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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 14  |  Issue : 2  |  Page : 200-205

Prevalence and risk factors of diabetic retinopathy in rural population of Belgaum district


Department of Ophthalmology, JN Medical College, KLE Academy of Higher Education and Research, Belagavi, Karnataka, India

Date of Submission24-Sep-2019
Date of Acceptance15-Oct-2020
Date of Web Publication31-May-2021

Correspondence Address:
Dr. Lisa Sunny
Department of Ophthalmology, J. N. Medical College, KLE Academy of Higher Education and Research, Belagavi - 590 010, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/kleuhsj.kleuhsj_204_19

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  Abstract 


BACKGROUND: Rural population is highly underprivileged in terms of access to tertiary eye care facilities.
AIMS: The aim of the study was to determine the prevalence of diabetic retinopathy (DR) and associated risk factors among known diabetics in the rural population of Belgaum district.
SETTINGS AND DESIGN: A cross-sectional population-based study was carried out from January 2018 to December 2018.
METHODOLOGY: Three hundred and forty patients underwent a detailed ocular examination. Clinical grading was based on early treatment of DR study guidelines. Random blood sugar, blood pressure, height, weight, hemoglobin, serum creatinine, and glycated hemoglobin (HbA1c) were measured.
STATISTICAL ANALYSIS: Chi-square and analysis of variance tests were used to assess risk factors.
RESULTS: The prevalence of DR was found to be 23.82%. Of this, 19.11% had nonproliferative DR (PDR) and 3.53% had PDR. Nearly 1.18% had clinically significant macular edema. A statistically significant association was found between DR and duration of diabetes, HbA1c, smoking, and family history of diabetes.
CONCLUSION: The significant prevalence of DR as per this study signifies the need for regular structured screening camps and the availability of basic vitreoretinal facilities at the primary level.

Keywords: Diabetic retinopathy, epidemiology, rural population


How to cite this article:
Tenagi AL, Sunny L, Wani V, Magdum MI, Smitha K S, Bhagyajyothi B K. Prevalence and risk factors of diabetic retinopathy in rural population of Belgaum district. Indian J Health Sci Biomed Res 2021;14:200-5

How to cite this URL:
Tenagi AL, Sunny L, Wani V, Magdum MI, Smitha K S, Bhagyajyothi B K. Prevalence and risk factors of diabetic retinopathy in rural population of Belgaum district. Indian J Health Sci Biomed Res [serial online] 2021 [cited 2021 Jun 17];14:200-5. Available from: https://www.ijournalhs.org/text.asp?2021/14/2/200/317400




  Introduction Top


Diabetes mellitus (DM) is a major pandemic with significant public health implications. Estimates point to 439 million of world population likely to be diabetic by the year 2030. This balance is tilted more to the side of developing countries as compared to the developed ones, putting a strain on the already limited health-care facilities in these nations for the management of diabetic complications.[1]

Diabetic retinopathy (DR) can be defined as a chronic microangiopathy, secondary to prolonged hyperglycemia, with a potential to impair vision.

The India Diabetes study conducted by the Indian Council of Medical Research has estimated the number of diabetics in India to be 62.4 million people. Over the next two decades, this can increase by more than 15 million, bringing the number of DR patients to 22.4 million and 2 million diabetics with sight-threatening DR.[1]

In India, the prevalence of DR is found to be around 13%–18% in urban areas and 9%–10% in rural areas.

It is the sixth leading cause of blindness in India. The awareness among diabetic patients as well as the diabetic care providers at the primary level regarding DR as a sight-threatening complication of long-standing diabetes is very low, especially in the rural area. This necessitates mass awareness and screening programs for better utilization of health-care services and preventing blindness.

This study was conducted to determine the prevalence of DR and assess its risk factors among known diabetic patients in rural Belgaum.


  Methodology Top


Study population

The source of data was 350 already diagnosed diabetic patients, attending DR screening camps organized in rural areas of Belgaum district.

Selection criteria

Inclusion criteria

All patients between 40 and 85 years of age, who are known Type II diabetics, for more than 6 months, visiting screening camps in rural Belgaum, were included in the study.

Exclusion criteria

  1. Ophthalmic diseases preventing a view of posterior segment such as senile mature cataract and corneal opacity
  2. Individuals with shallow anterior chamber
  3. Acute ocular inflammation.


Procedure

After the approval from the institutional review board and ensuring that all the study procedures adhere to the tenets of the Declaration of Helsinki, the study was carried out.

Screening camps for detecting DR were organized by the department of ophthalmology of the base hospital in the rural areas of Belgaum district.

A single observer study was carried out, and 340 patients who satisfy the above mentioned criteria were enrolled in the study as participants.

After obtaining consent from all the participants, a thorough history, patient particulars, ocular complaints, diabetic status and treatment, and comorbidities were duly noted.

Visual acuity was checked using Snellen's visual acuity chart. Detailed anterior and posterior segment examination was done by both direct and indirect ophthalmoscopy and recorded [Figure 1] and [Figure 2]. The patients were graded as per the abbreviated early treatment of DR study (ETDRS) classification of DR.
Figure 1: (a and b) Moderate nonproliferative diabetic retinopathy

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Figure 2: (a and b) are high risk proliferative diabetic retinopathy

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Blood pressure was recorded. The body mass index (BMI) of the patient was calculated according to height and weight records.

Hemoglobin and random blood sugar were recorded at the respective PHCs.

Mini RFT and HbA1C were done at the base hospital. These data were used to assess the risk factors of DR. The patients with no DR and very mild nonproliferative DR (NPDR) were asked for regular annual checkup. Mild NPDR patients were to review after 6–12 months. Moderate-to-severe NPDR patients were asked to review in 2-4 months. Very severe NPDR patients were advised 2 monthly follow-up. Proliferative DR (PDR) patients were referred to base hospital for further management. Ethical clearance was obtained from JNMC Institutional Ethics Committee on Human Subjects Research on 27/11/2017 reference MDC/DOME/.


  Results Top


Of the 350 self-reported diabetic patients, with an age group ranging from 40 to 85 years, five did not consent for blood investigations and five refused dilated fundus examination, thus leaving 340 patients for analysis.

The prevalence of DR was found to be 23.82% among this cohort of 340 patients.

Of this, 19.11% had NPDR and 3.53% had PDR. Nearly 1.18% had clinically significant macular edema (CSME).

There were 138 male and 202 female participants in the study. The odds of having retinopathy was more in males compared to females with an odds ratio of 1.71 and a confidence interval between 1.03 and 2.83.

The duration of diabetes ranged from 2 to 10 years in most participants. Sixty-eight were recently diagnosed diabetics and 21 had diabetes for more than 15 years.

Among the risk factors assessed, the most significant association was with the duration of diabetes [Graph 1] which showed a P < 0.0001 and HbA1c level [Graph 2], which showed a P < 0.00001 using analysis of variance (ANOVA) test. Majority of the participants had HbA1c values over 6.5%, with eight participants having a value of more than 12.5%.



Other risk factors associated with DR were smoking habit and family history of diabetes, which were assessed by Chi-square test and showed P values of 0.029 and 0.005, respectively.

DR was mostly present in patients who had a BMI value of over 23.4%. No significant difference was present over the mean levels of BMI (kg/sq m) and severity of DR [Table 1].
Table 1: Mean values of body mass index over varying severity of diabetic retinopathy

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Even though the majority of the participants were hypertensive, it was not found to have a significant association with the development of DR [Table 2].
Table 2: Comparison of hypertension with diabetic retinopathy

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The study population ranged from normal to moderately anemic. None of the participants had severe anemia. As per ANOVA test, which gave a P value of 0.304, there was no significant difference in the mean level of hemoglobin and the severity of DR.

More than 80% of the study participants had a normal serum creatinine value. Kruskal–Wallis test showed no significant difference in the mean of creatinine level (mg/dL) over the severity of DR.

Only 24 participants were on insulin. As per Chi-square test, insulin intake and development of DR are independent variables, with a P value of 0.166.

Among the 38 participants who had undergone cataract surgery, nine had retinopathy changes. However, a P value of 1.0 proved this association insignificant.


  Discussion Top


Prevalence of diabetic retinopathy

The All India Ophthalmological Society DR Eye Screening Study, a cross sectional-study conducted in 2014, which screened 6218 patients, showed a prevalence of DR of 21.7%.[2]

The Sankara Nethralaya DR Epidemiology and Molecular Genetics Study Report 2 (SN-DREAMS 2) conducted in Chennai, reported a higher prevalence in urban areas (18.0%)[3] compared to rural areas (10.8%).[4]

In this study, the prevalence of DR in a sample population of rural Belgaum was 23.82% in the 340 patients screened. Of this, 19.11% comprised NPDR, 3.53% PDR, and a 1.18% CSME.

A similar study conducted in rural population of Ramanagara and Chikaballapura districts of Karnataka, which screened 321 patients, showed DR in 21.2%[5] with NPDR in 18% and PDR in 3.12%.


  Risk factors associated with the development of diabetic retinopathy Top


Gender

In this study, DR was present in 34.05% of the males and 28.71% of the females. Odds of having retinopathy was more in the male gender.

Similar study in Villupuram, Tamil Nadu, by Nadarajan et al. showed a statistically insignificant (P value of 0.65) higher prevalence of DR in males.[6]

Body mass index

In this study, the prevalence of any DR was higher in participants with a BMI of 23.4% or more as compared to those with lower BMIs. However, this association is statistically insignificant (P value of 0.19).

In the Wisconsin Epidemiologic Study of DR (WESDR) study, patients who were obese at baseline (BMI > 31 kg/sq m for men and > 32.1 kg/sq m for women) had 35% more chance for progression of retinopathy, when compared to those who had a normal BMI at baseline.[7]

Duration of diabetes

Duration of diabetes continues to be the most significant risk factor for the development for DR in this study also, in concurrence with the global epidemiological data on DR.

The Chennai Urban rural epidemiology study eye study-4 also supported the positive association between duration of diabetes and DR (P < 0.0001).[8]

Glycemic control

In this study, glycemic control was demonstrated by the plasma values of glycated hemoglobin (HbA1C). Patients with HbA1C values of more than 8.95 ± 2.14 had higher prevalence of DR as compared to those with lower HbA1C values (more optimal glycemic control).

The positive association between higher HbA1C levels and retinopathy had a statistically significant P < 0.0001. The average HbA1C values for patients with PDR were 10.56 ± 2.15.

In a 2009 study on the relation between glycated hemoglobin and microvascular complications by Sabanayagam et al., the ideal threshold values for detecting mild and moderate retinopathy were 6.6% with a 87% sensitivity and 77.1% specificity.[9]

Smoking

Due to its vasoconstrictory effect on microvasculature[10] and enhancing the platelet aggregation and adhesiveness,[11] smoking is expected to have a deleterious effect on retinopathy. However, most epidemiologic data like the WESDR have not found any association between smoking and DR.[12]

In this study, the number of smokers compared to nonsmokers was less (66 and 274). Of the smokers, 23 had DR. The P value was statistically significant (0.029).

Studies have shown borderline significant association between pack-years smoked and progression to proliferative retinopathy in older onset insulin taking participants.

Anemia

In this study, there are 83 patients with mild (Hb 10–11 g/dl) and 79 patients with moderate (Hb: 7–10 g/dl) anemia, comprising mostly women. There was no significant difference in the mean value of hemoglobin over the severity of DR (P = 0.304).

Rani et al., in a study of 1414 patients, demonstrated that Type 2 diabetics with anemia had 1.80 times more risk of developing retinopathy than those without anemia.[13]

In the ETDRS study, David et al. observed that anemic patients (with a hematocrit lower than 40% in males and 32% in females) had a higher risk of developing proliferative retinopathy and resultant vision loss.

This lack of association between hemoglobin levels and DR in the present study may be due to the paucity of patients with significant anemia in this group.

Serum creatinine

In this study, there were only 85 patients with a serum creatinine value of more than 1.2 mg/dl. But, detailed history regarding other features of diabetic nephropathy was not elicited.

There was no significant difference in the creatinine level over the presence or severity of DR. It had a statistically insignificant P value of 0.348.

Insulin use

The (SN-DREAMS, Report number 35 reported a significant association between longer duration (>5 years) before commencing insulin therapy overall with the presence of DR (38% vs. 62% with a P value of 0.013). This may be attributed to the harmful effects of long-term hyperglycemia on the retinal microvasculature, owing to the delay in the initiation of insulin therapy.[14]

The present study had only 24 insulin users. However, as per Chi-square test, both insulin intake and DR are independent.

Hypertension

In the present study, there was no significant association between hypertension and the presence of DR (P = 0.228). Both are independent factors.

According to the United Kingdom prospective diabetes study, each 10 mmHg decrease in mean systolic blood pressure resulted in a 13% reduction in microvascular complications. A threshold was not observed for a retinopathy end point though.[15]

The present study shows higher incidence of CSME among diabetes patients with associated hypertension than nonhypertensives.

The WESDR study showed a higher risk of developing macular edema in diabetics who had associated hypertension.[16]

History of cataract surgery

In the present study, 38 participants had undergone previous cataract surgery. Details regarding the type of surgery, duration of surgery, and intra- or post-operative complications of the surgery were not known. Among them, nine had DR changes. However, the P value (1) was not statistically significant.

Hong et al. in a cohort study of 190 patients, with a 12-month follow-up period, observed an incidence of 28.2% DR in pseudophakic eyes in comparison to 13.8% in phakic eyes.[17]

Family history of diabetes

The present study has shown a positive association between family history of diabetes and presence of DR (P = 0.005). This might indicate the role of genetic predisposition.

Study limitations

The sample population assessed is very small and may not be entirely representative of the rural population of Belgaum.

Further large-scale epidemiological studies are necessary to acquire a more complete understanding of the magnitude of DR and its implications in rural northern Karnataka.


  Conclusion Top


The prevalence of DR in rural Belgaum as estimated by this study is 23.82%, similar to the study conducted in Ramanagara and Chikkaballapura districts.[5] This can even be an underestimation, considering the fact that, the people who voluntarily attend such screening camps are in better health than the nonparticipants.

Although it was present more in males, as compared to females, this did not amount to any statistical significance.

Among the risk factors assessed, the major factors were longer duration of DM, impaired glycemic control as indicated by higher HbA1C values, and smoking.

This study, in particular, has shown that a family history of diabetes has an important role, when it comes to the development of DR. Further genetic study is required in this area.

Other factors such as BMI, serum creatinine, hemoglobin level, insulin use, previous cataract surgery, and hypertension did not have any statistically significant correlation with retinopathy.

The burgeoning diabetic burden in India, with a significant section in rural India, warrants major advances in wholesome diabetic care.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Shaw JE, Sicree RA, Zimmet PZ. Global estimates of the prevalence of diabetes for 2010 and 2030. Diabetes Res Clin Pract 2010;87:4-14.  Back to cited text no. 1
    
2.
Gadkari SS, Maskati QB, Nayak BK. Prevalence of diabetic retinopathy in India: The all India ophthalmological society diabetic retinopathy eye screening study 2014. Indian J Ophthalmol 2016;64:38-44.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Raman R, Rani PK, Reddi Rachepalle S, Gnanamoorthy P, Uthra S, Kumaramanickavel G, et al. Prevalence of diabetic retinopathy in India: Sankara nethralaya diabetic retinopathy epidemiology and molecular genetics study report 2. Ophthalmology 2009;116:311-8.  Back to cited text no. 3
    
4.
Raman R, Ganesan S, Pal SS, Kulothungan V, Sharma T. Prevalence and risk factors for diabetic retinopathy in rural India. Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III (SN-DREAMS III), report no 2. BMJ Open Diabetes Res Care 2014;2:e000005.  Back to cited text no. 4
    
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Bharathi N, Kalpana S, Sujatha L, Nawab A, Kumar H. Prevalence of diabetic retinopathy in diabetics of rural population belonging to Ramanagara and Chikkaballapura districts of Karnataka. Int J Sci Res Publ 2015;5. Available from: http://www.ijsrp.org/research-paper-0315.php?rp=P393870. [Last accessed on 2019 Aug 15].  Back to cited text no. 5
    
6.
Nadarajan B, Saya GK, Krishna RB, Lakshminarayanan S. Prevalence of diabetic retinopathy and its associated factors in a rural area of Villupuram district of Tamil Nadu, India. J Clin Diagn Res 2017;11:LC23-LC26.  Back to cited text no. 6
    
7.
Klein R, Klein BE, Moss SE. Is obesity related to microvascular and macrovascular complications in diabetes? The Wisconsin epidemiologic study of diabetic retinopathy. Arch Intern Med 1997;157:650-6.  Back to cited text no. 7
    
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Rema M, Premkumar S, Anitha B, Deepa R, Pradeepa R, Mohan V. Prevalence of diabetic retinopathy in urban India: the Chennai Urban Rural Epidemiology Study (CURES) eye study, I. Invest Ophthalmol Vis Sci 2005;46:2328-33.  Back to cited text no. 8
    
9.
Sabanayagam C, Liew G, Tai ES, Shankar A, Lim SC, Subramaniam T, et al. Relationship between glycated haemoglobin and microvascular complications: Is there a natural cut-off point for the diagnosis of diabetes? Diabetologia 2009;52:1279.  Back to cited text no. 9
    
10.
Goldsmith JR, Landaw SA. Carbon monoxide and human health. Science 1968;162:1352-9.  Back to cited text no. 10
    
11.
Hawkins RI. Smoking, platelets and thrombosis. Nature 1972;236:450-2.  Back to cited text no. 11
    
12.
Moss SE, Klein R, Klein BE. Association of cigarette smoking with diabetic retinopathy. Diabetes Care 1991;14:119-26.  Back to cited text no. 12
    
13.
Ranil PK, Raman R, Rachepalli SR, Pal SS, Kulothungan V, Lakshmipathy P, et al. Anemia and diabetic retinopathy in type 2 diabetes mellitus. J Assoc Physicians India 2010;58:91-4.  Back to cited text no. 13
    
14.
Gupta A, Delhiwala KS, Raman RP, Sharma T, Srinivasan S, Kulothungan V. Failure to initiate early insulin therapy-A risk factor for diabetic retinopathy in insulin users with Type 2 diabetes mellitus: Sankara Nethralaya-Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS, Report number 35). Indian J Ophthalmol 2016;64:440-5.  Back to cited text no. 14
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Adler AI, Stratton IM, Neil HA, Yudkin JS, Matthews DR, Cull CA, et al. Association of systolic blood pressure with macrovascular and microvascular complications of type 2 diabetes (UKPDS 36): Prospective observational study. BMJ 2000;321:412-9.  Back to cited text no. 15
    
16.
Klein R, Klein BE, Moss SE, Cruickshanks KJ. The Wisconsin Epidemiologic Study of Diabetic Retinopathy. XV. The long-term incidence of macular edema. Ophthalmology 1995;102:7-16.  Back to cited text no. 16
    
17.
Hong T, Mitchell P, de Loryn T, Rochtchina E, Cugati S, Wang JJ. Development and progression of diabetic retinopathy 12 months after phacoemulsification cataract surgery. Ophthalmology 2009;116:1510-4.  Back to cited text no. 17
    


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