An objective test to assess upper limb functionality in patients with breast cancer-related lymphedema: investigation of the psychometric properties of the upper limb functional test (ULIFT)

Abstract

Background

Although upper limb (UL) functionality was reported to be adversely affected in patients with breast cancer- related lymphedema (BCRL), there is currently no validated, objective performance-based assessment tool designed to evaluate UL function in this population. The Upper Limb Functional Test (ULIFT) was adapted from the ADL test (TGlittre), which is widely used in clinical settings and research, and was developed to assess unilateral UL functionality. Therefore, the present study aimed to evaluate the psychometric properties of the ULIFT in patients with BCRL.

Methods

The study involved 36 women with unilateral BCRL and 30 healthy women controls. Intraclass correlation coefficients (ICC) were used to assess test-retest reliability. ULIFT was conducted a second time with 36 patients (100% of the total sample) over a period of 7 to 14 days for test-retest reliability analysis. The following measures were used to investigate ULIFT convergent validity: Range of motion was assessed using a universal goniometer; UL disability with the Disability of the Arm, Shoulder and Hand (DASH) questionnaire; hand grip strength with a Jamar dynamometer; and quality of life (QoL) with the Short Form 36-item Health Survey (SF-36) survey, and Upper Limb Lymphedema 27 (ULL-27). The receiver operating characteristic (ROC) curve analysis was conducted as part of the known-group validity assessment to establish a cut-off point for ULIFT in distinguishing between patients with BCRL and healthy controls.

Results

The ULIFT showed excellent test-retest reliability [ICC [95%] 0.92 (0.86–0.96)], a standard error of measurement of 3.91 s, and a minimum detectable change of 10.83 s. The sensitivity of 72.2%, specificity of 73.3% and AUC of 0.773 indicate a moderate ability of ULIFT to discriminate patients with and without impairment at a cut-off of 110.125 s. Significant correlations were found between ULIFT and UL functional measures (r ≥ 0.3), indicating convergent validity.

Conclusion

ULIFT is a reliable and valid objective measurement tool for assessing unilateral UL function. The cut-off time of 110.125 s may help in clinical decision-making, particularly when used in conjunction with other assessments.

Graphical abstract

Background

Breast cancer (BC) is the most common cancer in women worldwide, representing one in four cases of cancer in women [1]. The introduction of sensitive screening methods to predict the risk of developing BC and advances in treatment strategies have led to increased survival rates from the disease since the mid-2000s [2]. Although survival rates are increasing, patients with BC are experiencing short- and long-term disease-related side effects [2, 3].

Breast cancer-related lymphedema (BCRL) is one of the most common disease related side effects among BC survivors [3]. BCRL is an incurable and multifaceted condition characterized by swelling due to impaired capacity to remove protein-rich lymph fluid from the interstitial space as a result of mechanical failure of the lymphatic system [4]. This condition typically results from permanent damage to the lymph nodes and vessels during axillary lymph node dissection or BC treatment [5]. The progressive nature of BCRL, marked by fibro-adipose tissue accumulation and accompanying inflammatory processes, impairs UL functionality [6, 7]. The incidence of BCRL is reported to be approximately 17%, varying depending on the type of regional and systemic treatments [8]. The primary physical symptoms experienced by patients with BCRL include fatigue [9], pain [4] and seroma formation [10] followed by swelling, tightness, stiffness, loss of strength and decreased joint mobility [5]. These clinical manifestations may result in decreased range of motion (ROMs) further limiting functional mobility of the affected limb [11]. Besides, psychosocial problems and decreased social interaction due to poor body image present other significant barriers for UL functionality in BCRL patients [12, 13].

A recent systematic review reported Disability of the Arm, Shoulder and Hand Questionnaire (DASH), ROMs and/or hand grip strength as the most commonly used tools for functional assessment of UL in patients with lymphedema [14]. The review also emphasizes the lack of an accessible validated tool for assessing objective UL function [14]. A population-specific evaluation of the psychometric properties of a measurement tool is necessary to ensure its clinical relevance and confirm its suitability for use [15]. Therefore, a validated objective assessment tool for UL functionality may be beneficial in clinical settings.

The World Health Organization’s taxonomy in the International Classification of Functioning, Disability and Health defines functionality as the ability to perform a task using appropriate motor skills and proper biomechanics [16].The Upper Limb Functional Test (ULIFT) test was adapted from the Glittre-ADL test (TGlittre) that commonly used in the clinical setting, patients developed to assess unilateral UL functionality (ROMs and shifting) without activities involving the lower extremity [17]. The psychometric properties of ULIFT were examined in BC patients and demonstrated the test to be valid and reliable following BC surgery [18]. Considering the impact of the disease (e.g., swelling, tightness, heaviness, limitation of movement, tissue fibrosis) on the UL functionality of BRCL patients, ULIFT has potential to be a useful tool in this population. Objective measurement tools used to assess UL functionality in previous studies performed in various populations have included the Unsupported Upper Limb Exercise Test (UULEX) [19], the 6-minute Pegboard Ring Test (6PBRT) [20] and, The Timed Functional Arm and Shoulder Test (TFAST) [21]. However, as these tools evaluate bilateral performance, they may not be suitable in patients with involvement of a single limb. Furthermore, these tests have not been assessed for psychometric properties in the BCRL population, which may limit their group-specific applicability in this population. Additionally, although current objective measures, such as ROM and handgrip strength, assess isolated aspects of UL function, the ULIFT integrates multiple components -ROMs, grip strength, coordination and synchrony - to provide a more integrated assessment of UL performance. Thus, in patients with BCRL, utilizing a unilateral assessment method that prevents the help of unaffected limb may provide a more accurate measure of UL functionality of the affected limb. Therefore, the aim of this present study was to investigate the psychometric properties of the ULIFT in BCRL patients.

Methods

Study design

This study used a cross-sectional design. Patients who were referred to Dokuz Eylul University Hospital Medical Oncology Department and İzmir Katip Celebi University Atatürk Training and Research Hospital Medical Oncology Department to Dokuz Eylul University Faculty of Physical Therapy Rehabilitation Department were enrolled in present study. Informed consent was obtained from all participants, and all procedures were performed in accordance with the Declaration of Helsinki. Ethical approval was obtained from Dokuz Eylul University Non-Invasive Research Ethics Committee (Decision No: 2022/29 − 04, Date: 14.09.2022). The study was performed between December 2022 and January 2024.

Participants

Sixty BCRL patients were screened for eligibility during routine follow-up visits and 36 women who met the inclusion criteria were enrolled in the study. The healthy subjects consisted of 30 healthy female individuals selected from the relatives/acquaintances of the patients. Inclusion criteria for BCRL patients were: [1] being diagnosed with unilateral UL lymphedema following BC treatment [2], age of 18 or older [3], voluntary participation [4], no evidence of cancer recurrence for at least 12 months after completing adjuvant local and systemic therapies, and [5] ability to read and understand Turkish. Exclusion criteria were [1] prior surgeries or musculoskeletal conditions affecting physical mobility or ULIFT scores [2], active infections (e.g., lymphangitis, lymphadenitis) [3], neurological or psychiatric disorders [4], major organ failure (e.g., congestive heart failure, renal or hepatic dysfunction), and [5] use of medications (e.g., steroids, NSAIDs, calcium channel blockers) that could alter lymphedema severity. For healthy controls, inclusion criteria were: [1] voluntary participation [2], age 18 or older, and [3] ability to read and understand Turkish. Exclusion criteria for healthy subjects included any diagnosed chronic mental or physical conditions that could potentially affect the study outcomes.

Study sample

G*Power (Ver. 3.0.10, Germany) software was used to calculate the necessary sample size of the study. A priori sample size calculation was performed using data from a previous study that investigated the psychometric properties of the ULIFT in BC patients [18]. A minimum sample size of 36 patients was determined in the power analysis with an expected ICC value of 0.89, an invalid ICC value of 0.70, a Type I error rate of 0.05 and a power of at least 90%. Minimum necessary number of healthy controls for known group validity analysis was calculated as 30 by using an expected area under the curve (AUC) value of 0.70 at 90% power and 95% confidence interval [22].

Procedures

A comprehensive literature search was conducted to investigate the parameters associated with UL function in BCRL patients using various databases including PubMed, Scopus, Google Scholar and Pedro. The search term was “lymphedema” AND “function(s)” OR “functionality”. Potential functional parameters identified were lymphedema severity, lymphedema duration, ROMs, DASH score, peripheral muscle strength, and quality of life (QoL). These parameters were considered as potential associated factors for exploring convergent validity of ULIFT.

A detailed medical history was obtained from each participant, which included demographic information, disease-related characteristics (BCRL stage, disease duration, history of BC surgery and adjuvant local and systemic therapies) and exercise habits, using a structured form. After obtaining demographic information, other assessments were administered in the following order: ROMs, muscle strength, questionnaires, and ULIFT. Circumference measurements were taken before and after the ULIFT test and retest (to evaluate the effect of ULIFT on disease severity). Patients were also asked about any complaint (pain, discomfort, fatigue, etc.) following ULIFT. All assessments were performed by the same assessor on the same day to ensure consistency and reduce inter-rater variability. The psychometric properties of the ULIFT were investigated using test-retest reliability, convergent validity and knowns group validity. The preferred methodology for analyzing the psychometric properties of the study is based on the taxonomy defined by the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines [23]. ULIFT test-retest reliability analysis was conducted a second time with 36 patients (100% of the total sample) over a period of 7 to 14 days (considered both short enough for changes in disease severity and long enough to minimize the learning effect) [24]. Healthy controls were selected from the acquaintances/relatives of the BCRL patients and/or the researchers. The BCRL group completed the ULIFT with their affected UL, while 50% of the healthy group completed the test with their dominant UL and 50% with their non-dominant UL. This approach was used to ensure homogeneity and to match the patients and healthy controls in terms of dominance to control for the potential impact of hand dominance on functionality, as previous studies have reported that lymphedema is independent of dominance [5, 7].

Outcome measures

Upper limb functionality

ULIFT is a UL functionality test developed to unilaterally assess mobility and ROMs, components of integrated UL functionality [17, 18]. The ULIFT protocol is as follows: Participants stand in front of shelves at shoulder and waist height (a system of shelves with adjustable shelving tracks is used according to the height of the participants). Using only one hand, 3 objects of 1 kg must be moved consecutively from the top shelf (shoulder height) to the bottom shelf (waist height) and then to the floor. Participants perform the task for five repetitions. All participants were given verbal instructions to complete the task as rapidly as possible prior to the test and no verbal encouragement was provided during the test [18]. The original version of the ULIFT (TGlittre test) is performed by female participants with a 2.5 kg backpack load [17]. Considering the cohort in our present study (as existing studies have reported a negative impact of loads of more than 2 kg on the severity of lymphedema), we did not use a backpack [9]. Each repetition of the ULIFT was recorded in seconds using a simple stopwatch and the total time was used for analysis. The physiological variables (heart rate, oxygen saturation (Jumper pulse oximeter, Ulm), systolic and diastolic blood pressure (Erka Manual Sphygmomanometer, Bad Toelz, Germany)) were recorded before and after the ULIFT for all participants.

Lymphedema severity

A standard 2.54 cm (1 inch) retractable fiberglass tape was used to assess the severity of UL lymphedema. Circumference was measured at 5 cm intervals from the base of the third finger to the axilla with the arm in the anatomical position [25]. Using these circumference measurements, the volume of the extremities was calculated with the Frustum Formula. The severity of lymphedema was classified according to criteria defined by the International Society of Lymphology (ISL): mild lymphedema, <%20; moderate lymphedema, 21 to 40%; and severe lymphedema, > 41% [9].

Range of motion

The UL ROMs were evaluated as an indicator of the functionality of the UL during tasks of daily living. The ROM was measured using a universal goniometer (Standard BASELINE 12-inch plastic goniometer, (Model 12-1000), New York) to assess shoulder flexion and abduction, elbow flexion, wrist flexion and extension. UL ROMs were measured in the positions standardized for goniometric measurements: shoulder flexion abduction and elbow flexion ROMs were measured in the supine position, and wrist flexion and extension were measured in the sitting position [26]. A previously standardized procedure was used for goniometer measurements and recorded in degrees [27].

Disability of the arm, shoulder and hand questionnaire

DASH is a patient-reported outcome measurement (PROM) designed to assess the ability to perform common functional activities in people with musculoskeletal disorders, measuring disability of the UL, level of independence and symptoms (pain, weakness, tingling, numbness). The questionnaire consists of 30 items divided into 2 assessing sub-scores: disability/symptoms scores and work module score. Each item is assessed on a 5-point Likert scale (1 to 5) [28]. The total score ranges from 0 to 100, with a higher score indicating that UL functions is negatively affected. The questionnaire has been validated and found reliable for the Turkish population [28]. The DASH also has appropriate psychometric properties for assessing the UL functions in the BCRL population [29].

Muscle strength

Hand grip strength was utilized to measure peripheral muscle strength. Using a Jamar hydraulic hand dynamometer (Model 5030 J1, Sammons Preston Rolyan, Bolingbrook, IL, USA), a widely accepted and used device, hand grip strength was assessed. Measurements were performed in accordance with the standard position of the hand and arm recommended by the American Society of Hand Therapists (ASHT) [30]. The highest result in kilograms was used for the analysis, with three consecutive measurements taken with one-minute rest periods between each measurement.

Quality of life

Upper limb lymphedema quality of life questionnaire

Upper Limb Lymphedema Quality of Life Questionnaire (ULL-27) was used to assess QoL of BCRL patients. The ULL-27 consists of 27 total items and covers physical, psychological and social dimensions. Each item is scored on a five-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). The first 15 items evaluate the physical dimension (scores ranging from 15 to 75), items 16 to 22 evaluate the social dimension (scores ranging from 7 to 35) and items 23 to 27 evaluate the psychological dimension (minimum score is 5). Overall score and sub scores are calculated by summing the item scores and are adjusted to a score between 0 and 100 for all global and subscale scores, with higher scores indicating a worse QoL. ULL-27 has validity and reliability in Turkish language [31].

Short form 36-item health survey instrument

The SF-36 is one of the most standardized and widely used measures of health-related QoL [32]. The SF-36 consists of 8 subscales: physical functioning, role limitations due to physical problems, physical pain, general health perceptions, vitality, social functioning, role limitations due to emotional problems, and mental health. Higher scores on the subscales indicate higher levels of functioning and health-related QoL. The Turkish version of the SF-36 has been shown to be a reliable and valid instrument for assessing health-related QoL [33].

Statistical analysis

Statistical analysis was conducted using IBM SPSS Statistics for Windows (version 20.0, Armonk, NY: IBM Corp.). Normality of distribution was assessed using the Shapiro-Wilk test, histograms, detrended Q-plot graphs, kurtosis and skewness. Categorical variables are presented as numbers and percentages. Continuous data were expressed as mean (standard deviation) for normally distributed variables, and as median (minimum-maximum) for non-normally distributed variables. Statistical significance was considered to be p < 0.05.

Test-retest reliability

A two-way mixed model of interclass correlation coefficients (ICC 95%) with 95% confidence intervals was used to determine the test-retest reliability of the ULIFT. The ICC values obtained were classified as low reliability (ICC < 0.40), moderate reliability (ICC ≤ 0.75), high reliability (ICC > 0.75) and excellent reliability (ICC ≥ 0.90) [34]. The standard error of the measurement (SEM) in 95% confidence interval was calculated according to the formula “SEM₉₅ = SD ×  √(1-ICC)” [35]. The SEM represents the amount of variance due to measurement error in repeated testing. Minimum detectable change (MDC) was used to defined the smallest change that indicates real (clinical) improvement or deterioration for a participant. The MDC in 95% confidence interval was calculated using the formula MDC₉₅ = 1.96 x SEM x √2 [36].

Convergent validity

The Pearson correlation coefficient (r) was used to assess the convergent validity of the ULIFT between parameters related to UL function and disease-specific parameters. The r values were categorized as follows: 0.0 to 0.299 indicated negligible correlation, 0.300 to 0.499 indicated weak correlation, 0.500 to 0.699 indicated moderate correlation, 0.700 to 0.899 indicated strong correlation, and values greater than 0.900 indicated excellent correlation. Coefficient values of 0.3 or higher between the ULIFT and functionality and disease-specific parameters were considered as an indicator of convergent validity [37].

Known-groups validity

The receiver operating characteristic (ROC) curve was used to identify the cut-off point of optimal specificity and sensitivity values for ULIFT to differentiate BCRL patients from healthy controls in terms of UL functionality. AUC values are interpreted at 95% confidence interval as follows: 0.5 and below is considered failed, 0.7 to 0.8 is considered acceptable, 0.8 to 0.9 is considered excellent and > 0.9 is considered outstanding [38]. AUC values > 0.7 were considered as an indicator of known-groups validity [15].

Results

Sixty female participants with BCRL were assessed for eligibility and 36 patients met the inclusion criteria. A total of 24 patients were excluded for following reasons: eight had cancer metastases (bone and lung metastases) six declined to participate, two had axillary web syndrome, two had an active infection (lymphangitis), three had a history of previous surgery affecting UL mobility, and three had severe osteoporosis. Among the 45 healthy controls screened for eligibility, 15 were excluded from the analysis (Fig. 1): Five declined to participate, and 10 were excluded to match the patients and controls in terms of UL dominance of affected side. The study was completed with 36 women with unilateral lymphedema (age: 58.58 ± 9.11 years, BMI: 29.01 ± 4.33 kg/m²) and 30 healthy controls (age: 55.66 ± 6.14 years, BMI: 27.51 ± 2.83 kg/m²) (Table 1). All participants completed the ULIFT, and no adverse events were reported during the test. The BCRL group consisted of 18 (50%) patients with dominant arm lymphedema (16 (88.8%) right arm; 2 (11.2%) left arm). The healthy control group had 30 (100%) right dominant and half of the group performed the test with their dominant arm (15 participants), and the other half (15 participants) used their non-dominant arm. The dominance of the tested UL was not different between the groups (p > 0.999) (Table 1). The staging of BCRL patients was 27.8% (n = 10) stage I, 36.1% (n = 13) stage II and 36.1% (n = 13) stage III according to the ISL classification. UL functional outcomes are summarized in Table 2.

Fig. 1.

Flow diagram

Table 1.

Comparison of demographic and clinical characteristics of patients with upper limb lymphedema and healthy subjects

	Lymphedema Group (n = 36) Mean ± SD Median (min-max) n (%)	Healthy Group (n = 30) Mean ± SD Median (min-max) n (%)	p-value
Demographic Characteristics
Age (years)	58.58 ± 9.11	55.66 ± 6.14	0.127a
Height (cm)	158.13 ± 7.41	161.06 ± 5.00	0.070a
Weight (kg)	73.50 ± 11.62	71.06 ± 7.31	0.324a
BMI (kg/m2)	29.53 ± 5.06	27.51 ± 2.83	0.057a
Marriage status (married)	26 (72.2)	18 (60.0)	0.294b
Working status (working)	4 (11.1)	11 (36.7)	0.014b*
Assessed UL (Dominant)	18 (50.0)	15(50.0)	> 0.999b*
Chronic disease (yes)	17 (47.2)	0 (0.0)	< 0.001b**
Family history of cancer (yes)	20 (55.6)	2 (6.7)	< 0.001b**
Smoking (yes)	2 (5.6)	5 (16.7)	0.231c
Exercise habit (yes)	7 (19.4)	7 (23.3)	0.700b
Disease-Related Characteristics
Time since surgery (years) 5.60 ± 3.51
With lymphedema arm (right)	16 (44.4)
Lymphedema stage (ISL) Mild Moderate Severe	10 (27.8) 13 (36.1) 13 (36.1)
Duration of lymphedema (months)	60.0 (2.00-288.00)
Treatment
Surgical (yes) Lumpectomy (yes) Modified radical mastectomy (yes) Axillar dissection (yes)	36 (100.0) 14 (38.9) 22 (61.1) 36 (100.0)
CT (yes)	36 (100.0)
RT (yes)	36 (100.0)

SD: standard deviation, min: minimum, max: maximum, n: number, BMI: body mass index, cm: centimeter, kg: kilogram, m: meter, UL: Upper Limb, ISL: International Society of Lymphology, CT: chemotherapy, RT: radiotherapy, a: Student’s t-test, b: Chi-square test, c: Fisher’s exact test *: p < 0.05, **p < 0.001

Table 2.

Functional outcomes of groups

UL-Functional Outcomes	Lymphedema Group (n = 36) Mean ± SD Median (min-max)	Healthy Group (n = 30) Mean ± SD Median (min-max)	p-value
ULIFT (sec)	117.34 ± 15.28	103.73 ± 11.78	< 0.001 a **
Δ Heart rate (bpm)	11.50 (2.00–50.00)	14.00 (4.00–28.00)	0.628b
Δ BP systolic (mmHg)	13.50 (7.00–39.00)	12.50 (7.00–29.00)	0.811b
Δ BP diastolic (mmHg)	4.00 (1.00–13.00)	4.00 (1.00–11.00)	0.654b
Δ SpO2 (%)	0.00 (0.00–2.00)	0.00 (0.00–1.00)	0.791b
Range of Motion
Shoulder flexion	165.41 ± 11.36
Shoulder abduction	154.58 ± 18.56
Elbow flexion	136.25 ± 9.58
Wrist flexion	54.86 ± 12.86
Wrist extension	55.97 ± 15.29
DASH
Disability/symptom score	26.45 ± 14.08
Work module score	32.46 ± 19.75
Hand grip strength (kg)	20.97 ± 5.91
ULL-27
Physical score	40.16 ± 11.01
Psychological score	16.97 ± 6.49
Social score	8.41 ± 2.98
Global score	65.55 ± 14.89
SF-36
Physical functioning	75.00 (0.00–95.00)
Role limitations–physical	12.50 (0.00-100.00)
Role limitations–emotional	75.00 (0.00-100)
Energy/vitality	57.50 (20.00–90.00)
Mental health	66.00 (16.00–92.00)
Social functioning	87.50 (25.00-100.00)
Bodily pain	77.50 (22.50–100)
General health	65.00 (15.00–95.00)

SD: standard deviation, min: minimum, Max: maximum, N: number, ULIFT: upper limb functional test, Sec: second, %: percentage, Δ: change (final-initial values), BP: blood pressure, Bpm: beats per minute, MmHg: millimeters of Mercury, kg: kilogram, DASH: disabilities of the arm, shoulder and hand, ULL-27: upper limb lymphedama 27 questionnaire, SF-36: medical outcomes study Short-Form 36 a: student’s t-test, B: Mann-Whitney U test, *: p < 0.05, **p < 0.001

Test-retest reliability of ULIFT

The test-retest reliability of the ULIFT score was detected as good to excellent (ICC [95%] = 0.92 (0.86–0.96)) (Table 3). The SEM₉₅ and MDC₉₅ values of ULIFT were calculated as 3.91 (CI [95%] 3.91[1.00-2.77]) seconds and 10.83 (CI [95%] 2.77–7.67) seconds, respectively (Table 3).

Table 3.

Test-retest reliability of ULIFT

n = 36	Mean ± SD
	ULIFT1	ULIFT2	ICC Δ (95%CI)	SEM in 95% CI	MDC in 95% CI
Time (sec)	117.34 ± 13.85	115.45 ± 16.80	0.92 (0.86–0.96)	3.91 (1.00-2.77)	10.83 (2.77–7.67)

n: number, ULIFT₁: Upper Limb Functional Test initial test score ULIFT₂: Upper Limb Functional Test re-test score, ICC Δ: intraclass correlation coefficient of the initial and final variation between ULIFT₁ and ULIFT₂, CI: confidence interval, SD: standard deviation, sec: seconds, SEM: standart error measurement, MDC: minimal detectable change

Convergent validity of ULIFT

A significant strong positive correlation was detected between the ULIFT score and the severity of the lymphedema (r = 0.707, p < 0.001). A significant weak positive correlation was found between ULIFT score and lymphedema disease duration (rho = 0.456, p = 0.005). Weak negative correlations were detected between ULIFT score and shoulder flexion (r=-0.452, p = 0.006), shoulder abduction (r=-0.372, p = 0.025), elbow flexion (r=-0.406, p = 0.014), wrist flexion (r=-0.413 p = 0.012) and extension (r=-0.355, p = 0.034) ROMs. Weak positive correlations were also detected between ULIFT score and DASH Disability/Symptoms (r = 0.395, p = 0.017) and Work module score (r = 0.385, p = 0.020). The ULIFT score demonstrated significant negative moderate correlations with hand grip strength (r=-0.542, p = 0.001). There was a weak, positive correlation between the ULIFT score and ULL27 global score (r = 0.393, p = 0.018). A weak negative correlation was also found between the ULIFT score and the SF-36 general health score (r=-0.416, p = 0.012). Overall, the significant correlations obtained ≥ 0.3 were considered to indicate the convergent validity of the ULIFT. Correlations between ULIFT score and functionality and disease specific parameters are presented in Table 4.

Table 4.

Correlations of ULIFT Disease-specific-related and Functionality-related parameters (n = 36)

ULIFT	r/ rho	p-value
Severity of lymphedema (cm3)	0.707 a**	< 0.001
Duration of lymphedema (months)	0.456 b*	0.005
Range of Motion
Shoulder flexion	-0.452 a*	0.006
Shoulder abduction	-0.372 a*	0.025
Elbow flexion	-0.406 a*	0.014
Wrist flexion	-0.413 a*	0.012
Wrist extension	-0.355 a*	0.034
DASH
Disability/symptom score	0.395 a*	0.017
Work module score	0.385 a*	0.020
Hand grip (kg)	-0.542 a*	0.001
ULL-27
Physical score	0.432 a*	0.008
Psychological score	0.162a	0.189
Social score	0.161a	0.193
Global score	0.393 a*	0.018
SF-36
Physical functioning	-0.57 b*	0.008
Role limitations–physical	-0.461 b*	0.005
Role limitations–emotional	-0.140b	0.417
Energy/vitality	-0.501b	0.767
Mental health	-0.21b	0.901
Social functioning	-0.27b	0.830
Bodily pain	-0.471 b *	0.004
General health	− 0.416 b*	0.012

n: number, ULIFT: Upper Limb Functional Test, DASH: Disabilities of the Arm, Shoulder and Hand, ULL-27: Upper Limb Lymphedama 27 Questionnaire, SF-36: Medical Outcomes Study Short-Form 36, a: Pearson correlation coefficient, b: Spearmen correlation coefficient. *: p < 0.05, **p < 0.001

Known-groups validity

The mean ULIFT score for patients with BCRL was 117.34 ± 13.85 s and 103.73 ± 11.78 s for healthy subjects (Table 2). The optimum cut-off time was calculated as 110.125 s with 72.2% sensitivity and 73.3% specificity (AUC 0.773), (Fig. 2). These results showed that the ULIFT had an acceptable ability to differentiate BCRL patients from healthy controls in terms of UL dysfunction.

Fig. 2.

Receiver operating characteristic (ROC) curve

Discussion

This study is the first to evaluate the psychometric properties of a performance-based, objective measurement tool for assessing UL functionality in patients with BCRL. The study revealed the following main findings: [1] The ULIFT was found to have sufficient psychometric proprieties in BCRL patients [2] The ULIFT score was associated with the severity of lymphedema, disease duration, shoulder flexion-abduction, elbow flexion, wrist flexion-extension ROMs, DASH score, hand grip strength and physical sub-parameters, and global QoL questionnaire scores [3] The cutoff score of 110.125 s demonstrated acceptable sensitivity and specificity.

The ICCs were calculated to evaluate the reproducibility of ULIFT in the present study. The results of the analyses showed excellent test-retest reliability of the ULIFT in the BCRL population. This study showed similar reliability values to a previous study that investigated the test-retest reliability of ULIFT following BC surgery (ICC 95% CI = 0.89 (0.75–0.95) [18]. SEM₉₅ and MDC₉₅ are clinically more useful compared to ICC values due to the same units as the original measurement tools [39]. The SEM₉₅ for ULIFT in the current study was calculated as 3.91 s and the MDC₉₅ was calculated as 10.83 s. For example, if an individual’s ULIFT performance score is 110 s, there is a 95% probability that the actual score based on this time is between 106.09 and 113.91 s. Understanding the SEM₉₅ enables clinicians to more accurately interpret changes in ULIFT scores, distinguishing between true changes in functional performance and those that may be due to measurement variability. Additionally, differences of the ULIFT score above 10.83 s can be interpreted as a true improvement or impairment [36].

ULIFT is used to capture functional performance that may be affected by ROMs, muscle function and mobility [17, 18]. The ULIFT score was reported as 123.8 ± 20.83 s in a previous study performed in BC surgery patients [18], which is similar to the ULIFT score obtained in the present study (117.34 ± 13.85). However, a difference of approximately 15 s was detected in the ULIFT score of healthy controls in this study (103.73 ± 11.78) compared to the BCRL population which is higher than the MDC₉₅ value calculated in the present study. This result indicates the presence of a real impairment in UL performance in BCRL patients compared to healthy controls.

The BCRL participants in our study were at least one year post-operatively, and all possible causes of functional disability (pain, scar tissue, axillary web syndrome) were excluded, allowing only the effect of lymphedema on UL function to be assessed. Previous studies have demonstrated reduced UL functional mobility, movement amplitude and joint mobility in BCRL patients [5, 40, 41, 42]. Therefore, the previous results support our findings that BCRL patients have higher ULIFT durations than healthy controls. The cut-off point of 110.125 s [(AUC value of 0.773 (95% CI: 0.722–0.733)] for ULIFT may assist clinicians in evaluating UL deterioration in a clinical setting. Although ULIFT demonstrates an acceptable ability to differentiate UL impairment, combining the patient’s condition with additional clinical observations may provide a more thorough and accurate basis for definitive interpretation.

Unilateral UL mobility in patients with BCRL has been reported to be negatively affected by lymphedema severity [43], disease duration [44], physical symptoms such as decreased shoulder joint mobility [42] and muscle strength [42], as well as biopsychosocial factors affecting QoL [44]. As mentioned above, increasing findings suggest that UL mobility in patients with BCRL is negatively affected by a combination of factors. According to our knowledge, this study is the first to evaluate the psychometric properties of a performance-based, objective measurement tool for assessing UL functionality in BCRL patients. The results of the present study showed significant correlations between ULIFT and lymphedema severity, disease duration, joint mobility, disability score, peripheral muscle strength and overall QoL questionnaire scores in BCRL patients. A correlation coefficient between ULIFT and clinical parameters above 0.30 was used as a cut-off point to demonstrate the convergent validity of ULIFT. This threshold is in line with established previous psychometric validation studies [45, 46] and the COSMIN recommendations [47]. The present study findings showed acceptable convergent validity (r ≥ 0.3) for the ULIFT in BCRL patients, supporting the predefined hypothesis.

The DASH is the most commonly used functional disability assessment measure among PROMs in patients with lymphedema [14]. The DASH score for BCRL patients in the present study was 26.45 ± 14.08, which was above the previously established cut-off of ≥ 20, indicating significant disability in activities of daily living [48]. Additionally, this score is similar to previous findings in BCRL patients with a larger sample size (24.31 ± 14.33), which suggests BCRL patients have moderate UL disability in performing activities of daily living [49]. The DASH assesses the ability to perform a range of daily activities, from basic tasks to more complex movements. The current study found a significant correlation between ULIFT and DASH scores, indicating that the ULIFT may be a useful tool in assessing the performance of the affected limb during daily tasks. DASH reflects general functional disability in daily life, while the ULIFT provides an objective, performance-based measure of UL mobility and function. Using ULIFT and DASH together may offer a more comprehensive understanding UL dysfunction in patients with BCRL.

Hand grip strength is a key measure of UL function, essential for performing daily tasks [8]. The stiffness, feeling of heaviness, physical impairment and reduced use of the affected limb for functional tasks are frequently reported in lymphedema patients [49]. Additionally, chemotherapy can cause disruption of muscle metabolism (e.g. cytokine dysregulation, adenosine triphosphate dysregulation, and deprivation of satellite cells), leading to permanent muscle loss leading to reduced muscle strength [50]. The combination of these factors may have a negative effect on hand grip strength in patients with lymphedema and may result in a reduction in the functionality of the UL. Previous studies have reported handgrip strength as a predictor of maintained mobility, functional status, higher activities of daily living and reduced disability in women with BRCL and various other patient populations [30, 42, 51, 52]. The current study found significant relationships between hand grip strength and the ULIFT score The significant correlation between hand grip strength and ULIFT performance can be explained by several factors. Firstly, ULIFT is a test that assesses functional performance, with grip strength being a crucial component in performing the tasks involved. Additionally, handgrip strength reflects the overall coordination among various muscle groups in the UL [52]. ULIFT requires both muscle strength and coordinated motor control as it involves dynamic movements such as lifting and placing objects. The ability to perform these activities efficiently is influenced by the interaction of grip strength and muscle coordination, which may be another explanation supporting the relationship between handgrip strength and ULIFT performance.

The SF-36 findings demonstrated that ULIFT score is significantly associated with physical subscores (e.g., physical functioning, bodily pain, and role limitations-physical) but not with psychosocial subscores (e.g., mental health, social functioning, and role limitations-emotional). Compared with PROMs, which assess both physical and psychosocial aspects of health, the ULIFT provides an objective, task-based assessment of UL function [18] and thus primarily reflects physical impairments rather than psychological well-being. This finding is consistent with the inherent nature of the ULIFT as a performance-based test designed to assess UL mobility, strength and coordination. Similar results have been reported in previous studies in which instruments emphasizing physical performance showed stronger correlations with the physical dimensions of QoL, while correlations with psychosocial domains remained absent or relatively weak [53, 54].

The ULIFT is designed to provide an objective, performance-based assessment of UL function [18]. Notably, it evaluates unilateral coordination, ROMs, and task-based performance without support from the unaffected limb. This distinguishes ULIFT from other tests and may offer a new approach to assess unilateral UL function in patients with BCRL. BCRL is characterized by unilateral UL impairment (55), distinguishing it from other conditions with more generalized or bilateral effects. This aspect of BCRL enhances the relevance of ULIFT as a targeted, performance-based assessment tool, specifically designed to evaluate unilateral UL function and capture the localized functional deficits typical of this patient population. Additionally, a recent systematic review reported that a gold standard measurement tool is not available to assess UL functionality in patients with lymphedema [14]. Although the DASH questionnaire was not developed specifically for patients with BCRL, the DASH is the most common PROM for assessing UL dysfunction in this population (29, 51, 56). The ULIFT provides an assessment of UL mobility and functional performance, specifically with shifting and ROMs, however, it does not capture the subjective experience of patients regarding disability, pain, or QoL. Therefore, combining the ULIFT with PROMs such as the DASH [29] or ULL-27 [31], may provide a more holistic understanding of functional impairment. Additionally, as the ULIFT provides a single overall score, it may benefit from the inclusion of additional measurement tools, such as ROMs and region-specific muscle strength assessments, to better capture specific involvement of UL. Future studies may consider integrating these complementary tools with the ULIFT to develop a more comprehensive framework for assessing UL dysfunction in patients with BCRL.

No adverse events were reported during the study. Additionally, the BCRL group had no change in the severity of lymphedema (baseline and retest measurements). These outcomes suggest that the ULIFT is safe to use in patients with BCRL.

This study is the first to evaluate the psychometric properties of a performance-based, objective measurement tool for assessing UL functionality in patients with BCRL. Another strength is the comprehensive approach used to evaluate the psychometric properties of the ULIFT. The limitations of this study include the relatively small sample size and the absence of age and BMI matching for the selection of healthy controls.

Conclusion

The ULIFT is a reliable and valid objective measurement tool to assess UL function in patients with BCRL. The results also revealed the associations between lymphedema severity, disease duration, shoulder flexion-abduction, elbow flexion, and wrist flexion-extension ROMs, DASH score, hand grip strength and physical sub-parameters, global QoL questionnaire scores, and ULIFT outcomes. ULIFT can be used as a space efficient, inexpensive, systematic and effective assessment tool in the clinical settings to evaluate unilateral UL performance and mobility in BCRL patients. Studies with larger sample sizes could potentially include assessing the discriminant validity of the ULIFT across different lymphedema stages, affected areas, and levels of lymphedema progression to strengthen the external validity and clinical utility of the ULIFT.

Abbreviations

UL

Upper Limb

BCRL

Breast Cancer- Related Lymphedema

BC

Breast Cancer

ULIFT

The Upper Limb Functional Test

UULEX

Unsupported Upper Limb Exercise Test

6PBRT

6-minute Pegboard Ring Test

TFAST

The Timed Functional Arm and Shoulder Test

ICC

Intraclass Correlation Coefficients

DASH

Disability of the Arm, Shoulder and Hand

SF-36

Short Form 36-Item Health Survey

ULL-27

Upper Limb Lymphedema 27

ROMs

Range of Motions

PROMs

Patient-Reported Outcome Measurements

QoL

Quality of Life

ISL

International Society of Lymphology

ROC

The Receiver Operating Characterristic

AUC

Area Under the Curve

SEM₉₅

Standard Error of the Measurement at %95 cOnfidence Interval

MDC₉₅

Minimum detectable Change at %95 Confidence Interval

Author contributions

All authors contributed to the study conception and design. Material preparation and data collection were performed by Sukriye Cansu Gultekin, Ahmet Burak Cakir, Zeynep Gulsum Guc, Faruk Recep Ozalp, Merve Keskinkilic, Tugba Yavuzsen and Didem Karadibak. Analysis was performed Sukriye Cansu Gultekin. The first draft of the manuscript was written by Sukriye Cansu Gultekin and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

This research received no specific grant any funding agency in the public, commercial or not-for-profit sectors.

Data availability

The datasets used and/or analyzed during the present study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Informed consent was obtained from all participants and all procedures were performed in accordance with the Declaration of Helsinki. Ethical approval was obtained from Dokuz Eylul University Non-Invasive Research Ethics Committee (Decision No: 2022/29 − 04, Date: 14.09.2022).

Competing interests

The authors declare no competing interests.