Diabetic foot ulcer: risk factors among patients of a secondary healthcare facility in south west Nigeria

Background: Diabetic foot ulcer is a common long term complication of diabetes and the most common cause of non-traumatic amputation and prolonged hospitalization. These increases disease burden and further worsen quality of life. Aim: This study evaluated exposure risk factors for foot ulcers among diabetics attending a secondary healthcare facility in Southwest Nigeria. Methods: A case control study of exposure risk factors for diabetes foot ulcer (DFU) at General Hospital Marina Lagos. Using a structured interviewer administered questionnaire, information on foot care education, 24-hour dietary recall, medical history, anthropometric indices and social habits of participants were obtained and analyzed. Results: There were 636 participants in this study (106 cases and 530 controls) with median age of 61.1±11.0 years in both study groups and mostly females, (75.5% in cases and 78.7% controls) with female to male ratio of 3:1. Majority, (83% in cases and 85% in controls) were in the low socioeconomic class and had lived with DM for more than 5years. Of the studied risk factors, lacking foot care education, diagnosis of visual impairment and hypertension, dietary intake of large proportion of carbohydrate meal at breakfast and dinner and obesity occured in significantly higher proportion of cases and controls and were associated with presence of DFU. (p<0.05) Conclusions: Lack of foot care education, diagnosis of visual impairment, hypertension and poor dietary habit are associated with presence of DFU. Addressing these factors from point of diagnosis will go a long way in stemming the burden of diabetes foot ulcer.


INTRODUCTION
Diabetic foot Ulcer (DFU) is the most common chronic complication in persons with diabetes depending on disease duration and successful management. 1,2,3About 25% of persons with diabetes mellitus (PWDM) will develop DFU while 5% to 15% will be treated for foot or leg amputation in a lifetime. 4The prevalence of DFU varies widely between 0.9-8.3% in Nigeria, 1.4% in United Kingdom, 4-10% in United States of America and 18% in Sudan. 2,3,5,7The North-West Diabetes Foot Care Study reported more than 2% of community-based diabetic patients develop foot ulcers every year.Consequently, a neuropathy disability score using the 10 g monofilament coupled with palpation of foot pulses was recommended as screening tools. 8Established risk factors for DFU include peripheral sensory neuropathy, peripheral arterial occlusive disease, structural foot deformity and unintentional or imperceptible trauma in the presence of insensate feet. 2,9is combination of ischaemia, peripheral vascular disease and loss of protective sensation set the stage for pressure necrosis, superficial cellulitis, ulceration, infection and chronic osteomyelitis that may finally culminate in gangrene. [10]In a systematic review on predictive value of physical signs, diagnostic tests and patients' history related to DFU, there was paucity of evidence on predictive value of symptoms and medical history for DFU.This necessitates further research to establish factors from patients' history that may be associated with DFU. 11,12abetic foot ulcer, a major medical and socio-economic burden, contribute to high morbidity, prolonged hospitalisation and mortality. 6The economic burden of DFU is enormous with cost of treatment from ulcer to complete healing or amputation of between US$102 and US$3959. 13,15oot structure is complex, combine bones, muscles, blood vessels and nerves, each of which may be affected by nutritional, defensive and repair mechanisms.Managing diabetic foot lesions is always a challenge to health professionals.Failure of foot ulcer treatment/healing may result from lack of health providers' understanding of the impact of treatment on patient's life while patients' understanding of the disease process and treatment recommendations for foot ulcer/amputation are viewed as extremely difficult and results in disruption and loss of independence. 12,15,16e International Diabetes Federation (IDF) reported that only 1 in 5 healthcare professionals receive postgraduate training in diabetes, while less than 1 in 2 people with diabetes and less than 1 in 4 family members of people with diabetes have access to diabetes education programme.This makes patient education a fundamental component of diabetes care that should be readily available and accessible. 17Primary prevention of DFU include foot care education, maintenance of good nutrition and glyco-metabolic control among others. 18,19,20naging DM should include education on healthy lifestyle changes, regular exercise to control weight, quitting smoking, appropriate diet and treatment of glycaemic and lipid disorders. 19,21,22Shortage of trained diabetes care specialists, particularly at secondary health care facilities make patients seek treatment from other health care providers with little or no training in managing diabetes, diabetes foot lesion and also delay prompt referral. 22This study evaluated level of foot care education, past medical history, social and dietary habits with obesity as DFU risk factors among PLWD at a secondary health facility setting in Nigeria with aim to instituting appropriate measures of prevention to minimize DFU prevalence, burden and poor quality of life.

Study Design and Location
This was a case control study of exposure risk factors associated with DFU among PLWD attending General Hospital Marina Lagos, a secondary healthcare facility in southwest Nigeria and conducted between April 2014 and May 2015.The study participants had lived with DM for at least 5 years and were being managed with diet and oral anti-diabetic medications.The study design excluded study of established clinical and laboratory risk factors for DFU.

Sample size determination and technique
A previous study from the same center on the prevalence and pattern of DFU yielded 106 diabetics with DFU, a prevalence of 17.3%. 22This population was adopted and for each, 5 PLWD but without DFU were consecutively recruited till 530 participants as controls was achieved yielding a total of 636 study participants.These had their data collated and analyzed.

Data collection and instrument
Participants' socio-demographic and anthropometric parameters were obtained from their hospital records.They were then interviewed using semi-structured questionnaire for information on foot care education, past medical history, 24 hour dietary recall, use of alcohol and smoking as well as presence of DFU.

Pre-testing, data instrument and collection
Details for pre-testing the questionnaire and data collection had been previously described. 22ta management and analysis Data was organized and entered into Statistical Package for the Social Sciences (SPSS) version 17.0 software (IBM compatible).Categorical variables were compared using Chi-square test with logistic regression analysis for predictive values with level of statistical significance set at p<0.05.

Ethical consideration
Ethical approval was obtained from Olabisi Onabanjo University Teaching Hospital Health Research and Ethics Committee (OOUTH-HREC).Approval to carry out the study was obtained from the authorities of the General Hospital Lagos while written or thumb printed informed consent was obtained from each study participant.

Socio-demographic characteristics
The mean age of study participants was 61.1±11.0 years with age range of 30-70 years, more in 50-69 years bracket in cases than controls (69.8 and 58.1%, p<0.05), more females, [75.5% in cases and 78.7% in controls, (female to male ratio of 3:1] and mainly of Yoruba ethnic group (81.1% and 85.3% respectively, p<0.05).Majority of respondents were housewives and semi-skilled workers (83% vs 88.5%), with primary or secondary school education as highest educational qualifications (65.1% vs 61.9%) and earn less than N 49,000.00(about 150 US dollars) monthly (Table1).

Diabetes foot care education, lifestyle habits, medical history and diabetic foot ulcer
At the time of study, 21 (19.8%) of cases had leg amputation from DFU.Most study participants (90.2% of controls and 80.3% of cases) had never received foot care education, 80.4% of controls and 66.0% of cases were walking bare footed while 88.3% of controls and 81.1% of cases wore tight fitting shoes, a statistically significant difference.2).

Measures of Obesity, Twenty four-hour Dietary recall and meal time among participants.
The use of body mass index (BMI) and waist circumference (WC) as measures of obesity in this study showed that 88.7% of cases and 77.9% of controls using BMI, were overweight and obese using their BMI, a statistically significant difference (p<0.05).However, no such difference was noted when large proportion of carbohydrate meal was consumed at lunchtime (67%vs 63.0% in controls respectively).(p>0.05)(Table 3).All study variables except presence of foamy urine and history of alcohol intake predicted risk of developing DFU (Table 4).Those who did not receive foot care education were twice more likely to develop DFU compared with those who received foot care education (OR=2.27;CI=1.3014-3.9632;p<0.05) and being diag nosed with hypertension, visual defect and history of smoking were 2.03, 1.96 and 3.12 times more likely to develop DFU compared with those who were not so diagnosed.Those who did not walk bare footed, tight shoes and inspected foot for ulcer were less likely to develop DFU.

DISCUSSION
About fifty percent of all diabetes-related admissions are due to diabetic foot problems, an estimated 25% of PLWD will develop problems of diabetic foot (DF) during a lifetime and between 5% and 15% will be treated for foot problems and amputation. 12n this study, the demographic characteristics of participants, occupation, income level and educational attainment were neither different between cases and controls nor predictive of DFU though age group and ethnicity were contrary to available reports from Lagos and Benin-City in Nigeria with reported positive association of socio-economic status with DFU. 23,24This may be consequent on the generally prevailing low educational attainment, occupation and earning power among this study population who most times will engage in lifestyle habits averse to good health and attend healthcare facilities staffed by healthcare professionals with little or no postgraduate exposure or training in diabetes care. 13,17There is therefore the need for continuous medical education of medical practitioners entrusted with the care of diabetes at the secondary health care level.
A study at the University of Benin Teaching Hospital (UBTH) on risk factors, ulcer grade, and management outcome of DFU reported gender prevalence contrasting with our study finding though with similarity in age bracket, socio-economic status, obesity and lack of foot care education.Other established clinical and laboratory characteristics not part of our study design include DM neuropathy, glycaemic control, foot deformities and peripheral vascular disease, lending support to a multi factorial aetiology for DFU. 24Added to these are late presentation to hospital often times due to patients' ignorance and lack of understanding of diabetes, paucity of knowledge of diabetes self-care, funds for hospital management due to economic status and fear of limb amputation if they came to the hospital with lack of prompt referral to trained Diabetes care specialists. 22 this study, respondents without foot care education, walking bare footed, diagnosis of visual defect show significant association and prediction with development of diabetic foot ulcers similar to the report of Ogbera and Edo. 21,24 actors like diagnosis of hypertension and smoking are established as risk factors for non-communicable diseases-peripheral vascular disease, stroke, coronary heart disease and diabetes, DFU and its progression 23,24,25 Ill-fitting footwear with background of peripheral neuropathy, puncture wounds, thermal injury from application of hot compress to insensate (numb) feet are other preventable events preceding DFU.Education and increased awareness on avoiding these lifestyle habits should form cornerstone for diabetes management aimed to reduce adverse outcome. 9,10,12It is noteworthy that the average monthly admission for DFU within this study period was higher during the dry/harmattan season of December to March.
This may probably be because then, patients will likely walk bare-footed (both out and indoors) increasing the risk of puncture injuries.
A similar finding of increased occurrence of DFU during the harmattan season had been reported. 26Our study revealed association between presence of foot ulcers, BMI and intake of large carbohydrate meal at breakfast and dinner.
This may be predicated on the high glycaemic index (GI) of such meals with surge in blood glucose level within 90 minutes of ingestion intended to provide energy needed for heavy manual work in most of study participants with low educational attainment, earning power and socioeconomic class.Such blood glucose surge is as detrimental as is chronic and persistent hyperglycaemia. 13arbohydrates are important nutrient to monitor in diabetics since they increase blood glucose the most.
For persons with diabetes, dietary recommendation is in eating a consistently modified carbohydrate diet and American Diabetes Association advice that monitoring carbohydrate intake either by carbohydrate counting or experience-based estimation remain a key strategy in achieving glycaemic control.Report from the University of Michigan Diabetes center also emphasizes the importance of eating vegetables. 27This practice will improve clinic attendance and medication compliance consequent on financial ability. 22,24

CONCLUSION
Poor patient education on foot care, visual impairment, hypertension, obesity, smoking and alcohol use and inappropriately large carbohydrate meal at breakfast and dinner are associated with development of diabetic foot ulcers and that socio-economic status was not associated.

Table 1
Demographic Characteristics of Study Participants

Table 2
Foot care education, social habits and past medical history of study participants

Table 3
Measures of Obesity, Twenty four-hour Dietary Intake and time among participants

Table 4
Regression analysis of study variables as predictors of DFU