Study design and procedure
This prospective study was carried out in 2019 in a cohort of patients with diabetes referred to the DPO at Sahlgrenska University Hospital in Gothenburg, Sweden. The purpose of the visit to the DPO was to provide the patient with pressure-relieving footwear, insoles together with shoes, to counteract the occurrence of DFU. The referred patients were contacted by phone and patients interested in participating in the study were informed by the principal investigator and received an invitation letter to the DPO, Fig. 1. The letter included information on how to answer the patient questionnaire in the D-Foot, Additional file 1. The second way for the patients to answer this questionnaire was at the DPO, where the survey was visualised on a tablet (Samsung Galaxy Tab. A 10.1). The patients’ answers were registered before the clinical examination began. If needed, the investigator helped the patients to register their answers on the tablet. The clinical examinations were assessed by one of two CPOs, at the DPO, following the routine in the D-Foot. The daily clinical work process in the prescription is as follows: a) the CPO evaluated the patients’ need for prescribed footwear, b) suggested and discussed a care plan with the patient, c) gave self-care advice and d) provided the patient with footwear as described in clinical guidelines [35]. The information, advice and provision of footwear were based on the patient’s risk of developing DFUs according to the D-Foot examination. Finally, the D-Foot assessment summary was printed out as a PDF report and given to the patient. The footwear was delivered either on the first visit or on a second visit to the DPO, two to 8 weeks later, Additional file 9.
The CPOs documented the assessments, tests, care plan decisions and the information they gave to patients in the local EMR system, Pilot, used at the DPO situated in Region Västra Götaland, Sweden.
The patients’ experiences of the visit to the DPO and the D-Foot examination were evaluated using the Orthotics and Prosthetics Users’ Survey (OPUS) [34]. The survey was filled in after the patients had been provided with their prescribed footwear. The users’ experiences of using the D-Foot were explored by registering the users’ (patients and CPOs) comments as they used the D-Foot at the DPO, Fig. 1. The method used was the think-aloud method, a method frequently used in usability testing where the spontaneous comments from the users are registered, in this case the patients and CPOs [36]. The registration was made by the principal investigator.
The CPOs’ expectations and experiences of using the D-Foot were evaluated using the System Usability Scale (SUS), before and after the study period.
Study sample – CPOs
Two experienced CPOs at the DPO at Sahlgrenska University Hospital agreed to participate in the study. They were skilled in prescribing footwear to patients at risk of developing DFUs with assistive devices and had worked as CPOs for nine and 20 years respectively.
Before the start of the study, each CPO completed a D-Foot introductory course which lasted for 2 h on two separate occasions. Moreover, the CPOs participated in a workshop with the purpose of becoming familiar with the D-Foot examination routine.
The D-foot software
The D-Foot software has seven functions: 1) a booking system to schedule patients’ appointments, 2) a questionnaire to be answered by patients, 3) examinations to be completed by a healthcare professional, Additional files 2, 4) a system for generating a risk classification for each patient, Additional files 3, 5) a summary as a PDF report, 6) a database containing all registered information and 7) an administration part licensing the CPOs to obtain access to the program [25]. A brief description of some different components included in the D-Foot is also included in Additional file 4 and a summary in Additional file 10. A detailed description has been presented in a previous study by Hellstrand Tang et al. [25]. Based on the results from the previous study, the users (eight CPOs) [25] suggested refinements as compared with the first version. The following improvements were therefore made: 1) adding a test of signs of peripheral angiopathy with the question “Has a healthcare professional confirmed that you have peripheral angiopathy?”, 2) excluding the navicular drop test [37], 3) excluding the test entitled “Can you extend and flex you toes”, 4) excluding the question of whether the foot had areas of excessive pressure with calluses, 5) excluding the assessment “Gait deviation, affected from hip/knee joint” and 6) splitting the assessment of Charcot foot (acute Charcot foot and manifest deformed Charcot foot) [25].
Furthermore, in the current version, the order of the assessment was reorganised to fit more effectively into a more clinical flow with the patient being examined first in a sitting position, followed by standing assessments.
Based on the patients’ answers in the survey and the assessment made by the CPO, a risk classification (1–4) was generated according to the national risk classification system [26, 38], Additional file 3. In this risk classification, the symptoms that are related to each of the risk categories are presented: peripheral neuropathy/angiopathy, foot deformities, skin pathologies, previous DFU/amputation, active DFU/Charcot deformity and/or severe pain syndrome. The risk classification, together with the recommended interventions, such as podiatry, footwear, and regular foot examinations, was automatically displayed on the screen of the tablet and was also included in the PDF report that was given to the patient. Finally, the CPO copied the results from the D-Foot and pasted them into the patient’s EMR and, in addition, all the data were stored in a separate D-Foot database. The reliability and validity of the D-Foot software have previously been presented by Hellstrand et al. [25].
Equipment
The CPOs recorded their findings on a laptop. Patients answered the patient questionnaire using a smart phone, tablet, or personal computer. A goniometer was used to measure passive maximum dorsal flexion at the metatarsal phalangeal joint and passive dorsiflexion at the ankle joint, as previously described by Hellstrand Tang et al. [25]. A foot calliper was used to measure foot length and foot width, while toe height was measured with a ruler [25], Additional file 4.
Questionnaire – patients
The patients answered the Swedish version of the Client Satisfaction with Services module of the OPUS after they had received their footwear. The OPUS module assesses patients’ experiences of the service quality and has been validated with Swedish patients at DPOs [34]. The 10 items are answered on a three-level Likert scale (disagree = 1, agree = 2 and strongly agree = 3) and were analysed by calculating the mean and standard deviation for each question. The OPUS questionnaire is recommended by the Swedish Orthotic and Prosthetic industry advisory council to evaluate patient satisfaction with the services at DPOs located in Sweden [39].
Questionnaire – CPOs
In connection with the start of the study, a Swedish version of the System Usability Scale (SUS) was answered by the CPOs to capture their expectations of using the D-Foot in clinical work, Additional file 5. The SUS consists of 10 questions answered on a five-level Likert scale (from strongly disagree = 1, to agree completely = 5) and is a reliable tool for measuring usability [40]. At the end of the study, the CPOs answered the SUS a second time to assess their experiences of using the D-Foot, Additional file 6. These answers were transformed to a 0–100 scale, where a higher score indicates a higher level of usability.
In addition, at the end of study, the CPOs answered a study-specific questionnaire on how they had experienced the digital foot examination, what information they had given to the patients and how long it took for the CPOs to execute different sequences of the examination, Additional file 7. The questions on time estimations were related to how long it took to: 1) finalise the patient appointment and foot assessment when the D-Foot routine was used (< 30 min., 31–45 min., 46–60 min., > 60 min), 2) make the medical recording based on the D-Foot examination (< 6 min., 6–10 min., 11–15 min., 16–20 min.) and 3) order their prescribed footwear (< 6 min., 6–10 min., 11–15 min., 16–20 min.), Additional file 8.
Statistics
Descriptive statistics were used to present patient demographics. The mean and standard deviation were calculated for continuous variables. Differences between the included patients and the non-included patients were compared with an independent t-test for age and Pearson’s chi-square test for gender. IBM SPSS Statistics for PC, Version 25, was used for all statistical calculations.