Elsevier

Joint Bone Spine

Volume 79, Issue 3, May 2012, Pages 291-297
Joint Bone Spine

Original article
Body mass index and susceptibility to knee osteoarthritis: A systematic review and meta-analysis

https://doi.org/10.1016/j.jbspin.2011.05.015Get rights and content

Abstract

Objective

Excess bodyweight, expressed as increased body mass index, is associated with osteoarthritis risk, especially in weight bearing joints. However, the strength of the association was inconsistent. The study was conducted to quantitatively assess the association between body mass index and the risk of knee osteoarthritis and investigate the difference of the strength stratified by sex, study type and osteoarthritis definition.

Methods

We used published guidelines of the Meta-analysis of Observational Studies in Epidemiology Group (MOOSE) to perform the meta-analysis. The search strategy employed included computerized bibliographic searches of MEDLINE, PubMed, EMBASE, The Cochran Library and references of published manuscripts. Study-specific incremental estimates were standardized to determine the risk of knee osteoarthritis associated with a 5 kg/m2 increase in BMI.

Results

Twenty-one studies were included in the study. The results showed that body mass index was significantly positive associated with osteoarthritis risk in knee site. A 5-unit increase in body mass index was associated with an 35% increased risk of knee osteoarthritis (RR: 1.35; 95%CI: 1.21, 1.51). Magnitude of the association was significantly stronger in women than that in men with significant difference (men, RR: 1.22; 95%CI: 1.19, 1.25; women, RR: 1.38; 95%CI: 1.23, 1.54; p = 0.04). The summary effect size was 1.25(95%CI: 1.18, 1.32) in case-control studies and 1.37 (95%CI: 1.19, 1.56) in cohort studies (p = 0.28). Body mass index was positively associated with knee osteoarthritis defined by radiography and/or clinical symptom (RR: 1.25, 95%CI: 1.17, 1.35) and clinical surgery (RR: 1.54, 95%CI: 1.29, 1.83). The latter tended to be stronger than the former (p < 0.01).

Conclusion

Increased body mass index contribute to a substantially increased risk of knee OA. The magnitude of the association varies by sex and OA definition.

Introduction

Osteoarthritis (OA) is the most common joint disease and is one of the most prevalent symptomatic health problems for older individuals. The etiology of OA is multifactorial, including inflammatory factors, metabolic factors, and mechanical factors [1]. OA have incurred substantial disease burden and influenced the quality of daily life for the elderly. Knee joint is the most clinically affected site, and knee OA is the main indication for a large number of knee replacement surgeries performed annually [2].

Obesity has become a global problem leading to excess morbidity and mortality. According to the latest World Health Organization (WHO) report, more than 1.6 billion adults (aged 15 years old) are overweight [3]. Obesity has drawn interest in recent studies because of its modifiable status and its association with OA. There is considerable evidence indicating that obesity plausibly represents one of the most important risk factors for particular peripheral joint sites, predominantly the knee site and the hip site [4], [5], [6], [7], [8], [9], [10], [11].

Standard therapeutic modalities can alleviate symptoms and improve function but cannot alter the disease process [10]. Therefore, much attention has been invested in improving the recognition of epidemiology and in elucidating possible factors predisposing to OA development. Mechanical stress resulting from a high body mass index (BMI) is known to be a risk factor for the development of knee OA, and better understanding of the positive effect of obesity on OA development is likely to be valuable in the campaign against osteoarthritis. To our knowledge, many epidemiologic studies have been performed to investigate the association between obesity with knee OA, and obesity is an unequivocal risk factor for the onset and progression of knee OA [9], [12], [13]. However, the link between obesity and the risk of knee OA lack quantitatively assessment.

It is probable that once sufficient information is provided through systematic studies, we will be able to obtain a better understanding of the cause of OA as a whole and perhaps develop new interventions to lower the prevalence of obesity and knee OA in the future. Therefore, we conducted a meta-analysis and meta-regression to quantitatively clarify the association between BMI, as a measure of overall obesity, and the risk of developing knee OA based on available studies to date.

Section snippets

Search strategy and inclusion criteria

The search strategy included computerized bibliographic searches of PubMed (1966–2010), EMBASE (1974–2010) and references of published manuscripts. The Cochrane Library of Systematic Reviews also was queried. Other websites searched included National Institute for Clinical Excellence, National Electronic Library for Health- musculoskeletal specialist library, Arthritis Research Campaign, Arthritis Care, Arthritis and Musculoskeletal Alliance, and Arthritis Foundation National Office. The search

Studies included in the meta-analysis

The primary literature search had identified 414 potentially relevant studies. After review of these titles and abstracts, we retrieved full articles for further assessment. A total of 44 studies have been identified. Twenty-three studies were excluded for unavailable or incomplete data [7], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42]. Finally, 21 unique studies were available for this meta-analysis,

Discussion

The meta-analysis shows that the risk of knee OA increase with BMI and a dose-response relationship exist. A 5-unit increase in BMI is significantly associated with an increased risk of developing knee OA (RR: 1.35; 95%CI: 1.21, 1.51). That is, every 5-unit increase in BMI is associated with a 35% increased risk of knee OA. Our findings support the notion that there is a positive association between increased BMI and the risk of knee OA. Meanwhile, our results provide a quantitative risk

Disclosure of interests

The authors declare that they have no conflicts of interest concerning this article.

Acknowledgements

The study was supported by Heilongjiang Province office of education foundation (No. 11531166). The study received generous assistance from Yan Liu in Public Health College in Harbin Medical University.

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