Journal of Diabetes & Metabolism

Prevalence of Diabetic Retinopathy and Associated Risk Factors among Adult Diabetes Attending at Debre Tabor General Hospital, Northwest Ethiopia

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Introduction

Statement of the problem

Diabetic retinopathy is a long term and specific microvascular complication of diabetes, characterized by changes in small blood vessels of the retina, these include changes in vascular permeability, capillary microaneurysms, capillary degeneration, and excessive formation of new blood vessels (neovascularization) [1,2]. Most patients are asymptomatic, yet some patients may experience major visual changes including blurred, spotty and double vision [3].

If left untreated, diabetic retinopathy progresses from its milder abnormalities, to its sight threatening conditions such as growth of new blood vessels over the retina and towards the posterior vitreous and swelling of the highly light sensitive portion of the retina (macula) from leaky blood vessels and ultimately leads to clouding of vision and significant visual impairment [1].

Globally, the prevalence of diabetic retinopathy among adult diabetes is estimated to be 27.0% [4]. Based on a systematic review the prevalence of diabetic retinopathy in Africa is reported to be 31.6% [5]. The national prevalence of diabetic retinopathy in Ethiopia is reported to be 19.48% [3].

Out of 139 million visual impaired worldwide 3.7 (1.9%) million were visually impaired due to DR [6]. Visual impairment as a result of DR has a significant impact on patients’ quality of life, and can compromise their ability to manage their disease successfully, which can in turn have a positive impact on the incidence of other diabetic complications and negative impact on overall life expectancy and productivity [7].

The major risk factors for the development DR in DM patients are hyperlipidemia, obesity, puberty, longer diabetes duration, and poor glycemic and blood pressure control [8-10]. Complete understanding of the magnitude of DR in the patient population is crucial to design policies for prevention and timely treatment of the disease.

The risk of DR to sight can be greatly reduced by good blood glucose and blood pressure control, effective screening and timely laser treatment, intraocular injection of steroids and antivascular endothelial growth-factor agents and intraocular surgery [2,11]. The epidemiology and risk factors of DR has been well described in developed nations and a few numbers of studies have been attempted in the developing nations as well.

However, there is paucity of studies addressing the prevalence of diabetic retinopathy and underlying risk factors in Ethiopia particularly, in the study area. The purpose of this study is, therefore, to assess the prevalence of DR and associated factors among adult diabetes patients attending at Debre Tabor General

Materials and Methods

Study design and period

A hospital based cross sectional study was conducted at Debre Tabor General Hospital from June 29/2020 to August 28/2020. The hospital is located in Debre Tabor town, the capital city of South Gondar Zone of the Amhara National Regional State, and it is located 667 km from Addis Ababa. According to the Debre Tabor Hospital Planning and Information Department, the hospital is providing preventive and curative health care services for about ~2.7 million people in the zone and nearby districts and has a capacity of 250 beds for inpatient services in five disciplines and 12 outpatient departments (OPDs) [12]. The hospital has specialty chronic illness clinics where patients with specific chronic diseases are referred for follow-up. On average around 22 DM patients are visited in the two diabetic clinics per day during the working hours and general practitioners, internists and nurses are involved in the clinical service of diabetes patients. A secondary eye care service is given in the hospital with three optometrists, two ophthalmic nurses, one cataract surgeon and one ophthalmologist.

All adult diabetes patients of age ≥18 years visiting the diabetic clinic in DTGH during the study period were included. Patient with pregnancy induced diabetes (gestational diabetes), patients who were severely ill: unable to be sit and examined with slit lamp indirect ophthalmoscopy and patient with media opacity: obscuring the view of their retina were excluded from the study.

The sample size was determined based on a single population proportion formula by taking 13% prevalence from a similar study in Arba Minch [13], 95% CI, 4% margin of error and 15% nonresponse rate. Accordingly, the final computed sample size was 306. A systematic random sampling technique was applied to select study participants: there are around 700 diabetic patients who visit the diabetic clinic over 40 normal working days. Based on the decision to collect data in 2 months a sampling interval ‘’k’’ was determined by dividing the expected number of DM patients to the sample size 313 which was approximately 2. Then every other diabetes patient was approached for the study.

Ethical clearance was obtained from University of Gondar, College of Medicine and Health Sciences, School of Medicine ethical review committee. Moreover, permission to conduct the study in the hospital was obtained from Chief Executive Officer and Medical Director Offices of the hospital. Oral informed consent was obtained from each study participants after explaining the purpose of the study. All in all, the study was conducted in line with the Ethical Principle of the Declaration of Helsinki.

Data collection procedures and quality control

Semi-structured interviewer-administered questionnaire, document review and ocular examinations were used to collect data. The questionnaire consisted of 4 sections: Socio-demographic and economic variables (6 items), Behavioural measurements (14 items),diabetic follow up and eye checkup (5 items) and Checklist for clinical data extraction (7 items). Data quality was ensured through pre-testing the questioner on 5% of the sample before the actual data collection period and training of the data collectors. Each day during the data collection 5% of the data was cross checked for completeness by the principal investigator (Table 1).

Table 1: Socio-demographic and economic characteristics of study participants at Debre Tabor General Hospital, Northwest Ethiopia, 2020 (n=306).

Retinal examination was carried out with a 90 diopter of Volk lens with slit lamp biomicroscope by a trained senior optometrist after the pupillary dilation was done using 1% tropicamide eye drop on both eyes. Participants with complexity and/ or sight threatening retinopathy were double seen by a senior ophthalmologist working in the hospital. An eye with the highest grade of diabetic retinopathy was referred to label DR. Labeling of DR was done based on the Proposed International Clinical Diabetic Retinopathy and Diabetic Macular Edema Disease Severity Scales [14,15].

Data processing and analysis

After data was entered into EPI INFO 7 and exported to SPSS version 20 for analysis. The descriptive statistics was summarized and presented using summary statistics such as frequency tables. The model was checked by Hosmer and Lemeshow goodness of fit test. Binary logistic regression was used to identify candidate variables. Variables with p-value<0.2 in binary logistic regression, were entered into a multivariable logistic regression model. Variables having p-values <0.05 were considered as statistically significant.

Socio demographic characteristics of study participants

A total of 306 participants completed the study with a response rate of 97.7%. The median age of the respondents was 45 (IQR=30) years. Majority of the participants were male 166 (54.2%), were married 203 (66.3%), had no formal education 171 (55.9%), were farmer 90 (29.4%) and urban dweller 193 (63.1%). The median family monthly income of the respondents was 3577 Ethiopian Birr (ETB) (IQR=4500 Ethiopian Birr) (Table 2).

Clinical and behavioral characteristics of study participants

The median duration of diabetes was 4 (IQR=7) years the maximum duration of diabetes was 40 years and the minimum was 3 months in this study. The mean and median level of FBS was 150mg/dl (IQR=88). In this study, most of the participants were type I DM 163 (53.3%), had a good glycemic control 155(50.7%), used insulin alone as a treatment modality 171 (55.9%) (Table 2).

Table 2: Clinical and behavioral characteristics of study participants at Debre Tabor General Hospital Northwest Ethiopia, 2020 (n=306).

Systemic comorbidity, follow up and awareness of the participants

From the total participants, 93 (30.4%) had hypertension as a comorbidity, 228 (74.5%) visited the DM clinic every month, 72 (23.5%) had family history of DM, 126 (41.2%) had no prior eye exam and only 80 (58.8%) had awareness about diabetic retinopathy (Table 3).

Among the total study participants, the prevalence of diabetic retinopathy was found to be 96 (31. 4%).Of the total participants, 54 (17.6%) had NPDR, 6 (2%) had PDR and 36 (11.8%) had Diabetic Maculopathy.

Factors associated with diabetic retinopathy among diabetes

From bivariable logistic regression analysis, age, occupational status, family monthly income, duration of diabetes, glycemic control, hypertension and family history of diabetes were statistically and significantly associated with diabetic retinopathy. However, in a multivariable logistic regression analysis only family monthly income, duration of diabetes and glycemic control were remained significantly associated with diabetic retinopathy.

Regarding family monthly income of the study participants, those who had an income of <200 ETB were 7.4 times (AOR=7.4, 95% CI: 2.38-22.89) more likely to develop diabetic retinopathy compared to those who had income of >6500 ETB.

Participants who had a duration of 10 and above years were nearly 27 times (AOR=26.98, 95% CI: 11.45-63.62) more likely to develop diabetic retinopathy as compared to those who had a duration of less than 10 years.

Participants who had a poor glycemic control were about 3.17 times (AOR=3.17, 95%CI: 1.50-6.68) more likely to have diabetic retinopathy compared to those who had a good glycemic control (Table 4).

However, factors such as age, gender, marital status, educational status, occupational status, residence physical activity, alcohol drinking status, BMI, family history of diabetes, types of diabetes, mode of treatment, frequency of diabetes clinic visit, and having awareness about diabetic retinopathy had no association with diabetic retinopathy.

Discussion

The prevalence of diabetic retinopathy among adult diabetes attending at Debre Tabor General Hospital, Northwest, Ethiopia was found to be 31.40% (95% CI: 26.1%-36.3%). This finding was in line with the findings of studies conducted in United Kingdom (UK) [16] 28.50, China [17] (27.9%) Bangladesh [18] (36.10%), Nigeria [19] (26.20%), Zimbabwe [20] (28.40%) and Tanzania [21] (27.90%).

However, our finding was higher than the findings reported from USA [22] (14.70%), New Zealand [23] (22.50%), Spain [24] (14.90%), Slovakia [25] (15.50%), and Pakistan [26] (17.00%), Saudi Arabia [27] (16.00%), Egypt [28] (24.00%) and Uganda [29] (19.00%) Arba Minch [13] (13.00%), Gondar [30] 17.00%) and Bahir Dar [31] (25.50%). The discrepancy might be to the difference in the study population characteristics, sample size, inclusion criteria and methods of screening DR. For instance, studies in USA, Slovakia, Spain, Pakistan, Saudi, Egypt and Bahir Dar were only on type 2 diabetes, while our study included both types of diabetes, excluding type 1 diabetes may lower the actual prevalence of DR. Studies in New Zealand, Arba Minch, Gondar and Bahir Dar used the patients’ medical folder to screen DR, reviewing the patient’s medical folder results in lower prevalence of the disease since, not all diabetes are examined for their eyes in the absence of symptoms and complete recording of findings may not be available. Additionally, the difference in life style and health seeking behavior in the study settings may also be responsible for the difference.

On the other hand, this finding is lower than the study done in Pittsburgh USA [32] (44.0%), India [33] (60.9%), Cameroon [34] (40.3%), Zambia [35] (52.0%), Sudan [7] (82.6%), Jimma [36] (41.1%) and Addis Abeba[37] (51.1%). These variations could be attributed to the difference in the nature of study population, study settings and duration of diabetes. The study population in Pittsburgh USA were inpatient diabetes, who might have already encountered more systemic comorbidities, which increase the prevalence of DR. Participants in the Indian, Cameroonian, and Sudanese study were diabetes patients who were linked to Ophthalmology clinic for evaluation, and or patients who had been already on follow up in the retina clinic, assessing the prevalence in these setting could result in a high figure of DR. Similarly, the Jimman and Addis Abeban studies were at the referral centers, where patients with severe cases of diabetes and comorbidities are referred result in high prevalence of DR. Moreover, the median duration of diabetes in Addis Abeban study was 15 years which is longer than the median duration of diabetes in this study which was 4 years, this could also contribute to the difference in the prevalence of diabetic retinopathy.

This study also demonstrated that, low family monthly income, longer duration of diabetes and poor glycemic control were important risk factors of diabetic retinopathy. The likely hood of having diabetic retinopathy was high among participants who had an average monthly income of 2000 and below. This finding is in accordance with the finding of studies in India [38] and Sudan [39] which identified a low monthly income was a significant factor associated with the presence of diabetic retinopathy.

The possible reason for the association could be, participants with low monthly income may have constraints to cover their transportation, investigation and medication related costs hence, they might not be able stick with their follow up schedule and taking medications all the time. Besides, they may not be able to prioritize their diets to be taken, and this makes diabetes self-management even more challenging. All these factors are interrelated and may lead to poor glycemic control in turn linked to diabetic complications including diabetic retinopathy.

Our finding demonstrated that, the likely hood of developing diabetic retinopathy was high for participants with longer duration of diabetes (≥10 years) and this is consistent with what has been found previously in Arba Minch, Jimma and around the world [13,20,24-26,40,41] that longer duration diabetes was associated with the development of diabetic retinopathy. This might be due the fact that, in diabetes there are abnormalities in energy production which are thought to be the major contributor to the development of diabetic complications like diabetic retinopathy, and these abnormalities are considered to occur late in the development of the disease [1]. Moreover, this might be due to the widening of retinal vasculature along with the long duration of diabetes, which is a sub clinical marker of endothelial dysfunction which ultimately leads to diabetic retinopathy [2].

Our study also indicated that participants who had a poor glycemic control had an increased risk of developing diabetic retinopathy compared to those who had a good glycemic control. In this regard, our finding is similar with the findings previously reported in China [17], Bangladesh [18], Iraq [42], India [33], and Jimma [40]. Hyperglycemia instigates a cascade of events leading to retinal vascular endothelial dysfunction eventually leads to development of diabetic retinopathy [2]. High glucose level in the endothelial cells create an energetic imbalance and switching these cells to a demanding energy production from fatty acids and amino acids this will increase the oxidative stress to the endothelial cells and may lead diabetic complications like diabetic retinopathy. Moreover, during hyperglycemia, uncontrolled energy production inhibits the antioxidant capacity of the endothelial cells and this could be linked to diabetic complications including diabetic retinopathy.

Themain limitation of our study include: it was a single center and hospital based study, the patients recruited into our study may not be representative of the overall population with diabetes, and this affects the generalizability of our finding, the cross sectional nature of our study, did not allow us to identify the important predictors of diabetic retinopathy.

Conclusion

The prevalence of diabetic retinopathy was high compared to the global and national prevalence of diabetic retinopathy in Ethiopia. Low monthly income, longer duration of diabetes and poor glycemic control were found to be independently and significantly associated with the presence of diabetic retinopathy in this study. Therefore, it is better to embark a coordinated early diabetic retinopathy in the hospital. It is also equally important to draw more attentions and increase effort in provision of affordable and accessible health care service for diabetes patients, here by reduce devastating consequences of the disease.

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