Mendelian randomization analysis does not reveal a causal influence of smoking on rotator cuff tears.

While observational studies suggest smoking as a potential risk factor for rotator cuff tears (RCTs), causal evidence remains inconclusive. This bidirectional Mendelian randomization (MR) study investigates genetic causality between smoking behaviors and RCTs risk. Genetic instruments for smoking initiation, cessation, and cigarettes per day were derived from GSCAN (Sequencing Consortium of Alcohol and Nicotine Use) data. RCTs genome-wide association study (GWAS) summary statistics were obtained from a recent GWAS meta-analysis. Causal effects were evaluated using inverse variance weighted (IVW) fixed/random-effects models, supplemented by MR-Egger, weighted median, and MR-PRESSO methods. Sensitivity analyses assessed heterogeneity and horizontal pleiotropy. No significant causal relationship was found between smoking and RCTs and its subtypes. The sensitivity analysis confirmed the robustness of these results. The large MR analysis indicated that smoking may not be causally associated with a risk of RCTs.