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In a large retrospective analysis, midline catheters were associated with markedly lower risk of bloodstream infection and occlusion compared with peripherally inserted central catheters (PICCs).

Data from 48 Michigan hospitals over a 26-month period, covering more than 10,000 patients undergoing catheterization, showed that the odds of experiencing major complications were doubled with PICCs relative to midlines (OR 1.99, 95% CI 1.61-2.47) after adjustment for several patient and procedural factors, according to Lakshmi Swaminathan, MD, of St. Josephs Mercy Health System in Ann Arbor, Michigan, and colleagues.

The rates of device occlusion were lower by more than two-thirds with midlines (2.1% vs 7.0%) and bloodstream infections were lower by three-quarters (0.4% vs 1.6%, both P<0.001), the researchers .

One lingering question, however, is whether there's a difference in risk for deep vein thrombosis (DVT). The study results showed that DVT rates were substantially lower with PICCs versus midline catheters (HR 0.53, 95% CI 0.38-0.74), but Swaminathan and co-authors argued that this wasn't definitive evidence for a genuine risk difference. The odds ratio for DVT did not differ (OR 0.93, 95% CI 0.63-1.37). Whatever difference there was may have "reflect[ed] the higher number of events occurring over fewer total catheter days in midlines compared with PICCs," the researchers wrote.

What these data for DVT really mean, the team added, is that they serve "as a reminder to not dismiss the risk of thrombosis associated with midlines, especially in patients with hypercoagulability or preexisting risk factors," and that catheters of all types shouldn't be kept in place any longer than necessary.

"Thoughtful selection between these two devices, balancing the risk of venous thrombosis, appears necessary in clinical care," Swaminathan's group concluded. "Randomized clinical trials comparing these devices are needed to help inform patient safety."

Study Details

The data came from the , organized by the Blue Cross Blue Shield affiliate in Michigan. Swaminathan and colleagues combed records from December 2017 to January 2020 to find patients receiving either PICCs or midline catheters either because ordinary venous access (for blood draws, etc.) proved too difficult or for intravenous antibiotic treatment lasting 30 days or less. Ultimately, 10,863 such patients were identified, with just over half receiving PICCs.

Mean patient age was about 65, and 53% were women. The groups were similar for most demographic and medical parameters, except that the PICC group was more heavily white and male. Roughly one-quarter were in critical care units, with almost all the rest on medical wards. About 14% had histories of venous thromboembolism. Median Charlson scores for comorbidities were 3 (IQR 2-5) in both groups.

The study's primary outcome was major complications, defined as catheter occlusion, catheter- or central line-related bloodstream infection, DVT, and pulmonary embolism (PE). Adjustments in the statistical analyses included many factors including demographics, comorbidities, DVT/PE history, catheter lumen, and dwell time.

Swaminathan and colleagues noted some differences in device type and outcomes depending on whether catheter placement was for difficult access versus IV antibiotics. About two-thirds of patients needing lines for antibiotics received PICCs, while midlines were preferred in a 3:2 ratio for patients with difficult access.

As well, DVT was more common in the PICC group when used for IV antibiotics, whereas the reverse was seen in the difficult-access group. Only five bloodstream infections were seen with midlines used for antibiotics, versus 72 in the PICC group; this gap was much smaller, though still substantial and in favor of midlines, in the difficult-access patients.

Limitations to the analysis included its reliance on medical records and the potential for unmeasured confounders, including difference among specific devices used in the 48 hospitals, which, the authors noted, could well affect risks of adverse outcomes.

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