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Original article
Reasons why osteoarthritis predicts mortality: path analysis within a Cox proportional hazards model
  1. Ross Wilkie1,
  2. Simran Singh Parmar2,
  3. Milica Blagojevic-Bucknall1,
  4. Diane Smith3,
  5. Martin J Thomas1,
  6. Bethany Jane Seale2,
  7. Gemma Mansell4 and
  8. George Peat1
  1. 1Primary Care Centre Versus Arthritis, School of Primary, Community and Social Care, Keele University, Keele, UK
  2. 2Keele Medical School, Keele University, Keele, UK
  3. 3Manchester Metropolitan University, Manchester, UK
  4. 4Department of Psychology, Aston University, Birmingham, UK
  1. Correspondence to Dr Ross Wilkie; r.wilkie{at}keele.ac.uk

Abstract

Objectives To identify potentially modifiable factors that mediate the association between symptomatic osteoarthritis (OA) and premature mortality.

Methods A population-based prospective cohort study; primary care medical record data were linked to self-report information collected by questionnaire in adults aged 50 years and over (n=10 415). OA was defined by primary care consultation and moderate-to-severe pain interference in daily life. A Cox proportional hazards analysis determined the total effect (TE) of OA on mortality after adjustment for potential confounders. Within the Cox model, path analysis was used to decompose the TE to assess the indirect and direct effects for selected potential mediators (anxiety, depression, unrefreshed sleep and walking frequency). Results are expressed as HRs with 95% CIs derived from bootstrap resampling.

Results OA was significantly associated with mortality (TE-adjusted HR 1.14; 95% CI 1.00 to 1.29). The indirect effects for walking frequency were 1.05 (95% CI 1.04 to 1.06), depression 1.02 (95% CI 1.02 to 1.03), anxiety 1.01 (95% CI 1.00 to 1.02) and unrefreshed sleep 1.01 (95% CI 1.00 to 1.01).

Conclusions The analysis indicates that encouraging people to walk and ‘get out and about’ in addition to targeting OA could be protective against excessive mortality. The findings also suggest that depression, anxiety and unrefreshed sleep have a role in premature mortality for people with OA; however, this has low clinical significance.

  • osteoarthritis
  • outcomes research
  • health services research
  • epidemiology

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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Footnotes

  • Contributors All the authors contributed substantially to (i) the conception and design of the study, acquisition of data, and analysis and interpretation of data, (ii) drafting of this manuscript and have given final approval of this version for publication.

  • Funding This study is supported financially by a programme grant awarded by the Medical Research Council, UK (grant code: G9900220), and by funding secured from the North Staffordshire Primary Care R&D Consortium for NHS service support costs. MJT is supported by an Integrated Clinical Academic Programme Clinical Lectureship from the National Institute for Health Research (NIHR) and the Health Education England (HEE) (ICA-CL-2016-02-014).

  • Disclaimer The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR, the HEE or the Department of Health and Social Care.

  • Competing interests None declared.

  • Patient and public involvement statement Keele’s experienced primary care Research User Group has 75 members in 67 projects in all the stages of research. For this proposed body of research, we have actively listened to users’ experiences of the impact of osteoarthritis and the reasons for this. The need for dynamic approaches to care and for treatments that reduce symptoms and low priority given to musculoskeletal problems were recurrent findings.

  • Patient consent for publication Not required.

  • Ethics approval The North Staffordshire Local Research Ethics Committee approved this study (REC reference numbers: 1351, 1430 and 05/Q2604/20).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request.

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