Background
Methods/Design
Ethical approval
Study design
Participant recruitment, screening and eligibility criteria
Baseline appointment
Participants characteristics | Comorbidities | Laboratory blood test results |
---|---|---|
Age (years) | Diabetes (documented diagnosis in medical history, including type and duration) | C-reactive protein (mg/L) |
Sex (male or female) | Retinopathy (documented diagnosis in medical history) | Serum albumin (g/dL) |
Height (m) | Known peripheral neuropathy (documented diagnosis in medical history) | Total calcium (mmol/L) |
Weight (kg) | Known peripheral arterial disease or history of lower extremity revascularisation procedure (documented diagnosis in medical history or documented lower extremity revascularisation procedure e.g. angioplasty) | Serum phosphate (mmol/L) |
Parathyroid hormone (pmol/L) | ||
Glycated haemoglobin (%) | ||
Haemoglobin (g/L) | ||
Body mass index (kg/m2) | Hypertension (documented diagnosis in medical history and must be requiring medication) | |
Smoking history (past, current, never) | Dyslipidaemia (documented diagnosis in medical history) | |
Living arrangements (living alone) | Ischaemic heart disease (documented diagnosis of ischaemic heart disease, angina, myocardial infarction or coronary bypass surgery in medical history) | |
Ethnicity | ||
• Indigenous Australian (Aboriginal or Torres Strait Islander) | ||
• English | Congestive cardiac failure (documented diagnosis in medical history) | |
• European | ||
• American | ||
• African | Cerebrovascular disease (documented diagnosis of cerebrovascular accident or transient ischaemic attack in medical history) | |
• Asian | ||
• Pacific Islander | ||
• Other | ||
Cause of end-stage renal disease | ||
• Diabetic nephropathy | Osteoarthritis (documented diagnosis in medical history) | |
• Hypertensive nephropathy | ||
• Chronic glomerulonephritis | Inflammatory arthritis (documented diagnosis in medical history of a type of inflammatory arthritis e.g. gout, rheumatoid arthritis, psoriatic arthropathy) | |
• Polycystic kidney disease | ||
• Reflux nephropathy | ||
• Renovascular disease | ||
• Vasculitis | ||
• Unknown | Other (any other documented medical conditions) | |
• Other | ||
Dialysis treatment | ||
• Haemodialysis | ||
• Continuous ambulatory peritoneal dialysis | ||
• Automated peritoneal dialysis | ||
Duration of dialysis (months) |
Neurological assessments | Equipment | Procedure | Diagnosis/study definition |
---|---|---|---|
Known peripheral neuropathy | N/A | Medical record review. | History of peripheral neuropathy documented in medical records. |
Loss of protective sensation | Baily Instruments Ltd® (Salford Quays, UK) Semmes-Weinstein 5.07/10 g monofilament [37]. | • Monofilament is first applied to participant’s hand or elbow (so that the participant knows what sensation to expect) | Failure to detect the monofilament at a specific site, even after re-testing the deficit site, in at least one foot will result in a failed test (i.e. score of <3/3 on either foot) [36]. |
• Ensure the participant’s eyes are closed | |||
• Monofilament applied perpendicular to the skin and held for 1–2 secs, applying sufficient force to bend or buckle the monofilament fibre [16] | |||
• Participant is asked by the assessor to respond “yes” when they feel the monofilament | |||
• This is repeated for all 3 sites on each foot (6 sites in total) | |||
• Deficit sites will be re-tested once | |||
Vibration perception threshold | Horwell® Neurothesiometer (Wilford, Nottingham, UK). | • Neurothesiometer is first applied to the participant’s hand or elbow (so that the participant knows what sensation to expect) | |
• Participant is asked to close their eyes and to report “yes” when they first start to feel a vibratory sensation | |||
Note: Vibration perception threshold will be measured at the base of the first, third or fifth metatarsals if there are current ulcers on the hallux, or previous amputation of the hallux [43]. |
Arterial assessments | Equipment | Procedure | Diagnosis/study definition |
---|---|---|---|
Known peripheral arterial disease and/or history of lower extremity revascularisation procedure | N/A | Medical record review. | History of peripheral arterial disease and/or lower extremity revascularisation procedure documented in medical records. |
Pedal pulses | N/A | • Physical palpation of the dorsalis pedis and posterior tibial pulses on both feet with the examiners fingers (4 pulses in total) [52] | Absence of ≥2 pedal pulses will indicate peripheral arterial disease [52]. |
• Pedal pulses will be recorded as ‘present’ or ‘absent’ | |||
Toe-brachial pressure index | SysToe® (Atys Medical, Soucieu-en-Jarrest, France). | • Toe pressure measurement will be performed prior to the ankle pressure measurement to ensure arterial supply to the toes is not affected | |
• Room temperature (minimum 21–23 ± 1° C) to prevent vasoconstriction of digital arteries [92] | |||
• Participants will be rested for a minimum of 15 min prior to assessment | |||
• Double-sided tape is applied to sensor [47] | |||
• Toe pressure assessment is repeated for contralateral side (if appropriate) | |||
• Toe-brachial pressure index value is calculated by dividing the toe systolic pressure by the highest (or available) brachial systolic pressure | |||
• Toe brachial pressure index value calculated separately for left and right lower limbs | |||
Note: Brachial systolic pressures obtained in the ankle-brachial pressure index assessment will be used to calculate the toe-brachial pressure index value. | |||
Ankle-brachial pressure index | Hadeco Bidop ES100V3 Bi-Directional Doppler Complete with LCD Display and 8 MHz Probe. | • Room temperature (minimum 21–23 ± 1° C) to prevent vasoconstriction of digital arteries [92] | |
Erka® ‘Switch’ Sphygmomanometer and cuff. | • Participants will be rested for a minimum of 15 min prior to assessment | ||
• Brachial cuff is applied 3 cm above the cubital fossa | |||
• Brachial pulse located via palpation | |||
• Doppler ultrasound conducting gel is applied to the skin [92] | |||
• Doppler probe is applied at a 45° angle to the skin [92], in the direction of the arterial blood flow | |||
• Cuff is inflated to 20–30 mm Hg beyond the last audible signal and then slowly deflated until the audible signal returns [92] | |||
• Repeated for contralateral side (if appropriate) | |||
• Brachial systolic pressure(s) recorded | |||
Note: In the case of an arteriovenous fistula (i.e. vascular access for haemodialysis treatment) the brachial systolic pressure will be measured from the arm free of the fistula [45]. | |||
• Ankle cuff is applied 3 cm above the medial malleolus | |||
• Dorsalis pedis and posterior tibial pulses are located via palpation | |||
• Doppler ultrasound conducting gel is applied to the skin [92] | |||
• Doppler probe is applied at a 45° angle to the skin [92], in the direction of the arterial blood flow | |||
• Cuff is inflated to 20–30 mm Hg beyond the last audible signal and then slowly deflated until the audible signal returns [92] (maximum 240 mm Hg). Process is repeated for both the dorsalis pedis and posterior tibial pulses | |||
• Repeated for contralateral side (if appropriate). | |||
• The highest of the two systolic pressure values obtained from the dorsalis pedis and posterior tibial pulses will be recorded [92] | |||
Note: If the pressure needs to be repeated, the examiner will wait one minute before re-inflating the cuff [92]. | |||
• Ankle-brachial pressure index value is calculated by dividing the highest ankle systolic pressure (i.e. highest value between dorsalis pedis and posterior tibial pulses) by the highest (or available) brachial systolic pressure | |||
Note: Ankle-brachial pressure index value is calculated separately for left and right lower limbs. |
Biomechanical assessments | Equipment | Procedure | Diagnosis/study definition |
---|---|---|---|
Foot deformity | The Manchester Scale [57]. | • The presence of hammer/claw toes, hallux abducto valgus, bony prominences (e.g. prominent metatarsal heads), Charcot neuroarthropathy and any other foot deformities (e.g. forefoot pad atrophy) will be assessed visually [57] | Foot deformity will be recorded with the presence of ≥1 foot deformity on either foot. |
• Foot deformity will be recorded as ‘present’ or ‘absent’ | |||
Range of motion (1st metatarsophalangeal joint) | Goniometer. | • Passive range of dorsiflexion at the 1st metatarsophalangeal joint will be measured using goniometry with the ‘static non-weightbearing technique 1’ described by Hopson et al. [60] | Range of motion <65° indicates limited joint mobility of the first metatarsophalangeal joint [60]. |
Plantar pressures | Tekscan Matscan® system (Tekscan Inc, South Boston, MA, USA). | Mean peak plantar pressures will be investigated to determine whether they are predictive of foot ulceration. | |
5.7 mm thick floor mat (436 × 369 mm), 2288 resistive sensors (1.4 sensors/cm2), dynamic events captured with scan rates of 440 Hz. | • The two-step gait initiation protocol will be used, with the technique as described by Zammit et al. [64], except that both feet will be assessed | ||
FootMat™ 7.0 software (Tekscan Inc, South Boston, MA, USA). | • The mat will be calibrated for each patient using that patient’s own weight before each testing session | ||
• Peak plantar pressure will be measured at seven regions of the foot, including the heel, midfoot, first metatarsophalangeal joint, second metatarsophalangeal joint, 3–5 metatarsophalangeal joints, hallux and lesser toes [64] | |||
Footwear assessments | Procedure | Diagnosis/study definition |
---|---|---|
Fit, general features, style and condition | • The fit (length, width, depth), general features (fixation, forefoot sole flexion point, heel height, materials), style and condition of footwear will be assessed based on the footwear assessment tool described by Barton et al. [65] | Footwear will be deemed inappropriate if there are any issues with shoe fit, inappropriate style or condition. |
Dermatological assessments | Procedure | Diagnosis/study definition |
---|---|---|
Skin pathology | Skin pathology will be recorded with the presence of ≥1 skin pathology on either foot. | |
• Skin pathology will be recorded as ‘present’ or ‘absent’ | ||
Nail pathology | Nail pathology will be recorded with the presence of ≥1 nail pathology on either foot. | |
• Nail pathology will be recorded as ‘present’ or ‘absent’ |
Lower extremity complication | Procedure | Diagnosis/study definition |
---|---|---|
Foot ulceration | • Past or current foot ulcers will be determined by self-report, observation and medical record review | |
• The location, type and duration of a current foot ulcer will be recorded | ||
Lower extremity amputation | • Past lower extremity amputations will be determined by self-report, observation and medical record review | A lower extremity amputation will be defined as a ‘complete loss of any part of the lower extremity [74], including any digit, partial foot amputation or higher’. |
• Lower extremity amputations will be classified as minor (below ankle) or major (above ankle) | Lower extremity amputations resulting from trauma or the presence of a tumour will not be recorded. | |
Foot health care behaviours and podiatry attendance | Procedure | Diagnosis/study definition |
---|---|---|
Foot health care behaviours | • Foot health care behaviours will be investigated via participant interview | Foot health care behaviours will be considered ‘poor’ if the participant answers “no” to ≥3 questions. |
• Participants will be asked to respond “yes” or “no” to the following questions: | ||
(i) Do you inspect your feet daily? | ||
(ii) Do you avoid walking barefoot? | ||
(iii) Are you able to reach your feet? | ||
(iv) Do you treat your own nails and skin lesions? | ||
(v) Have you ever seen a podiatrist before? | ||
Podiatry attendance | • Podiatry attendance will be investigated via participant interview | Podiatry attendance will be recorded as the number of visits per year. |
• Participants will be asked: How many times have you seen a podiatrist in the last 12 months? |
Neurological assessment
Arterial assessment
-
Documentation of known peripheral arterial disease in the medical records and/or history of lower extremity revascularisation procedure;
-
Absence of ≥2 pedal pulses after palpating the dorsalis pedis and posterior tibial pulses on both feet [52];
Biomechanical assessment
-
Passive, non-weightbearing dorsiflexion is <65° (either foot) [60].
Footwear assessment
-
Poor shoe fit (i.e. length, width and depth);
-
Inappropriate shoe style (i.e. for foot type, activity, foot problems etc.) or;
-
Poor shoe condition [65].
Dermatological assessment
Foot health care behaviours and podiatry attendance
-
Do you inspect your feet daily?
-
Do you avoid walking barefoot?
-
Are you able to reach your feet?
-
Do you treat your own nails and skin lesions? (e.g. calluses or corns)
-
Have you ever seen a podiatrist before?
-
How many times have you seen a podiatrist in the last 12 months?
Follow-up appointment
Primary outcome
-
new foot ulcer(s) (including new and reoccurring ulcers).
Secondary outcomes
-
number of new foot ulcers;
-
time to onset of new foot ulcer(s);
-
new lower extremity amputation(s) (including level of amputation and reason for amputation);
-
episodes of infection of the foot or lower extremity (including type of infection);
-
episodes of osteomyelitis;
-
foot-related hospitalisations (including reason for admission, length of stay and foot-related treatments/procedures received during hospital admission);
-
revascularisation procedure(s) of the lower extremity (including type of procedure);
-
new podiatry interventions (e.g. nail reduction, prescription of foot orthoses);
-
kidney transplantation and;
-
mortality (including primary and secondary causes of death).
Sample size
Data handling and statistical analysis
Continuous variables | Categorical variables |
---|---|
Participant characteristics | Participant characteristics |
• Age | • Male sex |
• Body mass index | • Current smoker |
Health-related quality of life (SF-36v2®) | • Living alone |
• Physical Component Score | Comorbidities |
• Mental Component Score | • Diabetes mellitus |
Comorbidities | • Retinopathy |
• Duration of diabetes | • Peripheral neuropathy |
Dialysis-related variables | • Peripheral arterial disease |
• Duration of dialysis | • Arterial calcification |
Laboratory blood tests | • Hypertension |
• C-reactive protein | • Dyslipidaemia |
• Serum albumin | • Ischaemic heart disease |
• Total calcium | • Congestive cardiac failure |
• Serum phosphate | • Cerebrovascular disease |
• Parathyroid hormone | • Osteoarthritis |
• Glycated haemoglobin (HbA1c) | • Inflammatory arthritis |
• Haemoglobin | Lower extremity complications |
Other | • Previous foot ulceration |
• Peak plantar pressures | • Current foot ulcer present at baseline |
• Previous lower extremity amputation | |
Other | |
• Reduced range of motion of the 1st metatarsophalangeal joint | |
• Foot deformity | |
• Inappropriate/ill-fitting footwear | |
• Skin pathology | |
• Nail pathology | |
• Poor foot health care behaviours | |
• Regular podiatry attendance |