User‐only design to assess drug effectiveness in clinical practice: application to bisphosphonates and secondary prevention of fractures. (9th June 2014)

• Record Type: Journal Article
• Authors: Corrao, Giovanni; Ghirardi, Arianna; Segafredo, Giulia; Zambon, Antonella; Della Vedova, Gianluca; Lapi, Francesco; Cipriani, Francesco; Caputi, Achille; Vaccheri, Alberto; Gregori, Dario; Gesuita, Rosaria; Vestri, Annarita; Staniscia, Tommaso; Mazzaglia, Giampiero; Di Bari, Mauro; on behalf of the BEST investigators
• Is Part Of: Pharmacoepidemiology and drug safety. Volume 23:Number 8(2014:Aug.)
• Page Start: 859
• Page End: 867
• Publication Date: 2014-06-09
• Subjects: Pharmacoepidemiology -- Periodicals; Chemotherapy -- Periodicals; Epidemiology -- Periodicals; 615.705
• DOI: 10.1002/pds.3650
• Languages: English
• ISSNs: 1053-8569

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <sec id="pds3650-sec-0001" sec-type="section"> <title>Purpose</title> <p>Different strategies applicable to control for confounding by indication in observational studies were compared in a large population‐based study regarding the effect of bisphosphonates (BPs) for secondary prevention of fractures.</p> </sec> <sec id="pds3650-sec-0002" sec-type="section"> <title>Methods</title> <p>The cohort was drawn from healthcare utilization databases of 13 Italian territorial units. Patients aged 55 years or more who were hospitalized for fracture during 2003–2005 entered into the cohort. A nested case‐control design was used to compare BPs use in cohort members who did (cases) and who did not experience (controls) a new fracture until 2007 (outcome). Three designs were employed: conventional‐matching (D<sub>1</sub>), propensity score‐matching (D<sub>2</sub>), and user‐only (D<sub>3</sub>) designs. They differed for (i) cohort composition, restricted to patients who received BPs straight after cohort entry (D<sub>3</sub>); (ii) using propensity score for case‐control matching (D<sub>2</sub>); and (iii) compared groups of BPs users versus no users (D<sub>1</sub> and D<sub>2</sub>) and long‐term versus short‐term users (D<sub>3</sub>).</p> </sec> <sec id="pds3650-sec-0003" sec-type="section"> <title>Results</title> <p>Bisphosphonate users had odds ratios (95% confidence interval) of 1.20 (1.01 to 1.44) and 0.95 (0.74 to 1.24) by applying D<sub>1</sub> and D<sub>2</sub> designs, respectively. Statistical evidence that long‐term BPs use protects the outcome onset with respect to short‐term use was observed for user‐only design (D<sub>3</sub>) being the corresponding odds ratio (95% confidence interval) 0.64 (0.44 to 0.93).</p> </sec> <sec id="pds3650-sec-0004" sec-type="section"> <title>Conclusions</title> <p>User‐only design yielded closer results to those seen in RCTs. This approach is one possible strategy to account for confounding by indication. Copyright © 2014 John Wiley & Sons, Ltd.</p> </sec> </abstract>