P127 Factors associated with self-reported fatigue in hip and/or knee osteoarthritis: a systematic review

Background
Fatigue is an important, under-researched and poorly understood symptom among hip and/or knee osteoarthritis (OA) populations. To devise the best fatigue management strategy in these populations, it is necessary to evaluate the evidence on risk factors for fatigue. This study aimed to give an overview and evaluate the evidence on the factors associated with fatigue in hip and/or knee OA populations.

Methods
We conducted a systematic review using MEDLINE, AMED, CINAHL, ProQuest, and Web of Science Core Collections databases from inception to June 2019. Inclusion criteria comprised cross-sectional and longitudinal studies on patients with a diagnosis of hip and/or knee OA, included a measure of self-reported fatigue and studies that performed a subgroup analysis of hip/knee OA from other included populations. Two reviewers simultaneously screened articles for eligibility and extracted the following data: study design, fatigue outcome tool, follow-up time and association between factors and fatigue. The methodological quality of the included studies was assessed using the National Heart, Lung and Blood Institute quality appraisal tool. Study quality and study designs were combined to determine the level of evidence using best-evidence synthesis, which comprised six levels of evidence (Table 1).

Table 1
Best evidence synthesis levels
Strong evidence Generally consistent findings in multiple high-quality cohort studies.
Moderate evidence When one high quality cohort study and two or more high quality case-control studies or at least three high-quality case-control studies generally show consistent findings.
Limited evidence Generally consistent findings in a single cohort study, or in maximum two case-control studies, or in multiple cross-sectional studies.
Conflicting evidence Less than 75% of the studies reported consistent findings.
Insufficient evidence Less than two low quality studies available.
No evidence When no study could be found.

Results
Eighteen studies (10 cross-sectional designs, 8 longitudinal designs) were included. A majority of the studies included were of good quality, whilst two had fair quality and one poor quality. Lower physical function, more pain, higher depressive symptoms, lower physical activity, older age, increased anxiety, greater pain catastrophizing, worse radiographic evidence, higher body mass index, greater comorbidity/illness burden, lower six minutes walk and increased joint stiffness were included in the best evidence synthesis. From the best evidence grading, most of these factors had limited or conflicting evidence on its association with fatigue within the hip/knee OA populations. However, lower physical function and higher depressive symptoms were graded as having strong evidence on their associations with fatigue while higher pain levels had moderate evidence.

Conclusion
Lower physical function levels, higher depressive symptoms and higher pain are related to fatigue in the hip/knee OA population. More longitudinal studies are warranted to investigate the potential association of other identified factors and fatigue.