My mother, Peggy Lillis, died of a C. diff infection in April 2010. She was 56 years old. But here is something most people do not know: C. diff does not appear on her death certificate. What does appear are sepsis and toxic megacolon, which is what killed her at the end. C. diff is what set all of it in motion. She is not counted in any official C. diff mortality data.

I am telling you this because it matters to everything that follows.

A new study published in Gastroenterology Research and Practice analyzes 20 years of national C. diff mortality data and documents real progress alongside persistent disparities by age, race, and geography. The study is valuable and important. But it is built on death certificate data, and death certificate data systematically undercounts C. diff deaths. Understanding what the study shows requires understanding that limitation first.

The Data Has a Known Flaw

The researchers used CDC WONDER, a database built from U.S. death certificates, to identify C. diff deaths from 1999 through 2020. They are transparent about this limitation: death certificates are subject to human error, misidentification of cause of death, and data loss.

A 2012 study published in Emerging Infectious Diseases by Hota and colleagues at the University Health Network in Toronto put hard numbers on exactly how unreliable death certificate data is for C. diff. Researchers at three Ontario hospitals compared three methods for identifying C. diff deaths: death certificate, death within 30 days of diagnosis, and a physician panel review (the most rigorous standard). Among 151 deaths that underwent panel review and were found to be directly or strongly attributable to C. diff, only 37 percent were coded as such on the death certificate. Agreement between panel review and death certificate classification was rated as poor, with a kappa score of just 0.07.

My mother’s death certificate is a case study in exactly this problem. Sepsis and toxic megacolon killed her. Both are well-documented complications of C. diff infection. But C. diff itself does not appear. By the logic of death certificate coding, she does not count. She is one of an unknown number of Americans whose C. diff deaths are invisible in the very data sets we rely on to understand and respond to this epidemic.

This is not a minor methodological footnote. It shapes everything: how we estimate the scale of the problem, where we direct resources, which communities we recognize as most affected, and what policies we fight for. When C. diff is systematically undercounted, the people most likely to be undercounted are those already at the margins of our healthcare system.

What the Study Found

With that context in place, the Eldesouki et al. study is still worth examining carefully. The researchers analyzed 191,653 C. diff-related deaths from 1999 through 2020 among adults aged 35 and older, calculating age-adjusted mortality rates (AAMRs) per 100,000 people broken down by sex, race and ethnicity, geography, and urban versus rural setting.

The Good News: Mortality Has Fallen Significantly

The age-adjusted C. diff mortality rate rose sharply through the 2000s, climbing from 1.1 per 100,000 in 1999 to a peak of 7.3 in 2011, then falling to 3.6 by 2020, a decline of more than 50 percent from the peak. The study’s authors attribute this to updated clinical guidelines from IDSA, SHEA, and the American College of Gastroenterology; FDA approvals of fidaxomicin in 2011 and eventually fecal microbiota transplant; and stronger antibiotic stewardship and infection control in hospital settings.

This is real progress. It shows that better guidelines, better treatments, and sustained institutional effort can move the needle on C. diff deaths. We should not minimize it. But we also cannot let it obscure what the data shows when you look more closely.

Age: The Risk Climbs Sharply With Every Decade

The study confirms what clinicians have long observed: C. diff mortality rises sharply with age. Among adults aged 35 to 44, C. diff deaths represented less than 1 percent of the total over the study period. Among those aged 75 to 84, the figure was 33 percent. For those 85 and older, it reached nearly 38 percent.

My mother was 56. Her death sits in the data as a statistical outlier. But she was not unusual in the ways that matter most: she had a recent healthcare exposure, and she was not diagnosed promptly. The age data reflect population-level risk. It does not capture the individual stories of people who fall outside those categories and still die. We hear those stories regularly.

The study also found that 17.7 percent of all C. diff deaths occurred in nursing homes. That figure deserves more attention than it typically receives. Nursing home residents are among the most vulnerable C. diff patients, and infection control in long-term care settings has historically lagged behind acute care hospitals. And given what we know about death certificate accuracy, the true share of nursing home C. diff deaths is almost certainly higher than 17.7 percent.

Race: A Complex Picture That Demands Honest Interpretation

The racial breakdown requires careful handling. Non-Hispanic White individuals recorded the highest age-adjusted mortality rate (6.1 per 100,000 at the study’s peak), followed by non-Hispanic Black or African American individuals (5.1), American Indian or Alaska Native individuals (5.0), Hispanic or Latino individuals (3.0), and Asian or Pacific Islander individuals (2.3).

A surface reading might suggest White Americans bear the greatest C. diff burden. The study’s own authors are more careful than that. They note that higher mortality rates in White and African American populations likely reflect a combination of socioeconomic status, healthcare access, antibiotic use patterns, and underlying health conditions. Higher raw mortality rates among White Americans may partly reflect greater overall healthcare exposure and hospitalization rates, not inherently greater biological vulnerability.

What the aggregate numbers do not fully reveal is the quality and timeliness of care received. Research published in BMC Infectious Diseases has documented that Black patients have higher in-hospital C. diff mortality than White patients, even when infection rates are lower. A separate study at a Southern California academic hospital found that racially and ethnically minoritized patients with C. diff were younger, sicker on admission, more likely to require the ICU, and more likely to be underinsured than non-Hispanic White patients with the same diagnosis.

The death certificate problem compounds all of this. If C. diff is miscoded as sepsis or another complication on death certificates, and if that miscoding happens more often in communities with less access to thorough documentation and follow-up care, then minority communities are doubly disadvantaged: worse outcomes, and less likely to be counted.

Geography: The Rural Shift Is a Warning

The geographic findings are striking. Historically, C. diff death rates were higher in urban areas, where hospital-acquired infections were more prevalent. But after 2015, rural mortality rates surpassed urban ones and continued to diverge. By 2020, rural areas had a higher age-adjusted mortality rate than cities. The study’s authors suggest this reflects the uneven pace of adoption of stricter infection-control protocols and improved treatment options. Urban hospital systems implemented updated guidelines and new therapies more quickly. Rural healthcare facilities, more often under-resourced and more isolated from rapidly evolving clinical evidence, lag behind. At the regional level, the Northeast had the highest AAMR over the study period (4.8 per 100,000 at its 2008 peak), while the South had the lowest (3.1). At the state level, Rhode Island and Ohio had the highest mortality rates; Hawaii and Louisiana had the lowest.

The Surveillance Gap Makes All of It Worse

The Eldesouki study is a 20-year national analysis, and that scale is its strength. But it is constrained by the quality of its underlying data. As the authors acknowledge, the CDC WONDER database depends on death certificates, which systematically misattribute C. diff deaths. The Hota study gives us a sense of the magnitude of that problem: among deaths a physician panel identified as directly or strongly attributable to C. diff, only 37 percent appeared correctly coded on the death certificate.

PLF has raised this problem for years. Community-acquired C. diff infections and deaths in long-term care settings are undercounted. Seniors who die outside hospital settings are rarely tested or autopsied. People who die of sepsis or toxic megacolon triggered by C. diff, as my mother did, may never be counted at all. The 191,653 deaths documented in this study are the floor, not the ceiling.

This is especially consequential for communities already underserved by the healthcare system. If the data does not find you, the policy does not reach you.

What PLF Is Doing About It

The Peggy Lillis Foundation was built on the premise that no one should suffer or die from C. diff because they lacked access to information, timely diagnosis, or the best available care. That premise has always had an equity dimension.

One of our most concrete advocacy priorities right now is expanding Medicare and Medicaid coverage for live biotherapeutic products (LBPs). The FDA approved Rebyota in 2022 and Vowst in 2023, the first microbiome-based therapies to prevent C. diff recurrence. These treatments represent a genuine breakthrough for patients who have cycled through multiple recurrences. But coverage under Medicare and Medicaid remains inconsistent, meaning patients with the most to gain from these therapies are also the ones least able to access them. We are actively working with policymakers to change that.

We are also committed to reaching patients and families in communities that too often go underserved. Our peer support network, patient story archive, and educational resources at cdiff.org are free and publicly available. Every person who contacts us and says they had never heard of C. diff before their diagnosis is a reminder of what inadequate awareness costs. That lack of knowledge delays treatment. And delayed treatment, as my mother’s case showed, can be fatal.

What This Demands of Us

The progress documented in the Eldesouki study is real. Fifty percent fewer people are dying of C. diff at its mortality peak than in 2011. Better guidelines, better treatments, and sustained public health efforts saved lives. That is worth saying.

But the disparities by age, race, and geography are also real. And they are almost certainly larger than the data shows, because the data systematically misses C. diff deaths, particularly among those least able to advocate for themselves within a complex healthcare system.

My mother’s death certificate lists sepsis and toxic megacolon. It does not list C. diff. She is not in this data set. She is in mine.

That gap between the official record and the lived reality is exactly what we are fighting to close: through better surveillance, better access to treatment, stronger infection control, and a commitment to ensuring that every C. diff death in every community gets counted and responded to.

If you want to help us close these gaps, we invite you to explore volunteer opportunities with the Peggy Lillis Foundation. Every person who gives their time to this work helps us reach more patients, push for better policies, and make sure no one faces C. diff alone.