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analyses before building the multivariable logistic regression
model. Univariable logistic regression models containing each
covariate were fit. Covariates of known clinical significance or
with
P
value
<
0.05 in the univariable logistic models were
selected as candidates for the multivariable model. Statistical
significance was considered
a
-level 0.05.
RESULTS
Univariable Results
Table I displays the results of demographic or pre-
operative medical variables in univariable analysis.
Briefly, gender was only significantly associated with
MPT. Age was significantly associated with overall
grade, shimmer, NHR, MPT, postoperative VMUR, and
glottal closure. Preoperative VMUR was significantly
associated with overall grade, MPT, postoperative
VMUR, and glottal closure, whereas denervation dura-
tion was significantly associated with overall grade, jit-
ter, shimmer, NHR, MPT, and postoperative VMUR.
Multivariable Logistic Regression Model Results
Based on univariable logistic regression results, sig-
nificant candidate variables were identified (
P
<
0.05) for
assessment in the multivariable logistic regression
model. Table II shows the results of multivariable logis-
tic regression. These indicate that age of patients; sever-
ity of nerve injury, which was presented as preoperative
VMUR; and denervation duration had impact on the sur-
gical effect of laryngeal reinnervation. Stratification
analysis on other significant variables such as age of
patients and preoperative VMUR will be presented in
another report (unpublished). In the present study, we
performed further stratification analysis aimed at one of
the identified significant variables—denervation dura-
tion. The results are as follows (see Table III).
Videostroboscopic Findings
On preoperative videostroboscopy, the majority of
cases in each group had severely incomplete glottal clo-
sure, which did not differ significantly among the three
groups. On videostroboscopy performed 2 years after the
reinnervation operation, most patients showed complete
glottal closure. The postoperative stroboscopic findings
were significantly improved in total sample and within
each group compared with the corresponding preopera-
tive findings (
P
<
0.01). However, denervation duration
was not a significant variable with regard to multivari-
able logistic regression analysis in glottal closure.
Vocal Function Assessment
The preoperative values of perceptual evaluation
parameter (overall grade) and acoustic parameters—jit-
ter (local), shimmer (local), and the NHR—showed no
significant differences among the three groups. Two
years after the reinnervation operation, the postopera-
tive value of overall grade was significantly improved
within each of the three groups compared with the corre-
sponding preoperative values (
P
<
0.001). Postoperative
values of jitter (local), shimmer (local), and the NHR
were significantly lower within each group compared
with the corresponding preoperative values (
P
<
0.05).
The postoperative MPT was significantly longer than the
preoperative MPT in each group (
P
<
0.05).
Denervation duration was identified as a significant
variable with regard to parameters (overall grade), jitter,
shimmer, NHR, and MPT in multivariable logistic
TABLE I.
Univariable Analysis of Influencing Factors on the Surgical Outcome of Laryngeal Reinnervation.
Overall Grade
Jitter
Shimmer
NHR
MPT
Post-VMUR
Glottal Closure
Sex
0.7131
0.1844
0.1394
0.3456
<
0.001
0.1804
0.5141
Age
<
0.001
0.3441
<
0.001
0.0010
<
0.001
<
0.001
<
0.001
Pre-VMUR
<
0.001
0.3807
0.0630
0.1554
<
0.001
<
0.001
<
0.001
Denervation duration
0.0022
<
0.001
<
0.001
<
0.001
0.0007
0.0010
0.5410
Data in Table I represent
P
value calculated by univariable analysis.
P
<
0.05 is deemed as statistically significant.
MPT
5
maximum phonation time; NHR
5
noise-to-harmonics ratio; VMUR
5
voluntary motor-unit recruitment.
TABLE II.
Multivariable Analysis of Influencing Factors on the Surgical Outcome of Laryngeal Reinnervation.
Overall Grade
Jitter
Shimmer
NHR
MPT
Post-VMUR
Glottal Closure
Sex
0.6692
0.1124
0.0133
0.2320
<
0.001
0.4301
0.7663
Age
<
0.001
0.2588
<
0.001
<
0.001
<
0.001
0.0080
0.0004
Pre-VMUR
<
0.001
0.3374
0.4935
0.0091
<
0.001
<
0.001
<
0.001
Duration of denervation
<
0.001
<
0.001
<
0.001
<
0.001
<
0.001
0.0004
0.1809
Data represent
P
value calculated by multivariable analysis.
P
<
0.05 is deemed as statistically significant.
MPT
5
maximum phonation time; NHR
5
noise-to-harmonics ratio; VMUR
5
voluntary motor-unit recruitment.
Laryngoscope 124: August 2014
Li et al.: Denervated Duration on Reinnervation for UVFP
7