Adverse Outcomes in Patients With Hypothyroidism Undergoing Bariatric Surgery: A Retrospective Study Using TriNetX

Context: Bariatric surgery (BS) effectively reduces obesity-related risks, but its outcomes in patients with preexisting hypothyroidism are unclear. Objective: To evaluate the impact of preexisting hypothyroidism on adverse health outcomes following BS. Methods: In this retrospective cohort study utilizing the TriNetX Global Collaborative Network database, patients with obesity who underwent BS or not, with and without hypothyroidism, were propensity score-matched. Short-term outcomes comprised mortality, readmission, ICU admission, and surgical and systemic complications. Long-term outcomes included mortality, major adverse events, bone health, and metabolic, renal, and neurological outcomes. Results: There were 5700 patients in each cohort (46.7 ± 12 years, 88% female). In the short term, patients with hypothyroidism exhibited higher risks of readmission (risk ratio [RR]: 1.25; CI: 1.14-1.36), incisional hernia (RR: 1.56; CI: 1.12-2.18), and biliary diseases (RR: 1.39; CI: 1.05-1.86). In the long term, patients with hypothyroidism had higher risks of incident cerebrovascular events (hazard ratio [HR]: 1.25; CI: 1.00-1.55), diabetes (HR: 1.39; CI: 1.12-1.74), and dyslipidemia (HR: 1.20; CI: 1.02-1.42). There were also higher risks of fall (HR: 1.20; CI: 1.02-1.40), osteoporosis (HR: 1.30; CI: 1.07-1.58), polyneuropathy (HR: 1.34; CI: 1.08-1.66), hypoglycemia (HR: 1.51; CI: 1.23-1.87), as well as iron (HR: 1.17; CI: 1.04-1.31) and vitamin B (HR: 1.34; CI: 1.20-1.49) deficiencies. Hypothyroidism-associated risks of poor outcomes were higher in patients who underwent gastric bypass. Compared to the nonsurgical care, patients with hypothyroidism who underwent BS showed a lower risk of obesity-related outcomes but a higher risk of iron and vitamin B deficiencies, osteoporosis, and hypoglycemia. Conclusion: Preexisting hypothyroidism in bariatric patients increases the risks of adverse outcomes. However, the risk of obesity-related outcomes is decreased in this population when compared to nonsurgical care.