The relationship between body mass index and hip osteoarthritis: A systematic review and meta-analysis

Abstract

Objective

Body mass index, a measure of relative weight, is increasingly recognized as an important risk factor for osteoarthritis, especially in weight bearing joints. The objective was to assess the association between body mass index and hip osteoarthritis susceptibility and investigate the difference between sex, study type and osteoarthritis definition.

Methods

We did electronic searches of Medline, Embase and Cochrane library from the commencement to December 2009. A meta-analysis and meta-regression was executed to quantitatively assess the strength of associations between body mass index and hip osteoarthritis risk. Study-specific incremental estimates were standardized to determine the risk associated with a 5 kg/m² increase in body mass index.

Results

Fourteen epidemiological studies were included. Our study showed that body mass index was significantly positive associated with hip osteoarthritis risk. A 5-unit increase in body mass index was related to an increased risk of hip osteoarthritis (RR: 1.11; 95%CI: 1.07, 1.16). The magnitudes of associations were similar in women as compared with men (women, RR: 1.10; 95%CI: 1.05, 1.15; men, RR: 1.08; 95%CI: 1.04, 1.12; p > 0.05). The summary estimates were 1.12 (95%CI: 1.02, 1.24) in case-control studies and 1.11 (95%CI: 1.06, 1.16) in cohort studies (p > 0.05). Body mass index was positively associated with hip osteoarthritis defined by radiography and/or clinical symptom (RR: 1.04; 95%CI: 1.00, 1.07) and clinical surgery (RR: 1.16; 95%CI: 1.11, 1.22) with no significant difference (p > 0.05).

Conclusion

Increased body mass index contributes to a positive effect on susceptibility to hip osteoarthritis. Associations between body mass index and hip osteoarthritis risk do not vary by sex, study design or osteoarthritis definition.

Introduction

Osteoarthritis (OA) is the leading cause of disability in the older adults and the highest ranking among the musculoskeletal diseases. OA is the main indication for a large number of knee and hip replacement surgeries performed annually. The etiology of OA combines biomechanics and biochemistries. Recently, evidence is growing for the role of systematic factors (such as age, sex, genetics, dietary intake and estrogen usage) and local biomechanical factors (such as muscle weakness, obesity, and physical activity) [1]. Although OA represents a substantial disease burden and influences the quality of life, there is no effective treatment for it. Standard therapeutic modalities can alleviate symptoms and improve function but does not alter the disease process. Therefore, much attention has been invested in improving our recognition of the epidemiology of OA and in elucidating possible factors predisposing to the development of OA. 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 [2]. WHO endorses the use of body mass index (BMI) (kilogram per square meter) to define obesity as BMI ≥ 30 kg/m² and overweight as BMI ≥ 25 kg/m² [3]. Body mass index, a measure of relative weight, is increasingly recognized as an important risk factor for 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]. To date, the link between overweight or obesity and OA has been consistently demonstrated for knee OA [9], [12], [13]. With regard to the hip joint, evidence suggesting the deleterious role of overweight and obesity on hip OA is increasing. Epidemiologic data linking obesity with hip OA have shown a positive association, but results have also been inconsistent [14], [15], [16]. Comparison of associations across studies is difficult because of small sample size, study type, OA definition and different population. Although a systematic review about the effect of obesity on the development of hip OA was conducted in 2002 [17], it provided no obvious evidence for quantitative risk estimates of hip OA. The effect was still unclear due to sparse data and the possible methodological limitations of the conducted studies. We therefore undertook a meta-analysis and meta-regression to quantitatively assess the association between increased BMI, as a measure of overall obesity, and the risk of developing hip OA based on available studies.