Sunnybrook Facial Grading System: Intra-rater and Inter-rater Variabilities

Evaluate intra-rater and inter-rater variabilities of the Sunnybrook Facial Grading System (SFGS) and explore potential factors of variability.

Prospective test of hypothesis.

University tertiary referral center.

Facial video recordings of 20 patients with variable degrees of peripheral facial palsy (PFP) were anonymized then presented to 31 independents raters in 2 trials. The raters were senior and junior professionals involved in the management of PFP: ENT specialists, physiotherapists, and speech therapists. The SFGS was used for grading paralysis.

Intra-rater and inter-rater variabilities were estimated by intraclass correlation coefficient (ICC [95% confidence interval]) for the composite score and the three subscores of the SFGS. Factors of variability studied were: rater professions and rater experience (senior vs junior).

For the total population, the intra-rater ICC was 0.915[0.900-0.929] for the composite score considered to represent almost perfect repeatability. Repeatability was important for symmetry at rest (0.694[0.646-0.737]), almost perfect for voluntary movements (0.903[0.886-0.918]), and important to almost perfect for synkinesis (0.810[0.778-0.838]). The inter-rater ICC for the composite score was 0.847[0.755-0.923] indicating important to almost perfect agreement between all raters. Agreement between raters was important to almost perfect for voluntary movements (0.839[0.746-0.919]), but moderate to important for symmetry at rest (0.553[0.408-0.730]) and weak to important for synkinesis (0.476[0.333-0.666]). Some variability was found between raters groups; however, repeatability and agreement were good for all raters.

The SFGS is a reproducible scale. It can be used with good reproducibility by both novices and experts, and by all professionals involved in the management of PFP.