A fact‐finding survey on self‐efficacy of foot care behaviour in patients with diabetes: Analysis using the Diabetes Study from the Center of Tokyo Women’s Medical University 2017 (DIACET 2017)

Abstract Aim We aimed to determine the association between self‐efficacy of foot care behaviour and chronic complications in Japanese patients with diabetes. Methods We conducted a cross‐sectional study based on a questionnaire survey of 4571 patients with type 1 and type 2 diabetes who had (a) given consent to participate in the Diabetes Study from the Center of Tokyo Women's Medical University: DIACET 2017, and (b) completed all the questions of the Japanese Version of Foot Care Confidence Scale (J‐FCCS), consisting of 12 statements. Results A greater proportion of respondents answered that they were not confident in determining the condition of corns and/or calluses and the condition of toenails. The J‐FCCS total scores of the patients with retinopathy (p <.001) and numbness or pain in the feet (p <.001) were significantly lower than those of the patients without these complications. In both the multiple regression analysis and logistic regression analysis, lower J‐FCCS was significantly associated with retinopathy and numbness or pain in the feet. Conclusion Foot care education that emphasizes a psychological approach in improving confidence associated with foot self‐care is important for patients with advanced complications of diabetes.

by themselves so that they can start introducing changes in their daily lifestyles. To initiate this behaviour modification, patients need not only acquisition of knowledge and skills related to foot care, but also improvement of patient self-efficacy as a psychological approach. Self-efficacy is belief that what one intends to do is efficacious and confidence to properly conduct the behaviour. 5 Educational interventions targeting self-efficacy improvement in patients with diabetes have been recently reported to promote the aggressiveness of foot self-care behaviours. [6][7][8] The Foot Care Confidence Scale (FCCS) 9 which evaluates self-efficacy of foot care behaviour has been recently utilized as an effect measurement after foot care education programs. 10,11 While foot care education with an awareness of self-efficacy is required in Japan, there are very few studies on self-efficacy of foot care behaviour in patients with diabetes, the association between self-efficacy of foot care behaviour and clinical background has not been thoroughly investigated. 12,13 In addition, the sample size of these studies were small, limiting the generalizability. We therefore conducted this large study to clarify the association between self-efficacy of foot care behaviour and microvascular complications in patients with type 1 and type 2 diabetes, using the Japanese version of the FCCS (J-FCCS). 13

| Study design and ethical issues
This was a single-centre cross-sectional study that was approved by the Ethics Committee of Tokyo Women's Medical University

| Subjects
The subjects were Japanese patients with type 1 and type 2 diabetes and other types of diabetes were excluded. Patients who had withdrawn from insulin therapy after successful pancreas transplantation were included in patients with type 1 diabetes.

| Methods
As described previously, 14 self-administered questionnaires were distributed to all outpatients visiting our centre and in patients at admission to investigate the subject's status of glycemic control, subjective symptoms related to diabetic complications and history of clinical visit for cardiovascular diseases, as well as self-efficacy of foot care behaviour using the J-FCCS. Laboratory data and information on the presence or absence of any stage of diabetic retinopathy and nephropathy were collected from medical records.
The FCCS questionnaire includes 12 statements related to undertaking various foot care behaviour (Table 1), and the subjects were asked to rate the degree of self-efficacy. A five-point scale was scored from 1 to 5, each of which corresponds to 'strongly not confident', 'moderately not confident', 'confident', 'moderately confident' and 'strongly confident. The total score consisting of the 12 statements ranging 12 to 60 was then calculated. Higher scores indicates higher levels of self-efficacy of foot care behaviour. The validity and reliability of the Japanese version, J-FCCS, have been demonstrated in the past. 13 For haemoglobin A1c (HbA1c) and serum creatinine, mean levels measured between January and December 2017 were used. The estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine levels, age and sex. 15 An eGFR <60 ml/min/1.73 m 2 or being on dialysis therapy was defined as chronic kidney disease (CKD). 16

| Statistical analysis
Continuous variables were expressed as arithmetic mean ± standard deviation (SD) or geometric mean with 95% CI, as appropriate according to data distribution. Categorical data were expressed by number (%). Continuous data were compared using Student's t test and categorical data using Fisher's exact test. Analysis of covariance (ANCOVA) were used to compare the total J-FCCS scores by type of diabetes. Based on the median of the total J-FCCS score, the patients were classified into higher and lower J-FCCS score groups.
The associations between J-FCCS scores and diabetic complications were examined using the multiple regression analysis and logistic regression analysis adjusting for the following parameters: age, sex, body mass index (BMI), HbA1c, duration of diabetes, use of insulin, antihypertensive and antilipemic agents, and history of clinical visit for cardiovascular diseases. p values <.05 were considered significant. All statistical analyses were performed using the SAS version 9.4 (SAS Institute, Cary, NC, USA).  Table 2 shows the clinical characteristics of overall subjects and those classified by type of diabetes. Patients with type 1 diabetes were younger (p < .001), included more women (p < .001) and had a longer diabetes duration (p < .001) than those with type 2 diabetes. Patients with type 2 diabetes were more likely to have hypertension, dyslipidemia, and micro-and macroangiopathic complications. Table 1 shows the percentages of patients responding to each J-FCCS statement evaluated on a five-point scale. Of the 12 statements, that with the greatest proportion of the subjects responding 'strongly or moderately not confident' was ability to identify the condition of corns and calluses (Question 6), followed by ability to identify the condition of the toenails (Question 4).

| Comparison of the J-FCCS total scores by type of diabetes and sex
The median (range) and mean (±SD) J-FCCS total score of overall subjects was 51 (12-60) and 50.0 ± 8.6, respectively. The difference of the mean J-FCCS total scores for patients with type 1 and type 2 patients was minimal but statistically significant (Table 1). After adjustment for the above confounders, the significance of the J-FCCS score disappeared (p = .300). There was no significant difference in the J-FCCS total scores between men and women (p = .091).

| The association between the J-FCCS total scores and diabetic microangiopathy
The scores of the patients with microvascular complications were significantly lower than those of the patients without (

TA B L E 2 Clinical characteristics and laboratory data
feet associated with neuropathy [p < .001]). The multiple regression analysis showed that retinopathy (p < .001) and numbness or pain in the feet (p < .001), but not CKD (p = .118), were significantly associated with lower J-FCCS total scores (Table 3). In the logistic regression analysis, presence of retinopathy and numbness or pain in the feet were also significantly associated with lower J-FCCS score ( Table 4). The same trends were observed in the separate analysis by type of diabetes (Tables 3 and 4).

| D ISCUSS I ON
The aim of the present study was to determine the association be- The total J-FCCS score in this study was higher than that in another Japanese study. 13 We also found that diabetic retinopathy and neuropathy were significantly associated with the J-FCCS scores in both types of diabetes.
The lack or lower confidence in identifying the condition of corns, calluses and toenails in many patients was also reported by another Japanese group. 12   The association between diabetic microangiopathy and self-efficacy of foot care behaviour has not been clarified. Since this was a cross-sectional observational study, the causal relationship between self-efficacy of foot care behaviour and diabetic microangiopathy was not clarified. However, studies have found that many patients with diabetes with retinopathy and neuropathy did not engage in foot self-care behaviour. 19,20 From the present study, the reason may be associated with the lack of confidence in engaging in foot care behaviour due to visual impairment and sensory impairment of the skin. A study of patients with diabetic peripheral neuropathy found an association between daily foot observations and self-efficacy, 21 suggesting that foot care education that emphasizes a psychological approach to improve confidence associated with foot self-care may be needed in patients with advanced complications of diabetes.
Even with high self-efficacy, patients may not engage in self-care behaviour if they themselves do not sufficiently feel the need. 22 In addition to self-efficacy, engagement of self-care behaviour is reported to be associated with a high level of knowledge about diabetes, social support, and advice from family members and healthcare providers. 21,23 Therefore, it is important that healthcare providers (a) carefully and continuously explain the need for self-care, (b) motivate the patients, (c) check that self-care has been implemented and (d) conduct regular self-efficacy assessments. In this respect, we believe that the use of the J-FCCS, which quickly and conveniently checks the state of mind related to foot care behaviour, is useful.
The limitations of the study were as follows. Since this study was conducted at a single university hospital, the subjects may not be representative of Japanese patients with diabetes. Selection bias cannot be ruled out because subjects in DIACET was voluntary, and the present study also investigated self-efficacy of foot care behaviour using a self-administered questionnaire. Therefore, subjects who were unable to complete the questionnaire, due for example to severe visual impairment and dementia, were not included, probably TA B L E 3 Association between the J-FCCS total scores and diabetic microangiopathy. overestimating the results. Furthermore, there may be potential factors that affected self-efficacy, such as the assessment of blood flow in the lower extremities and clinical characteristics including lipids, blood pressure, smoking history, alcohol consumption and a history of diabetic foot ulcers. The presence of numbness or pain in the feet associated with neuropathy was also determined based on self-reporting by the patient. Conditions that trigger numbness and pain in the feet include spinal disorders such as herniated intervertebral disc and peripheral arterial diseases. It is desirable to conduct a comprehensive neuropathy assessment by testing vibration and pressure sense and the Achilles tendon reflex. Lastly, since this was a cross-sectional observational study, the causal relationship between self-efficacy of foot care behaviour and diabetic complications remains unknown.
Longitudinal studies are needed to assess causal association between self-efficacy of foot care behaviour and diabetic complications.

| CON CLUS ION
The present fact-finding survey showed that a large proportion of Japanese patients with diabetes were not confident in determining the condition of corns, calluses and toenails. Lower self-efficacy of foot care behaviour was strongly associated with diabetic retinopathy and neuropathy. Foot care education that emphasizes a psychological approach in improving confidence associated with foot self-care is considered to be important for patients with advanced complications of diabetes. Regular self-efficacy assessments using the J-FCCS are needed to improve self-efficacy and prevent the development of foot ulcers.

ACK N OWLED G M ENTS
The authors express their deep appreciation to the DIACET participants and the associated staff in Diabetes Center, Tokyo Women's Medical University School of Medicine.

CO N FLI C T O F I NTE R E S T
The authors declare that they have no competing interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.