Hypothyroidism as a risk factor for perioperative complications in lumbar spine surgery: a national database study

Hypothyroidism is a highly prevalent endocrine disorder increasingly recognized as a potential modifier of perioperative risk in orthopedic surgery. Emerging evidence indicates associations between hypothyroidism and adverse perioperative outcomes, including systemic complications and delayed recovery, in orthopedic populations. However, existing analyses remain limited by small sample sizes, lack of surgical subtype stratification, and insufficient focus on lumbar spine surgery (LSS) specifically. To address this gap, we leveraged data from the Nationwide Inpatient Sample (NIS) to clarify the association between hypothyroidism and perioperative complications in patients undergoing LSS.

A retrospective analysis was performed utilizing the NIS database (2013-2022). LSS patients were identified by ICD-9/10 codes and further divided into hypothyroid and non-hypothyroid cohorts. Propensity scores were calculated and matched in 1:1 ratios for patients with hypothyroidism to patients without hypothyroidism based on patient demographics, hospital characteristics, and Charlson Comorbidity Index, Perioperative complications were analyzed by multivariable logistic regression.

Among 873,110 LSS patients, 11.66% were diagnosed with hypothyroidism. Hypothyroid patients were older (median age 64 versus 59 years, P < 0.001). Before stratification, hypothyroidism was associated with significantly increased odds ratios (ORs) for the following complications in the overall lumbar spine surgery patient cohort: sepsis, postoperative shock, postoperative delirium, acute cerebrovascular disease, acute myocardial infarction, congestive heart failure, deep vein thrombosis, pneumonia, pulmonary embolism, respiratory failure, urinary tract infection, transfusion, wound infection, wound dehiscence, in-hospital mortality, and prolonged length of stay (LOS) (P < 0.001 for all). After stratification, patients who underwent lumbar fusion alone demonstrated significantly elevated Odds Ratios (ORs) for all complications. In contrast, among those who underwent lumbar decompression alone or discectomy alone, the increases in ORs for wound infection and wound dehiscence were not statistically significant. Furthermore, for the discectomy-alone subgroup, the elevated ORs for postoperative shock and acute myocardial infarction also lacked statistical significance. For all other complications, the subgroups showed elevated ORs that were statistically significant.

This study suggests a correlation between hypothyroidism and a higher risk of complications in patients undergoing lumbar spine surgery. This finding indicates that surgeons should exercise heightened vigilance with lumbar surgery patients who have co-existing hypothyroidism.