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br Methods br Results Of the
Methods
Results
Of the 9434 included participants, 1179 (12.5%) had CKD. The mean eGFR in participants with and without CKD were 46±12mL/min/1.73m2 and 89±15mL/min/1.73m2 respectively. Among the 1179 participants with CKD, 1051 (89.1%) had stage 3 CKD, 85 (7.2%) had stage 4 CKD and 43 (3.7%) had stage 5 CKD. 42.6% of those with CKD had diabetes mellitus.
Table 1 shows the baseline characteristics of participants stratified by CKD status. Those with CKD were older, more likely to be men, primary or below educated, less likely to be current smokers, alcohol drinkers, had higher prevalence of diabetes, hypertension, hyperlipidemia and CVD and had higher levels of systolic BP, BMI, triglycerides, 7 8-dihydroxyflavone and HbA1c levels and lower levels of LDL cholesterol levels (all p<0.001). Participants with CKD were also more likely to be on anti-hypertensive, diabetic and lipid lowering medications (all p<0.001).
The prevalence of VI was 15.8% (n=1481) in the study population. The prevalence of VI was nearly three times higher in persons with CKD than those without (36.1% vs 12.9%, p<0.001). Fig. 1 shows the prevalence of VI by CKD severity. The prevalence of VI increased with decreasing categories of eGFR (p-trend<0.001). The prevalence of other major ocular diseases is shown in Table 2. The prevalence of all major ocular diseases including cataract, any retinopathy, AMD, glaucoma, under-corrected refractive error and any ocular disease were significantly higher in persons with CKD than those without. Among those with diabetes, the prevalence of DR was also higher in those with CKD than those without (46.0% vs 31.6%).
Table 3 shows the associations of CKD with VI and ocular diseases. CKD was significantly associated with VI, any ocular disease, cataract, any retinopathy, and DR. The odds of VI increased with increasing severity of CKD. In models additionally adjusting for anti-hypertensive medication use, the associations of CKD with VI, any ocular disease, any retinopathy and DR remained significant, while the association with cataract lost significance (Supplementary Table). In analysis stratified by eGFR categories, compared to those with eGFR≥60, the odds of VI were 1.24 (1.05–1.48) for eGFR=30–60, 1.71 (1.05–2.79) for eGFR=15–30 and 4.99 (2.46–10.13) for eGFR<15 (data not shown).
When stratified by diabetes status (Table 4), CKD was found to be significantly associated with VI, and any ocular disease in persons with diabetes. CKD was also significantly associated with any retinopathy in persons with and without diabetes. Consistent with the main analysis, the odds of VI increased with the decreasing categories of eGFR among those with diabetes (eGFR=30–60: OR 1.61 95% CI 1.21–2.15; eGFR=15–30: OR 2.24 95% CI 1.23–4.09; eGFR<15: OR 8.43 95% CI 2.67–26.67). However, no significant interaction was found between diabetes and CKD on the association with VI (p-interaction=0.153). In a supplementary analysis stratified by ethnicity, although the association of CKD with VI was stronger in Indians (OR 1.81 95% CI 1.33–2.48), compared to Chinese (OR 1.01 95% CI 0.78–1.56) and Malays (OR 1.15, 95% CI 0.90–1.46), there was no significant interaction by race–ethnicity (p-interaction=0.62, data not shown).
Discussion
Several large epidemiological studies have reported the prevalence of ocular diseases in persons with CKD (Grunwald et al., 2010; Klein et al., 2009; Weiner et al., 2011). Grunwald et al. investigated the prevalence of fundus pathology and glaucoma in a population based cross sectional study of 1936 adults who participated in the Chronic Renal Insufficiency Cohort (CRIC) study. He found that 45% of persons with CKD had ocular pathology requiring follow up examination by an ophthalmologist. Diabetic, hypertensive or other retinopathy was present in 25.3%, 8.9% had signs of glaucoma and 7.6% had signs of AMD. Stage 4 and 5 CKD were associated with increased odds of any fundus pathology (OR 2.12 95% CI 1.62–2.78) and of any retinopathy (OR 2.99 95% CI 2.05–4.06), compared to persons with eGFR≥50mL/min/1.73m2 (Grunwald et al., 2010). In the Third National Health and Nutrition Examination Survey (NHANES III), Weiner et al. conducted a cross sectional nested case control study comparing markers of kidney disease in 7667 persons with and without AMD. He observed an independent association of lower eGFR with late AMD (OR 3.05 95% CI 1.51–6.13) (Weiner et al., 2011). In the Beaver Dam Eye Study, Klein et al. found an association of CKD with the 15-year incidence of early AMD (OR 1.36 95% CI 1.00–1.86) but not with exudative AMD or geographic atrophy (Klein et al., 2009). Although the prevalence and risk of ocular disease has been reported to be high in persons with CKD, none of these studies have examined the burden of VI in those with CKD.