Objectives: To analyze demographics and patient characteristics that can be used to predict hypocalcemia prior to discharge (HPTD) in thyroidectomy patients
Study Design: A retrospective analysis of the National Cancer Database (2016).
Methods: Eligible total thyroidectomy patients were stratified into cohorts depending on whether or not they developed HPTD. We identified demographic and surgical risk factors for the development of hypocalcemia via multivariate binary logistic regression, and utilized univariate and multivariate methods to identify the negative sequelae of HPTD.
Results: Total/Complete Thyroidectomy was the only surgical intervention associated with HPTD (p<0.001). We identified a total of 3364 patients who underwent a total thyroidectomy, of which 245 (7.3%) had HPTD. Predictors that were associated with an increased incidence of HPTD included female sex (OR 1.787 [95% CI: 1.225-2.605]; p=0.003), increased operative time (OR 1.004 [1.002-1.005]; p<0.001), and central neck dissection (OR 1.352 [1.004-1.820]; p= 0.047). However, factors that decreased incidence of HPTD included increased age, obesity (OR 0.597 [0.417-0.855]; p=0.005), and the use of vessel sealant devices (OR 0.719 [0.540-0.958]; p=0.024). Factors such as surgical specialty, ASA class, or presence of malignant neoplasm had no association with HPTD.
Upon univariate analysis, HPTD was associated with increased length of hospitalization, 30-day readmission, and significant hypocalcemia-related event, but not death or return to OR. Multivariate analysis further revealed that HPTD independently led to an increased hospitalization length after surgery (B 1.201 [0.989-1.413]; p<0.001), increased 30-day readmission rate (OR 2.626 [1.502-4.589]; p<0.001), and an increased incidence of a clinically-significant hypocalcemia related event (OR 20.595 [21.458-43.624]; p<0.001). Univariate analysis also revealed an association between HPTD and the incidence of both recurrent laryngeal nerve damage (p=0.008) and unplanned intubation (p<0.001), as well as serious adverse events in general (p<0.001); however, this was not analyzed in multivariate analysis due to uncertainty of temporal association.
Conclusion: In conclusion, we identified several demographic factors that were significantly associated with decreased rates of hypocalcemia prior to discharge after total thyroidectomy including obesity and increased age; conversely, females were more likely to experience HPTD. Moreover, we found that cases with longer operative times and/or including central neck dissections were also more likely to result in HPTD; of note, intra-operative VSD use also led to a protective effect. Delineating risk factors and protective factors for HPTD in total thyroidectomy patients is important as patients with HPTD were found to be at a significantly higher risk for longer post-operative stays, increased odds of 30 day readmission, and, most importantly, increased hypocalcemia related event. We demonstrated the potential association between HPTD and risk for serious adverse event, RLN damage, and unplanned intubations.
Given the negative consequences of HPTD, physicians should consider the aforementioned risk factors when creating treatment plans and managing thyroidectomy patients; doing so, may reduce hospital length of stay as well as overall adverse events. Physicians may be able to safely perform outpatient total thyroidectomies in patients without these risk factors, benefiting both patient outcomes and decreasing healthcare costs