To the best of our knowledge, this is the first study to examine the relationship of rest-activity rhythm with survival in older adults with lung cancer and to consider variations in rest-activity rhythm over time.
The aim of this study was to explore the relationship between rest-activity rhythm variations and survival in 33 older adults with lung cancer by considering rest-activity rhythm as a time-dependent covariate over time.
In this prospective study with 5 repeated measurements, patients' rest-activity rhythm over 3 days was measured using actigraphy. The rest-activity rhythm was represented using the dichotomy index I (in-bed activity) < O (out-of-bed activity). The median I < O was used as the cutoff point, with an I < O of greater than or equal to 85.59% and less than 85.59% indicating robust and disrupted rest-activity rhythms, respectively. Data were analyzed using the Cox regression model with time-dependent repeated measurements of a covariate.
In the time-dependent multivariate Cox model, a disrupted rest-activity rhythm was independently associated with a higher risk of death than was a robust rest-activity rhythm (hazard ratio, 16.05; P=.009).
A time-varying rest-activity rhythm is incrementally associated with mortality in older adults with lung cancer and represents a rigorous and independent prognostic factor for their survival.
Clinicians may need to pay more attention to the rest-activity rhythms of older adults with lung cancer during disease progression. Future studies should account for the variation in rest-activity rhythm over time.
Author Affiliations: School of Nursing, College of Nursing, Taipei Medical University, Taiwan (Ms Kuo and Drs Chang, Huang, and Lin); Taipei Medical University-Shuang Ho Hospital, Ministry of Health and Welfare, New Taipei City, Taiwan (Dr Chang); Li Ka Shing Faculty of Medicine, School of Nursing, The University of Hong Kong, Pokfulam (Dr Lin); and Alice Ho Miu Ling Nethersole Charity Foundation Professor in Nursing (Dr Lin), Tai Po, Hong Kong.
The authors have no funding or conflicts of interest to disclose.
Correspondence: Chia-Chin Lin, PhD, RN, FAAN, Li Ka Shing Faculty of Medicine, School of Nursing, The University of Hong Kong, 4/F William MW Mong Block Bldg, 21 Sassoon Rd, Pokfulam, Hong Kong (email@example.com).
Accepted for publication July 2, 2018.