(DFSQ-UMA) Diabetic Foot Self-Care. - Development, Validation and Psychometric [PDF]

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Development, validation and psychometric analysis of the diabetic foot self-care questionnaire of the University of Malaga... Article in Journal of tissue viability · November 2014 DOI: 10.1016/j.jtv.2014.11.001



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Jose Miguel Morales Asencio



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Jose Antonio Cervera-Marin



Gabriel Gijon-Nogueron



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Journal of Tissue Viability (2015) 24, 24e34



www.elsevier.com/locate/jtv



Clinical study



Development, validation and psychometric analysis of the diabetic foot self-care questionnaire of the University of Malaga, Spain (DFSQ-UMA) ´ Miguel Morales-Asencio a, Emmanuel Navarro-Flores a,*, Jose ´ Antonio Cervera-Marı´n a, Ma Teresa LabajosJose Manzanares b, Gabriel Gijon-Nogueron a a



Department of Nursing and Podiatry, Faculty of Health Sciences, University of Malaga, C/Arquitecto Francisco Pen˜alosa, Ampliacio´n del Campus de Teatinos, 29071 Ma´laga, Spain b Department of Physiotherapy, Faculty of Health Sciences, University of Malaga, C/Arquitecto Francisco Pen˜alosa, Ampliacio´n del Campus de Teatinos, 29071 Ma´laga, Spain



KEYWORDS Diabetes; Diabetic foot; Self-care; Instrument development; Reliability; Validity



Abstract This paper assessed the reliability and construct validity of a tool to evaluate the foot self-care of diabetic patients. The education of diabetic patients about their foot care is a major issue to avoid complications like amputations and ulcers. Specific tools aimed to assess patient’s knowledge in this area are needed. The study had two phases: in Phase 1, item-generation was carried out through a literature review, expert review by a Delphi technique and cognitive interviews with diabetic patients for testing readability and comprehension. In Phase 2, diabetic patients participated in a cross-sectional study for a psychometric evaluation (reliability and construct validity) was carried out on a sample of type I and II diabetic patients. The study was conducted at the University of Malaga (Spain), podiatric clinics and a Diabetic Foot Unit between October 2012 and March 2013. After psychometric-test analyses on a sample of 209 diabetic patients, the questionnaire resulted in 16 questions. Cronbach’s alpha was 0.89 after removing 4 items because of their low reliability. Inter-item correlations gave a mean value



* Corresponding author. E-mail addresses: [email protected] (E. Navarro-Flores), [email protected] (J.M. Morales-Asencio), [email protected] (J.A. Cervera-Marı´n), [email protected] (M aT. LabajosManzanares), [email protected] (G. Gijon-Nogueron). http://dx.doi.org/10.1016/j.jtv.2014.11.001 0965-206X/ª 2014 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.



Questionnaire of the diabetic foot self-care



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of 0.34 (range: 0.06e0.74). The rotated solution showed a 3-factor structure (selfcare, foot care, and footwear and socks) that jointly accounted for 60.88% of the variance observed. The correlation between the questionnaire scores and HbA1c was significant and inverse, (r ¼ 0.15; p < 0.01). The findings show that the questionnaire is a valid and reliable tool for evaluating foot self-care behavior in diabetic patients. ª 2014 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.



Introduction There are many instruments available for evaluating care and self-care behaviors in diabetic patients, like Neuropathic Total Symptom Score or S4-MAD [7,35], but very few exclusively evaluate foot self-care and they mix questions about selfcare with questions relative to general care, as the Diabetic Foot Ulcer Scale (DFS) or the Foot Ulcer Scale-short form (DFS-SF) [1,6]. On the other hand, current instruments more specific for foot self-care present some shortfalls, as an elevated number of items [12] or an insufficient or nonthorough validation process [27]. Generally, education on foot care is directed mainly at patients with a history of complications, above all those with rising levels of HbA1c and those having had diabetes for several years [33]. In addition, while many of the studies focus on preventing the risk of ulcers and amputations [9,11,15,41], very few are aimed to determine the specific degree of foot self-care in the population having diabetes mellitus [27,32,33,36,42]. World prevalence of diabetes is predicted to rise from 2.9% in the year 2000 to 4.4% by the year 2030, when an estimated 366 million people will suffer the disease [22]. Foot ulcers, one of the main complications of diabetes, appear in 15%e 25% of the patients at some point along their lives [13,41,45]reducing their health-related quality of life (HRQoL), both in terms of physical integrity, as well as psychological function [46]. All these factors can be prevented by adequate prevention measures and early diagnosis of alterations [9], particularly by patient’s self-care. Diabetological education is one of the key elements for this aim, being recommended in most of clinical guidelines as the standard for managing the diabetic foot [23]. In this sense, the development of tools with informed results for the patients themselves (Patient-Reported Outcomes, PRO) constitutes a growing approach in recent years, especially in the field of attention to chronic diseases. PRO are selfreports on the health status of patients without



any professional mediation [20] and are intended to record concepts related to the patients’ experiences and feelings, or how they function in relation to their illness and treatment [26]. These reports go further the classical end-points in trials (efficacy, safety, etc) and their use in experimental studies is proliferating, particularly in drug clinical trials. HRQoL is one of the most widespread, although it can also be applied to other areas, such as self-care. One of the consequences is the scarcity of the specific information, based on solid evidence when advising diabetic patients on foot care [21]. Currently, only two specific guides exist for this problem: the one published by the American Diabetes Association (ADA) and the one by the International Working Group on the diabetic foot [5,23]. Furthermore, patients qualified as low-risk can develop complications relatively fast in the absence of good glycemia monitoring and adequate self-care practices [33]. Consequently, focus should not be placed exclusively on patients with a record of complications. The foot care carried out by diabetic patients, regardless of their history of complications, would help to ensure early interventions in cases of deficient self-care. For this, it would be recommendable to use an instructive tool for the patient, easy to use in the daily practice, and with adequate validity and reliability. The aim of this study is to design and validate a tool to evaluate the foot self-care of diabetic patients in order to generate a specific PRO.



Methods Sample and setting A cross-sectional validation study was conducted at the University of Malaga (Spain), podiatric clinics and a Diabetic Foot Unit between October 2012 and March 2013. The study had two phases: in Phase 1, item generation was carried out through a literature review. This items list underwent an



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E. Navarro-Flores et al.



expert review and consensus by Delphi technique. Experts were professors from the Department of Nursing and Podiatry and two external reviewers, one of them a clinical nurse specialist on diabetic foot and the other one an endocrinologist. Following, cognitive interviews to diabetic patients for testing readability and comprehension were performed. In Phase 2, diabetic patients participated in a cross-sectional study for a psychometric evaluation of the questionnaire developed in the first phase (Fig. 1).



Phase 1 item generation and content validity The authors reviewed the literature on HRQoL, pain and functionality instruments for foot care questionnaires, selecting the Spanish versions of SF 36 [3], the Spanish versions of Manchester Foot Pain and Disability Index (MFPDI) [18], Disabilities of the Arm, Shoulder and Hand [38], Western Ontario and McMaster Universities Osteoarthritis Index [8], and Nottingham Assessment of Functional Footcare (NAFF) [28]. From this review, a total of 60 items for analysis were proposed to the expert panel to evaluate their appropriateness. The expert panel was integrated by two podiatrists specialized on diabetic foot, one endocrinologist, one specialist nurse on diabetic foot and one expert on questionnaire development and validation. All of them had more than 10 years of expertise on treating diabetic patients, except the methodologist. Additionally, panelists were asked



Fig. 1



to respond to the following open-ended questions: “What are the most important aspects of foot selfcare in diabetic patients? Why are they so important? Why do you think that other self-care aspects are not as much important as those ones that you have selected? The open responses were analyzed, grouping them by frequency and commonalities. The most frequent responses were some particular aspects of foot care as use of adequate shoes, foot hygiene, and the main reason argued was that they were associated with a decrease in foot amputations. The questionnaire was filled out individually by each expert scoring the 60 items on a scale from 1 to 9. Two rounds were necessary for obtaining consensus. Following the first round, 30 items were selected after applying the following criteria: consensus was determined when the median score given by more than 75% of the experts was over 6 (consensus on item selection), or below 4 (consensus on item deletion) [30]. Those items scored between 4 and 6 were undergone to a new round. Following this phase, the 22 items version was obtained [40]. Some examples of items deleted were “Use of socks for warming your feet”, “Use of sport shoes”, “Use of flip-flops”. This preliminary 22 items version was validated by diabetic patients through cognitive interviews. A group of 30 diabetic patients that regularly visit the Podiatry Clinic at the Faculty of Health Sciences in the University of Malaga were invited to participate in the interviews with the aim of evaluating the



Process of item evaluation.



Questionnaire of the diabetic foot self-care readability and understandability of the proposed items. Respondents first were asked to interpret in a consistent manner what did they understand about each item. They had to recall the information available to them in order to make a judgment and fit it into the question. All interviews were conducted in person by a member of the team, who recorded the answers by mean of a Likert scale (range 1e5 in ascending order of readability, understandability and fit of their information to the question), that represented their difficulties with the item. Moreover, verbal and non-verbal cues about their perception of the item contents were taken into account for the evaluation of their understanding [39]. The information given by the patients during the cognitive interviews led to revise or delete some items for clarity reasons (those items scored by patients below 3), and the questionnaire was reduced to 20 items. Once designed the definitive items, a scale with 5 possible options that represented the adequacy of the self-care behavior was added: (1, very inadequate; 2, inadequate; 3, fair; 4, adequate; and 5, very adequate), except some items that explored the frequency of a determined self-care activity (1, Never; 2, Rarely; 3, Sometimes; 4, Often; 5, Always) (Fig. 2). Fig. 2 represents the whole process from the item generation to the final version.



Phase 2 reliability analysis and construct validity test instrument 1) Inclusion criteria The inclusion criteria were: to have diabetes mellitus type I or II and to be over 18 years of age. The exclusion criteria were: to be illiterate, or to have any amputation of the lower limbs. 2) Recruitment process The Podiatry Clinic of the Faculty of Health Sciences of the University of Malaga were selected, private podiatric clinics and from the Diabetic Foot Unit, in Malaga.



27 years with diabetes, weight, height, and educational level).



Data analysis An exploratory data analysis was performed which included descriptive statistics and an analysis of data normality by the KolmogoroveSmirnov test. Internal consistency was evaluated by Cronbach’s a coefficient. Cronbach’s a coefficient of 0.7 or above was considered satisfactory [29], and Pearson’s correlations were used for inter-item and item-total correlations. Floor and ceiling effects were evaluated, selecting values between 1% and 15% as optimal [31]. For test-retest reliability, a sub-sample of patients (n ¼ 30) completed the questionnaire. Kappa statistics with 95% CIs were computed to verify the level of inter-rater agreement concerning the different care categories (minimum, intermediate, semi-intensive, and intensive). Weighted kappa was chosen to consider the level of disagreement, in terms of the seriousness between evaluators [4]. The k-values were interpreted using [4] levels of agreement, as follows: