Up to 20% of hospitalized patients experience AKI, a condition associated with adverse kidney and cardiovascular outcomes (1). Surprisingly, only approximately 10% of AKI survivors receive outpatient care within the first 90 days following hospital discharge, despite observational data suggesting that nephrologist-guided postdischarge care can reduce mortality and hospitalizations compared with matched controls (2–4). Importantly, there are few specialized clinics dedicated to following AKI survivors, and evidence to support best practices is scarce.
We established a network to share best practices and capture data that could inform future study design. These institutions with specialized AKI clinics include the University of Kentucky Medical Center (United States), St. Michael’s Hospital (Canada), Kingston Health Sciences Centre l (Canada), and Geisinger Medical Center (United States). Details of these clinics have been published previously (3–5). Briefly, survivors of AKI stage ≥2 and, occasionally, AKI stage 1 were eligible for follow-up in these clinics. One objective of this research network was to evaluate predefined processes of care across all clinics to help promote AKI recovery and mitigate its complications. In this report, we included adult patients without kidney transplants who were not dialysis dependent at hospital discharge and had at least one visit in the clinic. Postdischarge care in these clinics included patient/care partner education, evaluation of kidney recovery and proteinuria, medication reconciliation, nephrotoxin avoidance, and management of cardioprotective drugs with a focus on the optimized use of renin-angiotensin-aldosterone system inhibitors (RAASis) and diuretics. However, these processes were not protocolized and were subject to variations as per the discretion of the care team.
Baseline kidney function was determined using outpatient serum creatinine data between 7 and 365 days before admission or was adjudicated by the providers at the first clinic visit if unknown. AKI severity was defined according to Kidney Disease Improving Global Outcomes criteria. Prevalent hypertension was defined as systolic BP >140 mm Hg or diastolic BP >90 mm Hg on the basis of the average of three BP measurements or if the patient was taking antihypertensive drugs. Prevalent CKD was defined as baseline eGFR <60 ml/min per 1.73 m2. We evaluated four a priori–defined processes of care: (1) antihypertensive management (excluding RAASi management and diuretic management, which were considered separately); (2) stopping nephrotoxic medications (classified in three categories as nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and others as per the discretion of the clinician; the latter included medications that are typically avoided in settings of low eGFR with the exception of RAASis and diuretics, which were evaluated separately); (3) RAASi management; and (4) diuretic management. We classified medication management as dose adjustments, discontinuation, or initiation/reinitiation. Processes of care were evaluated at the first clinic visit and in a cumulative fashion counting all clinic encounters within 6 months following hospital discharge. The no-show rate to the first clinic visit ranged from 20% to 30%. Each participating site had institutional review board approval.
A total of 623 patients accounting for 945 clinic visits (mean [SD] of 1.5 [0.6] in-person clinic visits per patient) were evaluated. The cohort age was 62 (14) years, 37% were women, 72% were White patients, and 17% were Black patients. About one third of patients had CKD prior to AKI. Diabetes and hypertension were present in 35% and 67% of patients, respectively. The median time from hospital discharge to first clinic visit was 35 days. Although serum creatinine was evaluated in all patients at or before the first clinic visit, 29% of patients did not have proteinuria evaluation at or before the same clinic visit. Details of patient characteristics are reported in Table 1.
Table 1.
Patient characteristics and processes of care stratified by AKI clinic site
| Variables | All Patients, n=623 | University of Kentucky from September 16 to October 20, n=202 | Saint Michael’s Hospital from September 13 to January 18, n=220 | Kingston Health Sciences Centre from October 17 to July 20, n=149 | Geisinger Health System from September 19 to February 20, n=52 |
|---|---|---|---|---|---|
| Patient characteristics | |||||
| Age, yr, mean ± SD | 63±14 | 55±14 | 66±14 | 67±13 | 63±14 |
| Men, n (%) | 391 (63) | 112 (56) | 154 (70) | 95 (64) | 30 (58) |
| Race, n (%) | |||||
| White patients | 450 (72) | 175 (87) | 115 (52) | 110 (74) | 50 (96) |
| Black patients | 104 (17) | 22 (11) | 46 (21) | 36 (24) | — |
| Other | 67 (11) | 5 (3) | 59 (27) | 3 (2) | 2 (4) |
| Baseline SCr, mg/dl | 1.0 [0.8–1.3] | 1.0 [0.8–1.3] | 1.0 [0.8–1.2] | 1.1 [1.0–1.4] | 1.1 [0.8–1.3] |
| Baseline eGFR,a ml/min per 1.73 m2 | 68 [49–91] | 73 [50–102] | 73 [54–92] | 60 [42–78] | 67 [52–94] |
| Charlson Index, score | 4 [2–6] | 3 [1–6] | 2 [1–4] | 5 [3–6] | 4 [3–7] |
| Diabetes, n (%) | 215 (35) | 80 (39.6) | 38 (17) | 71 (48) | 26 (50) |
| Hypertension, n (%) | 417 (67) | 124 (61.4) | 159 (72) | 97 (65) | 37 (71) |
| CKD prior to admission, n (%) | |||||
| Stage 3 | 201 (91) | 53 (80) | 67 (96) | 66 (94) | 15 (100) |
| Stage 4 | 20 (9) | 12 (19) | 3 (4) | 4 (6) | — |
| Stage 5 | — | 1 (1) | — | — | — |
| Hospital LOS, d | 11 [6–19] | 14 [8–23] | 12 [7–24] | 10 [5–19] | 7 [5–10] |
| ICU admission, n (%) | 268 (43) | 96 (48) | 97 (44) | 58 (39) | 17 (33) |
| Peak SCr, mg/dl | 4.7 [3.2–7.2] | 4.9 [3.1–7.1] | 3.1 [2.4–5.4] | 5.8 [3.9–9.0] | 4 [3–7] |
| Last SCr in the hospital, mg/dl | 2.0 [1.4–3.0] | 2.1 [1.5–3.1] | 1.4 [1.1–2.1] | 2.0 [1.4–3.1] | 2 [2–4] |
| AKI KDIGO severity, n (%) | |||||
| Stage 1 | 60 (10) | 25 (12) | 20 (9) | 15 (10) | — |
| Stage 2 | 136 (22) | 23 (11) | 80 (36) | 25 (17) | 8 (15) |
| Stage 3 | 427 (68) | 154 (76) | 120 (55) | 109 (73) | 44 (85) |
| AKI etiology, n (%) | |||||
| Prerenal | 180 (28) | 31 (16) | 99 (45) | 46 (31) | 4 (8) |
| Acute tubular necrosis | 384 (62) | 159 (79) | 104 (47) | 90 (60) | 31 (60) |
| Obstructive | 34 (6) | 5 (2) | 13 (6) | 10 (7) | 6 (12) |
| Other | 25 (4) | 7 (3) | 4 (2) | 3 (2) | 11 (21) |
| KRT recipient, n (%) | 215 (35) | 77 (38) | 40 (18) | 92 (62) | 6 (12) |
| Discharge to first visit, d | 35 [21–57] | 36 [18–54] | 36 [20–65] | 56 [35–90] | 13 [9–18] |
| Discharge to first SCr, d | 27 [13–45] | 32 [13–52] | 31 [16–53] | 42 [19–67] | 5 [3–8] |
| Discharge to first proteinuria,b d | 36 [18–64] | 37 [15–55] | 34 [19–58] | 45 [25–71] | 26 [14–73] |
| SCr at first clinic visit, mg/dl | 1.3 [1.0–1.9] | 1.3 [1.0–2.1] | 1.3 [1.0–1.7] | 1.4 [1.1–1.9] | 1.8 [1.2–2.6] |
| eGFRa at first clinic visit, ml/min per 1.73 m2 | 49 [31–74] | 50 [31–80] | 53 [37–74] | 47 [31–66] | 35 [19–59] |
| Visits per patient within 6 mo, mean (SD) | 1.5 (0.6) | 1.5 (0.6) | 1.7 (0.7) | 1.1 (0.5) | 1.9 (0.8) |
| Processes of care | |||||
| Patients with ≥1 process at first visit, n (%) | 267 (43) | 70 (35) | 89 (41) | 76 (51) | 32 (62) |
| At first clinic visit (patients), n (%) | (623) | (202) | (220) | (149) | (52) |
| BP management | 77 (12) | 13 (6) | 29 (13) | 22 (15) | 13 (25) |
| Stop nephrotoxic medications c | 68 (11) | 31 (15) | 10 (5) | 16 (11) | 11 (21) |
| Adjustment of RAASi | 92 (15) | 15 (7) | 35 (16) | 30 (20) | 12 (23) |
| Adjustment of diuretics | 97 (16) | 38 (19) | 23 (11) | 22 (15) | 14 (27) |
| At first clinic visit (patients) | (77) | (13) | (29) | (22) | (13) |
| BP management, n (%) | |||||
| Dose adjustment | 16 (21) | 1 (11) | 5 (17) | 5 (23) | 5 (39) |
| Stopping | 16 (21) | 4 (28) | 4 (14) | 5 (23) | 3 (22) |
| Starting/restarting | 45 (58) | 8 (61) | 20 (69) | 12 (54) | 5 (39) |
| Indications for stopping BP drugs, n=16 | |||||
| Hypotension | 9 | 2 | 3 | 3 | 1 |
| Switch to another drug | 4 | 2 | 1 | — | 1 |
| Side effect(s) | 3 | — | — | 2 | 1 |
| At first clinic visit (patients) | (92) | (15) | (35) | (30) | (12) |
| Adjustment of RAASi, n (%) | |||||
| Dose adjustment | 13 (14) | 2 (13) | 6 (17) | 4 (13) | 1 (8) |
| Stopping | 18 (20) | 4 (27) | 8 (23) | 5 (17) | 1 (8) |
| Starting | 15 (16) | 3 (20) | 5 (14) | 4 (13) | 3 (25) |
| Restarting | 46 (50) | 6 (40) | 16 (46) | 17 (57) | 7 (59) |
| Indications for starting RAASi,c n=15 | |||||
| BP management | 10 | 4 | 1 | 3 | 2 |
| Diabetes and/or proteinuria | 4 | 2 | — | 1 | 2 |
| Heart failure | 7 | 2 | 4 | — | 1 |
| Other | 1 | — | 1 | — | — |
| Indications for restarting RAASi,c n=46 | |||||
| BP management | 29 | 5 | 9 | 10 | 5 |
| Diabetes and/or proteinuria | 20 | 3 | 5 | 10 | 2 |
| Heart failure | 11 | 2 | 1 | 6 | 2 |
| Other | 7 | 1 | 2 | 4 | — |
| Indications for stopping RAASi, n=18 | |||||
| Recurrent AKI | 7 | 4 | — | 2 | 1 |
| Decline in eGFR | 8 | — | 5 | 3 | — |
| Hypotension | 2 | — | 2 | — | — |
| Side effect(s) | 1 | — | 1 | — | — |
| At first clinic visit (patients) | (97) | (38) | (23) | (22) | (14) |
| Adjustment of diuretic, n (%) | |||||
| Dose adjustment | 25 (26) | 8 (21) | 5 (22) | 5 (23) | 7 (50) |
| Stopping | 35 (36) | 7 (18) | 12 (52) | 13 (59) | 3 (21) |
| Starting/restating | 37 (38) | 23 (61) | 6 (26) | 4 (18) | 4 (29) |
| Indications for stopping diuretic, n=35 | |||||
| Hypovolemia | 15 | 3 | 6 | 4 | 2 |
| Hypotension | 11 | 2 | 3 | 5 | 1 |
| Hyperkalemia | 9 | 2 | 3 | 4 | — |
| Within 6 mo (visits), n (%) | (945) | (311) | (379) | (157) | (98) |
| BP management | 108 (11) | 22 (7) | 35 (9) | 30 (19) | 21 (21) |
| Stop nephrotoxic medications | 99 (11) | 33 (11) | 28 (7) | 25 (16) | 13 (13) |
| Adjustment of RAASi | 125 (13) | 26 (8) | 47 (12) | 35 (22) | 17 (17) |
| Adjustment of diuretics | 124 (13) | 47 (15) | 26 (7) | 32 (20) | 20 (20) |
Continuous data are reported as medians and 25th to 75th percentile except for age, which is reported as mean and SD. Categorical data are reported as frequencies and percentages. Processes of care percentages are calculated according to the total number of patients in the corresponding category unless specified as according to the total number of clinic visits. —, none; SCr, serum creatinine; LOS, length of stay; ICU, intensive care unit; KDIGO, Kidney Disease Improving Global Outcomes; RAASi, renin-angiotensin-aldosterone system inhibitor.
Calculated by the Chronic Kidney Disease Epidemiology Collaboration equation.
Included dipstick proteinuria and spot albumin/protein-creatine ratio (23% of patients had dipstick only, 38% had albumin/protein-creatinine ratio only, 10% had both, and 29% did not have proteinuria evaluation).
Patients could have more than one indication for starting or restarting RAASi.
At least one prespecified process of postdischarge AKI care occurred in 267 of 623 (43%) patients during the first clinic encounter, with individual processes executed on average in 14% of patients during this encounter. Overall, there was a slightly higher frequency of processes at the Geisinger site, which also had earlier clinic evaluations after discharge. Details of processes at the first clinic visit and the cumulative data over the first 6 months postdischarge are summarized in Table 1. In the antihypertensive and RAASi categories, starting/restarting these medications was the most frequent action during the first clinic visit across all sites. Specifically, adjustment of RAASis was done in 15% of patients at the first clinic visit, and this adjustment consisted of restarting these drugs in 50% of instances. The most common indications for restarting RAASis were BP management, diabetes, and/or proteinuria followed by heart failure. On the other hand, there was variability in the management of diuretics across sites at the first clinic visit. Common reasons for stopping diuretics were hypovolemia and hypotension. Nephrotoxic medications were stopped in 11% of patients at the first visit and in 11% of all visits over 6 months. The most commonly stopped nephrotoxic categories at the first visit were nonsteroidal anti-inflammatory drugs and proton pump inhibitors. When cumulative data within the first 6 months postdischarge were evaluated, individual processes were executed on average in 12% of all 945 clinic encounters.
This report highlights that prespecified postdischarge AKI care processes could be successfully implemented in AKI survivors. Examining these processes across four AKI clinics, we showed that at least one prespecified process was executed in almost half of the patients at the first clinic visit. Systematically measuring these and other processes may help in further developing clinical consensus about post-AKI care components. Moreover, one should note that there are salient questions to be addressed in relation to which processes to implement and when and how to implement them in the most efficient way to favorably affect clinical and patient-centered outcomes. Standardization of postdischarge AKI care processes may require specialized multidisciplinary care teams, including primary care providers, as well as utilization of digital and telehealth solutions. Further, interventional studies testing novel models of postdischarge AKI care are needed to support evidence-based practices. Our data will assist in the design of such studies.
Disclosures
A. Chang reports employment with Geisinger Health System; consultancy agreements with Amgen, Novartis, and Reata; research funding from a Novo Nordisk investigator-sponsored study; advisory or leadership roles for Reata and Relypsa; and other interests or relationships with the National Kidney Foundation (NKF: grant support from the NKF Patient Network). J.A. Neyra reports consultancy agreements with Baxter Healthcare Inc., Biomedical Insights, and Leadiant Biosciences; serves as a guest editor for critical care nephrology in Advances in Chronic Kidney Disease and a section editor for Clinical Nephrology; and serves on the editorial boards for Advances in Chronic Kidney Disease, American Journal of Kidney Diseases, and Kidney360. V. Ortiz-Soriano reports honoraria from the University of Kentucky. S.A. Silver reports honoraria from Baxter, Novo Nordisk, and Otsuka. G. Singh reports employment with Geisinger Health. R. Wald reports research funding from Baxter; serves on the editorial boards of CJASN, Kidney360, and Kidney Medicine; and is a contributor to UpToDate. The remaining author has nothing to disclose.
Funding
None.
Footnotes
Published online ahead of print. Publication date available at www.cjasn.org.
Author Contributions
All authors conceptualized the study and were responsible for data curation, methodology, and visualization; V. Ortiz-Soriano and J.A. Neyra were responsible for formal analysis; J.A. Neyra provided supervision; V. Ortiz-Soriano wrote the original draft; and all authors reviewed and edited the manuscript.
Data Sharing Statement
All data used in this study are available upon request.
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