Comparison of carbon emissions, water use, and dialysis waste between incremental and full-dose peritoneal dialysis: A cohort study

Welcome to AudioScholar. Today we're covering "Comparison of carbon emissions, water use, and dialysis waste between incremental and full-dose peritoneal dialysis: A cohort study," by Nicdao and colleagues, published in *Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis*.

As clinicians, we're increasingly aware that healthcare has a significant environmental footprint. Nephrology, in particular, is one of the most resource-intensive specialties. Dialysis treatments generate enormous amounts of carbon emissions, consume vast quantities of water, and produce tons of plastic waste. Peritoneal dialysis, or PD, is no exception. A standard, full-dose regimen requires daily exchanges using single-use plastic bags and consumables. One potential way to mitigate this is through "incremental PD," where patients with significant residual kidney function start on a lower dose of dialysis, which is then titrated up as their native function declines. While this approach is gaining traction for its clinical and quality-of-life benefits, its environmental advantages have been mostly theoretical. This study aimed to change that by rigorously quantifying and comparing the environmental impact of incremental versus full-dose PD using real-world, patient-level data.

The researchers conducted a prospective cohort study at a large renal service in Sydney, Australia. They followed 365 adult patients who started peritoneal dialysis between 2019 and 2024. Of these, 187 began on an incremental regimen, and 178 started on a standard full-dose regimen. Incremental PD was defined as fewer than four exchanges per day for continuous ambulatory PD, or fewer than four cycles for automated PD. Full-dose was the standard four exchanges or cycles. The primary outcome was the difference in environmental impact across several key metrics: carbon dioxide equivalent emissions, "blue water" consumption—which is the clean water needed for manufacturing and handwashing—"gray water" generation, which is the wastewater effluent, and the volume of solid waste, separated into landfill and recyclables. The analysis was done using an intention-to-treat-like approach, meaning patients were analyzed in the group they were initially prescribed, even if their therapy was later escalated.

Over a median follow-up of 20 months, the study found that incremental PD was associated with a significantly lower environmental impact across every single metric measured. Let's look at the numbers on a per-patient, per-year basis.

For carbon emissions, the median for an incremental PD patient was 1016 kilograms of carbon dioxide equivalents per year. For a full-dose patient, it was 1360 kilograms. That’s a reduction of about 25 percent.

The difference in solid waste was similarly striking. Patients on incremental PD generated a median of 212 kilograms of landfill waste annually, compared to 271 kilograms for those on full-dose PD—a drop of over 20 percent.

The impact on water use was also substantial. While the reduction in "blue water" use was modest, the generation of "gray water," or wastewater, was significantly lower in the incremental group. Annually, they produced about 8,200 liters of gray water, compared to over 10,500 liters in the full-dose group.

When the authors calculated the cumulative savings over the entire study period, the numbers were impressive. The use of incremental PD in this cohort saved over 200,000 kilograms in carbon emissions—equivalent to the carbon sequestered by nearly 10,000 mature trees. It also saved over 5 million liters of blue water and prevented over 27,000 kilograms of plastic and other materials from going to landfill.

Of course, these environmental benefits would be meaningless if they came at the cost of patient safety or clinical outcomes. The study addressed this crucial point. The researchers found that overall survival was comparable between the two groups. And, notably, the incidence of permanent transfer to hemodialysis was actually *lower* in the incremental PD group. This suggests that the environmental gains were not achieved at the expense of clinical care.

Now, the study has some notable strengths. Its biggest advantage is the use of prospectively collected, detailed, patient-level prescription data. This provides a much more precise and realistic estimate of environmental impact compared to previous studies that relied on broad averages. The median follow-up of 20 months also allowed the researchers to capture the dynamic nature of dialysis prescriptions over time.

However, the authors are also clear about the study's limitations. As a single-center, observational study, the findings may not be fully generalizable to other healthcare systems with different patient demographics, prescribing patterns, or waste management infrastructure. The analysis also excluded transport-related emissions. This is an important omission, because incremental PD requires fewer supplies, meaning fewer and lighter deliveries. Including transport would likely have shown an even *greater* environmental advantage for the incremental approach. Finally, because this was not a randomized controlled trial, there is a potential for confounding, although the reassuring clinical outcomes help to mitigate this concern.

So what is the clinical bottom line? This study provides strong evidence that for appropriate patients starting peritoneal dialysis—namely, those with sufficient residual kidney function—an incremental start is a powerful tool for practicing more environmentally sustainable medicine. It significantly reduces the therapy's carbon footprint, water consumption, and waste production. Crucially, these substantial environmental benefits appear to be safe, with no compromise in survival and even a potential reduction in the need to switch to hemodialysis. Therefore, when you have a patient who is a candidate for PD, considering an incremental start should be a routine part of the conversation. It represents a practical, evidence-based strategy that aligns high-quality, individualized patient care with our growing responsibility to protect environmental health.

That's your AudioScholar summary. The full transcript and reference are on the episode page. Until next time.

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