(HealthDay News) — Cancer patients receiving chemotherapy intravenously have more than double the risk for developing a blood clot if the catheter occupies more than 45% of the vein, according to a study recently published online in BMJ Open.

Rebecca Sharp, PhD, from the University of South Australia in Adelaide, and colleagues assessed the effect of the catheter-to-vein ratio (CVR) on rates of symptomatic thrombosis in individuals with a peripherally inserted central catheter (PICC). The analysis included data from 2438 PICC insertions at 4 tertiary hospitals.

The researchers found that 1.6% of insertions resulted in cases of thrombosis. A 45% CVR cutoff (≤45 vs ≥46%) predicted thrombosis, with those with a higher ratio having a significantly higher risk (relative risk, 2.30). Findings were similar when only those with malignancy were included in the analysis. With a 33% CVR cutoff, there was no significant association observed with thrombosis either overall or in those with malignancy. There were no significant associations seen for thrombosis with either the 33 or 45% CVR cutoff in those with infection or other nonmalignant conditions.

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“Adherence to CVR cutoffs 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 minimize risk of thrombosis,” the authors write. “Further research is needed to determine the risk of thrombosis according to malignancy type and the optimal CVR for those with a nonmalignant diagnosis.”

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