Heterogeneous 30-day readmission risk in diabetic kidney disease: a nationwide analysis stratified by phenotype, age, and socioeconomic status.

BACKGROUND

Diabetic kidney disease (DKD) carries substantial hospital readmission burden. We characterized 30-day readmission patterns following DKD hospitalization, with stratified analyses by phenotype, age, and social determinants of health (SDOH).

METHODS

Using the 2018 Nationwide Readmissions Database (NRD) with complex survey-weighted analysis, we identified adult index hospitalizations with a discharge diagnosis of DKD (ICD-10-CM E10.21, E10.22, E11.21, or E11.22) in any diagnostic position (January-November 2018). Survey-weighted multivariable logistic regression compared type 1 versus type 2 DKD, with separate models fitted within strata of age group, insurance type, and median household income quartile. Wald interaction tests assessed whether the phenotype association differed across strata.

RESULTS

Among 1,291,033 index hospitalizations, the 30-day all-cause readmission rate was 15.96% (95% CI 15.78%-16.14%), higher for type 1 than type 2 DKD (22.42% vs. 15.69%; p<0.001). Non-diabetes-related systemic diagnoses accounted for 91.97% of readmissions. Type 1 DKD exhibited an inverse age-readmission gradient (28.8% in patients <40 years to 15.2% in those >79 years; age × phenotype interaction p = 9.28×10⁻14). The strongest independent predictors were ESRD (aOR 1.591), heart failure (aOR 1.348), and type 1 DKD (aOR 1.288; all p<0.001). Medicaid insurance was associated with higher readmission odds than Medicare (aOR 1.037; 95% CI 1.007-1.069; BH-adjusted p = 0.020). Median household income quartile was not independently associated with readmission.

CONCLUSIONS

Readmission risk in DKD is heterogeneous across diabetes phenotype, age, and socioeconomic strata, driven predominantly by non-diabetes-related systemic comorbidities. Insurance type modified the phenotype-readmission association, most markedly among Medicaid-insured patients.