Chronic kidney disease patients are characterized by impaired physical function. The goal of exercise-based interventions is an improvement in functional performance. However, improvements are often determined by “statistically significant” changes. We investigated the “minimum clinically important difference,” “the smallest change that is important to the patient,” for commonly reported physical function tests.
Nondialysis chronic kidney disease patients completed 12-wks of a combined aerobic (plus resistance training). The incremental shuttle walking test, sit-to-stand 5 and 60, estimated 1-repetition maximum for the knee extensors, and VO2peak were assessed. After the intervention, patients rated their perceived change in health. Both anchor- and distribution-based minimum clinically important difference approaches were calculated.
The minimum clinically important difference was calculated as follows: incremental shuttle walking test, +45 m; sit-to-stand 5, −4.2 secs; VO2peak, +1.5 ml/kg per min. Because of comparable increases in “anchor” groups, no minimum clinically important difference was estimated for the sit-to-stand 60 or estimated 1-repetition maximum.
We have established the minimum clinically important difference in chronic kidney disease for common tests of physical function. These values represent the minimum change required for patients to perceive noticeable and beneficial change to their health. These scores will help interpret changes after exercise interventions where these tests are used. These minimum clinically important differences can be used to power future studies to detect clinically important changes.
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From the Leicester Kidney Lifestyle Team, Department of Health Sciences, University of Leicester, United Kingdom (TJW, ELW, SX, DWG, ACS); Intensive Care National Audit & Research Centre (ICNARC), London, United Kingdom (DWG); and John Walls Renal Unit, Leicester General Hospital, University Hospitals of Leicester Trust, United Kingdom (ACS).
All correspondence should be addressed to: Thomas J. Wilkinson, PhD, Leicester Kidney Lifestyle Team, Department of Health Sciences, University of Leicester, United Kingdom, LE5 4PW.
Preliminary results from this analysis have been presented at the American Society of Nephrology Kidney Week 2016 at Chicago, IL on November 18, 2016.
This work was gratefully part-funded by the Stoneygate Trust. The research was supported by the National Institute for Health Research Leicester Biomedical Research Centre.
Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.