{"doi":"10.1016/j.contraception.2024.110720","title":"Comparison of etonogestrel bioanalytical assay results in plasma and serum within and across laboratories","abstract":"OBJECTIVES: To compare performance characteristics of etonogestrel bioanalytical assays across laboratories. STUDY DESIGN: We conducted a blinded, six laboratory study: five academic laboratories and one contracted commercial laboratory (reference). Etonogestrel was quantitated at each laboratory in both prepared serum and/or plasma samples of six known etonogestrel concentrations, and in 60 clinical samples from participants using etonogestrel-containing contraceptive methods. Per regulatory guidance, laboratory accuracy (percent bias) and precision (coefficient of variation; CV) were defined as ±15% of the nominal prepared concentration. We compared inter- and intra-laboratory agreement using a Kendall's Tau-B and Passing-Bablok regression. RESULTS: For prepared samples, six laboratories analyzed serum and three laboratories analyzed plasma. All etonogestrel results were within ±15% for accuracy across all concentrations at four labs, including the reference laboratory. All labs demonstrated high precision, with only one occurrence of CV >15%. We found a positive association between prepared plasma and serum etonogestrel results (Kendall's Tau-B 0.80-0.88). For clinical samples, five laboratories analyzed serum and three laboratories analyzed plasma. Compared to the reference laboratory, inter-laboratory serum etonogestrel concentrations were positively correlated (Kendall's Tau-B 0.76-0.95). Proportional bias was observed, meaning individual lab etonogestrel results were consistently higher (slope estimates 0.78-0.95) or lower (slope estimates 1.05-1.10) than the reference laboratory. In clinical samples, intra-laboratory results were well associated between plasma and serum (Kendall's Tau-B 0.92-0.96). CONCLUSIONS: There was good intra-laboratory agreement, irrespective of sample matrix; however, there was inter-laboratory variability in etonogestrel results. Differences between laboratory results should be considered when comparing etonogestrel pharmacokinetics across studies. IMPLICATIONS: Etonogestrel concentrations were highly precise within each laboratory and were comparable between serum and plasma. Results varied between laboratories (5-28% higher to 5-9% lower compared to the Organon commercial laboratory). To minimize variability, we recommend utilizing a single laboratory that conducts routine proficiency testing for etonogestrel analysis within a study.","journal":"Contraception","year":2024,"id":504087,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.6389,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":612662,"name":"Lee C. Winchester","orcid":"0000-0002-6118-024X","position":1,"is_corresponding":false},{"id":743606,"name":"Christopher Wichman","orcid":"0000-0003-4642-1591","position":2,"is_corresponding":false},{"id":565035,"name":"Sean N. Avedissian","orcid":"0000-0002-0935-6455","position":3,"is_corresponding":false},{"id":264242,"name":"David W. Erikson","orcid":"0000-0002-3383-9297","position":4,"is_corresponding":false},{"id":1354654,"name":"Molly Kernan","orcid":null,"position":5,"is_corresponding":false},{"id":279020,"name":"Mark A. Marzinke","orcid":"0000-0003-1670-8786","position":6,"is_corresponding":false},{"id":721919,"name":"Timothy Mykris","orcid":"0000-0002-0959-6563","position":7,"is_corresponding":false},{"id":721708,"name":"Renu Nandakumar","orcid":"0009-0009-9273-504X","position":8,"is_corresponding":false},{"id":363543,"name":"Thomas D. Nolin","orcid":"0000-0003-4339-1382","position":9,"is_corresponding":false},{"id":259564,"name":"Anthony T. Podany","orcid":"0000-0002-8371-0379","position":10,"is_corresponding":false},{"id":363540,"name":"Raymond E. West","orcid":"0000-0002-6362-8837","position":11,"is_corresponding":false},{"id":666408,"name":"Beatrice A. Chen","orcid":"0000-0002-4437-4632","position":12,"is_corresponding":false},{"id":459400,"name":"Catherine A. Chappell","orcid":"0000-0003-3631-3765","position":13,"is_corresponding":false},{"id":345925,"name":"Kimberly K. Scarsi","orcid":"0000-0001-9406-693X","position":14,"is_corresponding":false},{"id":1354653,"name":"Shawnalyn W Sunagawa","orcid":null,"position":0,"is_corresponding":true}],"reference_count":34,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T02:10:35.597333Z","pmid":"39362338","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}