An observational study investigating the use of patient-owned technology to quantify physical activity in survivors of critical illness

Samuel Gluck, Matthew James Summers, Mark Edward Finnis, Alice Andrawos, Thomas Paul Goddard, Carol Lynette Hodgson, Theodore John Iwashyna, Adam Michael Deane

Research output: Contribution to journalArticleResearchpeer-review


Background: Physical activity after intensive care unit (ICU) discharge is challenging to measure but could inform research and practice. A patient's smartphone may provide a novel method to quantify physical activity. Objectives: We aimed to evaluate the feasibility and accuracy of using smartphone step counts among survivors of critical illness. Methods: We performed a prospective observational cohort study in 50 patients who had an ICU length of stay>48 h, owned a smartphone, were ambulatory before admission, and were likely to attend follow-up at 3 and 6 months after discharge. At follow-up, daily step counts were extracted from participants’ smartphones and two FitBit pedometers, and exercise capacity (6-min walk test) and quality of life (European Quality of Life-5 Dimensions) were measured. Results: Thirty-nine (78%) patients returned at 3 months and 33 (66%) at 6 months, the median [interquartile range] smartphone step counts being 3372 [1688–5899] and 2716 [1717–5994], respectively. There was a strong linear relationship, with smartphone approximating 0.71 (0.58, 0.84) of FitBit step counts, P < 0.0001, R-squared = 0.87. There were weak relationships between step counts and the 6-min walk test distance. Conclusion: Although smartphone ownership and data acquisition limit the viability of using extracted smartphone steps at this time, mean daily step counts recorded using a smartphone may act as a surrogate for a dedicated pedometer; however, the relationship between step counts and other measures of physical recovery remains unclear.

Original languageEnglish
Pages (from-to)137-143
Number of pages7
JournalAustralian Critical Care
Issue number2
Publication statusPublished - Mar 2020


  • Accelerometer
  • Patient outcome assessment
  • Pedometer
  • Smartphone
  • Step count

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