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  • Identification of antithrombotic drugs related to total joint replacement using anonymised free-text notes: a search strategy in the Clinical Practice Research Datalink

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Epidemiology
Research
Identification of antithrombotic drugs related to total joint replacement using anonymised free-text notes: a search strategy in the Clinical Practice Research Datalink
  1. Johannes TH Nielen1,2,
  2. Bart J F van den Bemt3,4,
  3. Annelies Boonen5,
  4. Pieter C Dagnelie6,
  5. Pieter J Emans7,
  6. Nicole Veldhorst8,
  7. Arief Lalmohamed9,
  8. Tjeerd-Pieter van Staa1,
  9. Frank de Vries1,8
  1. 1Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht University, Utrecht, The Netherlands
  2. 2Department of Epidemiology, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands
  3. 3Department of Pharmacy, Sint Maartenskliniek, Nijmegen, The Netherlands
  4. 4Department of Pharmacy, Radboud University Medical Center, Nijmegen, The Netherlands
  5. 5Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre, Maastricht, The Netherlands
  6. 6Department of Epidemiology, CAPHRI School for Public Health and Primary Care, and CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
  7. 7Department of Orthopaedics, Maastricht University Medical Center, Maastricht, The Netherlands
  8. 8Department of Clinical Pharmacy and Toxicology, Maastricht University Medical Center, Maastricht, The Netherlands
  9. 9Department of Clinical Pharmacy, University Medical Center Utrecht, Utrecht, The Netherlands
  1. Correspondence to Johannes T.H Nielen; j.t.h.nielen{at}uu.nl

Abstract

Objectives We aimed to design and test a method to extract information on antithrombotic therapy from anonymised free-text notes in the Clinical Practice Research Datalink (CPRD).

Setting General practice database representative of the UK.

Participants All patients undergoing total hip replacement (THR, n=25 898) or total knee replacement (TKR, n=22 231) between January 2008 and October 2012 were included. Antithrombotic drug use related to THR or TKR was identified using anonymised free text and prescription data.

Primary and secondary outcome measures Internal validity of our newly designed method was determined by calculating positive predictive values (PPVs) of hits for predefined keywords in a random sample of anonymised free-text notes. In order to determine potential detection bias, total joint replacement (TJR) patient characteristics were compared as per their status of exposure to antithrombotics.

Results PPVs ranging between 97% and 99% for new oral anticoagulants (NOAC) or low-molecular weight heparins (LMWH) exposure related to TJR were obtained with our method. Our search strategy increased detection rates by 57%, yielding a total proportion of 18.5% of all THR and 18.6% of all TKR surgeries. Identified users of NOACs and LMWHs were largely similar with regards to age, sex, lifestyle, disease and drug history compared to patients without identified drug use.

Conclusions We have developed a useful method to identify additional exposure to NOACs or LMWHs with TJR surgery.

  • STATISTICS & RESEARCH METHODS
  • ORTHOPAEDIC & TRAUMA SURGERY
  • EPIDEMIOLOGY

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2015-009017

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