Introduction
Diabetes Mellitus (DM) poses a significant and escalating global public health concern, with an estimated prevalence of 643 million by 2030, projected to reach 784 million by 2045.1 People with diabetes are at high risk of developing lower-extremity complications, including peripheral neuropathy and peripheral artery disease, which can lead to foot ulceration and lower-extremity amputation.2 A particular challenge facing the Polish health care system is the provision of holistic, systematic, yet individual diabetes care. Based on the Polish report,3 whose title translates as: “Development of therapy in diabetology” the mean waiting time for a patient with diabetes to attend a diabetology clinic was about 100 days. The growing number of complications, including, among others, diabetic foot syndrome (DFS) is a challenge for the Polish of the health care system.3 DFS is defined by the International Working Group on the Diabetic Foot (IWGDF) as infection, ulceration, or destruction of tissues of the foot in a person with currently or previously diagnosed diabetes mellitus, usually accompanied by neuropathy and/or peripheral artery disease (PAD) in the lower extremity.4 DFS is foot ulcers that develop in the course of diabetes. These ulcers are the result of skin damage and are exacerbated by metabolic disorders, diabetic neuropathy and peripheral vascular disease. Hyperglycemia leads to micro-damage to small blood vessels, which results in chronic inflammation and ischemia, and consequently nerve degeneration. This pathophysiology leads to the development of diabetic neuropathy and the destruction of soft tissue. Diabetic neuropathy is damage and impairment of nerve conduction, which leads to reduced peripheral sensation, which affects the perception of pain. Reduced sensation increases the risk of skin damage in the feet, which can lead to DFS. Angiopathy (blood vessel disease) causes poorer tissue nutrition in the feet, which results in more difficult wound healing. Diabetes increases the risk of infection, which may spread to wounds and make treatment even more difficult.5 Estimates indicate that 19% to 34% of individuals with DM will experience at least one episode of diabetic foot ulcerations during their lifetime.6 They also substantially affect the health-related quality of life (HRQoL) of affected individuals.7 These studies predominantly focus on people with diabetes-related foot ulceration, and a recent meta-analysis has shown that the HRQoL of people with such foot ulcers is low, especially with respect to physical function and perceptions of general health.8 HRQoL has hardly been investigated in those people who heal from an ulcer. More insight into this population is important because of the high risk for ulcer recurrence and the association between HRQoL and worsening foot morbidity.9 Commonly used questionnaires for assessing quality of life (QoL) among people with diabetes include the 36-Item Short Form Health Survey (SF-36), World Health Organization Quality of Life – BREF (WHOQOL-BREF), EuroQol-5 dimensions (EQ-5D), and Diabetic Foot Ulcer Scale (DFS-SF).10–13 The Audit of Diabetes-Dependent Quality of Life (ADDQoL) is also used to assess the QoL of people with diabetes in Poland and worldwide.14,15 The tool applied for assessing the QoL of patients with diabetes was mainly the Audit of Diabetes Dependent Quality of Life (ADDQoL) scale, which is recommended by many diabetes research institutes as an individualized measure of diabetes-specific QoL. The scale is composed of a general assessment comprising two initial items to measure present QoL and diabetes-specific QoL, as well as a detailed assessment comprising 19 specific domains.16 According to authors’ knowledge, it has been applied for the first time in Poland and worldwide to assess the QoL of people with diabetes who have been diagnosed with DFS. There are no scientific reports indicating which factors contribute to poorer QoL in patients with type 2 diabetes with and without diabetic foot.
Objective
The aim of the paper was to determine the influence of T2DM on the level of QoL, taking into consideration the particular domains included in the ADDQoL, as well as examining QoL divided into patients with and without DFS, and indicating demographic and clinical factors affecting QoL among adult patients with and without DFS in Poland.
Materials and Methods
Organization of the Study
All the participants were patients of the Department of Internal Medicine with the Subdivision of Nephrology and the Surgical Outpatient Clinic at ICZ HealthCare sp. z o.o. Żywiec Hospital. The research was carried out from March 2023 to February 2024. Questionnaires were provided to patients after obtaining their informed, voluntary consent. Of all 181 patients hospitalized in such period, there were 151 people who met the eligibility criteria for the study. However, 30 respondents did not agree to participate. Further analysis revealed that there were 21 incomplete questionnaires, which were hence rejected in the study. That is why our cross-sectional study was performed among 100 patients – 50 patients (group 1) with DFS and 50 patients without DFS (group 2).
The recruitment process in detail is presented graphically in Figure 1
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Figure 1 Selection of a sample size for the study.
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Inclusion and Exclusion Criteria
The screening examination comprised consecutive patients of the diabetes clinic who met the age requirement of 40–80 years. The criteria for inclusion in the study were: informed consent, diagnosed type 2 diabetes, duration of the disease not less than one year, consent to participate in the study. The exclusion criteria: diagnosed type 1 diabetes mellitus, age less than 40, and duration of illness less than one year.
Procedure
All the patients attended the diabetes clinic. Such visits occurred more or less every four months. During the appointment at the clinic, the patients had their glucose levels determined, their pharmacological treatment was established, and they underwent educational activities aimed at adopting an appropriate diet, including the number of carbohydrate exchanges and food content considering carbohydrates, protein, and fats. There was conducted individual diabetes educational training according to requirements of a patient. The structure of such education included the following stages: initiation of therapy, re-education, and annual assessment of the patient’s educational needs. Keeping in mind the group of patients with long duration of diabetes and developed complications (DFS), re-education was used. Aerobic physical training was also recommended to the patients. During the appointment at the Surgical Outpatient Clinic, the patients with DFS were qualified according to the perfusion, extent, depth, infection, sensation (PEDIS) qualification, and the Wagner’s classification, and had surgical procedures performed, which included wound preparation. An important element of the treatment of diabetic foot ulcers is proper wound care, which is based on hygiene and cleansing. Local treatment in practice is based on two concepts: the Wound Hygiene Strategy and the TIMERS Local Wound Treatment Strategy. Wound hygiene includes washing the wound and skin, cleansing the wound, caring for the wound edges and selecting an appropriate dressing. The TIMERS Concept, on the other hand, includes the following elements:
- T for “tissue” – wound debridement;
- I for “inflammation” – infection control;
- M for “moisture” – maintaining proper moisture;
- E for “epidermis” – wound edge care;
- R for “repair and regeneration” – tissue repair and regeneration;
- S for “social and individual-related factors” – assessment and improvement of external factors related to the patient and influencing proper wound treatment.17,18
The procedure described above applies to patients undergoing the study.
Questionnaire Measures
The ADDQoL questionnaire (developed by Clare Bradley) is a tool specific for diabetes, which is used for examining the QoL in both type 1 diabetes mellitus (T1DM) and T2DM patients.16
It consists of two general questions referring to the QoL: 1) determination of the measurement of the general, present level of QoL, which includes a 7-grade scale (excellent, very good, good, neither good nor bad, bad, very bad, and extremely bad); 2) the specific influence of diabetes on QoL, which includes a 5-grade scale (very much better, much better, a little better, the same, and worse). The remaining components refer to the 19 domains of QoL without the disease and the influence of diabetes on the aspects of life. Each domain includes two components: Impact (from −3, maximum negative impact of diabetes, to +1, positive impact of diabetes) and Importance (3 – very important, 0 – not at all important). The product of impact and importance ratings determines the value of the weighted impact (WI) score. This value may range from −9 to +3 for every examined domain of the ADDQoL. The lower the value of the weighted impact score, the worse the aspect of life within the scope of a given domain. The AWI score was also calculated for the whole scale. The AWI score is derived by dividing the sum of the weighted ratings by the number of applicable domains. The ADDQoL comprises the following domains: leisure activities, working life, journeys, holidays, physical health, family life, friendship and social life, personal relationship, sex life, physical appearance, self-confidence, motivation, people’s reactions, feelings about the future, financial situation, living conditions, dependence on others, freedom to eat, and freedom to drink. The ADDQoL was applied in the studies with the consent and license received from the author, Clare Bradley (Health Psychology Research Unit, Royal Holloway, University of London via www.healthpsychologyresearch.com. The license for the Polish language version bore the number CB 1365). The studies applied the Polish language version of the ADDQoL, the psychometric properties of which, determined earlier, indicate that it is a reliable tool useful for the assessment of the level of QoL of adult patients in Poland with T1DM or T2DM.19 Before commencing the study, each patient was informed about its purpose by the authors. The questionnaires were completed personally and anonymously by the patients during a visit by a physician. The time needed for filling in the survey was 10–15 minutes.
In relation to 50 subjects suffering from DFS, two scales were used to assess the severity of wounds: the PEDIS scale and the Wagner scale. The PEDIS classification is a commonly used method for evaluating DFS, which allows for a systematic determination of the progression of changes and the risk of complications. This classification consists of five key components: Perfusion, Extent of lesion, Depth of lesion, signs of Infection, and protective Sensation. The second classification is the Wagner scale, which differentiates six degrees of advancement of pathological changes in a foot. The degree “zero” indicates the absence of ulcerative changes, yet the presence of deformity or a risk of an injury. A wide-ranging necrosis of an entire foot (ie extensive gangrene) is the final 5th degree.
Institutional Review Board Statement
The study was performed with the consent of the Research Ethics Committee (2023/01/6/E/6 dated as January of 15th, 2023). All patients provided informed consent and were informed that they could withdraw from the study at any time. The study was carried out in accordance with the tenets of the Declaration of Helsinki and Good Clinical Practice guidelines.
Statistical Analysis
Descriptive statistics were used to examine the variables. Variables measured on a quantitative scale were characterized by mean, standard deviation, while variables of the qualitative type, which were measured on a nominal scale, were presented by counts and percentages. The Shapiro–Wilk test was used to test the normality of the distribution of the variables. The significance of differences in the AWI level of the scale between the two groups, ie patients with and without DFS, was tested using the Mann–Whitney U-test. In the next step, a stepwise multiple linear regression model was used to determine the impact of multiple socio-demographic, clinical variables on patients’ QoL (AWI scale). The analysis was performed separately for the group of patients with DFS and patients without DFS. The coefficient of determination (R²) and adjusted R² used to assess the quality of a model fit. Confidence intervals are shown for the coefficients. Data were analyzed using R software, version 4.4.3. There were used the following three packages: olsrr, car, lmtest and p<0.05 as the level of significance.
Moreover, the study used a power analysis with the pwrss package (of R software) to achieve an expected power of 80% with the coefficient of determination of 0.7 (denoted R2), which is a measure that provides information about the goodness of a model fit. In addition, a maximum number of parameters of 30 was assumed. The analysis gave a target sample size of N=40, which is less than the size of each studied group (50 participants). Factors having a significant impact on AWI scale were identified for the groups.
Results
The study group consisted of 100 patients, half of whom were patients with type 2 diabetes without DFS, and the remaining 50 patients suffered from type 2 diabetes and DFS. Among all respondents, the majority were men (53%), while women were 47%. More than half (precisely 52%) of the patients with DFS were men. The most common age range of the respondents was from 50 to 64 and from 65 to 74. The respondents lived mainly in the countryside – 55% and had vocational education – 60%. Half of the respondents were pensioners. The clinical characteristics of the patients concerned, among others, the duration of the disease, the method of treatment, and complications, characteristics of the course of DFS. Detailed data on the characteristics of the study group are presented in Tables 1–3.
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Table 1 Socio-Demographic Parameters by a Patient Group
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Table 2 Clinical Parameters by Patient Group
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Table 3 Characteristics of the Course of Diabetic Foot Syndrome
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Tables 4 and 5 present the components of ADDQoL, ie the impact and importance rating together with the weighted impact score. It was demonstrated that in both studied groups of patients with and without DFS, the values of the impact rating and WI score were negative for all the domains of the ADDQoL. “Not applicable” replies for the impact rating indicator were provided by the patients with DFS most frequently in the following domains: “working life” (56% of respondents), “holidays” (52%), “sex life” (36% of respondents), “personal relationship” (34%), and “family life” (12%). In the case of patients without DFS, the “not applicable” replies were most frequent in the following domains: “working life” (54% of respondents), “sex life” (36%), “holidays” (36%), “personal relationship” (34%), and “family life” (4%).
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Table 4 General Quality of Life of with and without Diabetes Food Syndrome with Diabetes
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Table 5 Distribution of ADDQoL Responses by Impact, Importance Rating and Weighted Impact Score for Patients with and without Diabetes Foot Syndrome
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In the case of DFS, the negative values of the WI score in the analyzed domains ranged from −2.56 (“People’s reaction”) to −7.38 (“physical health”). For patients without DFS, the values ranged from −0.78 (“living conditions”) to −6.54 (“freedom to eat”). The AWI values for patients with DFS were −4.80±1.68, and for those without DFS, they were −2.63±1.44, which were statistically comparable (p<0.001). The overall reliability coefficients (Cronbach’s alpha) of the ADDQoL were 0.93 in the group with T2DM, indicating good internal consistency.
The study in Tables 6 and 7 examined the use of a stepwise multiple linear regression model to determine the impact of multiple socio-demographic and clinical variables on the QoL of patients with and without DFS. The use of this method allowed for the introduction of variables that have a significant impact on the AWI score. The set of independent variables in the regression analysis included qualitative variables (including ordinal variables and those measured on a nominal scale) and quantitative variables.
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Table 6 Multivariate Linear Regression Model for ADDQoL Diabetic with Foot Syndrome
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Table 7 Multivariate Linear Regression Model for ADDQoL Diabetic Without Foot Syndrome
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Worse QoL is observed in patients with diabetic foot who have complications from diabetes and who have necrosis. The study in Table 6 examined the use of a stepwise multiple linear regression model to determine the impact of multiple socio-demographic and clinical variables on the QoL of patients with DFS. The use of this method allowed for the introduction of variables that have a significant impact on the AWI score.
The results of the multivariate linear regression analysis show that, among people with DFS, good QoL was statistically affected by gender (β=0.642, p=0.055), method of treatment (β=1.222, p=0.008), and self-dressing (β=1.604, p=0.000). Statistically significant factors influencing worse QoL were: diabetes complications (β=−2.156, p=0.003), fasting blood glucose (β=−0.017, p=0.006), amputation of a fragment or the entire limb (β=−0.831, p=0.022), type of dressing (β=−1.102, p=0.009), wound size (β=−1.682, p=0.014), type of wound (β=−1.247, p=0.034), and the Wagner scale (β=−0.478, p=0.021). The above results are shown in Table 6.
For diabetic without foot syndrome, worse QoL was observed in patients who have hypo/hyperglycemia states. Patients with hyperglycemia had a decrease in AWI of 1.1 points (β=1.1, p=0.001), while hypoglycemia was associated with a decrease in AWI of 0.7 points (β=−0.7, p<0.001). Table 7 shows that better QoL is observed and employment status was associated with a 0.9-point increase in the AWI (β=0.9, p=0.021).
Before building the multiple linear regression model, the conditions for using this method were tested and verified:
- the residuals are normally distributed – using the Shapiro–Wilk test, the condition was examined (W=0.9736, p=0.3221) for group 1 and (W=0.9741, p=0.3359) for group 2. The p-value is greater than the accepted level of significance, so we assume that the residuals have a normal distribution.
- the independence of the residuals – the Durbin–Watson statistic of 1.576 for group 1 and 1.973 for group 2 lies within the acceptable range of 1.5 to 2.5, suggesting independence of residuals.
- the presence of outliers – a criterion based on Cook’s distance identified 3 outlier observations for group 1 (the cutoff value was 0.1396) and Cook’s distance identified 1 outlier observation for group 2 (the cutoff value was 0.2753).
- multicollinearity of independent variables – one of the most important assumptions of regression analysis. The parameters were verified by the VIF and Tolerance coefficient (the values are shown in Tables 8 and 9). The VIF values were less than 10 and the Tolerance vales were, in each case, greater than 0.2.
- homoscedasticity – the Breusch–Pagan test is used. The p-value for group 1 (0.7411) and for group 2 (0.3539) is greater than 0.05, we fail to reject the hypothesis of homoscedasticity.
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Table 8 Collinearity Statistics for Group 1
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Table 9 Collinearity Statistics for Group 2
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The adjusted R-squared coefficient of determination is equal to R²=78.5% (for the model including patients with DFS) and R²=62.2% (for the model including patients without DFS). Accordingly, the first model explains about 78.5% of the variability in patients’ QoL, while the second model explains 62.2% of the variability in patients’ QoL (Table 10).
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Table 10 Summary of Model Fit ADDQoL (AWI)
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Discussion
Summary of Key Findings
DFS problems had the greatest negative impact on health–related QoL (HRQoL). Our findings show that HRQL evaluated by the ADDQoL questionnaire, to the 17 domains of QoL, is lower in diabetic patients with foot syndrome to diabetic patients without foot syndrome. The “freedom to eat” domain is not statistically significant, and the “freedom to drink” domain is lower among patients without diabetic foot. On the other hand, the overall AWI results show that the QoL of patients with DFS is significantly lower compared to patients without DFS (p<0.001). The general QoL assessed by patients with diabetic foot as good was indicated by 8% of respondents, while among patients without diabetic foot 28% was given. If I did not have diabetes, my QoL would be much better – indicated 60% of patients with diabetic foot, and 24% without diabetic foot. To the authors’ knowledge, the presented study is the first in Poland and in Europe to assess the QoL of patients using the ADDQoL questionnaire, comparing it among patients with DFS and without diagnosed diabetic foot. In the majority of other studies that included studying the QoL using the ADDQoL in patients with T2DM in various countries, similar results were also obtained in terms of the biggest negative impact of diabetes on the “freedom to eat” domain. In our own studies, patients with type 2 diabetes without diagnosed DFS also rated the QoL the lowest, although this result was not statistically significant.
Critical Comparison with Literature
The lowest or low mean weighted impact scores for this domain were calculated in patients with T2DM in Malaysia.20 In patients in multicentre studies in Turkey and in eight countries of Western Europe,21 the good QoL among people without diabetic foot was statistically affected by the professional activity of the patients, and the QoL was negatively affected by hypoglycemia and hyperglycemia. Our research found a positive association between employment and HRQoL (AWI; p<0.021). Shetty et al22 proved that unemployment leads to a decreased HRQoL (p<0.001). Our research found a negative association between hypoglycemia and HRQoL (AWI; p<0.001). Similar results were obtained by Shetty et al,22 showing that HbA1C>7 (high glycemic levels) leads to a decreased HRQoL (p<0.055).
The results of the multivariate linear regression analysis show that, among people with DFS, good QoL was statistically affected by gender, method of treatment, and self-dressing. Statistically significant factors influencing worse QoL were diabetes complications, fasting blood glucose, amputation of a fragment or the entire limb, type of dressing, wound size, and the Wagner scale. Our data showed that women had significantly better HRQoL than men (p<0.055). Ahmad et al proved the opposite: women with DFS had significantly lower HRQoL than men.23 However, De Meneses et al24 reported that women had a significantly better overall HRQoL, which is consistent with our own research. Putri et al25 proved that women in Indonesia with DFS had worse QoL than men, which was pretty divergent compared to our own research.
DFS is one of the major complications of diabetes that affects QoL. Patients who were not using insulin but diet and oral medication (p<0.008) had significantly higher QoL in AWI. Similar research carried out in the Czech Republic showed that patients who were not using insulin had significantly higher QoL scores in these domains: daily activities, emotions, and physical health.26 The applied multivariate linear regression model verified whether any of the analyzed factors – complications of diabetes – may lead to deterioration of the QoL determined by a lower AWI value. Significant deterioration of the QoL was observed in patients with DFS with complications of this disease (neuropathy p<0.001, nephropathy p<0.003, retinopathy p<0.008). Similar results were obtained by Kolarić et al,27 confirming that complications in diabetes, including DFS, retinopathy, nephropathy, and neuropathy, cause a decrease in the QoL of patients with type 2 diabetes.
Patients were classified as Wagner grade 1 if the feet had a superficial wound; grade 2 for deep wounds penetrating to the tendon or joint capsule but not the bone; grade 3 for lesions involving deep tissues with abscess or osteomyelitis; and grades 4 and 5 for localized and generalized gangrene, respectively. Our own research has shown that the assessment of the wound using the Wagner scale (2.9±1.3) has a statistically significant negative impact on the QoL (AWI) of patients with DFS (p<0.021). Yao et al10 shows that a higher Wagner grade, representing deeper ulcer, larger size, more infection, ischemia, and oedema, can be translated to the clinical signs of odour, exudates, and pain, which will compromise patients’ physical and mental health and social networking. When we explored the links between Wagner grade and HRQoL by Pearson correlation analysis, we found that Wagner grade was negatively correlated with 8 subscales of SF-36 and the summary (p<0.05). The absolute value of the correlation coefficient for the SF-36 summary was the largest (r=−0.47).
QoL was statistically significantly different in 17 ADDQoL domains in patients with DFS compared to patients without diabetic foot. According to ranks, among patients with diabetes with a diabetic foot, the most significant impact on the QoL was “physical health” and among patients without diabetic foot, “freedom to eat”. Similar results were obtained by Valensi et al,28 showing that HRQoL was significantly lower (p=0.0001) in group 1 (with DFS) than in group 2 (without DFS) for all domains of the SF-36. Divergent studies were presented by Alosaimi et al,29 stating that QoL was similar in patients with and without DFS.
Limitations
Despite the supportive findings of the study, several limitations need to be acknowledged. Firstly, as the participants were only from one hospital in Poland the results might be difficult to generalize due to the particular sociodemographic and clinical characteristics. It is necessary to expand the study group in the future, as this study was pilot in nature. Secondly, the study was cross-sectional, so it was conducted at one point in time, which is why changes over time could not be analyzed. Considering that the average duration of diabetes was long, and the late complication arose (DFS), the obtained results seem to constitute a valuable scientific study. Thanks to them, it is known which factors influence and in what direction and magnitude on QoL. Methodological limitations restrict the interpretation of the obtained results, which, on the other hand, may provide important insights for further research.
Conclusion
Diabetes has a negative impact on the QoL of patients in Poland. Out of 19 domains, the ADDQoL questionnaire was significantly influenced by the “physical health” domain in patients diagnosed with DFS, and by the “freedom to eat” domain in patients without diabetic foot. The results of multivariate linear regression analysis show that, among people with DFS, good QoL was statistically affected by gender, method of treatment, and self-dressing. Statistically significant factors influencing worse QoL were diabetes complications, fasting blood glucose, amputation of a fragment or the entire limb, type of dressing, wound size, and the Wagner scale. In addition, among people without diabetic foot, good QoL was statistically affected by the professional activity of the patients, and the QoL was negatively affected by hypo- and hyperglycemia.
Implication Practice
Our results confirmed that the QoL of patients with type 2 diabetes decreases. Patients must be monitored by a diabetologist, a cardiologist, a surgeon, as well as through nurse education. With regular visits and continuous monitoring of their health, this can potentially change the therapeutic regimen, ultimately leading to good glycaemic values, and thus the desired effects of treatment, which has a positive effect on their QoL. This study provides valuable evidence that diabetic foot problems have the most negative impact on HRQoL. Therefore, paying more attention to foot care and foot evaluation is critical in preventing diabetes-related foot problems. Based on the results of this study, we believe that more emphasis should be applied to foot care in patients with and without DFS and self-monitoring.
Data Sharing Statement
The study does not contain data from any individual person and data obtained from the questionnaires is available upon request.
Ethics Statement
The study was performed with the consent of the Bioethics Committee of the in Bielsko-Biala on 15 January 2023 (Consent No. 2023/01/6/E/6). The study does not report on or involve the use of any animals.
Funding
The study was entirely Self-financed. The design of the study, the collection, analyses, interpretation of data, writing of the manuscript, and the decision to publish the results were performed only by the authors.
Disclosure
The authors declare no conflicts of interest, neither financial nor non-financial, and received no funds from sponsors.
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