An institutional longitudinal, cross-sectional design was used to conduct the study among patients presenting at Aldarga Diabetic Health Center in Wadmedani Town, Gezira State, Sudan, between the period September 2020 to December 2020. The center is located in the North of Wadmedani town, 186 KM south of Khartoum, the capital of Sudan. The center was established in 2007 and was opened as a specialized diabetic center, a reference for the Central Region of the country, with an area of 600 square meters. It consists of two departments, one for diabetic foot surgery and the second for diabetic internal medicine of internal diabetes. It consists of 4 doctors’ offices; each contains three doctors, two general doctors, and one family doctor. It also includes a general laboratory, a dental clinic, and statistical and computer labs. There is a special office for therapeutic nutrition for diabetics, health nutritional education for diabetics, and a section on immunization.
The study includes all diabetes mellitus patients who attended the diabetic follow-up clinic at Aldarga Diabetic Center in Wadmedani town. During the study period, all patients were targeted irrespective whether these patients had DFU or not because the prevalence methodology attempts to estimate the proportion of reported patients who develop DFU.
♦ Data collection: A structured data collection tool was developed after carrying out a literature review mainly adapted from the publications of WHO and UNICEF. Core questions were adapted from previous studies with four main dimensions: Sociodemographic variables: age, sex, family type, marital status, educational status, residence, and average monthly income; foot self-care attention variables: foot wear, fear of ulcers, foot cleaning, and foot washing; occasional foot inspection, Clinical variables were taken from the patients themselves, type of diabetes treatment ,duration of diabetes.
Diabetic foot: The International Working Group on the Diabetic Foot (IWGDF) has defined the diabetic foot as infection, ulceration, or destruction of tissues of the foot of a person with currently or previously diagnosed diabetes mellitus, usually accompanied by neuropathy and/or peripheral arterial disease (PAD to the lower extremity  Diabetic foot ulcer: these are nondramatic lesions of the skin on the foot distal to malleoli of a person who has diabetes mellitus.
Diagnostic criteria for diabetes mellitus or Measurement of Diabetes Mellitus:
Random plasma glucose values of ≥ 200 mg/dL (≥ 11.1 mmol/L) or 1(2) fasting plasma glucose values of ≥ 126 mg/dL (≥ 7.0 mmol/L) or (3) 2-h. Oral glucose tolerance test (GTT) value in venous plasma ≥ 200 mg/dL (≥ 11.1 mmol/L) (4) glycated hemoglobin (HbA1c) ≥ 6.5% (≥ 48 mmol/molHb).
♦ Sample size and sampling design
A random sampling method was used to select the sample in which population (Total diabetic patients in 2020 reported to the diabetic follow-up clinic.) The simple random sampling equation for the provisional sample size n*was calculated using the following formula:
n = (t²× p × q) / (d²)
n*: Required sampling size.
P: Anticipated population proportion was taken as 50% because it gives the maximum possible sample size. If we take the estimated prevalence rate for Sudan of 0.15 as P, the sample size will be 195, but we prefer a larger sample.
t: Confidence level taken as 95%.
d: Absolute precision required on either side of the anticipated proportion taken as 5 %
Then the provisional sample was multiplied by a design effect of 2 to give the final sample n:-
n = (2²×50×50) / (25) = 400
400 participants were successfully campassed by the field data collection team, which consisted of the principal researcher and the field data collectors. The field data collectors were all paramedical working in the center and trained for 10 days on data collection methods and the interview/observation methodology. The training sessions focused mainly on training the interviewers on measurement scales of hypertension, random blood sugar, height, length, and lipid. Twenty-one data collectors were trained. Quality of the collected data was checked by three well-trained paramedical staff who entered the data in SPSS program. Total Diabetic patients who reported to the center in 2020 were 40507 classified by months, with an average of 3376 diabetic patients per month.
The procedure used for selecting sampling units is twofold. First, we calculate the systematic sampling interval factor by dividing the number of diabetic patients during the data collection period (November-December 2020) by the sample size i.e. N/n = 1823/400 = 4.55\(\cong\)5. The sample unit number 5 was selected first. The rest of the sampling units were selected according Kish selection procedure to cater for gender (Kish, L., 2004).
The data collection instrument was a structured questionnaire written in English and then translated into Arabic. The structured data collection tool was developed after carrying out a literature review and was mainly adapted from the publications of WHO and UNICEF. The structured data collection tool was pretested. The pretest was carried out in 8% (60 households) of the total sample size of the study and the internal consistency measured under reliability by calculating Cronbach’s alpha coefficient. (The value of Cronbach’s Alpha coefficient was greater than 90%).
♦ Data Analysis methods
Descriptive statistics was initially undertaken to analyze the composition of the sample. Data were coded and entered into a computer using two of the latest versions of the prepared packages of statistical analysis, namely, Statistical Package for Social Sciences (SPSS) version 24.0/25.0 version for Windows. The program were used in different stages of data processing to process the raw data obtained from the questionnaires. Quantitative analysis of the question responses obtained from the questionnaire were summarized, portrayed, and analyzed on a statistical basis to offer the researcher the opportunity to analyze the responses and identify whether the results are skewed .
The following statistical analyses were run:
A pilot study was conducted to establish content validity.
Face validity was established through the circulation of the questionnaire to 60 pilot respondents.
In all analyses, the test was two-sided and a p value less than or equal 0.05 was considered
Statistically significant, while a p value less than or equal 0.01 was considered statistically
Prevalence of Diabetic Foot Ulcer
Of the 400 participants, 96 participants were clearly diagnosed as foot ulcer, giving a proportion of 33% in the sample. However, this proportion has to be adjusted by the total population of diabetic patients reported to the center, recorded as 40,127 in 2020 using the following equation.
P = the proportion with diabetic foot ulcer in the sample in 2020.
K = Total Patients with diabetic foot ulcer recorded in Aldarga center in 2020. (17,350)
N = Total patients with diabetic mellitus recorded in Aldarga Center in 2020.
n = sample size.
The values of p and key were obtained from Aldarga Center statistical office. Substituting in the prevalence equation, the prevalence rate in this study is estimated as 16.6% with 5 percent probability limit of (14.0 -19.2).
The DFU segregated by gender using the same methodology gives the prevalence rate for females as 16.1%, which is a little less than that for males of 17.1%.