Design
This was an observational cross-sectional study. The authors followed the STROBE guidelines for the reporting of observational studies.
Participants
A consecutive convenience sample of older individuals presenting as outpatients to a geriatric day hospital of an acute general teaching hospital were invited to participate in the study. Recruitment took place between June - July 2017. Participants were included if they were aged over 60 years, were living at home, were attending the geriatric day hospital, agreed to participate in the study, were able to stand independently and had the ability to understand simple instructions so as to allow completion of assessments. The senior physiotherapist in the day hospital acted as a gatekeeper. Participants deemed to be eligible were invited to take part in the study and provided with an information leaflet, and gave written informed consent. The study was approved by the hospital’s Research Ethics Committee (REC2017-05-6).
Procedure
Participant characteristics
Information on age, level of mobility, and co-habitation status (living alone or with others) was determined from participant self-report and medications were recorded from participant medical records. The Nottingham Extended Activities of Daily Living (NEADL) Scale was conducted with each participant to assess their self-reported level of functional independence and scored from 0 (low independence) to 22 (high independence) [21]. Functional mobility, as measured by a recent ‘Timed Up and Go’ (TUG) score was retrieved from the physiotherapy department records [22]. Polypharmacy, a known risk factor for falls, was defined as five or more medications daily [23, 24]. Self reported falls-history (one-month and six-month) was also collected [25]. The definition of a fall was taken from the work of Tinetti [26]. Participant functional ability was characterised in this study by use of mobility aid, TUG score and NEADL score.
Fit of Footwear
The definition used in this study for correctly fitting shoe size was taken from the work by Chantelau and Gede [27]. They describe the need for a gap of 10 to 15mm between the toes and the anterior of the shoe to allow "extra space for the toes when extending during walking and standing" [27]. A similar measure of “approximately 1.5cm between the hallux and the shoe end” was used by Menant et al [14]. The primary outcome of interest in this study was selected as having footwear within the suggested range (10 to 15mm) on at least one foot. This was decided as discrepancy between right and left sizes has been found to be one of the most common reasons for recommendation of larger shoes among older adults, as split-sizes would need custom order [28]. Foot and footwear assessments were administered in a quiet, bright physiotherapy treatment room by a student physiotherapist who had received specific training. We piloted the research procedures in the first week of the study to ensure standardised foot and footwear measurement.
Foot measurements
Both feet of each participant were measured in millimetres using a SATRA shoe size stick. Each participant stood barefoot and relaxed, with the feet slightly apart and with the weight evenly distributed between both feet. The fixed anvil of the SATRA shoe size stick (Figure 1a) was placed behind the heel of the foot (which was barefoot, socks off) being measured with the researcher firmly holding the participant’s ankle and device together. The researcher then moved the sliding caliper up to the longest toe and noted the foot length indicated. It is important to note that the longest toe was not necessarily the first toe. The same procedure was repeated for the other foot. The participant’s self-reported shoe size was also recorded.
Footwear measurements
The participant’s footwear was placed on a firm level surface. A calibrated Internal Shoe Size Gauge® (SATRA, UK) was then placed into the shoe and the flat bar of the device pushed into the shoe until it clearly contacted the end of the toe box (Figure 1b). The slide of the device was then adjusted until the rear curved bar section touched the heel of the shoe. The internal length of the shoe was recorded in mm. The same procedure was then repeated for the other shoe.
Footwear assessment
Footwear was assessed using the Footwear Assessment Form (FAF), which is a reliable tool for the assessment of shoe style, heel height, fixation, heel counter stiffness, longitudinal sole rigidity, sole flexion point, tread pattern and sole hardness [10]. We asked all participants if the shoes worn at the time of the assessments were their regular daily footwear.
Statistical analyses
The difference between foot length and internal shoe-length was calculated in mm. The proportion (with 95% confidence intervals) of participants whose foot to shoe length difference was outside the 10 to 15mm range was calculated. Those with shoes fitting on at least one foot were compared to those with ill-fitting footwear on both feet using the Chi-square test for categorical variables and the T-test or Mann–Whitney U test for continuous variables depending on normal quantile plots. Statistical analyses were carried out using SPSS® Statistics Version 16. The authors used the STROBE guidelines for the reporting of observational studies.