{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,8]],"date-time":"2026-03-08T21:45:35Z","timestamp":1773006335852,"version":"3.50.1"},"reference-count":32,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2026,2,9]],"date-time":"2026-02-09T00:00:00Z","timestamp":1770595200000},"content-version":"vor","delay-in-days":8,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,2,1]],"date-time":"2026-02-01T00:00:00Z","timestamp":1769904000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Pediatric Transplantation"],"published-print":{"date-parts":[[2026,2]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Variability in tacrolimus levels, measured with the Medication Level Variability Index (MLVI), and intrapatient variability (IPV) may be associated with graft outcomes in solid organ transplant recipients. However, the optimal method for measuring tacrolimus variability, the optimal timing for measurement, and intervention thresholds for pediatric kidney transplant recipients remain uncertain.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Our retrospective study included 149 pediatric kidney transplant recipients who received tacrolimus for maintenance immunosuppression. MLVI and IPV were assessed across 3 post\u2010transplant intervals: 2\u2010week to 3\u2010month; 3\u2010 to 6\u2010month; and 6\u2010 to 12\u2010month. Associations between MLVI or IPV and graft outcomes were analyzed using landmark survival analysis, adjusting for age at transplant, donor type, and transplant year. We used survival trees to identify optimal thresholds.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      MLVI during 2\u2010week to 3\u2010month (aHR: 1.65; 95% CI: 1.08\u20132.52;\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.02) and 6\u201312\u2010month intervals (aHR: 3.82; 95% CI: 1.39\u201310.5;\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.009) post\u2010transplant was significantly associated with the risk of graft failure. Similarly, IPV during 2\u2010week to 3\u2010month (aHR: 1.63; 95% CI: 1.03\u20132.59;\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.04) and 6 to 12\u2010month intervals (aHR: 2.22; 95% CI: 1.05\u20134.71;\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.04) was significantly associated with the risk of graft failure. IPV during a 2\u2010week to 3\u2010month interval was significantly associated with de novo donor\u2010specific antibody (dnDSA) development (aHR: 1.38; 95% CI: 1.07\u20131.78;\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.02). We observed no significant associations between the 3\u2010 and 6\u2010month interval and graft failure. Neither MLVI nor IPV during any interval predicted acute rejection.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>IPV during the first 3\u2009months was associated with dnDSA development. Both MLVI and IPV during the first 3\u2009months and at the 6\u2010 to 12\u2010month interval post\u2010transplant were associated with increased risk of graft failure.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/petr.70278","type":"journal-article","created":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T04:40:32Z","timestamp":1770698432000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Medication Level Variability During First Year After Pediatric Kidney Transplantation"],"prefix":"10.1111","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1618-6992","authenticated-orcid":false,"given":"Lidan","family":"Gu","sequence":"first","affiliation":[{"name":"Division of Clinical Behavioral Neuroscience, Department of Pediatrics University of Minnesota Medical School  Minneapolis Minnesota USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5122-0511","authenticated-orcid":false,"given":"Finola","family":"Kane\u2010Grade","sequence":"additional","affiliation":[{"name":"Division of Clinical Behavioral Neuroscience, Department of Pediatrics University of Minnesota Medical School  Minneapolis Minnesota USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael","family":"Evans","sequence":"additional","affiliation":[{"name":"Clinical and Translational Science Institute University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chelsey","family":"Jensen","sequence":"additional","affiliation":[{"name":"Masonic Children's Hospital  Minneapolis Minnesota USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Danielle","family":"Glad","sequence":"additional","affiliation":[{"name":"Medical College of Wisconsin  Milwaukee Wisconsin USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christopher","family":"Anzalone","sequence":"additional","affiliation":[{"name":"Boston Children's Hospital Harvard Medical School  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5824-7856","authenticated-orcid":false,"given":"Sarah","family":"Kizilbash","sequence":"additional","affiliation":[{"name":"Division of Pediatric Nephrology, Department of Pediatrics University of Minnesota Medical School  Minneapolis Minnesota 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