Catheter to vein ratio and risk of peripherally inserted central catheter (PICC)-associated thrombosis according to diagnostic group: a retrospective cohort study

  1. Rebecca Sharp1,
  2. Peter Carr2,3,
  3. Jessie Childs4,
  4. Andrew Scullion5,
  5. Mark Young6,
  6. Tanya Flynn7,
  7. Carolyn Kirker8,
  8. Gavin Jackson9,
  9. Adrian Esterman1

Correspondence to Dr Rebecca Sharp;


Objectives Determine the effect of the catheter to vein ratio (CVR) on rates of symptomatic thrombosis in individuals with a peripherally inserted central catheter (PICC) and identify the optimal CVR cut-off point according to diagnostic group.

Design Retrospective cohort study.

Setting 4 tertiary hospitals in Australia and New Zealand.

Participants Adults who had undergone PICC insertion.

Primary outcome measure Symptomatic thrombus of the limb in which the PICC was inserted.

Results 2438 PICC insertions were included with 39 cases of thrombosis (1.6%; 95% CI 1.14% to 2.19%). Receiver operator characteristic analysis was unable to be performed to determine the optimal CVR overall or according to diagnosis. The association between risk of thrombosis and CVR cut-offs commonly used in clinical practice were analysed. A 45% cut-off (≤45% versus ≥46%) was predictive of thrombosis, with those with a higher ratio having more than twice the risk (relative risk 2.30; 95% CI 1.202 to 4.383; p=0.01). This pattern continued when only those with malignancy were included in the analysis, those with cancer had twice the risk of thrombosis with a CVR greater than 45%. Whereas the 33% CVR cut-off was not associated with statistically significant results overall or in those with malignancy. Neither the 33% or 45% CVR cut-off produced statistically significant results in those with infection or other non-malignant conditions.

Conclusions Adherence to CVR cut-offs are an important component of PICC insertion clinical decision making to reduce the risk of thrombosis. These results suggest that in individuals with cancer, the use of a CVR ≤45% should be considered to minimise risk of thrombosis. Further research is needed to determine the risk of thrombosis according to malignancy type and the optimal CVR for those with a non-malignant diagnosis.


  • Contributors RS: contributions to conception and design, literature search, data analysis and interpretation, writing, final approval of the version to be published. PC and GJ: contributions to conception and design, data interpretation, writing, final approval of the version to be published. AS, MY, TF, CK: contributions to conception and design, acquisition of data, data interpretation, writing, final approval of the version to be published. AE, JC: contributions to conception and design, data analysis and interpretation, writing, final approval of the version to be published.

  • Funding This work was supported by a Pathfinder grant from the University of South Australia, Adelaide, Australia (School of Nursing and Midwifery). Award/grant number is not applicable. There was no conflict of interest, activities or potential for influencing this work by the funders.

  • Disclaimer The grant organisation had no financial interest or role in the design, conduct, analysis or manuscript preparation for this project.

  • 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.


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