{"doi":"10.1101/2021.05.18.21257375","title":"Frequent suboptimal thermocycler ramp rate usage negatively impacts MTBDR <i>sl</i> performance for second-line drug resistant tuberculosis diagnosis","abstract":"Abstract Strengthening the detection of second-line drug-resistance is a key tuberculosis (TB) control priority. The performance of MTBDR plus , a multidrug-resistant (MDR)-TB assay is reduced when suboptimal ramp rates are used. We investigated ramp rate’s effect on MTBDR sl ; the most widely-used molecular second-line drug-resistant TB assay. We tested 52 smear-negative Xpert MTB/RIF Ultra-positive sputa and a Mycobacterium tuberculosis ( Mtb ) dilution series at manufacturer-recommended (2.2°C/s) or most common suboptimal ramp rate (4.0°C/s; identified via an earlier survey). Mtb- complex DNA (TUB-band)-positivity, indeterminate rates, fluoroquinolone- and second-line injectable-resistance accuracy, banding differences and, separately, inter-reader variability were assessed. 39% of re-surveyed laboratories (5/13) did not use the manufacturer-recommended MTBDR sl ramp rate. On sputum, this ramp rate improved indeterminates vs. 4.0°C/s (0/52 vs. 7/51; p=0.006), false drug-resistance calls (0/104 vs. 6/102; p=0.013), and incorrect banding calls (0/1300 vs. 55/1275; p&lt;0.001). Valid results (neither TUB-negative, indeterminate, nor any false drug-resistance calls) (52/52 vs. 41/51; p=0.001) on sputa hence improved by +21% (95% CI: 8-34%) with optimal ramp rate usage. Suboptimal ramp rate increased banding call inter-reader variability [52/1300 (4%) vs. 34/1300 (3%); p=0.030] on sputa but not dilution series; highlighting the importance of using clinical specimens for assay performance evaluations. Suboptimal ramp rate contributes to poor MTBDR sl performance. Ramp rate correction will improve second-line drug-resistant TB diagnoses. Laboratories must ensure the optimal manufacturer-recommended ramp rate is used.","journal":"medRxiv","year":2021,"id":224247,"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":0.957,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":523478,"name":"Margaretha de Vos","orcid":"0000-0003-3059-2986","position":1,"is_corresponding":false},{"id":787760,"name":"Samantha Pillay","orcid":"0000-0002-4659-4364","position":2,"is_corresponding":false},{"id":523475,"name":"Rouxjeane Venter","orcid":"0000-0002-8710-8166","position":3,"is_corresponding":false},{"id":387484,"name":"John Metcalfe","orcid":"0000-0002-2279-7036","position":4,"is_corresponding":false},{"id":826254,"name":"Yonas Ghebrekristos","orcid":"0000-0003-2002-5240","position":5,"is_corresponding":false},{"id":523476,"name":"Stephanie Minnies","orcid":"0000-0003-2877-2419","position":6,"is_corresponding":false},{"id":524350,"name":"Tania Dolby","orcid":null,"position":7,"is_corresponding":false},{"id":826255,"name":"Natalie Beylis","orcid":"0000-0003-1860-6345","position":8,"is_corresponding":false},{"id":89652,"name":"Robin M. Warren","orcid":"0000-0001-5741-7358","position":9,"is_corresponding":false},{"id":244855,"name":"Grant Theron","orcid":"0000-0002-9216-2415","position":10,"is_corresponding":false},{"id":523477,"name":"Brigitta Derendinger","orcid":"0000-0001-7208-2154","position":0,"is_corresponding":true}],"reference_count":4,"raw_metadata":null,"created_at":"2026-07-18T23:54:18.470602Z","pmid":null,"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":[]}