The Foot 17 (2007) 15–20 An evaluation of the reliability and validity of capillary refill time test Nerida L. Klupp a,∗ , Anne-Maree Keenan b a School of Biomedical and Health Sciences, B24 Campbelltown Campus, University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 1797, Australia b Academic Unit of Musculoskeletal Disease, University of Leeds, Chapel Allerton Hospital, Chapeltown Rd, Leeds LS7 4SA, United Kingdom Abstract Background: While capillary refill time test (CRTT) has been commonly used as a quick and convenient clinical vascular assessment of the lower limb, the validity of this test has not been established. Objectives: There were three aims to this study: the first was to evaluate the reliability of CRTT, the second to investigate the premise that CRTT represents skin perfusion, and thirdly to determine whether CRTT can detect lower limb vascular disease. Method: Intra- and inter-tester reliability was evaluated for five experienced physicians who used CRTT on 10 participants. Criterion validity for measurement of skin perfusion was investigated by comparison with laser Doppler flowmetry on 49 participants, and for this same group the usefulness of detecting those persons with peripheral arterial disease and a state of impaired healing was evaluated. Results: CRTT had reasonable intra-tester reliability (ICC = 0.72) but poorer inter-tester reliability (ICC range = 0.12–0.81). For measurement of skin perfusion, CRTT was predictive of only 38% of the variance in laser Doppler flowmetry measures (r 2 = 0.38, P < 0.001). Finally, CRTT was not able to discriminate between patients with and without peripheral arterial disease (z = -1.86, P = 0.062), nor could it discern between patients with and without impaired lower extremity healing (z = -0.21, P = 0.830). Laser Doppler flowmetry was also unable to predict the presence of peripheral arterial disease (t 96 = 0.27, P = 0.787) and impaired healing (t 96 = 1.95, P = 0.054). Conclusion: These results question the usefulness of capillary refill time test for assessment of vascular status in the lower limb. © 2006 Elsevier Ltd. All rights reserved. Keywords: Capillary refill time test; Validity; Reliability; Laser Doppler flowmetry; Peripheral arterial disease 1. Introduction Capillary refill time test (CRTT), also known as subcuta- neous venous plexus filling time, subpapillary plexus filling time, capillary fill time and capillary return test, is one of the most commonly used vascular assessments of the lower limb. As a measure of cutaneous perfusion, the importance of CRTT is based on the premise that skin vascularity is a valid indicator of peripheral vascular status. Buerger first described assessment of vascular disease by blanching the skin and observing delayed skin colour return in 1924 [1], and since that time CRTT has become widely used and accepted by health professionals. It has been suggested that clinical ∗ Corresponding author. Tel.: +61 2 4620 3759; fax: +61 2 4620 3792. E-mail address: n.klupp@uws.edu.au (N.L. Klupp). assessment of peripheral macrovascular disease and cuta- neous microvascular disease should include the use of CRTT [2–8]. The widespread popularity of CRTT may be because it is accessible, easy to perform and requires no expense. The acceptance of CRTT has occurred despite a notable deficiency of research to determine its usefulness and application in a clinical setting. To date, there is only one study that has inves- tigated the validity of toe CRTT. Boyko et al. [9] investigated the ability of CRTT to determine macrovascular pathology in persons with diabetes mellitus with an ankle-brachial pres- sure index (ABPI) of less than 0.5. They found CRTT, using a 5s cut-off score, was sensitive to identifying large vessel pathology in only 28.3% of participants, although the speci- ficity of the test was higher (85.3%). As these results are not generalisable beyond this specific population and ABPIs 0958-2592/$ – see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.foot.2006.08.006