Validation of a Lymphedema-Specific Functional
Measure: The Lymphedema Life Impact Scale (LLIS)
Jan Weiss, PT, DHS, CLT-LANA
Todd Daniel, PhD
CoxHealth, Missouri State University
Missouri State University
Introduction
Results
Results
Content Validity
Lymphedema manifests as swelling resulting from lymphatic
system failure to remove excess tissue interstitial fluid. Due to the
specific impact of this disease, it is essential for practitioners to have a
condition-specific measure with which to assess the effects of
lymphedema, and upon which to base appropriate treatment. The few
existing lymphedema instruments focus mostly on the impact of upper
extremity lymphedema, use multiple forms, or not been available in
English. The Lymphedema Life Impact Scale (LLIS) was developed as
a comprehensive lymphedema-specific instrument that also addresses
the 2013 Medicare requirement for documentation of functional
outcomes for rehabilitation. The LLIS consists of 18 questions
including physical, functional, and psychosocial domains. The purpose
of this study was to investigate the reliability and validity of the LLIS in
a mixed (upper and lower extremity) lymphedema patient population.
Participants
Participants were recruited from Lymphedema and Rehab
Therapy Clinics across the U.S. The sample consisted of 93 patients;
approximately one third of whom had been diagnosed with upper
extremity (UE) lymphedema, one third had lower extremity (LE)
lymphedema and the remaining third comprised of patients at risk
for, but without lymphedema (MHx: obesity, cancer, DVT, CVI) who
served as controls. Participants were an average of 58.19 years old,
were 83.9% female, and almost exclusively white (98.9%). Roughly
half of the sample (51.6%) were employed. The control group was
selected because its members fit diagnostic categories associated
with lymphedema, but had no swelling. More patients with UE
lymphedema had a history of cancer compared to those with LE
lymphedema or the control.
Convergent Validity
Content validity was assessed by computing a content validity ratio
(CVR; Lawshe, 1975) for each item, then calculating the average of
the CVRs for a content validity index of the overall measure. Four
subject matter experts rated the items.
domains from functional and quality of life outcome measures currently
used in lymphedema research. The European Organization for
Research and Treatment of Cancer-Quality of Life Questionnaire-Core
Table 2
Mean Ratings of Four Reviewers for LLIS Items
Physical scale
1. The amount of pain associated with my lymphedema is
2. The amount of limb heaviness associated with my lymphedema is
3. The amount of skin tightness associated with my lymphedema is
4. In comparison to my unaffected limb, the size of my swollen limb seems
5. In comparison to my unaffected limb, the skin texture of my swollen limb
feels
6. Lymphedema affects movement of my swollen limb
7. The strength in my swollen limb compared with the unaffected limb is
8. How often have you become ill with an infection in your swollen limb
requiring oral antibiotics or hospitalization in the past 2 YEARS.
Psychosocial scale
9. Lymphedema affects my body image (i.e. “how I think I look”)
10. Lymphedema affects my socializing with others
11. Lymphedema affects my intimate relations
12. Lymphedema “gets me down” (i.e. feelings of depression, frustration, or
anger due to the lymphedema)
Functional scale
13. Lymphedema affects my ability to perform duties at home
14. Lymphedema affects my ability to perform duties at work
15. Lymphedema affects my performance of preferred recreational activities
16. Lymphedema affects the proper fit of clothing/shoes
17. Lymphedema affects my sleep
18. I must rely on others for help due to my lymphedema
Overall CVI for LLIS scale
Each of the domain scales of the LLIS were correlated with like
Item CVR
.875
1.00
1.00
.50
1.00
.50
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
.929
1.00
1.00
1.00
1.00
.50
1.00
.92
30 (EORTC QLQ-C30; Aaronson et al., 1987) is a self-report measure
used to assess quality of life among cancer patients. Although not
Discriminant Validity
Discriminant validity was assessed by comparing LLIS scale scores
from patients diagnosed with lymphedema to LLIS scores of those in a
control group. The control group was chosen because lymphedema
occurs from a variety of etiologies. Using one-way ANOVAs, the LLIS
was demonstrated to discriminate between patients with lymphedema
and those without lymphedema on all three LLIS scales (Physical:
F(2,90) = 42.10, p < .001; Psychosocial: F(2,90) = 24.33, p < .001;
Functional: F(2,90) = 29.25, p < .001). Post hoc tests conducted with
Tukey HSD showed that for all three scales, the lymphedema patients
formed homogeneous subsets distinct from the control group.
Construct Validity
Limb symptoms, pain, and physical limitations have been
demonstrated to correlate more closely with negative quality of life than
amount of edema. Construct validity was measured through
examination of six symptoms frequently associated with lymphedema.
The LLIS correlated moderately to highly (r = .44 to r = .85) with all
symptoms. This supports the use of the LLIS to provide additional
information about the impact of lymphedema on the individual.
specifically designed to be used with lymphedema patients, it is
frequently used in lymphedema research. Not surprisingly, the LLIS
correlations with the EORTC, although statistically significant, were
weaker than with other lymphedema measures. This might indicate
the limited suitability of using a cancer-specific measure with
lymphedema patients. Both the Lymphedema Quality of Life
(LYMQOL; Keeley et al., 2010) and the Disability of Arm, Shoulder, and
Summary
Hand (DASH; Institute for Work and Health, 2006) correlated with their
respective scales on the LLIS for UE participants at r = .73 to r = .80
(all statistically significant at the .01 level). The functional scale of the
LLIS correlated reasonably well (r = .538, p < .01) with the Lower
Extremity Functional Scale (LEFS; Binkley et al., 1999), and all three
LLIS scales correlated with their respective scales on the LE LYMQOL
between at r = .74 to r = .88 (all statistically significant at the .01 level).
Reliability
All scales on the LLIS produce Cronbach’s alpha values above .80.
Results
Table 4
LLIS Scale Correlations with Upper Extremity Scales Among Upper Extremity Patients (n = 32)
LLIS Physical
LLIS Psychosocial
LLIS Functional
**
**
EORTC physical
.545
.495
.609**
**
**
**
EORTC psychosocial
.483
.485
.617
EORTC functional
.526**
.472**
.627**
LYMQOL physical UE
.786**
.520**
.700**
LYMQOL psychosocial UE
.665**
.734**
.667**
**
**
**
LYMQOL functional UE
.806
.729
.801
**
*
**
DASH physical
.744
.364
.641
**
**
**
DASH psychosocial
.690
.767
.749
**
*
**
DASH functional
.711
.352
.769
Note. * Correlations are statistically significant at the .05 level. ** Correlations are statistically significant at the .01
level. Correlations in bold indicate the correlations between equivalent scales.
Table 5
LLIS Scale Correlations with Lower Extremity Scales Among Lower Extremity Patients (n = 30)
LLIS Physical LLIS Psychosocial LLIS Functional
LEFS total
.496**
.381*
.538**
**
**
**
EORTC physical
.623
.670
.786
**
**
EORTC psychosocial
0.271
.617
.559
EORTC functional
.683**
.765**
.881**
LYMQOL physical LE
.735**
.697**
.832**
LYMQOL psychosocial LE
.676**
.795**
.798**
**
**
**
LYMQOL functional LE
.726
.758
.879
Note. * Correlations are statistically significant at the .05 level. Correlations are statistically significant at the .01
level. Correlations in bold indicate the correlations between equivalent scales.
I wish to acknowledge and thank all of the lymphedema therapists and patients across the U.S. who assisted with survey submission. I would also like to
thank Dr. Todd Daniel at Missouri State University RStats Institute for his invaluable assistance with statistical analysis and project design.
This research suggests that the LLIS works adequately to assess
impairments, activity limitations, and participation restrictions in
patients with either upper or lower extremity lymphedema. The LLIS
demonstrates the following advantages:
• The LLIS is construct valid with established measures of
lymphedema, making it useful to practitioners.
• The LLIS is lymphedema-specific: it discriminates between
patients with lymphedema and without, even in those patients
with risk factors for lymphedema.
• The LLIS provides a single measure for both upper and lower
extremity lymphedema eliminating the need for multiple forms of a
measure.
• The LLIS measures three types of lymphedema-specific
impairment: physical, psychosocial, and functional.
• The LLIS can be used with an Excel worksheet allowing
practitioners to calculate Medicare severity codes to comply with
the 2013 Medicare requirements for the documentation of
functional outcomes for rehabilitation.
• The LLIS is short and quick to administer.
References
Lawshe (1975). A quantitative approach to content validity.
Personnel Psychology, 28, 563-575. doi:10.1111/j.17446570.1975.tb01393.x