The National Kidney Registry facilitated 675 transplants in the first half of this year, up 21% over the 560 transplants facilitated in the first half of 2022. The growth in NKR-facilitated transplants was primarily driven by increases in microsite patient transplants, strong growth in NKR donor candidates referred to Member Centers and an increase in compatible pairs seeking low eplet mismatched donors through our Kidney for Life platform.
NKR-facilitated transplants now account for 22% of all living donor kidney transplants in the United States. Our annualized 2023 donor registrations are on track to exceed last year by nearly 20,000 and NKR donor referrals are on pace to double this year to over 4,000.
The NKR achieved a significant milestone in 2022, facilitating one out of every five living donor kidney transplants in the United States. While living donor kidney transplants in the U.S. dropped by 2%, NKR facilitated transplants increased by 10%, to 1,164.
In this quarterly report, we have included a new chart that shows the top centers as measured by NKR donor referral conversion rates. Donations resulting from NKR donor referrals have nearly doubled this year (from 109 to 190). We expect this number to continue to increase as we optimize our referral process by improving donor service and reducing the number of centers included in our referral network.
The NKR is on track to facilitate 20% of all living donor kidney transplants in the United States this year. The majority of NKR-facilitated transplants are traditional paired exchange transplants, but a growing number of remote direct donation transplants and microsite direct donation transplants are fueling growth.
In early 2022, the NKR saw a significant reduction in transplants facilitated due to the COVID spike. However, the numbers recovered by March when we set a new record of 133 transplants facilitated in a single month. March exceeded our prior best month (105 in March 2021) by a wide margin. Q1 transplants facilitated were 273, which was 24% higher than the 221 transplants facilitated in Q1 of 2021.
The NKR facilitated 1,019 transplants in 2021. This accounted for 17% of all U.S. living donor kidney transplants representing a 46% growth rate over 2020, which was primarily driven by increased donor and patient referrals to our Member Centers and the continued rapid growth of the microsite and Donor Shield programs. The Donor Shield program is now providing comprehensive support and protection to over 25% of all U.S. living kidney donors.
The third quarter of 2021 saw a significant increase in qualified NKR donor referrals (labs completed) to Member Centers, driving an increase in expected donor referrals in 2021 to over 1,500. With the implementation of donor intake best practices, most centers should be able to achieve a 20% conversion rate on these NKR referrals, indicating the 1,500 donor referrals should result in approximately 300 living donor transplants.
The second quarter of 2021 was the NKR's largest to date, with a total of 286 transplants facilitated, approximately 10% of which (26 transplants) were low eplet mismatches. The NKR experienced record volumes beginning in March of this year. Data from the first half of the year indicated that NKR-facilitated transplants now account for 17% of all living donor kidney transplants in the United States, up from 11% in 2019.
The first quarter of 2021 concluded with the NKR setting a new monthly record of 105 transplants facilitated in March, surpassing the previous high of 91. As we go to press with this report, we have facilitated over 100 transplants in April, marking our first two months over 100. On the heels of the first two months of 2021, which saw transplants reduced to only 116 due to a high rate of swap failures, the recent volume spikes are an indication that the weight of the pandemic on living donor transplant is beginning to lift.