Table 4 An overview of previous studies of ΔFS

Kimura et al. (2006) [8]

82 sALS (15 possible, 32 probable, and 35 definite)

Death or tracheostomy or non-invasive ventilation

Mean ΔFS based on ALSFRS-R score on time of diagnosis.

Two groups:

ΔFS < 0.67 vs ΔFS ≥ 0.67

Three groups (arbitrary cut-off):

ΔFS < 0.5 vs 0.5 ≤ ΔFS < 1 vs ΔFS ≥ 1

Risk of death increased progressively from lowest to highest ΔFS. ΔFS is a good independent predictor of survival time.

Gordon et al. (2006) [13]

112 ALS patients (not further specified)

6-month change in ALSFRS-R.

ΔFS based on ALSFRS-R score on time of diagnosis

Two groups:

ΔFS < 0.5

vs ΔFS ≥ 0.5

ΔFS is an excellent predictor of the progression rate at time of diagnosis and for stratification in clinical trials.

Elamin et al. (2015) [9]

204 Irish patients

122 Italian patients (possible, probable or definite ALS)

Survival time from initial visit (until death or census date at least 50 months after initial visit)

ΔFS based on ALSFRS-R score on time of inclusion into study

Four groups:

ΔFS < 0.25

vs 0.25 ≤ ΔFS < 0.49

vs 0.50 ≤ ΔFS < 0.99

vs ΔFS ≥ 1.00

ΔFS for Irish cohort good as independent predictor but a poor predictor for Italian cohort

Labra et al. (2016) [12]

164 patients (suspected, probable, possible or definite)

Survival from initial visit (until death)

Three groups:

ΔFS < 0.47

vs 0.47 ≤ ΔFS < 1.11

vs ΔFS ≥ 1.11

ΔFS is a simple, robust independent prognostic biomarker usable for clinical trials.