Diabetic Foot Scale-Short Form

Abstract

Diabetic foot ulcerations represent one of the most debilitating, costly, and clinically complex chronic secondary complications of diabetes mellitus. Beyond precipitating substantial physiological morbidity, frequent hospital admissions, elevated infection risks, and limb-threatening amputations, diabetic foot pathology severely compromises overall psychosocial equilibrium, daily functioning, and quality of life. Standardized generic health status metrics (such as the Medical Outcomes Study 36-Item Short-Form Health Survey, SF-36) frequently fail to isolate the idiosyncratic biopsychosocial sequelae of localized, non-healing neuropathic or neuroischemic lesions from the broader systemic manifestations of chronic endocrine disease. To surmount these psychometric limitations, the Diabetic Foot Scale-Short Form (DFS-SF) was developed as a specialized, disease-specific self-report instrument designed to quantify health-related quality of life (HRQoL) across nuanced physical, psychological, and social dimensions.

This article provides an in-depth academic examination of the psychometric properties, structural architecture, and theoretical foundations of the DFS-SF, with a focused review of its cross-cultural adaptation and empirical validation within Turkish clinical populations conducted by Meryem Kiliç, Ayişe Karadağ, and Neşe Koçakgöl (2023). Comprising 29 items distributed across six empirically substantiated domains, the instrument captures physical functioning, leisure activities, activities of daily living, emotional well-being, ulcer-related worries, and social burden. The psychometric evaluation demonstrated exceptional measurement characteristics, including an overarching Cronbach’s alpha coefficient of 0.93 (with subscale coefficients ranging from 0.93 to 0.97), item-total correlation coefficients between 0.73 and 0.86, and robust confirmatory factor analysis fit indices (CFI = 0.900; NFI = 0.90–0.95; RMSEA < 0.08; χ²/df < 3). Demonstrating superior discriminant capability across varying stages of the Wagner ulcer classification system and significant convergent validity with generic health indices (r = 0.43 to 0.76), the DFS-SF represents a methodologically sound, low-burden assessment paradigm suitable for longitudinal clinical monitoring, wound management efficacy trials, and psychological intervention research in medical and surgical settings.

Keywords

Diabetic Foot Scale-Short Form, DFS-SF, diabetic foot ulcer, health-related quality of life, psychometric validation, confirmatory factor analysis, chronic wound care, patient-reported outcome measures, Wagner ulcer classification, medical psychometrics

Authors

The systematic cross-cultural adaptation, translation-back translation protocol, and psychometric validation of the Turkish Diabetic Foot Scale-Short Form (DFS-SF) were conducted by the following academic and clinical investigators:

• Meryem Kiliç, PhD, RN (Corresponding Author)
  Affiliation: Department of Nursing, Faculty of Health Sciences, SANKO University, Gaziantep, Türkiye.
  Contact Email: [email protected]
• Ayişe Karadağ, PhD, RN
  Affiliation: Department of Nursing, Faculty of Nursing, Koç University, İstanbul, Türkiye.
• Neşe Koçakgöl, MD
  Affiliation: Department of Endocrinology and Metabolism, Dr. Ersin Arslan Education and Research Hospital, Gaziantep, Türkiye.

Purpose

Chronic wounds of the lower extremities in individuals diagnosed with type 1 or type 2 diabetes mellitus constitute an escalating global public health challenge. The pathophysiology of diabetic foot ulceration involves a devastating interplay of peripheral neuropathy, micro- and macrovascular peripheral arterial disease, biomechanical deformities, repetitive minor trauma, and susceptibility to deep tissue infections. Patients facing chronic ulcerations endure substantial lifestyle disruptions, including mandatory mechanical off-loading, prolonged immobilization, painful daily dressing regimens, frequent necrotic debridement procedures, protracted hospitalizations, and the omnipresent threat of minor or major limb amputation.

Historically, researchers and clinical investigators evaluated the health status of these patients using generic assessment batteries, most notably the SF-36, the EuroQol 5-Dimension (EQ-5D), or the Nottingham Health Profile. Although generic instruments facilitate standardized comparisons across completely disparate disease populations (e.g., comparing cardiovascular patients with oncology patients), they exhibit a pronounced lack of clinical sensitivity and discriminative capability when applied to localized chronic wound pathology. When an individual with advanced diabetes displays low physical vitality or psychological distress on a non-specific generic survey, clinical evaluators cannot ascertain whether this impairment is driven primarily by an unhealed foot wound, chronic visual impairment from diabetic retinopathy, autonomic cardiac neuropathy, end-stage renal failure, or non-specific glycemic fluctuations. The primary purpose of the Diabetic Foot Scale-Short Form (DFS-SF) is to bridge this psychometric chasm by offering an isolated, disease-specific evaluative framework that directly measures the precise physical, emotional, and social functional disturbances caused specifically by diabetic foot lesions and their mandatory treatments.

From a research and clinical utility standpoint, the DFS-SF was engineered to fulfill several core functions:

• Evaluating Novel Wound Therapeutics: Quantifying patient-centered outcomes in pharmacological trials, bioengineered cellular tissue therapies, hyperbaric oxygen protocols, and advanced surgical interventions beyond standard biological end-points like granulation percentage or epithelialization speed.
• Monitoring Psychosocial Deterioration: Enabling clinical wound care nurses, endocrinologists, and liaison psychiatrists to detect early affective distress, loss of personal autonomy, depressive symptomatology, and existential dread related to potential limb loss.
• Optimizing Resource Allocation and Clinical Pathways: Supplying empirically robust data that informs holistic wound care management, multidisciplinary team planning, and post-discharge social rehabilitation strategies.
• Minimizing Respondent Burden: Providing a condensed 29-item questionnaire that preserves the multidimensional breadth of the original extensive instruments while curtailing cognitive fatigue, administrative time, and emotional exhaustion in medically vulnerable, often elderly or infirm patient populations.

Psychological Construct

The core psychological construct measured by the Diabetic Foot Scale-Short Form is disease-specific health-related quality of life (HRQoL) in the context of chronic diabetic lower-extremity ulceration. Within health psychology and behavioral medicine, HRQoL is operationalized as a multidimensional, subjective construct reflecting an individual’s evaluation of their physical functioning, emotional stability, personal agency, and social roles as constrained or modified by a medical condition and its therapeutic regimen. In the DFS-SF, this overarching construct is conceptualized not merely as symptom severity, but as the comprehensive biopsychosocial disruption enacted by the presence of a chronic, non-healing ulcer.

The scale captures this broad construct across six empirically identified, correlated yet distinct dimensions:

• 1. Physical Functioning and Mobility: This dimension assesses the extent to which the physical presence of the foot ulcer and mandatory clinical precautions (such as therapeutic footwear, total contact casting, crutches, or complete non-weight-bearing prescriptions) directly impede essential physical activities. It evaluates limitations in walking short distances, climbing stairs, maintaining standing balance, and performing basic bodily mobility. Unlike generic functional assessments, items in this domain explicitly gauge restrictions arising from the fear of exacerbating the wound or disrupting fragile debrided tissue.
• 2. Leisure and Recreational Activities: Chronic ulcers severely constrain participation in non-obligatory, health-promoting, or recreational pursuits. This dimension measures the subjective restriction of pastimes, hobbies, physical exercise, family outings, and spontaneous recreational social engagement. The inability to participate in valued lifestyle activities frequently induces anhedonia, secondary deconditioning, and profound frustration, which this subscale quantifies.
• 3. Daily Living and Personal Autonomy: Managing an open ulcer introduces demanding daily self-care rituals, strict hygiene regimens, moisture-barrier management, and reliance on caregivers for basic activities of daily living (ADLs). This subscale captures perceived impediments in completing household maintenance, personal hygiene (e.g., keeping the affected limb dry while bathing), grocery shopping, meal preparation, and vocational responsibilities, mapping the progression from functional self-sufficiency toward unwelcome dependency.
• 4. Emotional Well-Being and Affective State: Living under the chronic threat of systemic infection, septicemia, and progressive tissue death elicits profound negative affective responses. This dimension operationalizes the emotional toll of the ulcer, specifically measuring chronic worry, feelings of helplessness, depressive mood states, frustration regarding the protracted healing timeline, irritability, and demoralization driven by cyclical ulcer recurrence.
• 5. Ulcer-Related Worries and Amputation Dread: Highly specific to lower-limb diabetic pathology, this psychological subscale focuses on future-oriented existential anxieties. Patients experience persistent anxiety regarding wound enlargement, foul wound odor, visible exudate leakage, systemic complications, repeated hospitalization, surgical intervention, and, most prominently, the severe psychological trauma associated with minor (toe, forefoot) or major (transtibial, transfemoral) limb amputation.
• 6. Social Role Burden and Caregiver Dynamics: Chronic wounds fundamentally shift family systems and interpersonal relationships. This factor captures perceived disruptions in social interactions, interpersonal friction arising from restricted social mobility, perceived communicative withdrawal from peers, and the psychological distress caused by feeling like an emotional, physical, or financial burden to family members and primary caregivers.

Theoretical Framework

The development and construct validation of the DFS-SF are deeply rooted in contemporary paradigms of health psychology, psychometrics, and medical sociology. Three primary theoretical frameworks underpin the instrument’s operational structure:

1. The Biopsychosocial Model of Chronic Illness

Formulated by George L. Engel, the Biopsychosocial Model posits that health, illness, and clinical outcomes cannot be comprehended solely through biological or pathophysiological mechanisms. Instead, they represent a continuous, dynamic interaction between cellular-level phenomena (tissue ischemia, neuropathy, bacterial colonization), psychological vulnerabilities (affective processing, cognitive coping styles, illness perception), and social environmental factors (caregiver support systems, vocational security, access to medical resources). The DFS-SF explicitly incorporates this systemic philosophy by structuring its 29 items across biological-functional limits, psychological distress mechanisms, and micro-social relational consequences, rejecting any reductionist assertion that wound surface area directly equates to patient well-being.

2. Leventhal’s Common-Sense Model of Self-Regulation

Howard Leventhal’s Common-Sense Model (CSM) of Self-Regulation clarifies how individuals construct cognitive and emotional representations of illness threats and how these representations guide coping behaviors and psychological outcomes. According to the CSM, when patients are confronted with chronic somatic symptoms—such as an unhealing diabetic foot ulcer—they formulate internal cognitive representations along distinct attributes: Identity (the label and physical manifestations), Cause (etiological attributions), Timeline (acute, cyclical, or chronic expectations), Consequences (projected physical, financial, and emotional impact), and Controllability/Cure (the degree to which medical care or personal actions can resolve the issue). The DFS-SF taps directly into these cognitive-emotional feedback loops; the ‘Ulcer-Related Worries’ and ‘Emotional Well-Being’ subscales operationalize the patient’s perceived timeline chronicity and disastrous anticipated consequences, illustrating how perceived threat severity shapes global quality of life.

3. The Disablement Process Model

Developed by sociologists Lois M. Verbrugge and Alan M. Jette, the Disablement Process Model conceptualizes the longitudinal trajectory from pathology to disability. It outlines four sequential stages: (a) Pathology (cellular alterations, diabetes-induced microvascular damage), (b) Impairment (sensory loss, peripheral arterial insufficiency, structural foot deformities), (c) Functional Limitation (inability to walk, balance instability), and (d) Disability (inability to execute typical social, familial, or occupational roles in a given environment). The DFS-SF systematically captures the final two stages of this pathway, mapping how physiological impairments translate directly into acute functional limitations and subsequent socio-behavioral disabilities in home and community settings.

Validity

The psychometric evaluation of the translated and culturally adapted Diabetic Foot Scale-Short Form demonstrated robust empirical evidence supporting multiple facets of measurement validity. In the methodological study conducted by Kiliç, Karadağ, and Koçakgöl (2023), rigorous analytical procedures were executed across a well-characterized inpatient clinical sample of 174 adult patients undergoing specialized wound care.

Content and Face Validity

Content validity was evaluated systematically following standardized international guidelines for cross-cultural scale adaptation. The instrument underwent rigorous forward-translation by independent bilingual healthcare specialists, reconciliation, and subsequent blind back-translation into English. An expert panel comprising academic nursing faculty, endocrinologists, and clinical wound ostomy continence specialists appraised each translated statement for semantic, idiomatic, experiential, and conceptual equivalence. The calculated Content Validity Index (CVI) attained an outstanding value of 0.93. This empirical index confirmed that the 29 items adequately represent the intended functional, emotional, and social operational boundaries of quality of life in diabetic wound care.

Construct and Discriminant Validity via Known-Groups Technique

Construct validity was demonstrated utilizing the known-groups comparison methodology across clinical stages categorized by the internationally recognized Wagner ulcer classification system (grades 1 through 5, indexing progression from superficial skin lesions to localized osteomyelitis and extensive gangrene). The DFS-SF demonstrated sensitive discriminatory power: analysis of variance revealed statistically significant differences in subscale and composite scores across varying Wagner severity tiers. Patients presenting with advanced tissue destruction (Wagner Grades 3–5) scored significantly lower across physical functioning, leisure activities, and emotional well-being domains compared to individuals with localized superficial lesions (Wagner Grades 1–2), substantiating the instrument’s capacity to reflect genuine clinical disparities in wound severity.

Concurrent and Convergent Validity

Concurrent and convergent validity were established by correlating the DFS-SF dimensions against the established gold-standard generic health profile, the Medical Outcomes Study Short Form-36 (SF-36). As hypothesized, bivariate correlation analyses revealed statistically significant, moderate-to-strong positive associations between functionally congruent dimensions of both instruments:

• Physical Domains: Physical functioning subscales of the DFS-SF correlated strongly with the Physical Functioning (PF) and Role-Physical (RP) subscales of the SF-36 (r = 0.58 to 0.76, p < 0.001).
• Affective Domains: The emotional well-being and ulcer-worry factors correlated positively with the SF-36 Mental Health (MH) and Role-Emotional (RE) subscales (r = 0.43 to 0.64, p < 0.001).
• General Health Concordance: Across all convergent matrices, correlation coefficients ranged between r = 0.43 and 0.76. This moderate-to-strong magnitude confirms that while the DFS-SF aligns well with universal health domains, it captures a substantial proportion of unique, disease-specific variance unexplained by broad generic surveys.

Reliability

Reliability analysis demonstrates the degree to which a psychometric instrument is free from random measurement error, yielding stable, internally coherent scores across repeated evaluations. The psychometric investigation conducted by Kiliç et al. (2023) established exceptional reliability parameters for the DFS-SF across all subscales and composite metrics.

Internal Consistency

Internal consistency was examined via Cronbach’s alpha coefficients. The overall scale demonstrated an alpha coefficient of 0.93. Across the six individual subscale dimensions, internal consistency metrics remained remarkably high, ranging between 0.93 and 0.97. In classical test theory, alpha coefficients surpassing 0.80 indicate strong measurement consistency, whereas indices exceeding 0.90 confirm high precision appropriate for individual-level clinical decision-making and longitudinal outcome assessment. These values confirm that the items within each domain measure homogeneous, coherent psychological and functional facets without erratic measurement variance.

Item-Total Correlations

To evaluate the functional homogeneity of the individual scale components, corrected item-total correlation coefficients were calculated. Psychometric standards stipulate that items exhibiting correlation coefficients below 0.30 contribute poorly to the overarching construct and should be slated for structural elimination. In the DFS-SF validation, corrected item-total correlation coefficients ranged consistently between 0.73 and 0.86. This robust range indicates that every single item contributes meaningfully to the variance of its parent subscale, confirming that no items required deletion, rephrasing, or structural post-hoc modification.

Factor Analysis

To examine whether the empirical data conformed to the established theoretical model, the structural integrity of the 29-item DFS-SF was analyzed utilizing both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA).

Exploratory Factor Analysis (EFA)

Preliminary tests of sampling adequacy and data factorability supported structural extraction. The Kaiser-Meyer-Olkin (KMO) measure was well above the conventional threshold of 0.80, and Bartlett’s Test of Sphericity attained statistical significance (p < 0.001), indicating adequate correlation matrices for matrix reduction. Principal axis factoring with oblique rotation extracted six distinct latent factors corresponding directly to the original dimensions: Physical Functioning, Leisure Activities, Activities of Daily Living, Emotional Well-Being, Ulcer-Related Worries, and Social Role Burden. All 29 items exhibited substantial primary factor loadings, exceeding conventional psychometric thresholds (factor loadings > 0.50), without cross-loading anomalies requiring item elimination.

Confirmatory Factor Analysis (CFA)

A maximum-likelihood Confirmatory Factor Analysis was subsequently executed to rigorously test whether the observed covariance matrix aligned with the theoretical six-factor latent structure. Model fit indices confirmed that the multidimensional framework exhibited acceptable to good fit parameters:

• Comparative Fit Index (CFI): Reached 0.900, satisfying standard benchmark requirements (≥ 0.90) for acceptable model specification in complex clinical multidimensional instruments.
• Normed Fit Index (NFI): Fell within the well-established target range of 0.90 to 0.95.
• Root Mean Square Error of Approximation (RMSEA): Demonstrated a value below the conservative 0.08 threshold, confirming negligible residual error between the hypothesized and observed covariance structures.
• Chi-Square to Degrees of Freedom Ratio (χ²/df): Remained strictly below 3.0, representing robust model parsimony.

These structural findings confirm that the six-factor architecture of the DFS-SF remains psychometrically stable across cross-cultural translations, preserving the structural validity established in the initial instrument validation studies.

Instrument / Measurement Tool

The structured properties and administration parameters of the Diabetic Foot Scale-Short Form are detailed below:

• Instrument Name: Diabetic Foot Scale-Short Form (DFS-SF)
• Test Type: Patient-Reported Outcome Measure (PROM) / Clinical Health-Related Quality of Life Self-Report Questionnaire
• Format: 29 standardized items grouped across six multidimensional domains
• Target Population: Adult and geriatric patients diagnosed with diabetes mellitus (Type 1 or Type 2) presenting with active, chronic, or recurrent lower-extremity ulcerations
• Administration Modality: Pen-and-paper self-administration, digital tablet/electronic survey, or structured clinical interview by trained healthcare personnel for visually or physically impaired patients
• Completion Time: Approximately 7 to 12 minutes, minimizing respondent cognitive fatigue in clinical inpatient and outpatient settings
• Subscale Breakdown:
  • Physical Functioning
  • Leisure Activities
  • Activities of Daily Living (ADLs)
  • Emotional Well-Being
  • Ulcer-Related Worries
  • Social Role Burden
• Scoring and Transformation Rules:
  • Items are scored numerically, reflecting degree of limitation or psychological distress.
  • Subscale raw scores are calculated by summing the respective item scores within each validated dimension.
  • Raw scores are transformed linearly to a standardized 0–100 scale, where 0 represents the poorest possible health-related quality of life (maximal impairment/distress) and 100 represents the optimal health-related quality of life (zero perceived impairment/distress).

Permissions & Fee and Test Year

The original long-form Diabetic Foot Scale (DFS) was introduced in the early 2000s, followed by the development and structural streamlining of the Diabetic Foot Scale-Short Form (DFS-SF) to alleviate clinical response burden. The methodological adaptation and psychometric validation of the Turkish translation were conducted by Meryem Kiliç, Ayişe Karadağ, and Neşe Koçakgöl, published in 2023 in the Turkish Journal of Medical Sciences.

The DFS-SF is protected under academic and clinical copyright. While the scale is broadly accessible for non-commercial scientific research, academic dissertation projects, and non-profit clinical audits, prospective users must secure explicit permission prior to implementation. Researchers and clinicians wishing to utilize the Turkish version should contact the corresponding author, Dr. Meryem Kiliç ([email protected]), or the administrative copyright holders. Commercial applications, inclusion in sponsored pharmaceutical trials, or integration into proprietary electronic health record (EHR) software platforms generally require formal licensing agreements and institutional permissions from the primary copyright holders.

References

• Engel, G. L. (1977). The need for a new medical model: A challenge for biomedicine. Science, 196(4286), 129–136. https://doi.org/10.1126/science.847460
• Kiliç, M., Karadağ, A., & Koçakgöl, N. (2023). The validity and reliability of the Diabetic Foot Scale-Short Form (DFS-SF) in the Turkish population: a methodological study. Turkish Journal of Medical Sciences, 53(5), 1–10. https://doi.org/10.55730/1300-0144.5711
• Leventhal, H., Phillips, L. A., & Burns, E. (2016). The Common-Sense Model of Self-Regulation (CSM): A dynamic framework for understanding illness self-management. Journal of Behavioral Medicine, 39(6), 935–946. https://doi.org/10.1007/s10865-016-9782-2
• Verbrugge, L. M., & Jette, A. M. (1994). The disablement process. Social Science & Medicine, 38(1), 1–14. https://doi.org/10.1016/0277-9536(94)90294-1
• Ware, J. E., Jr., & Sherbourne, C. D. (1992). The MOS 36-item short-form health survey (SF-36): I. Conceptual framework and item selection. Medical Care, 30(6), 473–483. https://doi.org/10.1097/00005650-199206000-00002

Items of the Scale