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Original research
Treatment drop-in in a contemporary cohort used to derive cardiovascular risk prediction equations
  1. Jingyuan Liang1,
  2. Rodney T Jackson1,
  3. Romana Pylypchuk1,
  4. Yeunhyang Choi1,
  5. Claris Chung2,
  6. Sue Crengle3,
  7. Pei Gao4,5,
  8. Corina Grey1,
  9. Matire Harwood6,
  10. Anders Holt1,7,
  11. Andrew Kerr1,8,
  12. Suneela Mehta1,
  13. Susan Wells6,
  14. Katrina Poppe1,8
  1. 1Section of Epidemiology and Biostatistics, University of Auckland, Auckland, New Zealand
  2. 2Accounting and Information Systems, University of Canterbury, Christchurch, New Zealand
  3. 3Ngāi Tahu Māori Health Research Unit, University of Otago, Dunedin, New Zealand
  4. 4Department of Epidemiology and Biostatistics, Peking University, Beijing, China
  5. 5Key Laboratory of Epidemiology of Major Diseases (Peking University), Ministry of Education, Beijing, China
  6. 6Department of General Practice and Primary Health Care, University of Auckland, Auckland, New Zealand
  7. 7Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
  8. 8School of Medicine, University of Auckland, Auckland, New Zealand
  1. Correspondence to Jingyuan Liang, Section of Epidemiology and Biostatistics, University of Auckland, Auckland, New Zealand; jingyuan.liang{at}auckland.ac.nz

Abstract

Background No routinely recommended cardiovascular disease (CVD) risk prediction equations have adjusted for CVD preventive medications initiated during follow-up (treatment drop-in) in their derivation cohorts. This will lead to underestimation of risk when equations are applied in clinical practice if treatment drop-in is common. We aimed to quantify the treatment drop-in in a large contemporary national cohort to determine whether equations are likely to require adjustment.

Methods Eight de-identified individual-level national health administrative datasets in Aotearoa New Zealand were linked to establish a cohort of almost all New Zealanders without CVD and aged 30–74 years in 2006. Individuals dispensing blood-pressure-lowering and/or lipid-lowering medications between 1 July 2006 and 31 December 2006 (baseline dispensing), and in each 6-month period during 12 years’ follow-up to 31 December 2018 (follow-up dispensing), were identified. Person-years of treatment drop-in were determined.

Results A total of 1 399 348 (80%) out of the 1 746 695 individuals in the cohort were not dispensed CVD medications at baseline. Blood-pressure-lowering and/or lipid-lowering treatment drop-in accounted for 14% of follow-up time in the group untreated at baseline and increased significantly with increasing predicted baseline 5-year CVD risk (12%, 31%, 34% and 37% in <5%, 5–9%, 10–14% and ≥15% risk groups, respectively) and with increasing age (8% in 30–44 year-olds to 30% in 60–74 year-olds).

Conclusions CVD preventive treatment drop-in accounted for approximately one-third of follow-up time among participants typically eligible for preventive treatment (≥5% 5-year predicted risk). Equations derived from cohorts with long-term follow-up that do not adjust for treatment drop-in effect will underestimate CVD risk in higher risk individuals and lead to undertreatment. Future CVD risk prediction studies need to address this potential flaw.

  • Cardiovascular Diseases
  • Risk Assessment
  • Electronic Health Records
  • Treatment Outcome
  • Cohort Studies

Data availability statement

Data are available upon reasonable request. Researchers interested in using the datasets in collaboration with the Vascular Risk Equity in Aotearoa New Zealand (VAREANZ) programme should contact the corresponding author. Proposals would be expected to involve a VAREANZ team member as a co-investigator and would be subject to scrutiny by the VAREANZ research programme Governance Group. Applications will only be granted and data provided after agreement from our contributing providers and the New Zealand Ministry of Health and after ethical approval by the New Zealand Multi-Region Ethics Committee.

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Data availability statement

Data are available upon reasonable request. Researchers interested in using the datasets in collaboration with the Vascular Risk Equity in Aotearoa New Zealand (VAREANZ) programme should contact the corresponding author. Proposals would be expected to involve a VAREANZ team member as a co-investigator and would be subject to scrutiny by the VAREANZ research programme Governance Group. Applications will only be granted and data provided after agreement from our contributing providers and the New Zealand Ministry of Health and after ethical approval by the New Zealand Multi-Region Ethics Committee.

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Footnotes

  • X @J_Liang1983, @andersholt6

  • Contributors JL, RTJ and KP conceptualised and designed the study. RTJ, CC, YC and KP were involved in the data collection process. JL analysed the data with advice from all authors. JL wrote the first draft of the manuscript. All authors revised the manuscript for important intellectual content. All authors approved the final submitted version and had final responsibility for the decision to submit for publication. JL, RTJ and KP had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. JL is responsible for the overall content as guarantor.

  • Funding This work was supported by the Health Research Council of New Zealand (grant number 21/712); the Heart Foundation of New Zealand Heart Health Research Trust Senior Fellowship (grant number 1886); and the Chinese Scholarship Council (grant number 202106010103).

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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