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.
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
≈ 10
Is a difference between groups clinically meaningful? Sample-size planning.
Judging an individual patient
group-level quantity — not applied here
RCI, 95% two-sided
± 20.19
Did this patient really change, beyond measurement error?
Powering a trial
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RCI, lenient
± 16.95
Same, where improvement is the hypothesised direction (one-sided 5%).
Confirmatory single-case claims
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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 = 19.47 and r = 0.86 (z = 1.96 two-sided, 1.645 one-sided).
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, RCI, Jacobson–Truax classes, functional cutoffs, severity bands): responsiveness
analysis of repeat FEES within one admission (paired n = 511), manuscript under review —
these values are provisional 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.