View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NORA - Norwegian Open Research Archives Effects of psychological and social work factors on musculoskeletal pain complaints and headache Jan Olav Christensen Department of Work Psychology and -Physiology National Institute of Occupational Health, Norway Dissertation for the degree of philosophiae doctor (ph.d.) Institute of Psychology, Faculty of Social Sciences, University of Oslo February 2014 © Jan Olav Christensen, 2014 Series of dissertations submitted to the Faculty of Social Sciences, University of Oslo No. 450 ISSN 1504-3991 All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, without permission. Cover: Inger Sandved Anfinsen. Printed in Norway: AIT Oslo AS. Produced in co-operation with Akademika publishing, Oslo. The thesis is produced by Akademika publishing merely in connection with the thesis defence. Kindly direct all inquiries regarding the thesis to the copyright holder or the unit which grants the doctorate. CONTENTS ACKNOWLEDGEMENTS ....................................................................................................................................... - 7 - SUMMARY OF THE THESIS .................................................................................................................................. - 9 - LIST OF PAPERS ................................................................................................................................................. - 13 - 1. BACKGROUND ............................................................................................................................................... - 15 - 1.1. SCOPE OF THE PROBLEM ...................................................................................................................................... - 15 - 1.2. PAIN................................................................................................................................................................ - 18 - 1.2.1. The current definition of pain ............................................................................................................... - 18 - 1.2.2. Classifications of pain........................................................................................................................... - 19 - 1.2.3. A brief history of pain ........................................................................................................................... - 21 - 1.2.4. Biopsychosocial perspectives ............................................................................................................... - 24 - 1.3. “STRESS” ......................................................................................................................................................... - 25 - 1.4. PSYCHOLOGICAL AND SOCIAL WORK FACTORS .......................................................................................................... - 30 - 1.4.1. “Psychosocial work factors” ................................................................................................................. - 30 - 1.4.2. Job strain .............................................................................................................................................. - 31 - 1.4.3. Psychological and social work factors as antecedents of somatic pain complaints ............................ - 32 - 1.4.3.1. Neck- and back pain ........................................................................................................................................ - 32 - 1.4.3.2. Headache......................................................................................................................................................... - 35 - 1.4.4. Some limitations of previous research ................................................................................................. - 37 - 1.4.4.1. Few factors have been studied........................................................................................................................ - 37 - 1.4.4.2. Classification of exposure ................................................................................................................................ - 40 - 1.4.4.3. The modeling of exposure over time .............................................................................................................. - 41 - 1.4.4.4. Non-validated self-report instruments ............................................................................................................ - 42 - 1.4.4.5. Predicting the “incidence” of pain ................................................................................................................... - 46 - 1.4.5. Pathways: How can psychological and social working conditions influence pain? .............................. - 47 - 1.4.5.1. Neuroendocrine factors .................................................................................................................................. - 48 - 1.4.5.2. Muscle activity and mechanical load ............................................................................................................... - 50 - 1.4.5.3. Vulnerability to other exposures ..................................................................................................................... - 52 - 1.4.5.4. Cognition and emotion .................................................................................................................................... - 53 - 1.5. WORK EXPOSURES STUDIED FOR THE CURRENT THESIS ............................................................................................... - 54 - 1.5.1. Job demands ........................................................................................................................................ - 56 - 1.5.2. Job control ............................................................................................................................................ - 58 - 1.5.3. Support ................................................................................................................................................. - 59 - - 3 - 1.5.4. Role expectations ................................................................................................................................. - 60 - 1.5.5. Leadership ............................................................................................................................................ - 62 - 1.5.6. Predictability ........................................................................................................................................ - 63 - 1.5.7. Commitment ........................................................................................................................................ - 63 - 1.5.8. Social climate ....................................................................................................................................... - 65 - 1.5.9. Job satisfaction .................................................................................................................................... - 65 - 1.5.10. Mechanical factors ............................................................................................................................. - 66 - 2. STUDY OBJECTIVES ........................................................................................................................................ - 69 - 3. MATERIAL AND METHODS ............................................................................................................................ - 71 - 3.1. RECRUITMENT PROCEDURE .................................................................................................................................. - 71 - 3.2. SUBJECTS ......................................................................................................................................................... - 71 - 3.3. DESIGN ............................................................................................................................................................ - 73 - 3.4. MEASUREMENT OF PAIN...................................................................................................................................... - 74 - 3.5. MEASUREMENT OF EXPOSURE .............................................................................................................................. - 75 - 3.5.1. Scale construction ................................................................................................................................ - 75 - 3.5.2. Classification of exposure ..................................................................................................................... - 76 - 3.5.3. Longitudinal exposure modeling .......................................................................................................... - 76 - 3.5.3.1. Baseline exposure ........................................................................................................................................... - 77 - 3.5.3.2. Averaged exposure .......................................................................................................................................... - 77 - 3.5.3.3. Change variables ............................................................................................................................................. - 78 - 3.5.3.4.