2025
Power calculation for cross-sectional stepped wedge cluster randomized trials with a time-to-event endpoint
Baumann M, Esserman D, Taljaard M, Li F. Power calculation for cross-sectional stepped wedge cluster randomized trials with a time-to-event endpoint. Biometrics 2025, 81: ujaf074. PMID: 40557765, PMCID: PMC12188223, DOI: 10.1093/biomtc/ujaf074.Peer-Reviewed Original ResearchConceptsSW-CRTsCluster randomized trialStepped wedge cluster randomized trialTime-to-event endpointsTime-to-event outcomesRobust sandwich varianceMarginal Cox modelSandwich varianceWithin-periodElectronic reminder systemSW-CRTRandomized trialsBinary outcomesPower calculationsPower formulaReminder systemR Shiny applicationHospital settingCorrelation parametersSample sizePlanned trialsCox modelWaldFormulaTrialsAnalysis of Cohort Stepped Wedge Cluster‐Randomized Trials With Nonignorable Dropout via Joint Modeling
Gasparini A, Crowther M, Hoogendijk E, Li F, Harhay M. Analysis of Cohort Stepped Wedge Cluster‐Randomized Trials With Nonignorable Dropout via Joint Modeling. Statistics In Medicine 2025, 44: e10347. PMID: 39963907, PMCID: PMC11833761, DOI: 10.1002/sim.10347.Peer-Reviewed Original ResearchConceptsStepped wedge cluster randomized trialDropout processNonignorable missing outcomesParallel-arm cluster-randomized trialsCluster randomized trialNonignorable dropoutsJoint longitudinal-survival modelLongitudinal submodelData-generating scenariosMissingness patternsJoint modeling methodologyCorrelation structureMonte Carlo simulationsLongitudinal outcomesJoint modelEffective parametrizationPrimary care practicesGeriatric care modelsCarlo simulationsFrail older adultsAssociation structureSubmodelsCare modelUsual careCare practices
2024
Optimal designs using generalized estimating equations in cluster randomized crossover and stepped wedge trials
Liu J, Li F. Optimal designs using generalized estimating equations in cluster randomized crossover and stepped wedge trials. Statistical Methods In Medical Research 2024, 33: 1299-1330. PMID: 38813761, DOI: 10.1177/09622802241247717.Peer-Reviewed Original ResearchConceptsMaximin optimal designsStepped wedge cluster randomized trialLocally optimal designsCluster-period sizesClosed-form formulaCluster-randomized crossover trialCross-sectional sampling schemeInteger estimationOptimal design algorithmDesign algorithmLongitudinal cluster randomized trialsWorking correlation structureCluster randomized trialMethod of generalized estimating equationsTreatment effect estimatesSAS macroVariance expressionsExact valueCorrelation structureMaximinSampling schemeBetween-clusterOptimal designOptimization design researchEstimating equations
2022
Stepped Wedge Cluster Randomized Trials: A Methodological Overview
Li F, Wang R. Stepped Wedge Cluster Randomized Trials: A Methodological Overview. World Neurosurgery 2022, 161: 323-330. PMID: 35505551, PMCID: PMC9074087, DOI: 10.1016/j.wneu.2021.10.136.Peer-Reviewed Original ResearchConceptsStepped wedge designStepped wedge cluster randomized trialIntervention programsSample size determinationDelivery of patient careWedge designStepped wedge trial designHealth intervention programsCluster randomized trialRandomized trialsPatient careStudy designPragmatic settingSize determinationTrial design
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