliable-change and functional-cutoff criteria.
Up to two additional presentations tested at both examinations (e.g. water by teaspoon, tablet with puree). Presentations tested at FEES 2 only are added on the FEES 2 card.
A presentation trialled at the follow-up but not at baseline (newly tolerated). It has no FEES 1 rating: the direct change ignores it at baseline, the extended change enters it in the baseline at the floor.
FDI-S (Safety)
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0 = worst, 100 = no impairment
FDI-E (Efficiency)
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0 = worst, 100 = no impairment
FDI-C (Composite)
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(FDI-S + FDI-E) / 2
Orientation
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–
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FDI-C₁ (FEES 1)
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FDI-C₂ (FEES 2)
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Δ FDI-C
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FDI-C₂ − FDI-C₁
Reading the change
Enter PAS and both Yale ratings for at least one consistency at both examinations —
the change framework is defined for FDI-C.
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Threshold
Value
Question it answers
Not for
This case
MCID
≈ 8
Is a mean change, or a difference in mean change between groups, clinically meaningful? Sample-size planning.
Judging an individual patient
group-level quantity — not applied here
Clinical milestone severe baseline
≈ 13
In groups with severe dysphagia at baseline: the mean change separating patients who leave the severe grade from those who remain severe.
Judging an individual patient; non-severe baselines
group-level quantity — not applied here
RCI for improvement direct change
± 25.51
Did this patient really improve, beyond measurement error? Judged on the direct change (the two scores as reported), which testing more cannot inflate.
Powering a trial
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RCI for deterioration extended change
± 28.89
Did this patient really deteriorate? Judged on the extended change (baseline extended to newly tolerated consistencies at the floor), which a broader second examination cannot depress. If no consistency was newly introduced, the two change measures coincide and the direct threshold applies.
Powering a trial
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Functional cutoff, primary
FDI-C ≥ 75
Has the patient reached an essentially oral diet (FOIS ≥ 6)? AUC 0.85
Measuring change
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Functional cutoff, secondary
FDI-C ≥ 60
Is the patient off tube feeding (FOIS ≥ 4)? AUC 0.88
Measuring change
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Formulas: FDI-S = (1 − (mean PAS − 1) / 7) × 100 FDI-E = (1 − (mean Yalecombined − 1) / 4) × 100
where Yalecombined = mean of valleculae and pyriform sinus scores per consistency. FDI-C = (FDI-S + FDI-E) / 2 RCI = z × SDbaseline × √(1 − r) × √2
with SDbaseline = 19.04 (direct change, improvement) or 21.57 (extended change, deterioration)
and r = 0.767, the empirical reliability in anchor-stable patients, applied to both change measures (z = 1.96 two-sided, 1.645 one-sided),
giving ±25.51 / ±28.89 (lenient ±21.41 / ±24.25). The projected r = 0.86 (±19.75 / ±22.37) is an optimistic alternative. Two ways of reading a change. Direct change: FDI-C₂ − FDI-C₁, each examination scored over the consistencies actually tested.
Extended change: the baseline is extended to the consistencies first trialled at FEES 2 (newly tolerated); each such consistency
enters the baseline at the floor (PAS 8 / Yale 5). Improvement counts on the direct change,
deterioration on the extended change (or on the direct change if no consistency was newly introduced, when the two coincide);
the follow-up score is never imputed.
Means are taken over the consistencies actually tested — that is what makes the index resilient to
selective-consistency testing.
Sources. Cross-sectional constants (mortality zones, FOIS orientation, pneumonia calibration):
Werner et al., J Neurol 273:359 (2026),
N = 2,943; FOIS mapping from mean FDI-C per FOIS level (Cohort 2, n = 1,545); mortality zones from
restricted cubic spline analysis (n = 1,557, 65 events).
Change constants (MCID, clinical milestone, measurement error and RCI, direction-specific change classes, functional cutoffs, severity bands): responsiveness
analysis of repeat FEES within one admission, Aachen 2021–2025 (paired n = 533), Werner et al.,
manuscript in preparation — these values may change until publication.
Research use only. The FDI Calculator is provided for research and educational purposes.
It is not a medical device and must not be used as the sole basis for clinical decisions.
The FDI is the swallowing-physiology input to a diet decision, not the diet decision: functional status,
diagnosis and the patient's individual context carry the rest. The mortality zones are hypothesis-generating
(65 events, wide tail intervals). Pending external validation.