Combined effect of diabetic retinopathy and diabetic kidney disease on all-cause, cancer, vascular and non-cancer non-vascular mortality in patients with type 2 diabetes: A real-world longitudinal study

Abstract

Aims/Introduction: We assessed the relationship between diabetic retinopathy (DR) and/or diabetic kidney disease (DKD) according to their severity and all-cause, cancer, vascular and non-cancer non-vascular mortality in real-world patients with type 2 diabetes. Materials and Methods: A total of 1,902 patients with type 2 diabetes were enrolled from 1995 to 1999 and followed to 2017. At baseline, DR was diagnosed in 374 patients, DKD in 529, vision-threatening DR in 123 and advanced DKD in 287. Patients were classified by the status of DR and DKD. Multivariate Cox regression analysis was carried out. Results: There were 266 deaths during a median follow-up period of 18.6 years. Among these, 92 were from cancer, 78 were from vascular causes and 82 were from non-cancer non-vascular causes. DR and/or DKD predicted all-cause, vascular and non-cancer non-vascular mortality, but not cancer mortality. Similarly, vision-threatening DR and/or advanced DKD predicted all-cause, vascular and non-cancer non-vascular mortality, but not cancer mortality. Hazard ratios for all-cause, vascular and non-cancer non-vascular mortality were highest in the DR(+)DKD(+) group, and higher in the DR(−)DKD(+) and the DR(+)DKD(−) groups than in the DR(−)DKD(−) group. The results for vision-threatening DR and advanced DKD were similar. The interaction for non-cancer non-vascular mortality, but not all-cause and vascular mortality, between DR and DKD and between vision-threatening DR and advanced DKD might be significant. Conclusions: DR and DKD may be jointly and independently associated with all-cause, vascular and non-cancer non-vascular mortality, but not cancer mortality, according to their severity in real-world patients with type 2 diabetes.