title: The Use of Functional Data Analysis to Evaluate Activity in a Spontaneous Model of Degenerative Joint Disease Associated Pain in Cats.
abstract: OBJECTIVE
  Accelerometry is used as an objective measure of physical activity in humans and veterinary species. In cats, one important use of accelerometry is in the study of therapeutics designed to treat degenerative joint disease (DJD) associated pain, where it serves as the most widely applied objective outcome measure. These analyses have commonly used summary measures, calculating the mean activity per-minute over days and comparing between treatment periods. While this technique has been effective, information about the pattern of activity in cats is lost. In this study, functional data analysis was applied to activity data from client-owned cats with (n = 83) and without (n = 15) DJD. Functional data analysis retains information about the pattern of activity over the 24-hour day, providing insight into activity over time. We hypothesized that 1) cats without DJD would have higher activity counts and intensity of activity than cats with DJD; 2) that activity counts and intensity of activity in cats with DJD would be inversely correlated with total radiographic DJD burden and total orthopedic pain score; and 3) that activity counts and intensity would have a different pattern on weekends versus weekdays.
  
  
  CONCLUSIONS
  Results showed marked inter-cat variability in activity. Cats exhibited a bimodal pattern of activity with a sharp peak in the morning and broader peak in the evening. Results further showed that this pattern was different on weekends than weekdays, with the morning peak being shifted to the right (later). Cats with DJD showed different patterns of activity from cats without DJD, though activity and intensity were not always lower; instead both the peaks and troughs of activity were less extreme than those of the cats without DJD. Functional data analysis provides insight into the pattern of activity in cats, and an alternative method for analyzing accelerometry data that incorporates fluctuations in activity across the day.
authors.affiliation: Comparative Pain Research Program, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America.|Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Gruen
authors.affiliation: Department of Statistics, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Marcela
authors.initials: M
authors.lastname: Alfaro-Córdoba
authors.affiliation: Comparative Pain Research Program, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Thomson
authors.affiliation: Comparative Pain Research Program, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Alicia C
authors.initials: AC
authors.lastname: Worth
authors.affiliation: Department of Statistics, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Staicu
authors.affiliation: Comparative Pain Research Program, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America.|Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina, United States of America.|Center for Pain Research and Innovation, University of North Carolina School of Dentistry, Chapel Hill, North Carolina, United States of America.
authors.forename: B Duncan X
authors.initials: BD
authors.lastname: Lascelles
mesh_terms: D061725:Accelerometry; D000818:Animals; D002371:Cat Diseases / Q000503:physiopathology*; D002415:Cats; D005260:Female; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010003:Osteoarthritis / Q000503:physiopathology / Q000662:veterinary*