Executive Summary

Key Points

• “Partial” or incremental peritoneal dialysis (IPD) is a strategy — not a fixed regimen — in which less than conventional “full-dose” PD is prescribed at initiation, the individualized clearance target is met by the sum of residual kidney function (RKF) plus peritoneal clearance, and the PD dose is deliberately escalated as RKF declines [1, 2].
• The scientific rationale rests on a hard fact from the CANUSA reanalysis: in PD patients, native kidney clearance — not peritoneal clearance — drives survival. Each 5 L/week/1.73 m² of residual GFR carried a 12% lower risk of death, and each 250 mL/day of urine a 36% lower risk, while peritoneal creatinine clearance showed no independent association [3].
• The ADEMEX randomized trial proved the corollary: increasing peritoneal small-solute clearance did not improve survival (relative risk of death 1.00; 95% CI 0.80–1.24). More dialysis, without more native function, buys no survival benefit [4].
• The best comparative evidence — a 2024 systematic review of 10 studies and a 2019 meta-analysis of 22 cohorts — shows no significant difference in mortality, peritonitis, or technique survival between incremental and full-dose PD, and suggests incremental starts defer full-dose dialysis by roughly one year [5, 6].
• The single dedicated randomized trial (Yan 2017, 3 vs 4 CAPD exchanges) found no difference in residual GFR, urine volume, or time to anuria and concluded incremental starts “appear safe when patients are monitored.” Observational cohorts — including a propensity-weighted study showing lower anuria risk (HR 0.61) — suggest better RKF preservation, but the highest-quality data support non-inferiority rather than proven superiority [7, 22].
• Incremental PD reduces treatment burden, glucose exposure, cost, and environmental footprint, and aligns with the shift to person-centered, goal-directed prescribing endorsed by the 2020 ISPD recommendations — with life participation now a formal core patient-reported outcome for PD trials [10, 12, 20, 21].
• The dominant hazard is escalation inertia — failing to raise the dose as RKF quietly fails. Partial PD is safe only when paired with disciplined quarterly adequacy and volume monitoring [2, 5, 15].

1. Definition: What “Partial” PD Actually Means

Conventional PD adequacy targets — a weekly Kt/V_urea of approximately 1.7 for continuous ambulatory PD (CAPD) or its automated equivalent — were derived largely from populations with little or no residual kidney function. Incident PD patients transitioning directly from advanced non-dialysis CKD are a different population. They still make urine. They retain measurable glomerular filtration. In them, a full four-exchange CAPD prescription frequently delivers more clearance than the adequacy target requires, at the cost of greater treatment burden, higher cumulative peritoneal glucose exposure, and, plausibly, faster loss of the native function that matters most.

Partial PD is best understood as a strategy rather than a specific prescription. Blake, Dong, and Davies proposed three defining features [1]:

1. Less than standard full-dose PD is prescribed at initiation, in explicit recognition of the value of RKF;
2. Peritoneal clearance alone is below the individualized clearance goal, but the combination of peritoneal plus renal clearance meets or exceeds that goal; and
3. There is a clear, pre-declared intention to increase the PD dose as renal clearance declines or symptoms appear.

In practice this means starting CAPD with two or three exchanges instead of four, or automated PD with fewer cycles, fewer nights per week, or no daytime dwell. The concept is not new — Golper described incremental dialysis within the NKF-DOQI framework in 1998, formalizing what experienced centers had long done informally [16]. What is new is the modern, RKF-centered articulation and its endorsement in the 2020 ISPD recommendations, which moved partial PD from folk practice to guideline-supported strategy [1, 12].

2. Scientific Rationale: Why Residual Kidney Function Is the Prize

The entire case for partial PD stands or falls on one premise: that residual kidney function is uniquely valuable and worth protecting. Two landmark analyses established it.

The CANUSA reanalysis (Bargman 2001). The original CANUSA study assumed renal and peritoneal clearances were equivalent and therefore additive. Bargman and colleagues reanalyzed 601 of the 680 CANUSA patients with a time-dependent Cox model and demolished that assumption [3]. For each 5 L/week/1.73 m² increment in GFR, the risk of death fell 12% (RR 0.88; 95% CI 0.83–0.94). For peritoneal creatinine clearance, there was no association at all (RR 1.00; 95% CI 0.90–1.10). When urine volume entered the model, each 250 mL/day increment carried a 36% lower risk of death (RR 0.64; 95% CI 0.51–0.80), and the GFR association itself disappeared — implicating the volume and clearance functions of the native kidney, not dialysis, as the physiologically decisive variables.

The ADEMEX trial (Paniagua 2002). If peritoneal clearance were as valuable as renal clearance, increasing it should improve survival. ADEMEX tested exactly this in a randomized controlled trial of 965 patients: a control group on four 2-L exchanges versus an intervention group prescribed to a peritoneal creatinine clearance of 60 L/week/1.73 m² [4]. Despite a durable, statistically significant separation in delivered peritoneal clearance, survival was identical. The intent-to-treat relative risk of death was 1.00 (95% CI 0.80–1.24), unchanged after adjustment for age, diabetes, albumin, nutrition, and anuria.

Together these studies make the foundational argument: survival tracks native kidney function, not peritoneal dose. Beyond survival, RKF delivers clearance and functions that dialysis replicates poorly — continuous middle-molecule clearance (β₂-microglobulin and larger uremic solutes), steady euvolemia without episodic glucose-driven ultrafiltration, and residual endocrine activity such as erythropoietin production and vitamin D 1-α-hydroxylation. If a lower PD dose can meet clearance goals while plausibly protecting RKF, the burden of proof shifts to whoever would prescribe more [2, 11, 17].

3. The Approach: Candidate Selection

Partial PD suits the incident patient who still has meaningful native function and is clinically stable. Drawing on the ISPD/KDOQI person-centered framework and the enrollment criteria of the supporting trials, reasonable criteria are [2, 7, 11, 12]:

• Meaningful residual function — urine output that materially contributes to clearance and volume control. The Yan RCT enrolled patients with residual GFR ≥ 2 mL/min/1.73 m² and urine ≥ 500 mL/day [7].
• No urgent uremic indication — no encephalopathy, pericarditis, refractory hyperkalemia, or uncontrolled volume overload at initiation.
• Controllable volume status — the patient can be kept euvolemic on the reduced prescription, counting both urine output and peritoneal ultrafiltration.
• Not a rapid progressor — a steep pre-dialysis GFR slope predicts RKF loss before escalation can be arranged.
• Committed to monitoring — the patient and program will reliably perform quarterly collections and act on the results.

Candidate selection is a shared decision. The 2020 ISPD recommendations deliberately reframed the field from “adequacy” — a clearance number — to high-quality, goal-directed, person-centered care, and the accompanying report from people who do PD drove the shift in language from “patient-centered” to “person-centered” [12, 14]. Partial PD is among the clearest expressions of that philosophy: it fits the therapy to the person’s remaining physiology and life, rather than imposing a maximal fixed dose on everyone.

4. The Approach: Prescription and Escalation

CAPD-based partial prescriptions typically begin with two or three 2-L exchanges per day rather than four. When the residual renal Kt/V contributes meaningfully to the total, two to three exchanges can reach a combined weekly Kt/V near 1.7. Automated PD offers additional levers: fewer nightly cycles with longer dwells, night-only cycling without a daytime dwell (preserving daytime mobility and cutting glucose load), or fewer cycler nights per week.

Escalation is the non-negotiable half of the strategy. The prescription is designed to grow.

Escalation must respond to volume as well as solute. High-quality PD prescribing treats clinical euvolemia — accounting for both urine output and peritoneal ultrafiltration — as a primary goal, precisely so the reduced prescription does not compromise fluid status or, paradoxically, accelerate RKF loss through under- or over-filtration [13].

5. The Approach: Adequacy and RKF Monitoring

Because partial PD banks on the renal contribution, it demands more disciplined accounting than full-dose PD, where the renal share can be ignored once it is trivial. A practical protocol:

• 24-hour urine collection (volume, urea, creatinine) at initiation and every 3 months — the renal Kt/V and creatinine clearance are computed from this.
• 24-hour dialysate collection simultaneously, for peritoneal Kt/V and creatinine clearance.
• Combined weekly Kt/V = peritoneal + renal, with renal clearance taken as the mean of urea and creatinine clearances per ISPD convention.
• Monthly chemistries — BUN, creatinine, electrolytes, bicarbonate, phosphate, albumin.
• Volume and blood pressure at every clinical encounter, with objective adjuncts where available.

The single most important failure mode is escalation inertia: a patient whose urine has quietly diminished, running an unrecognized clearance deficit because the dose was never advanced. This is a human-factors problem, not a pharmacologic one — no drug compensates for a missed escalation decision. Systematic quarterly review and explicit patient education to report falling urine output are the safeguards [2, 5].

6. Evidence of Effectiveness: Survival, Technique, and Peritonitis

The comparative evidence for partial versus full-dose PD is observational-heavy but consistent on the outcomes clinicians most fear.

Systematic reviews and meta-analyses. The most recent synthesis — Xu, Wu, and Cheng (BMC Nephrology 2024), pooling 10 comparative studies — found no significant difference between incremental and standard PD in patient survival, peritonitis, or technique survival. Definitions of “incremental” were heterogeneous, so much of the synthesis was necessarily qualitative, and the authors judged the RKF evidence specifically to be “conflicting” [5]. The earlier meta-analysis by Garofalo and colleagues (Journal of Nephrology 2019), pooling 22 cohorts and 75,292 patients across both incremental hemodialysis and PD, likewise found no significant mortality difference (RR 1.14; 95% CI 0.85–1.52, high heterogeneity), lower residual-function loss with incremental therapy, and deferral of full-dose dialysis by approximately 12 months [6].

Representative cohort data. Single-center series echo the pooled picture. A retrospective comparison by Fernandes and colleagues (Clinical Nephrology 2023) reported that incrementally started patients retained higher GFR at 6 and 24 months, had longer technique survival, fewer hospital admissions, and lower mortality than full-dose starters — with the important caveat that this reflects both the therapy and the healthier physiology of patients selected for it [8]. A Spanish cohort begun on three exchanges reported good clinical and biochemical stability with a low peritonitis rate (one episode per 99 patient-months) over two years [18].

The randomized anchor. Yan and colleagues (American Journal of Kidney Diseases 2017) randomized 139 incident CAPD patients to 3 versus 4 daily exchanges [7]. After 24 months there was no difference in residual GFR (1.6 vs 1.7 mL/min; p = 0.8), urine volume, or time to anuria. The three-exchange arm had, as expected, lower total Kt/V (1.95 vs 2.19; p = 0.03) and ultrafiltration, and nominally fewer peritonitis episodes (13% vs 26%; p = 0.06, not significant). Patient and technique survival were similar. The authors’ conclusion is the honest headline for the whole field: incremental starts “appear safe when patients are monitored.” This demonstrates non-inferiority and safety, not superiority — a distinction worth defending against the temptation to overstate the case.

7. Evidence on Residual Kidney Function Preservation

RKF preservation is the mechanistic promise of partial PD, and here the evidence is genuinely mixed — a point honest advocacy must concede.

The biological rationale is strong: a lower PD dose means less cumulative glucose and glucose-degradation-product exposure to the peritoneal membrane and systemic circulation, gentler and less episodic ultrafiltration, and avoidance of the volume swings that transiently compromise renal perfusion [2, 17].

The observational signal favors preservation. The largest such study — Lee and colleagues (Scientific Reports 2019), 347 incident PD patients at Seoul National University, analyzed with inverse-probability-of-treatment weighting — found that incremental PD carried a lower risk of progression to anuria (HR 0.61; 95% CI 0.43–0.88) with equivalent patient, technique, and peritonitis-free survival [22]. The Portuguese cohort found incremental PD independently associated with GFR ≥ 5 mL/min/1.73 m² at 24 months, and the Spanish series described markedly slower residual-function loss on incremental PD than during the immediate pre-dialysis period [8, 18]. Garofalo’s meta-analysis found lower RKF loss with incremental therapy across the studies reporting it [6].

Against this, the randomized Yan trial found no GFR difference between three and four exchanges, and the 2024 meta-analysis explicitly labeled the RKF evidence “conflicting” and heterogeneous [5, 7]. The most defensible reading: partial PD at least does not accelerate RKF loss, is biologically plausible to slow it, and has consistent observational support — but lacks confirmation from an adequately powered randomized trial.

Whatever the modality, RKF preservation is an active clinical program, not a passive hope. Evidence-supported adjuncts include renin-angiotensin system blockade — a Cochrane review found that long-term (≥ 12 months) ACE inhibitors or ARBs better preserved residual function in CAPD patients, with ramipril delaying progression to anuria (RR 0.64; 95% CI 0.41–0.99) — alongside avoidance of nephrotoxins and unnecessary contrast, prevention of volume depletion and hypotension, and vigilant treatment of peritonitis, itself a driver of RKF loss [19].

8. Evidence on Quality of Life and Life Participation

Partial PD is, at its core, a quality-of-life proposition: fewer exchanges, less time tethered to the therapy, fewer mechanical symptoms (abdominal fullness, hernias, leaks, reflux), lower glucose absorption and its metabolic consequences, and reduced cost and plastic and water waste [2, 10, 15]. Narrative reviews and the PD-outcomes literature consistently list better-preserved RKF, greater treatment satisfaction, and better quality of life among PD’s advantages, and position incremental PD as a lever to enhance them [10, 15].

The candid limitation: rigorous comparative quality-of-life data are sparse. Much of the QoL argument is inferential, derived from reduced burden rather than from head-to-head trials with validated instruments. The field is correcting this. Through the Standardized Outcomes in Nephrology (SONG) initiative, life participation has been established as a core outcome that should be reported in all PD trials, and a dedicated SONG-PD consensus process is developing a validated, cross-culturally applicable measure of it [20, 21]. Life participation — the capacity to do the things that make life meaningful — is precisely the dimension on which a lower-burden, RKF-sparing strategy should show its value. Its formal adoption as a core outcome means the next generation of incremental-PD trials will finally be measuring the right thing.

9. Risks, Limitations, and the Honest Case

Partial PD is not free of hazards, and a credible white paper names them:

• Escalation inertia — the central risk; a delayed dose increase in a patient losing RKF produces an unrecognized clearance and volume deficit [2, 5].
• Underdetected RKF loss — episodic monitoring can miss a rapid decline; hence the quarterly-collection discipline.
• Middle-molecule clearance — shorter total dwell time reduces clearance of larger uremic solutes, which depends on time on therapy; this matters most once RKF is gone [2].
• Patient reluctance to escalate — having adapted to a lighter regimen, some patients resist adding exchanges; anticipatory education at initiation mitigates this [2, 15].
• Evidence quality — the comparative base is dominated by observational studies with heterogeneous definitions and selection bias; the one dedicated RCT is small and single-center. Conclusions of non-inferiority are well supported; claims of superiority in survival or RKF are not [5, 6, 7].

Set against these is a coherent, guideline-aligned upside: equivalent short- to medium-term hard outcomes, a lighter and more livable therapy, protection — or at least non-erosion — of the prognostic variable that matters most, lower cost, and a smaller environmental footprint, all consistent with the person-centered, goal-directed model the field has adopted [11, 12, 13].

10. Summary and Recommendations

Partial (incremental) peritoneal dialysis is an evidence-supported, guideline-consistent strategy for the incident PD patient with meaningful residual kidney function. Its logic is anchored in two of nephrology’s most durable findings — that survival on PD tracks native kidney function rather than peritoneal dose (CANUSA reanalysis), and that adding peritoneal clearance alone does not improve survival (ADEMEX). The comparative evidence supports non-inferiority for mortality, technique survival, and peritonitis, with observational signals — but not randomized confirmation — of better RKF preservation and quality of life.

Practical recommendations:

1. Offer partial PD to appropriately selected incident patients with meaningful RKF and no urgent uremic indication, as a shared decision.
2. Prescribe to a combined (renal + peritoneal) clearance and euvolemia goal, not to a fixed number of exchanges.
3. Monitor relentlessly — quarterly 24-hour urine and dialysate collections, monthly chemistries, volume at every visit.
4. Pre-commit to escalation and teach the patient at initiation that the dose is designed to grow; treat declining urine output as an action trigger.
5. Run an active RKF-preservation program — RAS blockade where tolerated, nephrotoxin and contrast avoidance, euvolemia, and prompt peritonitis treatment.
6. Measure what matters — incorporate life participation and other patient-reported outcomes, now that SONG has established them as core PD trial endpoints.

The clinical bottom line: partial PD lets the native kidney do the work it does best while dialysis fills the gap — and quietly grows to meet the patient as that native function fades. Its safety depends entirely on the discipline of the monitoring and escalation that surround it.

References

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2. Fernandes A, Matias P, Branco P. Incremental peritoneal dialysis—definition, prescription, and clinical outcomes. Kidney360. 2023;4(2):272–277. https://pubmed.ncbi.nlm.nih.gov/36821618/

3. Bargman JM, Thorpe KE, Churchill DN. Relative contribution of residual renal function and peritoneal clearance to adequacy of dialysis: a reanalysis of the CANUSA study. J Am Soc Nephrol. 2001;12(10):2158–2162. https://pubmed.ncbi.nlm.nih.gov/11562415/

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5. Xu S, Wu W, Cheng J. Comparison of outcomes of incremental vs. standard peritoneal dialysis: a systematic review and meta-analysis. BMC Nephrol. 2024;25(1):308. https://pubmed.ncbi.nlm.nih.gov/39285336/

6. Garofalo C, Borrelli S, De Stefano T, et al. Incremental dialysis in ESRD: systematic review and meta-analysis. J Nephrol. 2019;32(5):823–836. https://pubmed.ncbi.nlm.nih.gov/30604150/

7. Yan H, Fang W, Lin A, et al. Three versus 4 daily exchanges and residual kidney function decline in incident CAPD patients: a randomized controlled trial. Am J Kidney Dis. 2017;69(4):506–513. https://pubmed.ncbi.nlm.nih.gov/27751610/

8. Fernandes A, Matias P, Branco P. Incremental peritoneal dialysis: is it better for preservation of residual kidney function and clinical outcomes? Clin Nephrol. 2023;99(1):11–17. https://pubmed.ncbi.nlm.nih.gov/36472405/

9. Cheetham MS, Cho Y, Krishnasamy R, et al. Incremental versus standard (full-dose) peritoneal dialysis. Kidney Int Rep. 2022;7(2):165–176. https://pubmed.ncbi.nlm.nih.gov/35155856/

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11. Auguste BL, Bargman JM. Peritoneal dialysis prescription and adequacy in clinical practice: core curriculum 2023. Am J Kidney Dis. 2023;81(1):100–109. https://pubmed.ncbi.nlm.nih.gov/36208963/

12. Teitelbaum I, Glickman J, Neu A, et al. KDOQI US commentary on the 2020 ISPD practice recommendations for prescribing high-quality goal-directed peritoneal dialysis. Am J Kidney Dis. 2020;77(2):157–171. https://pubmed.ncbi.nlm.nih.gov/33341315/

13. Wang AY, Dong J, Xu X, Davies S. Volume management as a key dimension of a high-quality PD prescription. Perit Dial Int. 2020;40(3):282–292. https://pubmed.ncbi.nlm.nih.gov/32063208/

14. Corbett RW, Goodlet G, MacLaren B, et al. International Society for Peritoneal Dialysis practice recommendations: the view of the person who is doing or who has done peritoneal dialysis. Perit Dial Int. 2020;40(3):349–352. https://pubmed.ncbi.nlm.nih.gov/32301374/

15. Dhoot A, Brown EA, Robinson B, Perl J. Incremental peritoneal dialysis: incremental gains. Perit Dial Int. 2023;43(5):355–358. https://pubmed.ncbi.nlm.nih.gov/37674305/

16. Golper TA. Incremental dialysis. J Am Soc Nephrol. 1998;9(12 Suppl):S107–S111. https://pubmed.ncbi.nlm.nih.gov/11443756/

17. Wong J, Vilar E, Davenport A, Farrington K. Incremental haemodialysis. Nephrol Dial Transplant. 2015;30(10):1639–1648. https://pubmed.ncbi.nlm.nih.gov/26038351/

18. Borràs Sans M, Chacón Camacho A, Cerdá Vilaplana C, et al. Incremental peritoneal dialysis: clinical outcomes and residual kidney function preservation. Nefrologia. 2016;36(3):299–303. https://pubmed.ncbi.nlm.nih.gov/27137104/

19. Zhang L, Zeng X, Fu P, Wu HM. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for preserving residual kidney function in peritoneal dialysis patients. Cochrane Database Syst Rev. 2014;(6):CD009120. https://pubmed.ncbi.nlm.nih.gov/24953826/

20. Cheetham MS, Wilkie M, Loud F, et al. Establishing a core outcome measure for life participation in patients receiving peritoneal dialysis: a Standardised Outcomes in Nephrology–Peritoneal Dialysis consensus workshop report. Perit Dial Int. 2022;42(6):562–570. https://pubmed.ncbi.nlm.nih.gov/35538693/

21. Hughes A, Scholes-Robertson N, Ju A, Jauré A. Core patient-reported outcomes for trials in nephrology. Semin Nephrol. 2024;44(3–4):151549. https://pubmed.ncbi.nlm.nih.gov/39289130/

22. Lee Y, Chung SW, Park S, et al. Incremental peritoneal dialysis may be beneficial for preserving residual renal function compared to full-dose peritoneal dialysis. Sci Rep. 2019;9(1):10105. https://pubmed.ncbi.nlm.nih.gov/31300708/

Andrew Bland, MD, FACP, FAAP Medical Associates Dept of Nephrology | University of Illinois College of Medicine at Peoria | UDPA | Butler College of Osteopathic Medicine

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• Nephrology Hub — Parent index
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