Association of Preoperative Anemia With 30-Day Morbidity and Mortality Among Patients With Thyroid Cancer Who Undergo Thyroidectomy.

Importance: Despite the ease of preoperative anemia diagnosis and the availability of treatment options, the morbidity and mortality associated with this condition remain unacceptably high, and the literature describing the association of preoperative anemia with postoperative outcomes following thyroid surgery in patients with thyroid cancer remain sparse. Reporting outcomes in this patient population may help to facilitate preoperative optimization. Objective: To assess whether an association exists between preoperative anemia and outcomes following thyroid surgery in patients with thyroid cancer. Design, Setting, and Participants: This retrospective, cross-sectional, cohort study used the American College of Surgeons National Surgical Quality Improvement Program database to identify 32 166 patients between 2007 and 2016 with Current Procedural Terminology codes for thyroid surgery and with the International Classification of Diseases, Ninth Revision code of malignant thyroid cancer. Exposures: Preoperative anemia as defined using the World Health Organization criteria of hematocrit less than 36% in nonpregnant females and less than 39% in males. Main Outcomes and Measures: Multivariable logistic regression analysis was conducted to assess the association of preoperative anemia with the following 30-day postoperative outcomes: pulmonary, infectious, and cardiac complications, overall and serious morbidity (surgical site infection and medical complications), prolonged hospital length of stay (≥75th percentile for the cohort), and mortality. Results: Among the 24 912 patients with thyroid cancer who underwent thyroidectomy included in the final analysis, the median (interquartile range) age was 51 (40-62) years and the majority were women (18 705 [75.1%]). The prevalence of preoperative anemia was 12.5% (n = 3108). Within the overall study population, hypertension (9242 patients [37.1%]) followed by active smoking (2992 patients [12.0%]) were the most prevalent comorbidities. The unadjusted odds of anemia vs no anemia were significantly higher for every 10-year increase in age (odds ratio [OR], 1.10; 95% CI, 1.08-1.13) and for black vs white patients (OR, 2.82; 95% CI, 2.51-3.17). The adjusted odds of postoperative overall morbidity (OR, 1.68; 95% CI, 1.29-2.17), mortality (OR, 3.36; 95% CI, 1.37-8.28), and pulmonary (OR, 2.36; 95% CI, 1.65-3.34) and infectious (OR, 1.62; 95% CI, 1.12-2.29) complications were higher in patients with preoperative anemia than in those without preoperative anemia. Conclusions and Relevance: The findings from this study suggest that preoperative anemia may not only be associated with racial differences and a higher comorbidity burden but may also increase the likelihood of postoperative morbidity and mortality. These results may provide a basis for further risk reduction strategies and preoperative optimization.