3. Statistical considerations
According to the penetration aspiration scale (PAS), dysphagia was
classified four degrees: no dysphagia (PAS score = 1 to 2), mild
dysphagia (PAS score = 3 to 4), moderate dysphagia (PAS score = 5 to 6),
and severe dysphagia (PAS score =7 to 8), corresponded to
minimal、low、moderate and high risks of aspiration.14We compared the hierarchical entries of MAPS (Table.1) and PAS, and also
classified MAPS to four degrees: no dysphagia (MPAS score = 1) with a
minimal risk of aspiration, mild dysphagia (MPAS score = 2) with a low
risk of aspiration, moderate dysphagia (MPAS score = 3 to 4) with a
moderate risk of aspiration, and severe dysphagia (MPAS score = 5 to 6)
with a high risk of aspiration. The highest score achieved in
solid、semisolid or liquid swallowing trials was taken as the final
score.
Dysphagia severity of modified GUSS was graded to four degrees that were
the same as GUSS. 0 to 9 points were rated as severe dysphagia with a
high risk of aspiration, 10 to 14 points as moderate dysphagia with a
moderate risk of aspiration, 15 to 19 points as mild dysphagia with a
low risk of aspiration, and 20 points as no
dysphagia.6 Reliability for modified GUSS was
calculated by Spearman’s rank correlation coefficient and Kappa
statistics and the proportion of overall agreement (P0) as a raw
agreement index. A rs or κ coefficient between 0.4 and
0.8 was rated substantial, and values > 0.8 were considered
excellent. Sensitivity and specificity, as well as positive and negative
predictive values, were determined by comparing the results of modified
GUSS with the results of VFSS. Spearman’s rank correlation coefficient
was also used to predict the correlation between results of modified
GUSS and days from oral feeding to gastric tube extubation. Test
validity of the values of rs or κ coefficient was the
same as above. Wilcoxon signed rank tests was used to distinguish the
risks of aspiration caused by solid、semisolid、and liquid food.
Statistical analyses were performed with SPSS 17.0, and descriptive
analyses were performed according to data characteristics.