Abstract
Purpose :
Diabetic retinopathy (DR), a complication of diabetes mellitus (DM), is a leading cause of blindness. DR often progresses from non-proliferative retinopathy (NPDR) to proliferative diabetic retinopathy (PDR). NPDR further classifies into mild, moderate, and severe stages. No studies have investigated the impact of HbA1c on how long patients stay in each stage of NPDR. Our aim is to estimate the duration of progression and effect of HbA1c on duration in each stage of NPDR.
Methods :
A retrospective study of DM patients who had eye exams from 1/2010 to 6/2017 at Lyndon B. Johnson Hospital was done. Patients initially with PDR, less than 2 years follow-up, or less than 3 clinic visits were excluded. If both eyes were eligible, the right eye was included. Demographics and baseline characteristics were recorded. DR stage, progression date, and annual HbA1C were collected during follow-up. Continuous-Time Markov Chain with HbA1c as the time-dependent covariate was used to analyze the data.
Results :
226 patients were included. Mean age was 42.7 years (±11.7) at DM diagnosis and 56.1 years (±10.1) at initial eye exam. 139 (61%) were female. 154 (68%) were Hispanic, 50 (22%) Black and 20 (9%) White. Mean HbA1C at initial visit was 9.7 (±2.4, range 5.4 to 16.8). 65 eyes (29%) had no NPDR, 72 (32%) mild, 57 (25%) moderate and 32 (14%) severe. Patients were followed for a mean of 5.8 years (±2.0, 2.1-9.8) and estimated to stay in stages none, mild, moderate and severe for 3.5 (±1.3), 3.9 (±1.4), 4.3 (±1.5), and 3.9 (±1.4) years, respectively. In the first year, patients without NPDR with average HbA1c levels at baseline had an 18% chance of progressing to mild, 7% to moderate, 2% to severe and 1% to PDR. Mild NPDR patients had a 15% chance to moderate, 2% to severe and 4% to PDR. Moderate NPDR patients had a 10% chance to severe and 5% to PDR. Severe NPDR patients had a 20% chance to PDR. When HbA1c increased 1 unit per year, the progression time to any further stages decreased by 28%, 22%, 16% and 21% for none, mild, moderate, and severe stages, respectively.
Conclusions :
Patients stay approximately 4 years in each NPDR stage. Those who do not properly control HbA1c have progression time decreased 16-28% per unit increase in HbA1c. With progression rates to PDR greatly increasing after reaching severe NPDR, patients with severe NPDR should control HbA1c and be closely monitored with eye exams to minimize vision loss.
This is a 2020 ARVO Annual Meeting abstract.