Care pathway, site of service, and what is already in the room — potassium monitoring in CKD

1. Summary

RAASi titration monitoring has a stated guideline cadence, but the published record of what actually happens in outpatient practice shows that cadence is routinely missed, in both a US and a UK primary-care cohort [4][6]. Where a clinic assigns a pharmacist rather than the prescriber alone to run the titration, two independent, differently-located programs report better completion of guideline-directed medical therapy, and one reports a shorter interval between visits [8][9]. The one structured, protocol-driven counter-example located — a hospital-based rapid up-titration trial — gates each dose increase on a lab value with an explicit turnaround requirement, which is the only place in this pass's search where "how fast does the result need to come back" has any answer at all [2][3]. This report does not close the domain dossier's open questions about who physically draws the specimen or what lab equipment already sits in a cardiology or nephrology clinic; those remain unsearched.

2. What Changed

_Baseline (v1). No prior version; this establishes the starting point for future diffs._

3. Details

The guideline cadence, and that it is not one number

The interval a clinician is told to re-check potassium and creatinine after starting or increasing a RAASi is not a single figure across sources. A 2022 nephrology review states the practice its authors follow:

"We usually check the serum creatinine and potassium within 2–4 weeks of initiation or intensification of RASi to evaluate and manage these side effects." — PMID 34789477 [single-source]

A UK primary-care cohort study frames the interval its own national guidance sets at a tighter window and measures adherence against it directly, discussed below [6]. The two figures — roughly 2–4 weeks in one review's stated practice and 2 weeks in the UK guideline referenced by [6] — are not the same number, and no source in this pass reconciles them; they are carried here as two distinct, sourced statements rather than as one settled interval.

What actually happens: the adherence gap in outpatient practice

Two US and two UK cohorts, run by unaffiliated research groups in different health systems, converge on the same shape of finding: the guideline-recommended follow-up test is the exception, not the rule, once a RAASi is started or increased. In a cohort of 8,217 individuals with stage 3–5 non-dialysis CKD newly prescribed a RAASi (52.3%) or a diuretic (47.7%) across 36 primary care offices affiliated with Brigham and Women's Hospital and Massachusetts General Hospital, 2009–2011:

"Overall, 3306 (40.2%) individuals did not have pre-prescription labs done within 2 weeks, and 5957 (72.5%) did not have post-prescription labs done within 2 weeks... Close monitoring occurred in only 1547 (20.1%)." — PMID 31804307 [single-source]

In a UK Clinical Practice Research Datalink cohort of 223,814 new ACE inhibitor/ARB users, 2004–2014:

"Only one-tenth of patients initiating ACEI/ARB therapy receive the guideline-recommended creatinine monitoring." — PMID 28069618 [single-source]

A second UK primary-care cohort, 10,546 patients adding an aldosterone antagonist onto an ACEI/ARB between 2004 and 2014, found monitoring within the guideline's 2-week window in 3,291 of 10,546 (31.2%) [single-source]. The same paper reports that among those who were monitored within 2 months, potassium reached ≥6 mmol/L in 2.0% and creatinine reached ≥220 µmol/L in 2.7% [7] [single-source]. A related US cohort of 4,661 individuals from the same 36-office network, restricted to those with at least one follow-up lab within 90 days of a new RAASi or diuretic prescription, found:

"Creatinine level increase of at least 30% after RAASI therapy initiation was found in 158 of 2354 individuals (6.7%); hyperkalemia of greater than 5.0 mEq/L, in 251 of 2354 (10.7%)." — PMID 30646338 [single-source]

That US cohort overlaps in institution and years with [4] and is not treated as independent corroboration of it; it is read here as a second, related measurement from the same primary-care network rather than a second source agreeing with the first. Taken together with the two UK cohorts, the pattern — guideline-recommended re-checks routinely missed in unscheduled, prescriber-ordered outpatient monitoring — is plainly stated above because it holds across two countries and at least three unaffiliated research groups; the specific percentages attached to it are each single-source.

An alternative site of service: pharmacist-run titration clinics

Two unaffiliated studies, in different countries, describe a different care-pathway model — a pharmacist embedded in or running a titration clinic rather than a prescriber ordering labs independently — and both report the same direction of effect on guideline-directed therapy completion. A US "heart failure medication titration clinic" seeing 80 of 974 screened HFrEF patients found:

"There was a significant improvement in the proportion of patients who achieved quadruple GDMT (p = 0.001) and triple GDMT (p-value = 0.020) at 90-day post-enrollment compared to baseline." — PMID 35501544 [single-source]

A collaborative pharmacist-prescribing model introduced across two Australian community heart failure services, compared by interrupted time series over 12 months pre- and post-implementation (302 patients), reported not only more optimization but a denser visit schedule:

"Median time between visits decreased from 49 to 28 days (p < 0.001), while mean monthly attendance increased from 9 to 16 (p < 0.001)." — PMID 42467354 [single-source]

Neither study reports who draws the blood sample or what turnaround the clinic requires between a draw and a dosing decision; both describe the visit and prescribing model, not the specimen-handling step this domain's dossier flags as unanswered.

The one place a turnaround requirement is stated explicitly

The STRONG-HF trial protocol is the only source located in this pass that ties a specific lab turnaround window to a specific titration decision. Its design paper states that in the high-intensity arm, up-titration of a beta-blocker, ACEi/ARB/ARNi and an MRA proceeds toward 100% of target dose within 2 weeks of discharge, and that:

"Up-titration will be delayed if the patients develop worsening symptoms and signs of congestion, hyperkalaemia, hypotension, bradycardia, worsening of renal function or significant increase in N-terminal pro-B-type natriuretic peptide between visits." — PMID 31423712 [single-source]

The trial's own registry record sets a hard turnaround requirement at the point of enrollment rather than during titration itself: eligibility required "All measures within 24 hours prior to Randomization of serum potassium ≤ 5.0 mEq/L (mmol/L)" [3] [single-source]. The registry record carries no posted results (hasResults=false) and an enrollment figure of 1,800 that is the sponsor's registered target, not a count of anyone enrolled [3] [sponsor-reported]. This is a hospital-based, cardiology-led protocol responding to an acute admission, not the ambulatory RAASi-titration setting the rest of this domain concerns — it is carried here as the one concrete example of a lab-gated titration workflow with a stated timing requirement, not as evidence about outpatient practice.

4. Sources

[1] Optimizing Renin-Angiotensin System Inhibitor Use in CKD — Clinical Journal of the American Society of Nephrology (published 2022-01; accessed 2026-09-01). PMID 34789477 — https://pmc.ncbi.nlm.nih.gov/articles/PMC8763146/ [peer-reviewed] [2] Safety, Tolerability and efficacy of Rapid Optimization, helped by NT-proBNP and GDF-15, of Heart Failure therapies (STRONG-HF): rationale and design for a multicentre, randomized, parallel-group study — European Journal of Heart Failure (published 2019-11; accessed 2026-09-01). PMID 31423712 — https://pubmed.ncbi.nlm.nih.gov/31423712/ [peer-reviewed] [3] Safety, Tolerability and Efficacy of Rapid Optimization, Helped by NT-proBNP testinG, of Heart Failure Therapies (STRONG-HF) — ClinicalTrials.gov (record snapshot dated 2021-02-12; accessed 2026-09-01). NCT03412201 — https://clinicaltrials.gov/study/NCT03412201 [trial-registry] [4] Lab monitoring and acute care utilization during initiation of renin angiotensin aldosterone inhibitors or diuretics in chronic kidney disease — Medicine (published 2019-12; accessed 2026-09-01). PMID 31804307 — https://pubmed.ncbi.nlm.nih.gov/31804307/ [peer-reviewed] [5] Association of Changes in Creatinine and Potassium Levels After Initiation of Renin Angiotensin Aldosterone System Inhibitors With Emergency Department Visits, Hospitalizations, and Mortality in Individuals With Chronic Kidney Disease — JAMA Network Open (published 2018-11-02; accessed 2026-09-01). PMID 30646338 — https://pubmed.ncbi.nlm.nih.gov/30646338/ [peer-reviewed] [6] Adherence to guidelines for creatinine and potassium monitoring and discontinuation following renin-angiotensin system blockade: a UK general practice-based cohort study — BMJ Open (published 2017-01-09; accessed 2026-09-01). PMID 28069618 — https://pubmed.ncbi.nlm.nih.gov/28069618/ [peer-reviewed] [7] Biochemical monitoring after initiation of aldosterone antagonist therapy in users of renin-angiotensin system blockers: a UK primary care cohort study — BMJ Open (published 2017-11-16; accessed 2026-09-01). PMID 29150471 — https://pubmed.ncbi.nlm.nih.gov/29150471/ [peer-reviewed] [8] Impact of Pharmacist-Led Heart Failure Clinic on Optimization of Guideline-Directed Medical Therapy (PHARM-HF) — Journal of Cardiovascular Translational Research (published 2022-12; accessed 2026-09-01). PMID 35501544 — https://pubmed.ncbi.nlm.nih.gov/35501544/ [peer-reviewed] [9] Collaborative pharmacist prescribing in community heart failure clinics: a pre-post intervention comparison — International Journal of Clinical Pharmacy (published 2026-07-17; accessed 2026-09-01). PMID 42467354 — https://pubmed.ncbi.nlm.nih.gov/42467354/ [peer-reviewed]

5. Sourcing & Gaps

Well established: that guideline-recommended potassium/creatinine re-checks after a RAASi is started or increased are routinely missed in unscheduled, prescriber-ordered outpatient monitoring rests on two independent, non-affiliated cohorts in two countries — a US Brigham/MGH-affiliated primary-care network [4] and a UK CPRD-based general-practice cohort [6] — and is stated plainly in the Summary and in Details for that reason. That a pharmacist-run titration clinic model improves completion of guideline-directed therapy rests on two independent, non-affiliated programs in two countries [8][9] and is likewise stated plainly.

Thin: every specific percentage, count, or interval attached to those two plain findings rests on a single study and is marked [single-source] — the 20.1% close-monitoring figure [4], the under-10% UK figure [6], the 31.2% and 2.0%/2.7% figures [7], the 6.7%/10.7% figures [5], the 90-day GDMT improvement [8], and the 49-to-28-day visit interval [9]. The 2–4 week guideline interval [1] and the STRONG-HF lab-gating example [2][3] are each single-source. The JAMA Network Open cohort [5] shares an institution and study years with the Medicine cohort [4] and is treated here as a related, non-independent measurement rather than as corroboration of it.

Rescoped from class 3: none in this report. The dossier's open care-pathway questions — where titration happens, who draws the sample, what turnaround is needed, what lab infrastructure is already present — are registry or published-finding questions in shape, not questions about what a person would do, so none required rescoping; several remain genuinely unanswered rather than unanswerable, and are recorded below as not searched or not found.

Out of scope: CPT descriptors, which are AMA-licensed and not reproduced in this repo; any HCPCS, CLFS, or CMS coverage-policy material, which belongs to this domain's reimbursement section rather than care pathway and is already partially addressed there; fda.gov guidance documents, which gate automated requests intermittently.

Not searched vs. not found:

• Not searched: who physically draws the specimen (phlebotomist, nurse, medical assistant, or patient self-collection) in any of the settings described; what point-of-care testing equipment, if any, is already present in an outpatient cardiology or nephrology clinic; the turnaround time a titration decision requires outside the single STRONG-HF eligibility window; primary care vs. cardiology vs. nephrology vs. pharmacist-clinic site-of-service volumes for RAASi titration monitoring specifically.
• Not found: no source located in this pass reconciles the 2–4 week interval in [1] with the 2-week interval referenced in [6] into one guideline-sourced number; no US study located reports a site-of-service breakdown (primary care vs. specialty clinic) for where RAASi titration monitoring is actually ordered from.

[inference] Framing the venous-draw-plus-send-out-lab pathway as the common point of friction across both the guideline-adherence cohorts and the pharmacist-clinic studies is this writer's synthesis. No single source states that framing directly; it follows from every cited study describing a lab order and a subsequent, separately-timed result rather than an in-visit measurement.

6. Claim Candidates