title: Correlates of Agreement between Accelerometry and Self-reported Physical Activity.
abstract: Understanding factors that influence accurate assessment of physical activity (PA) and sedentary behavior (SB) is important to measurement development, epidemiologic studies, and interventions. This study examined agreement between self-reported (International Physical Activity Questionnaire-Long Form [IPAQ-LF]) and accelerometry-based estimates of PA and SB across six countries and identified correlates of between-method agreement.
  
  
  
  Self-report and objective (accelerometry-based) PA and SB data were collected in 2002-2011 from 3865 adult participants in eight cities from six countries (Belgium, Czech Republic, Denmark, Spain, United Kingdom, and United States). Between-method relative agreement (correlation) and absolute disagreement (mean difference between conceptually and intensity-matched IPAQ-LF and accelerometry-based PA and SB variables) were estimated. Also, sociodemographic characteristics and PA patterns were examined as correlates of between-method agreement.
  
  
  
  Observed relative agreement (relationships of IPAQ-LF with accelerometry-based PA and SB variables) was small to moderate (r = 0.05-0.37) and was moderated by sociodemographic (age, sex, weight status, and education) and behavioral (PA-type) factors. The absolute disagreement was large, with participants self-reporting higher PA intensity and total time in moderate-to-vigorous-intensity PA than accelerometry. Also, self-reported sitting time was lower than accelerometry-based sedentary behavior. After adjusting for sociodemographic and behavioral factors, the absolute disagreement between pairs of IPAQ-LF and accelerometry-based PA variables remained significantly different across cities/countries.
  
  
  
  Present findings suggest systematic cultural and/or linguistic and sociodemographic differences in absolute agreement between the IPAQ-LF and the accelerometry-based PA and SB variables. These results have implications for the interpretation of international PA and SB data and correlate/determinant studies. They call for further efforts to improve such measures.
authors.affiliation: 1Institute for Health and Ageing, Australian Catholic University, Melbourne, AUSTRALIA; 2School of Public Health, The University of Hong Kong, Hong Kong, CHINA; 3Department of Family Medicine and Public Health, University of California, San Diego, CA; 4Department of Physiotherapy, College of Medical Sciences, University of Maiduguri, Maiduguri, NIGERIA; 5Physical Activity, Sport and Recreation Research Focus Area, Faculty of Health Sciences, North-West University, Potchefstroom, SOUTH AFRICA; 6Baker IDI Heart and Diabetes Institute, Melbourne, AUSTRALIA; 7Centre for Research and Action in Public Health, University of Canberra, Canberra, AUSTRALIA; 8Department of Movement and Sport Sciences, Ghent University, Ghent, BELGIUM; 9Research Unit for Active Living, Department of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, DENMARK; 10Faculty of Physical Culture, Institute of Active Lifestyle, Palacký University, Olomouc, CZECH REPUBLIC; 11National Institute of Public Health, University of Southern Denmark, Copenhagen, DENMARK; and 12Department of Health Sciences, Public University of Navarra, Pamplona, SPAIN.
authors.forename: Ester
authors.initials: E
authors.lastname: Cerin
authors.forename: Kelli L
authors.initials: KL
authors.lastname: Cain
authors.forename: Adewale L
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authors.lastname: Oyeyemi
authors.forename: Neville
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authors.lastname: Owen
authors.forename: Terry L
authors.initials: TL
authors.lastname: Conway
authors.forename: Tom
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authors.lastname: Cochrane
authors.forename: Delfien
authors.initials: D
authors.lastname: VAN Dyck
authors.forename: Jasper
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authors.lastname: Schipperijn
authors.forename: Josef
authors.initials: J
authors.lastname: Mitáš
authors.forename: Mette
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authors.lastname: Toftager
authors.forename: Ines
authors.initials: I
authors.lastname: Aguinaga-Ontoso
authors.forename: James F
authors.initials: JF
authors.lastname: Sallis
mesh_terms: D061725:Accelerometry; D000367:Age Factors; D001835:Body Weight; D004522:Educational Status; D015444:Exercise; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D057185:Sedentary Behavior; D057566:Self Report; D012737:Sex Factors