ISSLS Prize in Clinical Science 2020. Examining causal effects of body mass index on back pain: a Mendelian randomization study.
PURPOSE
Measures of body fat accumulation are associated with back pain, but a causal association is unclear. We hypothesized that BMI would have causal effects on back pain. We conducted a two-sample Mendelian randomization (MR) study to assess the causal effect of body mass index (BMI) on the outcomes of (1) back pain and (2) chronic back pain (duration > 3 months).


METHODS
We identified genetic instrumental variables for BMI (n = 60 variants) from a meta-analysis of genome-wide association studies (GWAS) conducted by the Genetic Investigation of ANthropometric Traits consortium in individuals of European ancestry (n = 322,154). We conducted GWAS of back pain and chronic back pain (n = 453,860) in a non-overlapping sample of individuals of European ancestry. We used inverse-variance weighted (IVW) meta-analysis as the primary method to estimate causal effects.


RESULTS
The IVW analysis showed evidence supporting a causal association of BMI on back pain, with a 1-standard deviation (4.65 kg/m2) increase in BMI conferring 1.15 times the odds of back pain (95% confidence interval [CI]: 1.06-1.25, p = 0.001]; effects were directionally consistent in secondary analysis and sensitivity analyses. The IVW analysis supported a causal association of BMI on chronic back pain (OR 1.20 per 1 SD deviation increase in BMI [95% CI 1.09-1.32; p = 0.0002]), and effects were directionally consistent in secondary analysis and sensitivity analyses.


CONCLUSION
In this first MR study of BMI and back pain, we found a significant causal effect of BMI on both back pain and chronic back pain. These slides can be retrieved under Electronic Supplementary Material.
['Elgaeva|Elizaveta E|EE|', 'Tsepilov|Yakov|Y|', 'Freidin|Maxim B|MB|', 'Williams|Frances M K|FMK|', 'Aulchenko|Yurii|Y|', 'Suri|Pradeep|P|0000-0002-9449-4165']
D001363:Awards and Prizes D001416:Back Pain D015992:Body Mass Index D055106:Genome-Wide Association Study D006801:Humans D057182:Mendelian Randomization Analysis D020641:Polymorphism, Single Nucleotide
Epidemiology Low back pain Obesity Prognosis Risk factor