MON-618 National In-Hospital Trends in Acquired Hypothyroidism

Background - Factors contributing to acquired hypothyroidism have increased in the United States during recent years. Known factors include advanced age, thyroidectomy, anti-thyroid and thyroid-affecting medications, susceptibility to autoimmune thyroiditis, iodine intake, radioactive ablation, and external beam neck irradiation. However, it is not understood how this increase in contributing factors impacts inpatient trends related to acquired hypothyroidism. Research aim - The objective of this epidemiological study is to describe the national inpatient trends in acquired hypothyroidism including prevalence, in-hospital mortality, length of stay (LOS), and healthcare expenditure. Methods - The National Inpatient Sample database was used to identify individuals 18 years or older, hospitalized between January 2000 and December 2014, with ICD 9 Code 244 acquired hypothyroidism as the principal discharge diagnosis. Longitudinal differences related to acquired hypothyroidism in the total number of hospital discharges, mean LOS, in-hospital mortality percentage, and inflation-adjusted cost were assessed. Linear regression analysis was used to assess the relationship between these variables and time. Relationships with a p-value of less than or equal to 0.05 were deemed significant. Analyses were performed using SAS® Software (version 9.4; Cary, NC). Results - During the 15-year period, the total number of discharges with the principal diagnosis of acquired hypothyroidism increased by 95 cases/year (p<0.0001), and the mean charges per acquired hypothyroidism hospitalization increased by $1218/year (p<0.0001). Conversely, the mean LOS per hospitalization decreased by 0.06 days/year (p= 0.0423) and the mean age of hospitalization decreased by 0.32 years/year (p<0.0001). Acquired hypothyroidism-related in-hospital mortality rate did not change over time (p=0.2048). Discussion - This is the first study to describe the trends in acquired hypothyroidism in the United States over a 15-year period utilizing the largest publicly available inpatient database. The considerable rise in the incidence of acquired hypothyroidism along with a significant growth in associated health care costs in this condition may be attributable to the rise in risk factors for acquired hypothyroidism and the general rise in health care cost, respectively. Hospitalization LOS has decreased possibly indicating better utilization of outpatient follow up for these patients. While the decrease in mean age may be secondary to a younger population exposed to more risk factors. In-hospital mortality in patients with acquired hypothyroidism did not change, which should be further evaluated in future studies focusing on better outcomes and treatment strategies.