Investigating the Causal Relationship Between Physical Activity and Chronic Back Pain: A Bidirectional Two-Sample...

Area of Science:

• Genetics and Epidemiology
• Pain Research
• Public Health

Background:

• Observational studies suggest a link between physical activity and chronic back pain (CBP), but causality is unclear.
• Mendelian randomization (MR) is a powerful tool to investigate causal relationships using genetic variants.
• Understanding this relationship is crucial for developing effective interventions for CBP.

Purpose of the Study:

• To investigate the causal relationship between physical activity and chronic back pain (CBP) using a bidirectional Mendelian randomization (MR) approach.
• To determine if physical activity protects against CBP or if CBP leads to reduced physical activity.
• To provide robust evidence for public health recommendations regarding physical activity and CBP management.

Main Methods:

• Utilized a two-sample MR design with large genome-wide association study (GWAS) data for physical activity and CBP.
• Employed independent genetic variants as instrumental variables for both exposures and outcomes.
• Applied inverse variance-weighted meta-analysis and sensitivity analyses (weighted median, MR-Egger) to ensure result validity.

Main Results:

• No evidence of a causal effect of physical activity on chronic back pain (CBP) was found (OR, 0.98; 95% CI, 0.85-1.13; p = 0.81).
• A significant causal effect of CBP on reduced physical activity was detected (β = -0.07; 95% CI, -0.12 to -0.01; p = 0.02).
• This suggests individuals with CBP experience approximately 146 MET-minutes/week less moderate-vigorous physical activity.

Conclusions:

• The observed negative association between physical activity and CBP is likely due to reduced activity levels in individuals with pain.
• Physical activity may not have a direct protective effect against developing chronic back pain.
• Findings highlight the importance of addressing physical activity reduction in CBP management strategies.