Seasonal Patterns of Living Kidney Donation in the United States From 1995 to 2019

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.