Background: The number of living kidney donors in the United States has declined since 2005, with variations based on the donor-recipient relationship. The reasons for this decline are unclear, and strategies to mitigate declined donations remain elusive. We examined the change in donor number monthly (within-year) versus annually (between-years) to inform potentially modifiable factors for future interventions.
Methods: In this registry-based cohort analysis of 141 759 living kidney donors between 1995 and 2019, we used linear mixed-effects models for donor number per month and year to analyze between-year and within-year variation in donation. We used Poisson regression to quantify the change in the number of donors per season before and after 2005, stratified by donor-recipient relationship and zip-code household income tertile.
Results: We observed a consistent summer surge in donations during June, July, and August. This surge was statistically significant for related donors (incidence rate ratio [IRR] range: 1.12-1.33) and unrelated donors (IRR range: 1.06-1.16) across donor income tertiles.
Conclusion: Our findings indicate lower rates of living kidney donation in non-summer months across income tertiles. Interventions are needed to address barriers to donation in non-summer seasons and facilitate donations throughout the year. Since the Organ Donor Leave Law provides a solid foundation for supporting year-round donation, extending the law's provisions beyond federal employees may mitigate identified seasonal barriers.
Keywords: barriers; living kidney donors; nephrectomy; racial groups; seasonality.
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