POS0011 THE ASSOCIATION BETWEEN BARIATRIC SURGERY AND CARPAL TUNNEL SYNDROME: A COHORT STUDY FROM SWEDISH NATIONWIDE HEALTHCARE REGISTRIES

Background:Carpal tunnel syndrome (CTS) is a chronic compression neuropathy caused by entrapment of the median nerve in the wrist causing pain and sensory loss. Prior observational research suggested that obesity increased the risk of CTS. However, the impact of weight loss among obese patients on CTS has not been assessed to date.Objectives:To assess the association between bariatric surgery and CTS in a secondary care setting.Methods:We performed a propensity score (PS)-matched cohort study using data from Swedish nationwide healthcare registries (patient registry [secondary care], causes of death registry, prescribed drug registry). Patients aged 18-79 years who underwent bariatric surgery between 2006 and 2019 were matched to up to 2 obese bariatric surgery-free patients (called unexposed patients) based on their PS. PS-matching was carried out in risk set sampling to reduce selection bias, within 4 sequential cohort entry blocks to account for time trend biases. The outcome CTS was defined as a diagnosis of CTS in secondary care or carpal tunnel decompression surgery. After a 1-year run-in period, patients were followed in an “as-treated” approach. We applied Cox proportional hazard regression to calculate hazard ratios (HR) with 95% confidence intervals (CIs) of CTS among bariatric surgery patients when compared to obese unexposed patients overall, and in subgroups of age, sex, bariatric surgery type, and by duration of follow-up.Results:A total of 40 619 bariatric surgery patients were PS-matched to 63 540 obese unexposed patients. A total of 72.3% of bariatric surgery patients were women. Bariatric surgery patients had a mean age of 41.7 years and a mean follow-up of 6.8 years. All patient characteristics in obese unexposed patients were highly similar. We observed 1 356 and 1 938 severe CTS cases among bariatric surgery and obese unexposed patients, respectively. Bariatric surgery was not associated overall with CTS (HR of 0.98, 95% CI 0.91-1.05). However, the risk of CTS seemed to decrease with age at bariatric surgery – the lowest CTS risk was observed among bariatric surgery patients aged 18-34 years (HR of 0.87, 95% CI 0.74-1.01), when compared to obese unexposed patients. Sex did not modify the risk of CTS among bariatric surgery patients compared to obese unexposed patients. Restrictive bariatric surgery yielded lower risks of CTS (HRs of 0.81, 95% CI 0.69-0.88) than did malabsorptive bariatric surgery (HR of 0.95, 95% CI 0.88-1.02) when compared to obese unexposed patients. The risk of CTS increased with duration of follow-up. The lowest risk was observed 1-3 years after bariatric surgery (HR of 0.77, 95% CI 0.68-0.88) and the highest risk 6-13 years after bariatric surgery (HR of 1.20, 95% CI 1.05-1.36) when compared to obese unexposed patients.Conclusion:Our results suggest that substantial weight loss is not overall associated with severe CTS in an obese patient population. However, bariatric surgery was associated with an initial decreased risk of CTS after bariatric surgery followed by an increased risk in later follow-up. Furthermore, restrictive bariatric surgery but not malapsorptive bariatric surgery was associated with a decreased risk of CTS.Acknowledgements:We thank Prof. Dr. Jesper Lagergren (Karolinksa Institutet, Stockholm, Sweden) for hosting Dr. Theresa Burkard for a research stay at the Upper Gastrointestinal Surgery Group and making the data available for use. Furthermore, we thank Dr. Giola Santoni (Karolinksa Institutet, Stockholm, Sweden) for her technical support.Disclosure of Interests:None declared.