The U-Shaped Association between Bilirubin and Diabetic Retinopathy Risk: A Five-Year Cohort Based on 5323 Male Diabetic Patients

الملخص EN

Aims.

This study aimed at assessing the impact of baseline bilirubin (TBiL) on the incidence of diabetic retinopathy (DR) based on a five-year cohort study which consisted of 5323 Chinese male diabetic patients.

Methods.

A cohort study based on 5323 male diabetic patients was conducted in Beijing, from 2009 to 2013.

Both baseline TBiL and follow-up changes were measured.

Cox proportional risk model was used to calculate the hazard ratio (HR) of TBiL for DR risk.

Results.

During the follow-up period, there were 269 new DR cases.

The incidence of five-year follow-up was 5.1% (95% CI: 4.5%~5.6%).

The TBiL level of those who had diabetic retinopathy was lower than that of those without (12.51+ 1.20 mol/L and 13.11+ 1.32 μmol/L, P=0.033).

And more interestingly, along with the quintiles of baseline TBiL, there showed a U-shaped curve with DR incidence.

And the RRs were 0.928 (95% CI: 0.646–1.331), 0.544 (95% CI: 0.365–0.811), 0.913 (95% CI: 0.629–1.324), and 1.035 (95% CI: 0.725–1.479) for the second, third, fourth, and fifth quintiles of baseline TBiL levels, respectively, compared with the first quintile.

For follow-up TBiL changes, after being adjusted for related covariables and baseline TBiL levels (as continuous variable) in the model, the RRs for DR were 1.411 (95% CI: 1.081–1.842) for those who had decreased TBiL level and 0.858 (95% CI: 0.770–0.947) for those who had increased TBiL level during follow-up.

And this association was more prominent among those with lower baseline TBiL level.

Conclusions.

Serum TBiL had a U-shaped relationship with DR incidence, which was independent of control status of diabetes and other related covariates.