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Michigan Studies Find MALDI Microbial ID Improves Patient Outcomes, May Lower Costs


NEW YORK (GenomeWeb) – A University of Michigan analysis has found that use of MALDI-TOF platforms for microbial identification in hospitals does not raise per-patient costs and might even lower them slightly.

Detailed in a paper published last week in the Journal of Clinical Microbiology, the findings build on an earlier University of Michigan study of the method's clinical efficacy that found that implementation of MALDI-based microbial ID improved patient care by reducing time to effective antibiotic therapy, length of intensive care unit stays, infection recurrence, and mortality.

Taken together, the two studies suggest that MALDI clinical microbiology platforms like Bruker's MALDI Biotyper and BioMérieux's Vitek MS improve patient outcomes while, at worst, breaking even with traditional methods in terms of cost, James Stevenson, professor at the University of Michigan College of Pharmacy and senior author on the JCM paper, told GenomeWeb.

Both the Biotyper and Vitek MS platforms identify microbes by matching the protein profiles of sample organisms generated via MALDI mass spec to profiles contained in a proprietary database. Compared to traditional biochemical methods of microbe detection, MALDI-based systems can offer improvements in speed, price, and accuracy. Both systems have received US Food and Drug Administration 510(k) clearance and the CE-IVD mark in Europe and have seen strong uptake for clinical use.

For their analysis, Stevenson and his colleagues looked at 480 patients in the University of Michigan Health System hospitalized with bloodstream infections, 247 of whom were treated using organism identification and susceptibility information generated via conventional methods on a BioMérieux VITEK-2 platform, and 233 who were treated using information generated by a Bruker MALDI Biotyper system.

They found that using the Biotyper, 30-day mortality improved from 21 percent of patients to 12 percent, while lowering total costs per infection from $45,019 to $42,580 and intensive care unit costs per infection from $13,727 to $10,833. Stevenson noted that these cost savings were not statistically significant, however.

While the data, therefore, doesn't confirm cost savings attributable to use of the Biotyper, it also doesn't indicate that use of the Biotyper increases costs, which, Stevenson said, he and his colleagues found somewhat surprising.

"If anything, I might have guessed that the cost [of using the Biotyper] would have been greater, because [the MALDI technology] improves mortality, and when patients live longer they stay in the hospital longer and their costs go up," he said. "We were surprised that there was really no difference in cost or that, numerically [but not statistically], there were cost savings."

The JCM study contrasted with previously similar work that found implementation of MALDI systems led to much more significant cost savings.

For instance, a 2012 study by clinicians at Houston's Methodist Hospital found that using the MALDI Biotyper as part of the institution's antibiotic stewardship program reduced average patient length of stay by 2.6 days and lowered average hospitalization costs from $45,709 to $26,162 per patient.

That study looked at patients with gram-negative bloodstream infections, comparing 100 patients whose treatment was guided using conventional microbiology platforms, including Becton Dickinson's Phoenix system, to 101 patients with treatment guided by the Biotyper.

It found that the Biotyper allowed for significantly faster identification of the infecting organisms than conventional techniques, leading to the observed reductions in patient stay and hospitalization costs. The Biotyper cohort also saw a reduction in mortality with six of that group compared to 12 of the conventionally evaluated group dying within 30 days of treatment.

The Methodist Hospital group also published a study in 2014 looking at use of MALDI in the treatment of patients with multidrug-resistant gram-negative infections, again finding dramatic cost savings — $26,298 per patient.

Stevenson and his coauthors also noted a 2010 paper published in Clinical Infectious Disease looking not at MALDI but another rapid organism identification technology, real-time PCR, that reported a cost savings of $21,387 per patient in a study looking at Staphylococcus aureus infections.

The Michigan researchers addressed these findings, noting several reasons why they might have found larger savings due to MALDI implementation.

The previous studies, they noted, "focused on specific pathogens which are known to cause higher rates of mortality and complications," while the Michigan analysis "included patients with any type of bacterial or fungal pathogen." This, the authors said, likely contributed to the larger reductions in length of stay observed by the other researchers, and, consequently, larger cost savings.

They also noted that the previous studies did not include the cost of implementing the new technology, which are not reflected in in-patient cost figures.

The authors also cited several factors in their study design that likely led to "a more conservative cost-savings estimate."

These included the fact that, while the analysis included "the cost of pharmacist and microbiology technologist time … the level of effort required to implement this initiative could be absorbed within the daily workflow," without requiring additional hours worked.

Additionally, because their institution is "continually close to full capacity," the researchers did not factor in potential revenue increases from "back-filling hospital beds" opened up by the decreased length of stay.

"Actual cost savings may be greater if hospitals have a stewardship pharmacist already in position and do not need to hire additional personnel, and if beds could be filled as a result of greater throughput," they wrote.

Regardless, Stevenson said, the analysis convinced him and his colleagues that MALDI is at least break-even in terms of cost, while providing superior care than conventional testing alone.

More commonly, he noted, medical advances provide "incremental improvement" in care "for an increase in costs."

"So you have to decide whether the improvement is worth the cost," he said. "Here, we were fortunate that it improved outcomes and actually probably saved on costs."