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\begin{document}

\title{The Facial Clinimetric Evaluation scale underestimates social well-being
and synkinesis in overall facial palsy-specific quality of life: A
cross-sectional study in 80 patients}



\author[1]{Seung-Jae Yoon}%
\author[2]{Tessa Bruins}%
\author[3]{Paul Werker}%
\author[2]{Martinus van Veen}%
\affil[1]{University Medical Centre Groningen}%
\affil[2]{University Medical Center Groningen}%
\affil[3]{University of Groningen, University Medical Center Groningen}%


\vspace{-1em}



  
  \date{May 21, 2024}


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\selectlanguage{english}
\begin{abstract}
Key Points: * The Facial Clinimetric Evaluation (FaCE) scale, consisting
of six subscales, measures facial palsy-specific quality of life. * Each
subscale's weight in the total FaCE score is based on the number of
questions but may not reflect the subscale's true contributions to
`overall' facial-palsy specific quality of life. * In 80 patients, we
analyzed the subscales' correlations with a validated Visual Analogue
Scale (VAS) score that quantifies overall facial palsy-related burden. *
Social function and facial comfort had stronger correlations with
overall facial palsy-related quality of life than their weights in the
FaCE total score suggests. * Greater importance should be placed on
social function and facial comfort when estimating the quality of life
of patients with facial palsy.%
\end{abstract}%



\sloppy


\textbf{Key Points} :

\begin{itemize}
\tightlist
\item
  The Facial Clinimetric Evaluation (FaCE) scale, consisting of six
  subscales, measures facial palsy-specific quality of life.
\item
  Each subscale's weight in the total FaCE score is based on the number
  of questions but may not reflect the subscale's true contributions to
  `overall' facial-palsy specific quality of life.
\item
  In 80 patients, we analyzed the subscales' correlations with a
  validated Visual Analogue Scale (VAS) score that quantifies overall
  facial palsy-related burden.
\item
  Social function and facial comfort had stronger correlations with
  overall facial palsy-related quality of life than their weights in the
  FaCE total score suggests.
\item
  Greater importance should be placed on social function and facial
  comfort when estimating the quality of life of patients with facial
  palsy.
\end{itemize}

\textbf{Key words:}

Facial palsy; Facial Clinimetric Evaluation scale; Quality of life;
Social function; Facial comfort; Synkinesis

\textbf{INTRODUCTION}

Patient-reported outcome measures (PROM) are essential for the
evaluation of facial palsy. The most commonly used PROM for facial palsy
is the Facial Clinimetric Evaluation (FaCE) scale, which consists of 15
questions with a 5-point Likert scale.\textsuperscript{1,2} It consists
of six subscales -- facial movement, facial comfort, oral function, eye
comfort, lacrimal control, and social function -- which sum up to a
total score representing `overall' facial palsy-related quality of life.
The current importance of each subscale in calculating the total score
is determined by the number of questions composing each subscale. It has
not been analyzed whether FaCE subscales' weight in the total score
reflects subscales' importance to overall facial palsy-specific quality
of life. In this study, we aim to calculate the contribution of the FaCE
subscales to overall quality of life.

\textbf{METHODS}

Institutional review board approval was acquired before the start of
this study. Facial palsy patients older than 18 years and fluent in
Dutch visiting the outpatient clinic of a tertiary plastic surgery
center were invited for participation between June and August 2020.

Patients were asked to complete the validated Dutch FaCE questionnaire
and to score overall facial palsy-related burden on a Visual Analogue
Scale (VAS). As the FaCE scale addresses impairments experienced in the
past week, the VAS was also used to score the burden experienced during
the previous week.

The reliability and validity of the VAS were tested in a separate group
of patients visiting the same outpatient clinic. On two occasions (T1
and T2), 1 week apart, patients were asked to complete both the FaCE
scale and the VAS.

\emph{Statistical Analysis}

Descriptive statistics are presented using numbers and percentages, mean
and standard deviation (SD) or median and interquartile range (IQR) when
appropriate. Patients with missing or incomplete responses were excluded
from all analyses.

The test-retest reliability of the VAS was analyzed with the intraclass
correlation coefficient (ICC, two-way random effects model, absolute
agreement, single measures). As a measure of validity, the VAS score was
correlated to the FaCE total score.

Two multiple linear regression models were examined. First, the FaCE
subscale scores were correlated with total FaCE score. The regression
coefficient of each subscale represents the size of the subscale's
correlation with the total FaCE score, which should exactly reflect the
number of questions contained in each subscale.

Second, a linear regression analysis between the FaCE subscales and a
transformed VAS score was performed. The original VAS scores were
inverted so that a higher score indicated better quality of life, as
seen with FaCE scale scores. The sizes of the regression coefficients
were examined and compared with those from the first regression
analysis.

The presence of multicollinearity in the second analysis was checked for
by looking at the correlation, tolerance, and variation inflation factor
(VIF) between each variable. A tolerance larger than 0.2 and a VIF less
than 10 was considered to indicate the absence of multicollinearity.

All analyses were performed in the Statistical Package for the Social
Sciences (SPSS) version 26 (IBM Corporation, NY, USA).

\textbf{RESULTS}

In the VAS validation group, 21 individuals responded, of whom 3 were
excluded for not submitting a second VAS score. A slight majority of the
18 participants was female (n = 10 {[}56\%{]}) and median (IQR) age was
71 (55; 76) years. The most common etiology of facial palsy was parotid
gland tumor (n = 8 {[}28\%{]}), followed by acoustic neuroma (n = 2
{[}11\%{]}). Median time since diagnosis of facial palsy (IQR) was 1.8
(0.8; 8.7) years. A median time of 7 days elapsed between the responses.
Median (IQR) VAS score was 60 (23; 74) at T1 and 61 (17; 73) at T2.
There was a moderate, positive correlation between the VAS score and
FaCE total score that was statistically significant (r\textsubscript{s}=
0.561, p \textless{} 0.001), indicating acceptable validity. Test-retest
reliability was high, with an intraclass correlation coefficient of 0.91
(95\% CI = 0.78-0.97).

A total of 80 participants were included in the linear regression
analysis; of the 130 eligible patients, 14 were not interested in
participating, 28 did not respond to the invitation for the following
measurement, and eight respondents submitted incomplete responses.
Forty-one participants were male (51\%), and median (IQR) age was 63
(51; 73) years (Table 1). Median (IQR) duration of facial palsy was 17.1
(9.6; 33.1) years, and the most common etiology was acoustic neuroma (n
= 22 {[}27\%{]}). Median (IQR) FaCE total and VAS scores were 51.7
(38.3; 62.9) and 70 (52; 93), respectively.

The multivariate linear regression analysis of the FaCE subscale scores
on the FaCE total score resulted in regression coefficients that were
exactly proportional to the number of questions contained in the
subscales (Table 2). In the second regression analysis, social function
and facial comfort contributed significantly to the VAS score (Table 3).
Social function showed a higher regression coefficient than in the first
regression analysis (\selectlanguage{greek}β \selectlanguage{english}= 0.456; +0.189 compared to the original
coefficient), as did facial comfort (\selectlanguage{greek}β \selectlanguage{english}= 0.334; +0.134 compared to
original coefficient). All other subscales were non-significant
contributors to the VAS score. The explained variance in the model was
50.4\% (R\textsuperscript{2} = 0.504). The mean (range) values for
tolerance and VIF were 0.85 (0.756-0.912) and 1.18 (1.096-1.323)
respectively, indicating no multicollinearity.

\textbf{DISCUSSION}

\emph{Key findings}

The current study aimed to determine the true contribution of FaCE
subscales to overall facial palsy-specific quality of life. According to
our findings, social well-being and synkinesis are the most relevant
components of `overall' facial palsy-related quality of life. Both
constructs are currently underestimated in the calculation of the FaCE
total score.

Our analysis shows that the social burden patients experience is the
most important component of `overall' quality of life and is
underestimated in the FaCE total score. Our results suggest that almost
half of `overall' facial palsy-related quality of life is socially
related. With this, our findings more closely reflect a different facial
palsy PROM: the Facial Disability Index (FDI), which consists of 10
questions evenly split between the physical and social domain.

Synkinesis, which is described in the facial comfort subscale, was found
to be the second most important component of `overall' facial
palsy-related quality of life, and the only other statistically
significantly contributing subscale. In a previous study, synkinesis was
found to contribute significantly to the prediction of quality of
life.\textsuperscript{3} A high degree of synkinesis was also found to
be associated with ``non-effective'' self-reported emotional
expression.\textsuperscript{4} Synkinesis may thus reduce quality of
life by both causing physical discomfort and impairing social function,
and it should form a larger component of facial palsy-specific quality
of life assessment.

Surprisingly, eye comfort and lacrimal control were insignificant
predictors of overall quality of life. This is in line with previous
research suggesting that periocular muscle function is of low importance
in estimating quality of life.\textsuperscript{5} However, this is not
in line with our clinical expertise or the findings of other researchers
that the treatment of periocular complaints leads to a significant
improvement in total FaCE score.\textsuperscript{6} A possible
explanation for this could be that most patients in our sample already
received periocular treatment, and therefore no longer experience
periocular problems. This is especially plausible in our sample of
chronic facial palsy patients but requires further investigation.

\emph{Limitations}

There were various limitations to the current study. First, the sample
was selected from a tertiary care setting and had a long median duration
of facial palsy. The character of complaints experienced by patients has
been reported to evolve over time.\textsuperscript{7} This might mean
that the relative importance of each FaCE subscale in acute facial palsy
may be different from our findings. Second, the tertiary care setting
meant that acoustic neuroma was the most common etiology, instead of
Bell's palsy as is seen in the general facial palsy population. Third,
patients at our clinic are generally suffering from severe facial palsy
requiring surgery. Mild cases only involving regional paralysis or
synkinesis are infrequently seen. Lastly, the sample size to evaluate
validity and reliability of the VAS was relatively small.

\emph{Implications}

Our study suggests that the current weight of the FaCE subscales in
calculating the FaCE total score, does not actually reflect the true
weight of each component in calculating `overall' facial palsy-related
quality of life. Our findings can be used when developing a revised
version of the FaCE scale or a novel facial palsy-specific PROM.

\textbf{CONCLUSION}

Social function is more important in estimating overall facial
palsy-specific quality of life than indicated by its weight in the FaCE
total score. Additionally, more questions regarding synkinesis are
indicated and should be included in, perhaps, a novel questionnaire.

\textbf{Word count: 1424}

\textbf{REFERENCES}

\begin{enumerate}
\tightlist
\item
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  10.1097/00005537-200103000-00005. PMID: 11224766.
\item
  Fattah AY, Gavilan J, Hadlock TA, Marcus JR, Marres H, Nduka C,
  Slattery WH, Snyder-Warwick AK. Survey of methods of facial palsy
  documentation in use by members of the Sir Charles Bell Society.
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\item
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  Werker PMN, Dijkstra PU, Hadlock TA. Patient-perceived severity of
  synkinesis reduces quality of life in facial palsy: A cross-sectional
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  doi: 10.1111/coa.13322. Epub 2019 Mar 25. PMID: 30828959.
\item
  Coulson SE, O'dwyer NJ, Adams RD, Croxson GR. Expression of emotion
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\item
  van Veen MM, Tavares-Brito J, van Veen BM, Dusseldorp JR, Werker PMN,
  Dijkstra PU, Hadlock TA. Association of Regional Facial Dysfunction
  With Facial Palsy-Related Quality of Life. JAMA Facial Plast Surg.
  2019 Jan 1;21(1):32-37. doi: 10.1001/jamafacial.2018.0804. PMID:
  30073264; PMCID: PMC6440235.
\item
  Henstrom DK, Lindsay RW, Cheney ML, Hadlock TA. Surgical treatment of
  the periocular complex and improvement of quality of life in patients
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  Mar-Apr;13(2):125-8. doi: 10.1001/archfacial.2011.9. PMID: 21422446.
\item
  Bylund N, Hultcrantz M, Jonsson L, Marsk E. Quality of Life in Bell's
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  Laryngoscope. 2021 Feb;131(2):E612-E618. doi: 10.1002/lary.28751. Epub
  2020 May 28. PMID: 32463963.
\end{enumerate}

\textbf{LIST OF TABLES}

\begin{itemize}
\tightlist
\item
  Table 1. Patient characteristics in the sample used in the linear
  regression analyses.
\item
  Table 2. Multivariate linear regression analysis of FaCE subscale
  scores on FaCE total score, with the number of questions in each
  subscale.
\item
  Table 3. Multivariate linear regression analysis of FaCE subscale
  scores on a transformed VAS score.
\end{itemize}

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