Superbugs in Seniors Led to Nearly 12,000 Deaths in a Single Year

Six common antibiotic-resistant microbial infections in Medicare-age Americans resulted in close to 12,000 deaths in 2017, and cost the U.S. nearly $1.9 billion, a new study found.

This population of older Americans, therefore, accounted for more than one-third of the total national costs and deaths associated with antimicrobial resistance, reported David Hyun, MD, director of the Pew Charitable Trusts' Antibiotic Resistance Project, and co-authors, writing in Clinical Infectious Diseases.

"Congress and federal agencies such as CMS [Centers for Medicare & Medicaid Services] need to prioritize actions and investments that will strengthen the existing arsenal against antibiotic-resistant infections by spurring the development of new antibiotics and slowing the emergence of these infections by reducing inappropriate antibiotic use," the project team wrote in a Pew analysis that accompanied the study, which was co-published by the Infectious Diseases Society of America, Pew, and the University of Utah School of Medicine.

The study "really adds to the urgency for addressing antibiotic resistance and the role the federal government has," Hyun told MedPage Today.

Community-onset infections cost a total of $1.1 billion and 9,564 deaths, while hospital-onset infections cost $781 million and 2,288 deaths, according to the research.

"Despite substantially fewer invasive infections relative to noninvasive infections (39,535 vs 263,412), the aggregate burden of these infections with onset in the community was approximately equal ($535.8 million; 95% CI $411.8 million-$659.8 million) for invasive infections and $568 million for noninvasive infections (95% CI $368.8 million-$767.1 million)," Hyun and co-authors wrote.

The largest mean cost was associated with Carbapenem-resistant (CR) Acinetobacter, for both community ($47,866) and hospital ($125,840) patients. The highest unadjusted mortality rates were also associated with this pathogen, for both community (24.3%) and hospital (44.6%) patients.

When the researchers controlled for observable characteristics, the attributable costs per infection were found to be highest for this pathogen as well -- both for hospital ($54,494, 95% CI $31,844-$77,145) and community invasive infections ($16,952, 95% CI $3,209-$30,695).

Attributable cost estimates are likely low, the researchers said. "While estimates were generated using VA patients, they have enhanced generalizability due to the utilization of the VA HERC [Health Economics Resource Center] costs that are based on Medicare costs."

Antibiotic stewardship programs are essential to reduce overprescribing and counter the resistance problem, according to the Pew analysis, which recommended that Congress financially help healthcare centers implement these programs.

"However, even with appropriate prescribing, bacteria will eventually become resistant to available therapies, so a robust pipeline of new antibiotics to address emerging resistance will be important," the authors wrote.

But return on investment for developing these drugs is low, along with "resource-intensive" development, Hyun noted, adding that four of every five drugs that make it into clinical trials fail to gain FDA approval.

The team, therefore, urged that "Congress enact a package of economic incentives that includes the PASTEUR Act to spur development ... [and] make it financially feasible for companies to re-enter the antibiotic development market."

CMS should "incentivize tracking antibiotic use and resistance data and reporting it to public health authorities," Hyun and co-authors said. Only 38% of acute care hospitals voluntarily reported antibiotic use data to the CDC's National Healthcare Safety Network and only 18% submitted antibiotic-resistance data, according to the Pew analysis. Those figures follow a 2020 U.S. Government Accounting Office report citing low rates of hospital participation in CDC data collection programs.

The researchers also suggested that CMS "develop and implement quality measures around antibiotic prescribing and resistance in nursing homes," and "improve antibiotic prescribing in outpatient facilities by incorporating antibiotic stewardship activities into existing quality measure and value-based reimbursement programs for outpatient health care providers."

"Clearly there still needs to be a lot more done in terms of what CMS can do to help," Hyun said. "That's even more so the case for antibiotic use, especially in outpatient care settings ... Public payers like CMS are well positioned to provide that support."

The new study also follows a Pew report in March that found that more than one-half of hospitalized COVID-19 patients received antibiotics in the early months of the COVID-19 pandemic, while only a fraction actually had bacterial infections.

Study Details

The researchers analyzed 2017 patient data from CDC national figures, conducting a retrospective cohort analysis of inpatient stays in VA centers between 2007 and 2018, comparing each with up to 10 controls. The cohort featured 87,509 infected patients and 835,048 controls.

Patients were identified as having either invasive or noninvasive infections associated with one of the following:

• Methicillin-resistant Staphylococcus aureus

• Extended-spectrum cephalosporin resistance in Enterobacteriaceae suggestive of extended spectrum β-lactamase production

• Vancomycin-resistant Enterococcus

• CR Acinetobacter species

• CR Enterobacteriaceae

• Multidrug-resistant Pseudomonas aeruginosa

Patients' mean age ranged from 75.2 to 78.3 across the pathogen groups, with more than 90% being male for all six groups; the most common race was white (ranging from 37.8% to 75.8% across groups).

Each patient with a positive culture was matched using an exposure density sampling approach, with control patients who had not had a positive culture up until that point in their hospitalization but were admitted to the same inpatient facility and had the same admitting diagnosis, the researchers explained.

Potential control patients could either have had a negative culture or no culture obtained, and patients with positive cultures up to a year before being admitted were excluded.

Elderly patients were studied because they are more exposed to bacterial infections and have higher risks for contracting them.

Mortality was not limited to just in-hospital deaths; the researchers tracked this outcome at 30 days and again at 90 days after infection was detected.

The investigators assessed healthcare costs applying VA HERC data and converted cost values to 2017 dollars using the Personal Consumption Expenditures index. Not all costs could have been prevented, because the reported costs included both fixed and variable sums, the team explained, adding that national estimates were derived by multiplying pathogen-specific estimates by national case counts from hospitalized U.S. patients.

Positive clinical cultures were used to identify true infections, the researchers said, noting that a limitation was that "it is highly likely that the invasive positive cultures in our study represent true infections, while the noninvasive positive cultures likely contain a mix of true infections and colonizations."

Other study limitations were that attributable cost and mortality estimates could have been subject to residual confounding bias, and that the population of veterans is different from the overall U.S. Medicare population.

Comment