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ORIGINAL ARTICLE
Year : 2022 | Volume
: 21
| Issue : 4 | Page : 339-347
Diabetes mellitus foot ulcer and associated factors among Type 2 diabetes patients in a Tertiary Institution in Southwest Nigeria
Adedayo Idris Salawu1, Gbadebo Oladimeji Ajani2, Michael Osisiogu Soje2, Owolabi Dele Ojo3, Eunice Oluremi Olabinri4, Omotola Olawale Obajolowo2, Olakunle Fatai Babalola1, Tope Michael Ipinnimo5, Hameed Banjo Oguntade6, Olufemi Olusola Adediran7
1 Department of Surgery, College of Health Sciences, Afe Babalola University, Ado-Ekiti; Department of Surgery, Federal Teaching Hospital, Ido-Ekiti, Ekiti State, Nigeria
2 Department of Medicine, College of Health Sciences, Afe Babalola University, Ado-Ekiti; Department of Internal Medicine, Federal Teaching Hospital, Ido-Ekiti, Ekiti State, Nigeria
3 Department of Surgery, College of Health Sciences, Afe Babalola University, Ado-Ekiti; Department of Orthopaedic and Trauma, Federal Teaching Hospital, Ido-Ekiti, Ekiti State, Nigeria
4 Department of Radiology, College of Health Sciences, Afe Babalola University, Ado-Ekiti; Department of Radiology, Federal Teaching Hospital, Ido-Ekiti, Ekiti State, Nigeria
5 Department of Community Medicine, Federal Teaching Hospital, Ido-Ekiti, Ekiti State, Nigeria
6 Department of Medicine, Federal Teaching Hospital, Ido-Ekiti, Ekiti State, Nigeria
7 Department of Medicine, Faculty of Clinical Sciences, College of Health Sciences, University of Abuja, Abuja, Nigeria
Correspondence Address:
Adedayo Idris Salawu
Department of Surgery, Federal Teaching Hospital, Ido-Ekiti, Ekiti State
Nigeria
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/aam.aam_57_21
Abstract
Aim: This study aims to assess the proportion of diabetic foot ulcer (DMFU) and associated factors among patients with type 2 diabetes in a tertiary hospital in Southwest Nigeria. Methods: A pretested semi-structured interviewer-administered questionnaire adapted from the STEPwise Approach to Surveillance of Noncommunicable Disease Risk Factors of WHO.14 was used for data collection from a sample of 181 patients with type 2 diabetes mellitus. Sociodemographic, behavioral, clinical, and laboratory variables were collated from the participants. Chi-square test and logistic regression were used to identify the predictors of DMFU. Results: A total of 166 patients had their questionnaires completed. The mean age (standard deviation) of the respondents was 62.6 (14.3) years. The proportion of DMFU was 18.7%. More than two-third (71.1%) of our respondents had clinical symptoms suggestive of peripheral neuropathy while 34.3% of the patients seen in the study had evidence of peripheral vascular disease on duplex Doppler ultrasound. Male patients were about five times more likely to have DMFU than female patients (adjusted odds ratio [AOR] =5.27; 95% confidence interval [CI] = 1.001–27.841). Those with duration of diabetes ≥10 years were more likely to have DMFU than those with disease duration <10 years (AOR = 15.47; 95% CI = 1.201–199.314). Patients with fasting blood glucose (FBG) of ≥ 7.2 mmol/L were about four times more likely to have DMFU than those with FBG of <7.2 mmol/L (AOR = 4.19; 95% CI = 1.618–18.463). Conclusions: The proportion of DMFU was 18.7%, and the predictors identified included sex, duration of disease, and FBG level.
Abstract in French Résumé
Objectif: Cette étude vise à évaluer la proportion de l'ulcère du pied diabétique (DMFU) et des facteurs associés chez les patients atteints de diabète de type 2 dans un hôpital tertiaire du sud-ouest du Nigéria. Méthodes: Un questionnaire prétesté à un intervieweur semi-structuré adapté à l'approche par étapes de la surveillance des facteurs de risque de maladie non transmissibles de l'OMS.14 a été utilisé pour la collecte de données à partir d'un échantillon de 181 patients atteints de 17 diabète de type 2. Les variables sociodémographiques, comportementales, cliniques et de laboratoire ont été rassemblées auprès des participants. Le test du chi et la régression logistique a été utilisé pour identifier les prédicteurs du DMFU. Résultats: Un total de 166 patients ont réussi leurs questionnaires. L'âge moyen (écart-type) des répondants était de 62,6 (14,3) ans. La proportion de DMFU était de 18,7%. Plus de deux tiers (71,1%) de nos répondants présentaient des symptômes cliniques suggérant une neuropathie périphérique tandis que 34,3% des patients observés dans l'étude avaient des signes de maladie vasculaire périphérique sur l'échographie Doppler duplex. Les patients masculins étaient environ cinq fois plus susceptibles d'avoir du DMFU que les patientes (rapport de cotes ajustée [AOR] = 5,27; intervalle de confiance à 95% [IC] = 1,001–27,841). Ceux qui ont une durée de diabète ≥ 10 ans étaient plus susceptibles d'avoir du DMFU que ceux souffrant de durée de la maladie <10 ans (AOR = 15,47; IC à 95% = 1,201–199,314). Les patients atteints de glycémie à jeun (FBG) ≥ 7,2 mmol / L étaient environ quatre fois plus susceptibles d'avoir du DMFU que ceux avec FBG de <7,2 mmol / L (AOR = 4,19; IC à 95% = 1,618–18,463). Conclusions: La proportion de DMFU était de 18,7% et les prédicteurs identifiés comprenaient le sexe, la durée de la maladie et le niveau de FBG.
Mots-clés: Ulcère du pied, Nigéria, diabète sucré de type 2
Keywords: Foot ulcer, Nigeria, type 2 diabetes mellitus
Introduction 
Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both.[1] The prevalence of DM is 5.8% in Nigeria.[2] This translates to about 16 million people. Of concern is that the incidence of DM is increasing worldwide, with the low- and middle-income countries being worse hit.[3] The sustained hyperglycemia among several other factors in DM is associated with complications. One of such chronic complications of DM is the diabetic foot ulcer (DMFU). Patients with DM are at increased risk of developing foot ulcer when compared to those without diabetes.[4] The lifetime risk of developing DMFU among diagnosed DM is estimated at 15%.[5] Some recent data have reported lifetime risk as high as 25%.[6] The hospital prevalence of DMFU in Nigeria is 9.5%.[7]
The impact and burden of DMFU is multifold. It is one of the most dreaded DM complications as its can lead to amputation and in some instances death.[7],[8] The risk of lower-limb amputation has been reported to be 15–46 times higher in persons with DM than those without DM.[9] DMFU affects several aspects of the patients' life[4],[7],[10] – social, psychological, and financial among others. It also confers a burden on the health-care providers and strains the health-care system. Patients with DMFU have increased hospitalization and spend more days in the hospital; they visit the emergency room more often and expectedly have more work hour loss when compared to DM patients without ulcer.[10],[11] DMFU is expensive to manage.[12] It has been reported that the average cost for successfully treating a patient with DMFU in Nigerian was ₦180,581.60 (about US$488 using 2018 mid-year conversion rate).[7] This is about six times higher than the national minimum wage in a month. In the United States, the average annual expenditure of diabetic foot care is US$8,659 per patient.[13] The health insurance scheme coverage in Nigeria is low, hence the financial implication combined with work hour loss and psychological impact of DMFU in a developing country like Nigeria makes this complication one which requires urgent attention.
The increased hospitalization and prolonged hospital stay constitute a burden on health-care providers and the facilities. Nigeria has a low physician–patient ratio which is reported as 0.4 per 1000 by the World Bank in 2021.[14] Expectedly, the number and access to specialists is lower. Preventing the development of DMFU is a clinically smart approach to DMFU management. In doing this, it is important to identify the contributing factors to its development. Several factors have been identified,[15] but despite efforts made to modulate these previously identified factors, the prevalence of DMFU is on the increase. It is against this background that this study was conceived. It is expected that results from this study will enrich the literature, improve our understanding of the associated factors of DMFU, and when modulated will reduce the risk of DMFU in type 2 DM patients. This study aims to determine the proportion of DMFU and its associated factors among patients with type 2 DM in Southwest Nigeria.
Methods This is a cross-sectional study that was carried out in a Federal Teaching Hospital, Southwest Nigeria, between September 2019 and January 2020. Study participants were recruited from the diabetic clinic of the hospital. It included all patients managed for type 2 DM at the diabetic clinic of the hospital, who were 18 years and above. Patients with leg ulcers due to known (e.g., major trauma) cause other than DM were excluded. Sample size was determined using the Fisher's formulae.[16] A sample size of 181 patients was obtained after considering a nonresponse rate of 10%, prevalence of DMFU of 12%,[17] and standard normal deviation at 1.96 which correspond to the 95% confidence interval (CI) and degree of accuracy of 0.05.
Patients were consecutively recruited from the diabetic clinic until the required sample size was obtained. Sociodemographic, behavioral, clinical, and laboratory variables were collected from the participants using a pretested semi-structured interviewer-administered questionnaire. The questionnaire was adapted from the STEPwise Approach to Surveillance of Noncommunicable Disease Risk Factors of WHO.14.
Patients were examined to get their clinical information while laboratory data were retrieved from patients' records. The study involved two consultant endocrinologists, two plastic surgeons and one orthopedic surgeon, as well as two nephrologists, a consultant radiologist skilled in duplex Doppler sonology, and a community health physician all acting as a team in the study. At every point during data collection, at least two consultants were part of the physical assessment of patients and data entry process to ensure quality assurance.
Definition terms
A DMFU was regarded in this study as a discontinuation in the epithelial layer of the skin in the anatomical region of the foot that is not due to a known cause (e.g. major trauma) other than DM.
Peripheral neuropathy (PN) was defined as lack of feeling/protective sensation (at 4 or more of 10 sites), loss of sensation to joint vibration using 128 Hz tuning fork over bone prominences of the tibia, malleolus, abnormal deep tendon reflexes on the patella or tendoachilles, and/or the symptoms suggestive of PN (tingling sensation, burning sensation, involuntary twitching, loss of sensation, etc.).
Statistical analysis
The data collected were coded, entered into the computer, and analyzed using computer software, IBM SPSS Statistics for Windows Version 20.0 (IBM Corp., Armonk, N.Y., USA). Descriptive statistics was presented using frequency tables and a bar chart. Continuous variables such as age and average monthly income were summarized as mean and standard deviation (SD). Pearson Chi-square test was used in cross tabulations at bivariate level, and logistic regressions was used to identify the predictors of DMFU at multivariate level. Level of significance was set at 5%.
Ethical considerations
Ethical clearance was obtained from the Human Research and Ethics Review Committee of Federal Teaching Hospital, Ido-Ekiti. Informed consent of each participant was obtained. Confidentiality and anonymity were ensured by not collecting personal information and interviewing a single participant at a time.
Results A total of 181 type 2 DM patients were recruited in the study, however, only 166 patients had complete data. The sociodemographic characteristics of the 15 patients excluded due to incomplete data were not different from that of the patients included in this study. The sociodemographic characteristics of the respondents are shown in [Table 1]. The mean age (SD) of the respondents was 62.6 (14.3) years. There were more female respondents with a male-to-female ratio of 1:1.8. About two-third of the respondents were employed (66.9%), earn ₦30,000 or more (60.8%), and were married (68.7%). More respondents had tertiary level of education (44.6%) and reside in semi-urban areas (47.0%). [Table 2] shows that the mean duration of DM among respondents was 9.5 ± 7.4 years. More than half (53.0%) of the respondents were diagnosed as having type 2 DM <10 years, about two-third (68.7%) had hypertension, 36.1% were overweight, 77.1% use their drugs as prescribed every time, 66.9% attend clinic every time, 53.6% inspected their feet every day, 57.8% had fasting blood glucose (FBG) ≥7.2 mmol/L, and 34.3% had features of peripheral vascular disease (PVD) on duplex Doppler. Other clinicopathological characteristics are shown in [Table 2].
According to [Table 3], the proportion of patients with the presence of foot lesions (deformities and skin changes) considered to be diabetic foot at risk among the respondents was 46.4%. However, the proportion of DMFU (patients with at least Wagner Grade 1) was 18.7%. More than half (58.1%) of these respondents with DMFU, had the foot ulcer on the right foot only. It was also revealed that 4 (2.4%) respondents have had amputation in the past, out of which 3 of them were below the knee. [Figure 1] shows that a large proportion (right foot ulcer – 71.4% and left foot ulcer – 46.2%) of the foot ulcers were in Grade 2 Wagner diabetic foot.
Table 3: Presence foot lesions (deformities and skin changes), foot ulcer, and amputation among respondents (n=166)[Table 4]a and [Table 4]b shows factors (sociodemographic and clinic-pathological) associated with DMFU among the respondents. The proportion of respondents with DMFU significantly differ across age group (P = 0.005), sex (P = 0.005), employment status (P = 0.004), income (P = 0.047), duration of DM (P < 0.001), duration of hypertension (P < 0.001), frequency of drug use as prescribed (P = 0.010), FBG (P = 0.001), and presence of features of PVD on duplex Doppler (P = 0.008). After multivariate binary logistic regression that assessed the predictors of DMFU among the respondents, [Table 5] shows that sex, duration of DM, and FBG were factors that remained significant. Regression analysis revealed that male patients with type 2 DM were about five times more likely to have DMFU than female patients (adjusted odds ratio [AOR] =5.27; 95% CI = 1.001–27.841). Those with duration of diabetes ≥10 years were about 15 times more likely to have DMFU than those with disease duration <10 years (AOR = 15.47; 95% CI = 1.201–199.314). Finally, patients with FBG ≥7.2 mmol/L were about four times more likely to have DMFU than those with FBS <7.2 mmol/L (AOR = 4.19; 95% CI = 1.618–18.463).
Table 5: Multivariate binary logistic regression for the predictors of diabetic foot ulcer among respondents Discussion This study assessed proportion of DMFU and its determinants among type 2 DM patients managed in the diabetic clinic of a Federal Teaching Hospital located in Southwest Nigeria. The proportion of DMFU was found to be 18.7%. This is similar to the findings in Gondar, Arba Minch, and Mekele regions of Ethiopia,[15],[17],[18] where 13.6%, 14.8%, and 12% were reported, respectively. Another similar prevalence rate (15%) was noted by Nathan in Massachusetts General Hospital, Boston. However, this result is at variance with the findings in some studies in and outside Nigeria.[19],[20],[21] These differences in prevalence may reflect differences in the demographic characteristics of the population investigated. Another factor that may account for these differences is the variance in study design. This study recruited all the study subjects from a tertiary health facility unlike other studies that were recruited from multiple centers including primary health-care centers. Primary health-care centers may not have enough specialists to properly cater for DM patients and therefore giving rise to more patients coming down with complications including DMFU. What is pertinent to note from all the study, is that at least a tenth of the patients seen for diabetes in Ethiopian and Nigerian (Africans) studies have lesions considered to be DMFU.
Concerning foot care, it was observed that half (50.6%) of the patients were using shoes considered appropriate according to recommendation by their diabetologist and 53.6% of the patients were inspecting their foot. This is an improvement from the findings by Desalu et al. from a multicenter study in 2011 (which included the present study center). They noted that 78.4% of their patients had poor knowledge/poor foot care, while 88.6% were not using the appropriate footwear to prevent diabetic foot.[22]
In this study, we observed that the proportion of DM patients with hypertension was 68.7%, which is at variance with the findings of Ajayi and Ajayi (49.2%) in a previous finding done in 2009 in the same center.[21] The difference may reflect the difference in study designs. However, it does highlight the fact that patients with DM are at higher risk of hypertension, which significantly increases their risk of cardiovascular disease including PVD which can contribute to the development of DMFU.[23]
Furthermore, this study identified the predictors of DMFU. Age group, sex, employment status, income, duration of DM, duration of hypertension, frequency of drug use as prescribed, FBG, and presence of features of PVD on duplex Doppler were significantly associated at the bivariate level of analysis while sex, duration of DM, and FBG remained significant at multivariate level. Age ≥65 years was found to confer a higher risk of DMFU in the respondents. A study in Bangladesh revealed that patients older than 50 years of age, had a higher risk of developing diabetic foot.[20] The occurrence of DMFU in the older age group may reflect the longer duration of diabetes in these patients and hence its other complications, i.e. PVD, neuropathy, retinopathy, and nephropathy, which have a positive correlation with the occurrence of DMFU.[24] This study also revealed that male respondents were about five times more likely to develop DMFU. This is consistent with findings from another study in Bangladesh.[24] The explanation for this may be that women are more sensitive to health issues and more likely to seek health-care services compared to men.[25],[26],[27] In addition, males in this environment are more likely to engage in outdoor activities that may result in trauma to the feet which may not heal if the patient has background DM.
Worthy of note is that 34.3% of the patients seen in this study, had evidence of PVD on duplex ultrasound. The severity of the PVD ranges from mere presence of isolated atheromatous plaques in the infrapopliteal vessels to vessel narrowing with impaired or altered flow of blood to the feet. This result may be because majority of the patients were in older age group apart from the fact that they had type 2 DM. Generally, the incidence of PVD increases with advancing age. Another explanation for the high frequency of PVD may be due to the method of identifying PVD. The authors in previous studies utilized palpation of the foot pulses and ankle-brachial indices, while this study utilized imaging technique of duplex Doppler ultrasound as the main method of determining the presence of PVD.[12],[28],[29],[30]
When the presence of PVD was assessed using ankle-brachial index, only 16.3% of the patients had ankle-brachial index <0.9 on the right leg while 15.7% had ankle-brachial index <0.9 on the left leg. This is an indication that the use of duplex Doppler ultrasound in the hands of an experienced sonologist may be a more sensitive modality of identifying patients with PVD in patients with type 2 DM.[31] The variation observed in this study, may suggest that ankle-brachial index has more confounding factors affecting its interpretation, i.e. presence of foot ulcer, edema, and medial calcific sclerosis, which may make it more difficult to identify PVD in the earlier phases of the disease in patients with DM but useful in more advanced staged of the disease.[30]
More than two-third (71.1%) of the respondents had clinical symptoms suggestive of PN. This is quite high because, in other studies, diabetic sensory neuropathy affects about 30% of hospital-based populations, 20% of community-based samples, and 10% of the DM patients' population identified by screening. These differences in prevalence rate of PN may be because of the differences in the methods of determining the presence of peripheral sensory neuropathy (symptoms and signs, monofilament test, nerve conduction studies, etc.) and differences in the races studied. Furthermore, some of the studies were hospital based while others were community-based studies; many of the studies also combined the study of both type 1 and type 2 DM patients.[32]
Glycemic control of ≤7.2 mmol/L was associated with less likelihood of developing DMFU. Patients with FBG ≥7.2 mmol/L were about four times more likely to have DMFU than those with FBG <7.2 mmol/L (AOR = 4.19; 95% CI = 1.618–18.463). This result is in keeping with the findings by Elhadd et al. and Singh et al.,[29],[33] where it was noted that elevated fasting plasma glucose was not only associated with a higher incidence of PVD (a key factor in development of DMFU) but also associated with a higher incidence of re-occlusion following balloon intervention for infrapopliteal PVD. The elevated plasma glucose in general increases proinflammatory cytokines, leading to chronic inflammation with endothelial dysfunction, thrombogenesis with the end point of atherogenesis.[34]
Limitation of the study is that it is a hospital-based study utilizing only the diabetic clinic, hence the findings may not be exactly the same as in the general Nigerian population. However, the findings do provide a template for larger studies and will aid the design of treatment protocols in the diabetic clinic in our district.
Conclusions The proportion of DMFU was 18.7%, and the predictors identified included sex, duration of DM, and FBG level. Some of the factors identified in this study can be modified to achieve the prevention of DMFU, if better and earlier primary health care is given to the community.
We wish to encourage more health-care screening for patients in the community to identify patients at risk for diabetes using efficient primary health-care and creation diabetic foot clinics at the tertiary centers where comprehensive multidisciplinary care can be given to patients with complications of diabetes involving the foot.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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