title: Claims Data Analysis of Tumor Necrosis Factor Inhibitor Treatment Dosing Among Patients with Rheumatoid Arthritis: A Systematic Review of Methods.
abstract: BACKGROUND
  With tumor necrosis factor inhibitors, changes of dosing, switching between drugs, insufficient adherence, and persistence are frequent in rheumatoid arthritis. Because this is often associated with decreased efficiency and increased costs, dosage analyses based on claims data are of increasing interest for healthcare providers and payers. Nevertheless, no standardized methods exist to ensure high-quality research.
  
  
  OBJECTIVE
  In this review, we compare and discuss applied methods in claims data-based dosage analyses of tumor necrosis factor inhibitor prescriptions in patients with rheumatoid arthritis.
  
  
  METHODS
  A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The dosage analysis methods performed within the selected studies were classified into switching, persistence, adherence, and dosage-change analyses, and were then compared and finally discussed.
  
  
  RESULTS
  A total of 45 studies were found to be relevant. In most studies, a change in dose or persistence was evaluated, followed by switching and adherence analyses. Analyses of changed dose exhibit the most extensive variation of methods. We divided them into three principal methods, where a specified reference dose is compared with (1) the last dose, (2) any dose, or (3) all doses.
  
  
  CONCLUSIONS
  The systematic review identified a high variation of methods. Our results may be helpful for choosing appropriate methods in future studies. The results also demonstrate the need for evidence-based recommendations of methods used in claims data research.
authors.affiliation: Munich Center of Health Sciences (MC-Health), Ludwig Maximilian University of Munich, Ludwigstraße 28, 80539, Munich, Germany. krack@bwl.lmu.de.|German Research Center for Environmental Health (GmbH), Institute of Health Economics and Health Care Management, Helmholtz Zentrum München, Neuherberg, Germany. krack@bwl.lmu.de.
authors.forename: Gundula
authors.initials: G
authors.lastname: Krack
authors.affiliation: Division of Immunology and Rheumatology, Medical School Hannover, Hannover, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Zeidler
authors.affiliation: Center for Health Economics Research Hannover (CHERH), Leibniz University Hannover, Hannover, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Zeidler