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Analysis of pH data.
Acid reflux episodes were defined
as drops in pH to
<
4 for at least 5 seconds. Total acid exposure
time (%) was calculated as total time of acid reflux episodes
divided by monitoring time. Johnson/DeMeester score
20
was
obtained using six parameters: 1) total percentage time pH
<
4.0, 2) percentage time pH
<
4.0 in an upright position, 3) per-
centage time pH
<
4.0 in a recumbent position, 4) total number
acid reflux episodes, 5) total number acid reflux episodes longer
than 5 minutes, and 6) duration of longest acid reflux episode.
Analysis of MII data.
Recorded meal periods were
excluded from analysis. On impedance, gas reflux was defined
as rapid (
>
3,000
X
/s) retrograde moving increase in impedance
in at least two impedance sites. Liquid reflux was defined as
retrograde moving 40% fall in impedance in two distal imped-
ance sites. Proximal reflux was considered when refluxate
reached the 15-cm impedance sensor. Total bolus exposure time
(%) was defined as the combination of durations of gas and liq-
uid reflux events divided by total time monitored.
Interpretation of combined dual-channel MII/pH
data.
Participants were assigned to cohorts—GERD, LPR, nor-
mal—based on MII/pH data. GERD was defined by acid expo-
sure percent time of the distal pH probe
>
4.0, DeMeester score
>
14.7, and/or bolus exposure percent time of more than 1.4%.
21
LPR was defined by
>
31 proximal reflux events.
22,23
Normal
was defined by the following criteria: acid exposure percent
time of the distal pH probe
<
4.0, DeMeester score
<
14.7, and
<
31 proximal reflux events.
22
Statistical Analysis
To determine inter-rater reliability, intraclass correlation
coefficients (ICC) were calculated. Pearson correlation coeffi-
cients were used to evaluate intrarater reliability. Average
within rater agreement across all eight raters was computed
for each RFS item. RFS ratings for each videostroboscopic
examination were averaged across all ratings from eight indi-
vidual raters. Pearson correlation coefficients were used to
determine correlations between average RFS ratings and find-
ings on MII/pH and correlations between age and average RFS
ratings. General linear models, including repeated measures
analysis of variance and analysis of covariance, were fitted to
assess main effects of age, cohort, sex, and smoking status, as
well as the two-, three-, and four-way interaction effects of
age*sex, age*cohort, age*smoking status, cohort*sex, cohort*s-
moking status, sex*smoking status, age*sex*smoking status,
age*cohort*smoking status, age*sex*cohort, cohort*sex*smok-
ing status, and age*cohort*sex*smoker for all RFS ratings.
t
-
tests were used to examine differences in variables that could
not be accounted for by linear modeling. All analyses were per-
formed with SAS software (SAS Institute Inc., Cary, NC) with
type I error set at 0.05.
RESULTS
Clinical and Demographic Characteristics
Of 155 original video clips included in the montages
provided to raters, 13 were excluded from rating and
analysis due to insufficient views from anterior commis-
sure to posterior pharyngeal wall. Data from 142 partici-
pants including videolaryngostroboscopic recordings,
MII/pH variables (Table II), and averaged RFS ratings
(Table II) were therefore included in the final analysis.
Analysis of MII/pH data revealed 38 participants with
GERD (27%), 44 with LPR (31%), and 60 normal (42%).
Of 142 participants, 116 (82%) had total RFS
>
7, and 55
(39%) had total RFS
>
11. Age, sex, smoking, reflux
cohort, and total RFS characteristics of these partici-
pants are summarized in Table III. Videostroboscopic
examination and MII/pH testing were completed with an
average of 61 days between each procedure.
RFS Rater Reliability and Agreement
ICC for intrarater reliability ranged from 0.05 to
0.45 (Table IV). Results demonstrate poor to fair reliabil-
ity for all RFS rating items. Inter-rater reliability was
assessed on 256 observations from eight raters. ICC
ranged from 0.21 to 0.48 (Table IV), indicating poor to
fair inter-rater reliability for all RFS rating items. Aver-
age intrarater agreement examines overall levels of
rater self-consistency, for each rater and RFS rating.
Results are based on repeated ratings of 16 video clips,
and indicate that individual raters were 54.8% to 71.7%
reliable across all ratings, and that they produced the
same value for any individual variable 48.75% to 78.75%
of the time (Table V).
TABLE I.
Reflux Finding Score Rating Rubric Adapted From Belafsky, Postma, and Koufman.
7
Reflux Finding Score
Subglottic edema (pseudosulcus; aka “infraglottic edema”)
2
5
present, 0
5
absent
Ventricular obliteration (false vocal fold edge is indistinct;
“complete” refers to the true and false folds appearing to touch)
2
5
partial, 4
5
complete
Erythema/hyperemia (redness)
2
5
arytenoids only, 4
5
diffuse
Vocal fold edema (mild is slight swelling, moderate is
more perceptible, severe is sessile)
1
5
mild, 2
5
moderate, 3
5
severe, 4
5
polypoid
Diffuse laryngeal edema (size of airway relative to size of larynx)
1
5
mild, 2
5
moderate, 3
5
severe, 4
5
obstructing
Posterior commissure hypertrophy (pachydermia;
mild is mustache-like appearance, moderate is straight
line across back of larynx, severe is bulging into airway,
and obstructing is airway obliterated)
1
5
mild, 2
5
moderate, 3
5
severe, 4
5
obstructing
Granuloma/granulation
2
5
present, 0
5
absent
Thick endolaryngeal mucus
2
5
present, 0
5
absent
Total
5
Laryngoscope 124: October 2014
Jette et al.: Correlation of Reflux Findings With MII/pH
134