Observational Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Nephrol. Feb 21, 2019; 8(2): 33-43
Published online Feb 21, 2019. doi: 10.5527/wjn.v8.i2.33
Associations of renal function with diabetic retinopathy and visual impairment in type 2 diabetes: A multicenter nationwide cross-sectional study
Wisit Kaewput, Charat Thongprayoon, Ram Rangsin, Prajej Ruangkanchanasetr, Michael A Mao, Wisit Cheungpasitporn
Wisit Kaewput, Ram Rangsin, Department of Military and Community Medicine, Phramongkutklao College of Medicine, Bangkok 10400, Thailand
Charat Thongprayoon, Michael A Mao, Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, MN 55905, United States
Prajej Ruangkanchanasetr, Department of Medicine, Phramongkutklao Hospital and College of Medicine, Bangkok 10400, Thailand
Wisit Cheungpasitporn, Division of Nephrology, Department of Medicine, University of Mississippi Medical Center, Jackson, MS 39216, United States
Author contributions: Kaewput W, Thongprayoon C, and Cheungpasitporn W designed research; Kaewput W and Thongprayoon C performed research and analysis; Rangsin R, Ruangkanchanasetr P, Mao MA, and Cheungpasitporn W supervised this research project; Kaewput W, Thongprayoon C wrote the original manuscript; Rangsin R, Ruangkanchanasetr P, Mao MA, and Cheungpasitporn W reviewed, edited, and revised the final manuscript.
Institutional review board statement: This study was approved by both the Institutional Review Board of the Royal Thai Army Medical Department and the Ethical Review Committee for Research in Human Subjects, the Ministry of Public Health of Thailand (IRB# S043h/60Exp). Well-trained research nurses reviewed medical records and collected data into a case record form. Data entry into the case record form was then transferred to the central data management of the Medical Research Network of the Consortium of Thai Medical Schools to adjudicate that the process of data collection was compiled according to study protocol. The data management team was responsible for inquiries to study sites to verify data. Site monitoring was randomly performed in approximately 10% of study sites.
Informed consent statement: Patients were all patients were recruited from the outpatient clinic. Written informed consent was obtained from patients before enrolment.
Conflict-of-interest statement: The authors deny any conflict of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Wisit Kaewput, MD, Assistant Professor, Department of Military and Community Medicine, Phramongkutklao College of Medicine, 315 Ratchawithi Rd, Chang Wat, Bangkok 10400, Thailand. wisitnephro@gmail.com
Telephone: +66-23547600-93613 Fax: +66-23547733
Received: September 26, 2018
Peer-review started: September 26, 2018
First decision: October 26, 2018
Revised: November 7, 2018
Accepted: January 28, 2019
Article in press: January 28, 2019
Published online: February 21, 2019
ARTICLE HIGHLIGHTS
Research background

The evidence for an association of renal function with diabetic retinopathy (DR) and visual impairment among type 2 diabetes mellitus (T2DM) patients is limited, particularly in the Asian population. Currently, many studies have demonstrated an association between diabetic nephropathy and DR in T1DM patients, but this association is less strong in T2DM. This study aimed to assess the association between glomerular filtration rate (GFR) and DR, severe DR, and severe visual impairment among T2DM patients in Thailand.

Research motivation

If such an association of renal function with DR and visual impairment existed, it would provide further support to the importance for regular monitoring of GFR in T2DM patients. Furthermore, it would motivate future research on whether more intensive monitoring of T2DM patients may allow earlier detection and prevention of DR and visual impairment. Visual impairment secondary to DR can be corrected if early sight threatening disease is detected and treated with laser photocoagulation. To further investigate the association between GFR and DR, severe DR, and severe visual impairment were assessed using multivariate logistic regression, the authors conducted a nationwide cross-sectional study based on the DM/HT study of the Medical Research Network of the Consortium of Thai Medical Schools.

Research objectives

We conducted this study to determine whether such an association between GFR with DR and visual impairment exists, and if so the prevalence and magnitude of this association.

Research methods

We conducted a nationwide cross-sectional study based on the DM/HT study of the Medical Research Network of the Consortium of Thai Medical Schools. This study evaluated adult T2DM patients from 831 public hospitals in Thailand in the year 2013. GFR was categorized into ≥ 90, 60-89, 30-59 and < 30 mL/min/1.73 m2. The association between GFR and DR, severe DR, and severe visual impairment were assessed using multivariate logistic regression.

Research results

In this study, a total of 13192 T2DM patients with available GFR were included in the analysis. The mean GFR was 66.9 ± 25.8 mL/min/1.73 m2. The prevalence of DR, proliferative DR, diabetic macular edema, and severe visual impairment were 12.4%, 1.8%, 0.2%, and 2.1%, respectively. Patients with GFR of 60-89, 30-59 and < 30 mL/min/1.73 m2 were significantly associated with increased DR and severe DR when compared with patients with GFR of ≥ 90 mL/min/1.73 m2. In addition, increased severe visual impairment was associated with GFR 30-59 and < 30 mL/min/1.73 m2.

Research conclusions

We found that decreased GFR was independently associated with increased DR, severe DR, and severe visual impairment. GFR should be monitored in diabetic patients for DR awareness and prevention.

Research perspectives

This study demonstrated significantly associations of decreased GFR with increased DR, severe DR, and severe visual impairment among diabetic patients. This finding suggests the importance of timely and frequent eye screening in T2DM and CKD patients cannot be over-emphasized. The early intervention to preserve renal function and adequate control of diabetes is keys to the reduction of ocular disease and prevent irreversible visual loss.