Patient Self-Testing of Kidney Function at Home, a Prospective Clinical Feasibility Study in Kidney Transplant Recipients

Jonathan S Murray; Cameron J Williams; Clare Lendrem; Joanne Smithson; Clare Allinson; Jennifer Robinson; Alycon Walker; Amanda Winter; A John Simpson; Julia Newton; Caroline Wroe; William S Jones

doi:10.1016/j.ekir.2023.03.003

Patient Self-Testing of Kidney Function at Home, a Prospective Clinical Feasibility Study in Kidney Transplant Recipients

Kidney Int Rep. 2023 Mar 28;8(6):1170-1182. doi: 10.1016/j.ekir.2023.03.003. eCollection 2023 Jun.

Authors

Affiliations

¹ Renal Unit, South Tees Hospitals NHS Foundation Trust, Middlesbrough, UK.
² NIHR Newcastle In Vitro Diagnostic Cooperative, Newcastle University, Newcastle upon Tyne, UK.
³ Academic Health Science Network North East and North Cumbria, Newcastle-Upon-Tyne, UK.
⁴ The What Works Center for Wellbeing, London, UK.
⁵ North East Innovation Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
⁶ Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
⁷ NIHR Newcastle In Vitro Diagnostic Cooperative, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
⁸ Faculty of Science and Engineering, Center of Excellence for Data Science, Artificial Intelligence and Modeling, The University of Hull, Hull, UK.

Abstract

Introduction: People with long-term health conditions often attend clinics for kidney function tests. The Self-Testing Own Kidneys (STOK) study assessed feasibility of kidney transplant recipients using hand-held devices to self-test kidney function at home and investigated agreement between home self-test and standard clinic test results.

Methods: A prospective, observational, single-center, clinical feasibility study (TRN: ISRCTN68116915), with N = 15 stable kidney transplant recipients, investigated blood potassium and creatinine results agreement between index self-tests at home (patient self-testing of capillary blood, using Abbott i-STAT Alinity analyzers [i-STAT]) and reference tests in clinic (staff sampled venous blood, analyzed with laboratory Siemens Advia Chemistry XPT analyzer) using Bland-Altman and error grid analysis.

Results: The mean within-patient difference between index and reference test in creatinine was 2.25 μmol/l (95% confidence interval [CI]: -12.13, 16.81 μmol/l) and in potassium was 0.66 mmol/l (95% CI: -1.47, 2.79 mmol/l). All creatinine pairs and 27 of 40 (67.5%) potassium pairs were judged clinically equivalent. Planned follow-up analysis suggests that biochemical variables associated with potassium measurement in capillary blood were predominant sources of paired test result differences. Paired patient and nurse i-STAT capillary blood test potassium results were not statistically significantly different.

Conclusions: This small feasibility study observed that training selected patients to competently use hand-held devices to self-test kidney function at home is possible. Self-test creatinine results showed good analytical and clinical agreement with standard clinic test results. Self-test potassium results showed poorer agreement with standard clinic test results; however, patient self-use of i-STATs at home was not a statistically significant source of difference between paired potassium test results.

Keywords: creatinine; home; kidney; point-of-care test; potassium; self-test.