This cross-sectional observational study aims to evaluate the validity and reliability of the Four Square Step Test (FSST) in individuals with rheumatoid arthritis. In addition, the study will investigate the associations between FSST performance and clinical parameters including disease activity, quality of life, pain, and muscle strength. All assessments will be conducted according to a pre-defined standardized protocol. The order of measurement tools will be randomized to minimize potential bias, and sufficient rest intervals will be provided between tests to prevent fatigue and performance effects. Participants will include individuals aged 18-65 years with a diagnosis of rheumatoid arthritis according to the ACR/EULAR 2010 classification criteria, who have been followed for at least 6 months, have had no major changes in treatment regimen in the last 4 weeks (e.g., initiation or change of DMARDs/biologics, high-dose steroid increase), can walk at least 10 meters independently, have a Mini-Mental State Examination score of 24 or higher, and are able to follow verbal instructions in Turkish to comply with study procedures. Appropriate statistical methods will be applied to assess validity, reliability, and associations between FSST and clinical parameters.
Rheumatoid arthritis (RA) is a chronic, autoimmune connective tissue disease that affects approximately 0.5-1% of the global population. The disease is characterized by symmetrical joint pain, swelling, and restricted mobility. Synovial inflammation in its pathogenesis leads to structural damage, cartilage erosion, joint deformities, and irreversible functional impairments. Beyond joint involvement, RA significantly affects daily living activities, work capacity, and overall quality of life through its impact on the musculoskeletal system. Muscle weakness, reduced joint range of motion, and impaired proprioception occurring during the disease process particularly compromise lower extremity function and contribute to impaired postural control. Consequently, balance deficits, an increased risk of falls, and fall-related injuries are observed more frequently in individuals with RA compared to the healthy population. Balance is generally divided into static and dynamic balance. Static balance refers to the ability to maintain the center of mass within the base of support while standing still, whereas dynamic balance denotes the ability to sustain the center of mass safely and in a controlled manner within the base of support during movement. In RA, balance impairments become especially evident in daily activities such as walking, changing direction, and climbing stairs. These difficulties elevate fall risk and adversely influence both physical independence and social participation. Several assessment tools have been developed to evaluate balance in RA. The Berg Balance Scale (BBS), Tinetti Balance Test, Timed Up and Go Test (TUG), and Mini-BESTest are among the most widely used instruments in this field. However, many of these tools require lengthy administration, specialized equipment, or advanced clinical expertise. Such limitations can complicate rapid patient assessment, particularly in busy outpatient clinical settings. The Four Square Step Test (FSST) is a practical assessment that can be administered within a short period of time using simple materials, measuring an individual's ability to step in multiple directions. The reliability and validity of FSST have been established in various clinical populations, including those with ankle injuries, hemophilia, cerebral palsy, Duchenne muscular dystrophy, Down syndrome, hip arthroplasty, and anterior cruciate ligament reconstruction. Nevertheless, no validity and reliability study of the FSST has yet been conducted in individuals with RA. The primary objective of this study is to determine the validity and reliability of the Four Square Step Test (FSST) in individuals with rheumatoid arthritis. The secondary objective is to examine the relationship between FSST outcomes and clinical indicators such as disease activity, quality of life, pain and muscle strength. First, demographic and clinical data of all participants will be collected, including age, height, weight, smoking and alcohol consumption, dominant side, use of assistive devices, age at diagnosis, comorbidities, medications, and history of falls within the past 1-2 years. Body mass index (BMI) will be calculated. All analyses will be conducted as two-tailed, with a significance level set at α = 0.05, and results will be reported with 95% confidence intervals. The distribution of continuous variables will be assessed using the Shapiro-Wilk test. Normally distributed variables will be presented as mean ± standard deviation, while non-normally distributed variables will be reported as median values. Categorical variables will be presented as frequency (percentage). The relationships between FSST time and the scores of the Berg Balance Scale (BBS) and Mini-BESTest will be examined using Pearson's or Spearman's correlation coefficients, depending on data distribution. The predictive ability of FSST for poor balance status will be evaluated with receiver operating characteristic (ROC) curve analysis, and results will be reported in terms of area under the curve (AUC), sensitivity, specificity, Youden's index, and optimal cutoff values. Test-retest reliability will be determined using the intraclass correlation coefficient (ICC\[3,1\]) based on repeated FSST measurements performed by the same rater. Measurement error and minimal detectable change will be calculated as follows: SEM = SD × √(1 - ICC) and MDC95 = SEM × 1.96 × √2. Agreement between repeated measures will be illustrated using Bland-Altman plots (mean bias and ±1.96 SD limits). Comparisons of FSST times between clinical subgroups (e.g., disease activity level, history of falls) will be performed using independent-samples t-test/ANOVA if normality assumptions are met, or Mann-Whitney U/Kruskal-Wallis tests otherwise. Effect sizes will be reported as Hedges' g, r, and η²/partial η². Reporting will follow the STROBE guidelines for observational cross-sectional studies. The sample size was calculated using the G\*Power software with α = 0.05 and 1-β = 0.80. Previous studies have reported that the FSST demonstrates moderate to high levels of validity in different clinical populations. For example, in patients with hip osteoarthritis and total hip arthroplasty, correlations between FSST and other balance scales were found to range between r = 0.60 and r = 0.70. In individuals with total knee arthroplasty, FSST was reported to correlate with the TUG at r = 0.65 and with the HSS at r = -0.40. Furthermore, studies conducted in populations with hemophilia and Parkinson's disease indicated excellent reliability of FSST and modified FSST, with ICC values approximately between 0.96 and 0.99. Such studies have typically been conducted with sample sizes ranging from 17 to 28 participants. In light of these findings, it was determined that including approximately 40 participants in the present study would be sufficient to ensure adequate statistical power for the planned validity analyses.
Study Type
OBSERVATIONAL
Enrollment
50
Inonu University Turgut Ozal Medical Center
Malatya, Turkey (Türkiye)
Four Square Step Test (FSST)
The Four Square Step Test (FSST) is used to assess dynamic balance, specifically the ability to rapidly step over obstacles and change direction in a clinical setting. FSST is a quick and easily administered test that evaluates an individual's capacity to step in multiple directions over low obstacles. Four squares are created by intersecting lines at right angles, with each side approximately 90 cm in length. Low obstacles of 2.5 cm height are placed along the square boundaries. The participant starts in the lower-left square with feet together. In the first phase, the participant steps clockwise through each square-forward, right, backward, and left-returning to the starting position. The same sequence is then repeated counterclockwise. Participants must step into each square with both feet. After one practice trial, the test is performed twice, and completion times are recorded in seconds. The fastest time is considered the FSST score, with lower times indicating better dynamic bal
Time frame: Two assesstment ( one at baseline and one in the afternoon)
Disease Activity Score-28 (DAS-28)
DAS28 is a widely used instrument for evaluating disease activity in individuals with rheumatoid arthritis. This index incorporates the number of tender and swollen joints out of 28, the patient's self-assessment of general health using a 100-mm visual analog scale (VAS), and acute-phase reactants, including erythrocyte sedimentation rate (ESR, mm/h) or C-reactive protein (CRP, mg/L). The resulting total score provides a quantitative measure of disease activity, with lower scores indicating remission and higher scores reflecting active disease
Time frame: Baseline (First assessment)
Numeric Rating Scale (NRS)
The NRS is a unidimensional measure of pain intensity commonly used in adults. Multiple versions exist, but the 11-point scale (0-10) is the most widely employed. Patients are asked to select a number that best represents their pain intensity, where 0 indicates no pain and 10 represents the worst imaginable pain experienced over the past 24 hours.
Time frame: Baseline (First assesstment)
Rheumatoid Arthritis Quality of Life (RAQoL) scale
The Rheumatoid Arthritis Quality of Life (RAQoL) questionnaire is a disease-specific self-report instrument designed to assess quality of life in individuals with rheumatoid arthritis. The scale consists of 30 items with "yes/no" response options. Each "yes" response is scored as 1 point and each "no" response as 0 points, resulting in a total score ranging from 0 to 30. Lower scores indicate better quality of life, whereas higher scores reflect greater impairment in quality of life.
Time frame: Baseline (First assesstment)
Mini-Balance Evaluation Systems Test (Mini-BESTest)
The Mini-Balance Evaluation Systems Test (Mini-BESTest) is designed to assess dynamic balance using 14 items organized into four subscales: anticipatory postural adjustments, reactive postural control, sensory orientation, and dynamic gait. Each item is scored on a 3-point ordinal scale, with 0 indicating inability or need for assistance and 2 representing normal function. Total scores range from 0 to 28. Two items are evaluated for both the right and left sides, and only the lower score is included in the total score calculation.
Time frame: Baseline (First assesstment)
Berg Balance Test(BBS)
The Berg Balance Scale (BBS) is a balance assessment tool that evaluates an individual's ability to maintain stability while performing 14 functional tasks commonly encountered in daily activities. Each item is rated on a 5-point ordinal scale ranging from 0 to 4, where 0 indicates inability to perform the task and 4 represents the ability to complete the task independently. The maximum possible total score is 56. Administration of the test typically requires approximately 15-20 minutes.
Time frame: Baseline ( First assessment)
Baseline Hydraulic Hand Dynamometer
Participants are seated upright on a chair with their feet supported. The tested upper extremity is positioned with the shoulder in adduction and neutral rotation, the elbow at 90° flexion, the forearm in neutral position, and the wrist at 0-30° extension and 0-15° ulnar deviation. Participants are instructed to place their fingers around the dynamometer handle and squeeze with maximal force. The test is repeated three times, and the highest value obtained is used for analysis.
Time frame: Baseline (First assesstment)
5 Times Sit To Stand Test (5TSTS)
To assess quadriceps muscle strength and functional lower limb strength, the Five Times Sit-to-Stand Test (5TSTS) will be used. In the 5TSTS, participants are instructed to stand up and sit down five times as quickly as possible. A stopwatch is started with the command "start" and stopped upon completion of the fifth full standing position.
Time frame: Baseline (First assesstment)
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