To evaluate the impact of hypothyroidism in patients undergoing 1- to 2-level lumbar fusion (1–2LF). Hypothyroidism is a common cause of morbidity and mortality following surgery. Studies have demonstrated the effects of hypothyroidism following orthopedic surgery, but not 1–2LF.

Patients undergoing 1–2LF with hypothyroidism were identified within the Medicare population, and served as the study group. Study group patients were randomly matched to controls in a 1:5 ratio by age, sex, and medical comorbidities. Primary outcomes analyzed included in-hospital lengths of stay (LOS), 90-day readmission rates, 90-day medical complications, and costs of care. Pearson χ2 tests were used to compare patient demographics. Logistic regression analyses were used to calculate odds ratios (OR) for medical complications and readmissions. Welch t test was used to test for significance in cost between the cohorts. An α value <0.002 was considered statistically significant.

The query yielded 417,483 patients who underwent 1–2LF with (n=69,584) and without (n=347,899) hypothyroidism. Hypothyroid patients had significantly longer in-hospital LOS (8 vs. 4 d; P<0.0001) compared with controls. In addition, study group patients had significantly higher incidence and odds of 90-day readmissions (20.22% vs. 17.62%; OR, 1.18; P<0.0001) and 90-day medical complications (6.38% vs. 1.89%; OR, 3.53; P<0.0001) compared with controls. Study group patients had higher day of surgery costs ($97,304.01 vs. $95,168.35; P=0.014) and 90-day costs of care ($113,514.15 vs. $108,860.60; P=0.0001) compared with controls.

After adjusting for age, sex, and medical comorbidities, the study demonstrates patients who have hypothyroidism have longer in-hospital LOS and higher rates of readmissions, complications, and costs. The study is vital as it can allow orthopedic surgeons to adequately counsel and educate these patients of the potential complications that may occur following their procedure.