Systematic Reviews and Meta- and Pooled Analyses Obesity as a Risk Factor for Sciatica: A Meta-Analysis Rahman Shiri*, Tea Lallukka, Jaro Karppinen, and Eira Viikari-Juntura * Correspondence to Dr. Rahman Shiri, Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FI-00250 Helsinki, Finland (e-mail: rahman.shiri@ttl.fi). Initially submitted October 29, 2013; accepted for publication January 7, 2014. The aim of this study was to assess the associations of overweight and obesity with lumbar radicular pain and sciatica using a meta-analysis. We searched the PubMed, Embase, Scopus, and Web of Science databases from 1966 to July 2013. We performed a random-effects meta-analysis and assessed publication bias. We included 26 (8 cross-sectional, 7 case-control, and 11 cohort) studies. Both overweight (pooled odds ratio (OR) = 1.23, 95% confidence interval (CI): 1.14, 1.33; n = 19,165) and obesity (OR = 1.40, 95% CI: 1.27, 1.55; n = 19,165) were associated with lumbar radicular pain. The pooled odds ratio for physician-diagnosed sciaticawas 1.12 (95% CI: 1.04, 1.20; n = 109,724) for overweight and 1.31 (95% CI: 1.07, 1.62; n = 115,661) for obesity. Overweight (OR = 1.16, 95% CI: 1.09, 1.24; n = 358,328) and obesity (OR = 1.38, 95% CI: 1.23, 1.54; n = 358,328) were associated with increased risk of hospitalization for sciatica, and overweight/obesity was associated with increased risk of surgery for lumbar disc herniation (OR = 1.89, 95% CI: 1.25, 2.86; n = 73,982). Associations were similar for men and women and were independent of the design and quality of included studies. There was no evidence of publication bias. Our findings consistently showed that both overweight and obesity are risk factors for lumbar radicular pain and sciatica in men and women, with a dose-response relationship. back pain; hospitalization; intervertebral disc displacement; obesity; overweight; sciatica Abbreviations: BMI, body mass index; CI, confidence interval; OR, odds ratio. Low back pain is the number 1 debilitating condition glob- ally, and in 2010 it contributed 10.7% to the total number of years lived with disability (1). Among low back disorders, sciatica and lumbar disc herniation are the most persistent and disabling conditions (2). Lumbar radicular pain is de- fined as low back pain radiating to the leg below the knee level, while sciatica is defined as lumbar radicular pain along with clinical findings suggestive of nerve root compression (2, 3). Sciatica is usually caused by compression or irritation of one of the lumbosacral nerve roots, often due to derange- ment of a lumbar intervertebral disc such as lumbar disc her- niation (4), although other causes for sciatica have also been reported (5). The prevalence of lumbar radicular pain during the preced- ing 12 months ranges between 13% and 36% (6–8) and that of clinically defined sciatica between 2% and 5% (9–11). The incidence of lumbar radicular pain increases with age, where- as that of nonspecific low back pain tends to decrease with age (12). Lumbar radicular pain and sciatica have poorer prognoses than nonspecific low-back-pain syndromes, and they can cause prolonged work disability (2, 13). The etiologies of lumbar radicular pain and sciatica are not well known, but they seem to be multifactorial. Known risk factors for lumbar radicular pain and sciatica include occupa- tional workload, such as carrying heavy items, bending, or kneeling (14, 15), and body height (16, 17). Lifestyle risk fac- tors have also been suggested as possible risk factors for lum- bar radicular pain and sciatica (18). Obesity is a prevalent public health problem and is associ- ated with various outcomes—in addition to cardiovascular diseases, obesity has recently been associated with musculo- skeletal disorders (18, 19). Previously we conducted a sys- tematic review on the associations of weight-related factors with lumbar radicular pain and sciatica (18). Based on a qual- itative assessment of 13 studies, we found associations of weight-related factors with lumbar radicular pain or sciatica 929 Am J Epidemiol. 2014;179(8):929–937 American Journal of Epidemiology © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. Vol. 179, No. 8 DOI: 10.1093/aje/kwu007 Advance Access publication: February 24, 2014 by guest on March 26, 2015 http://aje.oxfordjournals.org/ Downloaded from