Survey of factors related to diabetic foot pruritus in the elderly in Shanghai

Abstract

The objective of the study is to explore the status quo of foot pruritus and related factors in elderly diabetics and provide a reference for targeted preventive measures. The study involved a survey using a self‐designed foot pruritus assessment scale to understand the status quo of foot pruritus among 411 cases of elderly diabetics from 5 communities in Shanghai. The morbidity rate of foot pruritus in elderly diabetics in the community was 20.1%. Good self‐management behaviour was the protective factor, while diabetic peripheral neuropathy, hyperlipidemia, and dry skin were risk factors (all P < 0.05). The incidence of foot pruritus in elderly diabetics was high and influenced by several factors. We recommend that self‐management behaviour of patients be improved. Additionally, screening and interventions to address hyperlipidemia, diabetic peripheral neuropathy, and dry skin should be conducted regularly to prevent diabetic foot ulcers.

1. INTRODUCTION

The growing population ageing has resulted in China having the highest number of elderly diabetics in the world. ¹ Diabetic foot is one of the most serious chronic complications of diabetes. The high morbidity, high disability rate, and high medical costs resulting from this constitute a significant public health burden. Pruritus is a common diabetic complication with a prevalence of 7%–43%. It mainly manifests as generalised or restricted pruritus. In addition, scratches, blood scabs, skin hypertrophy, and mossy lesions may occur in severe cases. ² Scratching and similar self‐stimulatory behaviour are usually caused by pruritus, and can result in clinically significant tissue damage and eventually develop into diabetic foot or even lead to amputation. ³ , ⁴ , ⁵ The mechanism of pruritus in diabetic patients remains unclear. It may be related to abnormal glucose metabolism, peripheral neuropathy, peripheral vasculopathy, dry skin, and so on. ⁶ At the same time, the elderly are also a high risk population for pruritus. Cross‐sectional surveys of several countries have found that the morbidity rate of pruritus in the elderly ranges from 22% to 40.6%. The main cause is the decreased lipid composition in the skin associated with aging, leading to a corresponding degeneration of the moisturising and barrier function of the skin, which eventually triggers pruritus. ⁷ , ⁸ , ⁹ To understand the current status of foot pruritus in elderly diabetics and explore the associated factors, we surveyed 411 elderly diabetics with foot pruritus in the community. Our findings are presented in the following sections.

2. MATERIALS AND METHODS

2.1. Patients

Elderly diabetics from five communities in Shanghai were enrolled in the study between July and September 2021 using convenience sampling. Inclusion criteria: ① age ≥60 years old; ② meeting the diagnostic criteria of type 2 diabetes ¹⁰ ; ③ with normal communication skills and willing to participate in the study. Exclusion criteria: ① presence of factors other than diabetes causing foot pruritus, such as rheumatic immune diseases; ② patients with impaired consciousness or patients who had difficulties in cooperating in the study.

2.2. Methods

2.2.1. Study tool

We used a self‐developed foot skin assessment scale for diabetic patients, which was drafted and revised following a literature review and several modifications by 12 subject experts. The experts consulted for developing this scale were from the fields of endocrinology, dermatology, diabetes nursing, and geriatric nursing, and consisted of 2 chief physicians, 3 associate chief physicians, 4 chief nurses, and 3 associate chief nurses. In all, there were 2 experts with a doctoral degree, 6 with a master's degree, and 4 with a bachelor's degree. ① General information—included gender, age, height, weight, education level, occupation, residence, health care payment method, duration of diabetes, peripheral neuropathy and/or vasculopathy, medical history of hypertension, hyperlipidemia, heart disease, stroke, smoking and alcohol consumption, footwear, whether received health education related to the foot, foot deformities, and activities of daily living. ② Current assessment using the foot pruritic scale—the scale consists of the following 5 dimensions covering 23 skin problems: skin colour, skin temperature, skin appearance, skin itching, and the presence of fungal skin infections. Skin temperature was measured using an infrared thermometer. A dermatologist determined the presence of fungal infection based on the clinical manifestations of tinea pedis, such as itching and reddish skin. ③ We also used the foot skin self‐management behaviour scale consisting of the following 8 items: ‘checking skin daily’, ‘cleaning skin daily’, ‘using a mild bath shampoo’, ‘drying skin with soft towels’, ‘using moisturizer daily’, ‘wearing soft, breathable socks’, ‘taking steps when exposed to sunlight’, and ‘adhering to the doctor's instructions’. Responses were on a 5‐point Likert scale. There were 5 options offered for assessing the frequency of each behaviour—never, occasionally, sometimes, often, and always. The score for frequency of each behaviour ranged from 0 to 4 with a total score of 20 points as per the response. The higher the total score, the better is the foot skin self‐management behaviour of the diabetics. According to the standard score analysis, the standard score = (actual score/highest possible score) × 100. The standard score is interpreted as follows: <60 is poor, 60–80 is moderate, and >80 is good. ④ We also surveyed the methods used for dealing with foot skin problems based on a scale. Items included self‐medication, self‐trimming, itching, and scratching, as well as timely consultation at the hospital, with a total of 5 entries. This section had multiple choices. Timely consultation refers to the interval with no more than 24 hours between the first presentation of foot injury and the first consultation with a professional diabetic foot treatment team in a hospital. ¹¹ In all, 30 patients who met the inclusion criteria were initially enrolled for the study. The content validity of the scale was 0.825 and the Cronbach's α was 0.823.

2.2.2. Study method

Nursing staff from five health service centres in Shanghai were responsible for conducting the survey. They underwent a standardised training program offered by the medical and nursing staff of the podiatry integration clinic in our hospital. The training on the survey included the objectives, study participants, assessment of foot skin and precautions when administering the scale, and so on. The investigators examined each patient's foot skin, assessed the condition using uniform criteria, and recorded the responses accurately. Dermatologists in our hospital were consulted to confirm the diagnosis if they encountered foot problems that they were unclear about. Once the questionnaires were returned, the investigator first checked the form, clarified ambiguities, and filled up blank items after confirming with the respondent and mailed the questionnaires to the head of the research study. A total of 432 questionnaires were given out, and 411 valid questionnaires were collected back. The effective return rate of the questionnaires was 95.13%.

2.2.3. Statistical methods

SPSS 26.0 statistical software was used for statistical analysis. Count data were described using frequency and percentage, and χ² test was used for comparison between groups. Logistic regression was used for the analysis of categorical variables to analyse the related factors in diabetic patients with associated foot skin problems. P < 0.05 or P < 0.01 were regarded as statistically significant. α = 0.05.

3. RESULTS

3.1. General profile

Among the 411 elderly diabetic patients, 209 (50.9%) were male and 202 (49.1%) were female; age ranged from 62 to 95 years with an average age of 74.09 (±9.74) years; educational level: 68 cases (16.5%) had elementary schooling and lower, 162 cases (39.4%) had middle school education, 128 cases (31.1%) studied up to high school, and 53 cases (12.9%) had college education and higher; residence mode: 48 cases (11.7%) lived alone 363 cases (88.3%) did not live alone; duration of diabetes: In 219 cases (53.3%) it was <10 years and in 192 cases (46.7%) it was ≥10 years; 83 cases (20.2%) had complications of peripheral neuropathy, 71 cases (17.3%) had complications of peripheral vasculopathy, 45 cases (10.9%) had complications of both peripheral neuropathy and vasculopathy, and 74 cases (18.0%) had complications of retinopathy; 271 cases (65.9%) had a history of hypertension, 100 cases (24.3%) had a history of hyperlipidemia, 66 cases (16.1%) had a history of heart disease, 76 cases (18.5%) had a history of stroke, and 35 cases (8.5%) had foot deformity; smoking was reported in 80 cases (19.5%); alcohol consumption was reported in 49 cases (11.9%); 313 cases (76.2%) showed no dependence in activities of daily life, 59 cases (14.3%) had mild dependence, 23 cases (5.6%) had moderate dependence, and 16 cases (3.9%) had severe dependence.

3.2. Foot pruritus in elderly diabetics

The survey showed that foot pruritus existed in 20.1% (88/411) of elderly diabetic patients.

3.3. Factors related to foot pruritus in elderly diabetic patients

3.3.1. Univariate analysis of foot pruritus in elderly diabetic patients

Elderly diabetic patients with foot pruritus were identified as the pruritus group, and those without foot pruritus were identified as the normal group. The incidence of foot pruritus in patients is shown in Table 1.

TABLE 1.

Foot pruritus in elderly diabetic patients (n = 411)

Items	Case number	Normal group	Pruritus group	F/X2	P
Gender
Male	209	156	53	5.503	0.025
Female	202	169	33
Age
61~	188	155	33	5.090	0.165
71~	149	117	32
>80	74	52	22
Course of DM (year)
<10	219	186	33	9.903	0.002
≥10	192	139	53
Fasting blood‐glucose
<7	226	194	32	13.888	<0.001
≥7	185	131	54
Insulin injection
Yes	127	84	43	18.581	<0.001
No	284	241	43
Diabetic peripheral neuropathy
Yes	83	45	38	38.842	<0.001
No	328	280	48
Diabetic peripheral vasculopathy
Yes	71	41	30	23.597	<0.001
No	340	284	56
Diabetic retinopathy
Yes	74	46	28	15.603	<0.001
No	337	279	58
Diabetic nephropathy
Yes	28	17	11	6.122	0.013
No	383	308	75
Diabetic foot
Yes	18	9	9	9.618	0.002
No	393	316	77
Hyperlipidemia
Yes	100	60	40	29.062	<0.001
No	311	265	46
Smoking
Yes	80	55	25	6.401	0.011
No	311	270	61
Alcohol drinking
Yes	49	32	17	6.375	0.012
No	362	293	69
Foot deformity
Yes	35	19	16	14.209	<0.001
No	376	306	70
Skin temperature
Normal	380	314	66
Increased	6	1	5	14.333	<0.001
Decreased	25	10	15
Dry skin
Yes	63	25	38	69.782	<0.001
No	348	300	48
Callus
Yes	16	9	7	5.242	0.022
No	395	316	79
Foot oedema
Yes	13	3	10	25.442	<0.001
No	398	322	76
Foot fungal infection
Yes	35	17	18	21.515	<0.001
No	376	308	68
Daily activity ability
Independence	313	260	53	15.173	0.002
Mild dependence	59	36	23
Moderate dependence	23	17	6
Severe dependence	16	12	4
Health care education on skin protection
Yes	228	193	35	9.614	0.002
No	183	132	51
Timely consultation
Yes	71	48	23	6.824	0.009
No	340	277	63
				X2	P
Feet self‐management
Poor	249	191	58	11.170	0.004
Medium	108	82	26
Good	54	52	2

3.3.2. Multi‐factor analysis of foot pruritus in elderly diabetic patients

The presence of foot pruritus was used as the dependent variable (yes = 1, no = 0). The statistically significant variables in the univariate analysis were used as independent variables for the logistic regression analysis and the results are shown in Table 2.

TABLE 2.

Multi‐factor analysis of foot pruritus in elderly diabetic patients

Items	β	SE	Wald X2	P	OR	95% CI
Constant	−4.871	2.081	5.480	0.019	–	–
Self‐management behaviour	−1.632	0.819	3.969	0.046	0.196	0.039–0.974
Diabetic peripheral neuropathy	2.000	0.865	5.348	0.021	7.389	1.357–40.247
Dry skin	1.969	0.407	23.460	<0.001	7.167	3.230–15.902
Hyperlipidemia	0.847	0.348	5.938	0.015	2.333	1.180–4.611

Note: For self‐management behaviour, poor = 1, medium = 2, good = 3; For Diabetic peripheral neuropathy, dry skin, hyperlipidemia, No = 0, Yes = 1.

4. DISCUSSION

Results showed that the morbidity rate of foot pruritus in elderly diabetic patients was 20.1%, which is consistent with the findings of Stefanik et al. ¹² Pruritus is commonly complicated by diabetes that may last throughout the whole course, with an insidious onset often not diagnosed early and delayed treatment. With a long course and a tendency for recurrent episodes, it is difficult to cure. Additionally, patients with pruritic problems repeatedly scratch the affected area. Scratching can damage the integrity of the skin as well as impair the barrier function of the skin, providing access for pathogens to invade and increase risks of infections and ulcers. A vicious cycle is triggered when pruritus‐caused infections aggravate the pruritus and lead to repeated scratching, increasing the risk of diabetic foot ulcers. This indicates that close attention should be paid to foot pruritus in elderly diabetic patients. Targeted treatment and care should be given to address the causes of pruritus.

Elderly individuals experience a decline of various functions, and in the presence of basic diseases, the incidence of diabetes complicated with skin lesions in elderly patients is higher than that of patients of other ages. The barrier function of the skin is damaged as the skin ages and mainly presents as changes in various lipids, structural proteins, proteases, surface PH, and oestrogen in the skin. Differential expression of lipids in the skin surface presents as increased levels of ceramide, diacylglycerol, and fatty acids, and decreased levels of triacylglycerol in the stratum corneum of patients with pruritus. ¹³ These changes in lipids lead to impairment of the normal barrier function of the skin, which forms a major pathological mechanism of pruritus. Skin is the largest immune organ in the human body, and T cells play a central role in the human skin defence system. The decline of T cell function in the corium and cuticular layers and the induced inflammatory mediators have a role in the development and progression of pruritus. Immunosenescence refers to the immune system dysfunction that sets in with aging, which is characterised by the reduced genetic diversity of T cell receptor gene. Type 2 immune response is usually triggered by a disruption of the skin barrier. A large number of Th2 cells produced in response to environmental stimuli are the main regulators of chronic pruritus. On one hand, these cytokines may function as primary sensory neurons, that is, they direct pruritogens to trigger pruritus. On the other hand, these cytokines may alter the sensitivity to the pruritic mediators of type 2 inflammatory and immune‐dominated skin diseases, which leads to pruritus. ¹⁴ , ¹⁵

The pathogenesis of pruritus in diabetic patients remains partially understood. Various factors have been described to promote the development of the symptom. Our study shows that dry skin and diabetic neuropathy are risk factors for foot pruritus associated with pruritus. It has been reported that damage to pruritic neurons or other cells involved in the pruritic circuit can lead to neuropathic pruritus. However, damage to peripheral nerves is more likely to cause pruritus than damage to the central nervous system. ¹⁶ Skin is rich in nerve endings, among which autonomic nerves closely interact with skin keratinocytes and immune cells, and play an important role in the regulation of the skin's physiological functions. Sweat glands are not protected by the stratum corneum, but external antigens and pathogens are difficult to enter the body through skin appendage under physiological conditions, suggesting that there is a special immune protection mechanism in sweat glands. Sweat is a natural moisturiser and antibacterial agent. Studies have found that when the skin water content is reduced for a long time, haptens are more likely to pass through the skin, increasing the chance of skin sensitization. ¹⁷ Dry skin is the most important factor influencing the presence and intensity of pruritus. Autonomic neuropathy can cause perspiration dysfunction and reduced secretion of skin sweat and sebaceous glands, which reduces the keratin water content and leads to dry foot skin. ¹⁸ The autonomic nervous system also affects the chemical barrier and bacterial barrier of the skin, and participates in the occurrence and development of atopic dermatitis, causing itching sensation in the skin. ¹⁹

Long‐term hyperglycemia and osmotic diuresis leave the skin in a dehydrated state, which can also lead to dry skin. Dry skin leads to a decrease in the skin barrier function, thus lowering the threshold of pruritus and predisposing the skin to pruritus. In addition, diabetes mellitus (DM)‐induced increases in advanced glycosylation products in dermal collagen and skin ageing in the elderly may both lead to reduced hydration of the stratum corneum and cause dry skin followed by pruritus. Complications of peripheral neuropathy in elderly diabetic patients may also lead to the impaired barrier function of the skin, resulting in sensory dysfunction of cutaneous nerve endings of C fibres, leading to abnormal discharge of sensory C nerve fibres and causing pruritus. ²⁰ Peripheral nerve injury can result in sensory abnormalities accompanied with inflammation. Pruritic neurons express a variety of inflammatory mediator receptors triggering pruritus, such as protease, trypsin, chymotrypsin, cathepsin, cytokines, thymic stromal lymphopoietin, and IL‐4, IL‐13, IL‐31, and IL‐33. Based on the expression of the receptors mentioned above, it is possible that inflammatory activation of molecular receptors is a component of nervous pruritus. ¹² Results show that hyperlipidemia is a risk factor for foot skin damage in elderly diabetic patients (P < 0.05). Augustin et al conducted a cross‐sectional survey in Germany, and their results showed that patients with higher lipid levels were more likely to develop pruritus. ²¹ For elderly diabetic patients with hyperlipidemia, medical staff must instruct patients to take lipid‐lowering drugs regularly, adhere to a reasonable diet and restrict intake of high‐fat, high‐cholesterol food, and maintain an appropriate exercise regimen such as jogging and tai chi to control weight. It is important to regulate patients' blood lipid levels through a combination of drug, diet, and exercise interventions to reduce the occurrence of foot pruritus.

Our study shows that good self‐management behaviour is a protective factor for foot pruritus in elderly diabetic patients (P < 0.05). The level of self‐management behaviour was poor in 66% of patients with pruritus, indicating the lack of awareness about foot skin care and self‐care behaviour in most patients. We recommend that patients should actively participate in foot skin management, increase their awareness of foot skin protection, and improve their ability for self‐management of the condition. Medical staff should promote the knowledge of foot skin protection through various communication channels. The content should be concise and easy to understand, to inform patients of the appropriate care methods for dealing with skin problems. For instance, patients with fungal infections should follow medical advice to use antifungal drugs, etc. Medical staff should also help patients to correct erroneous ways of dealing with skin problems such as seeking advice from pedicure stores, self‐medication, repeated scratching, and so on.

5. LIMITATIONS

The perception of pruritus is a highly subjective central operation process, which is the main reason for the differences in individual symptoms. Patients mostly describe the feeling and severity of pruritus based on their subjective feelings, and the lack of objective and quantifiable indicators makes it almost impossible to conduct a standardised clinical evaluation of pruritus. This study only diagnosed the existence of pruritus and diabetic peripheral neuropathy in elderly patients with diabetes, without measuring their severity. Further studies are needed to verify their intrinsic relationship.

According to the survey data, hyperlipidemia is one of the risk factors for skin pruritus, but in the process of literature review, no direct evidence has been found that reducing blood lipids can reduce the occurrence or degree of skin pruritus. Therefore, further research is needed to verify the relationship between hyperlipidemia and skin pruritus.

6. SUMMARY

This cross‐sectional survey reflects the status of foot pruritus, self‐management behaviour, and the need for timely consultation by elderly diabetic patients in the Shanghai community. This was a limited survey, and a larger study in a wider area is further needed to explore the status and factors related to foot pruritus in elderly diabetic patients. In addition to regular screening and assessment of foot skin, routine screening and assessment of diabetic peripheral neuropathy, a risk factor for pruritus, should also be incorporated into the clinical management of elderly diabetic patients. Timely individualised interventions should be taken up to reduce the incidence of pruritus‐induced skin damage in elderly diabetic patients and prevent the incidence and development of diabetic foot ulcers.

FUNDING INFORMATION

Advanced Appropriate Technology Promotion Project of Shanghai Municipal Health Bureau, ‘The promotion and application of whole‐course rehabilitation series of techniques for senile diabetic dangerous foot’ (No. 2019SY007). Clinical Research Project of Huadong Hospital Affiliated to Fudan University ‘The key to promote muscle strength rehabilitation in elderly patients with diabetes Research and transformation of technology’ (No. HDLC2022008). Fudan University Fuxing Nursing Research Fund Key Project, ‘The construction and application of nursing plan for preventing the recurrence of diabetic foot ulcer in the elderly based on the concept of active health’ (No. FNF202101).

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

This study was conducted with the approval from the Ethics Committee of Huadong Hospital Affiliated to Fudan University (No. 20220104). This study was conducted in accordance with the declaration of Helsinki. Written informed consent was obtained from all participants.

Zhou L, Tang J, Cai Q, et al. Survey of factors related to diabetic foot pruritus in the elderly in Shanghai. Int Wound J. 2023;20(6):2020‐2027. doi: 10.1111/iwj.14065

DATA AVAILABILITY STATEMENT

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.