The interrelationship between depression and kidney disease: Temporal diagnosis, predictive factors, and impact on quality of life

Depression (Dep) is common among individuals with kidney disease (KD), and their co-occurrence is linked to marked impairment in health-related quality of life (QOL). Although prior studies suggest a bidirectional association, uncertainties remain regarding diagnostic sequencing and independent predictors. We analyzed nationally representative data from the Korea National Health and Nutrition Examination Survey (2007–2021). After applying predefined criteria, 94,119 adults were included, of whom 2746 had complete information on Dep and KD. Participants were classified as Group 1 [Dep (+)/KD (−), n = 2354], Group 2 [KD (+)/Dep (−), n = 333], and Group 3 [Dep (+)/KD (+), n = 59]. Relative frequency analysis assessed comorbidity; ANCOVA and Cox proportional hazards models examined diagnostic timing; logistic regression identified predictors; and ANCOVA with multivariable regression evaluated QOL (EQ-5D). The frequency of KD among those with Dep was 2.4 % (59/2413), while Dep prevalence among KD cases was 15.0 % (59/392). Temporal analyses showed Dep was diagnosed later in Group 3 than Group 1 (54.4 vs. 46.8 years, p < 0.001), whereas KD diagnosis did not differ significantly between Group 2 and 3 (50.5 vs. 49.0 years). Cox models confirmed this delay (HR = 0.64, 95 % CI: 0.50–0.83), while KD timing was nonsignificant (HR = 0.83, 95 % CI: 0.63–1.09). Predictors of Dep included older age (OR = 1.01/yr), female sex (OR = 2.82), lower education (OR = 0.81), smoking (OR = 1.66), and KD (OR = 2.57). Predictors of KD included older age (OR = 1.04/yr), lower alcohol consumption (OR = 0.57), and Dep (OR = 2.58). Group 3 had the lowest EQ-5D scores (0.77 vs. 0.86/0.88; p < 0.01). Multivariable regression confirmed independent QOL decrements (βDep = −0.07, βKD = −0.05). Depression and KD independently predict each other and jointly reduce QOL. Cox models highlight delayed recognition of Dep in comorbid cases, underscoring the need for early detection and integrated management. • Depression and Kidney disease (KD) show a close and bidirectional association. • Patients with comorbid Depression and KD experience delayed recognition of Depression. • Depression increases the likelihood of KD, while KD raises the risk of Depression onset. • Co-occurrence of Depression and KD is associated with markedly reduced quality of life (QOL). • Early detection and integrated management are essential to improve outcomes and preserve QOL.