Endocrine Abstracts

Background: Hyperthyroidism often runs an indolent course and may be undiagnosed for prolonged periods. Most patients are treated in the outpatient setting and the effects of hyperthyroidism on hospitalised patients are poorly studied. We set out to determine the prevalence of hyperthyroidism in a large cohort of inpatients and evaluated their comorbidities, reasons for hospitalisation and rehospitalisation rates.

Methods: A case-control study was conducted using a computerised system of admissions (n=279 162) to a large tertiary centre between 2007 and 2011. Hyperthyroid patients were identified based on ICD-10 coding and/or administration of thionamides and matched by age, gender and year of the first admission with the general hospital population.

Results: Six hundred and seventy three subjects (0.5% of total hospitalised cohort) were hyperthyroid, which was newly diagnosed in 92. Hyperthyroid inpatients were more frequently re-admitted (mean 3.07 admissions during study period in cases vs 2.22 in controls; P<0.001) and their total (25.4 vs 15.7 days during 5-year period; P<0.001) and mean length of hospital stays (8.7 vs 7.0 days per stay; P=0.003) were significantly longer. Hyperthyroid patients were more frequently admitted with cardiovascular disorders (CVD) compared with controls (37.4% vs 26%; P<0.001) while proportions of admissions for respiratory, nervous and digestive causes were not different. Similarly CVD were more frequently recorded in hyperthyroid subjects (67.0% vs 57.1% in controls; P=0.02). Hypertension (37.6%), atrial fibrillation (29.0%), ischaemic heart disease (18.6%) and heart failure (12.6%) were the most common CVD comorbidities in hyperthyroid patients; AF and heart failure were recorded twice as often in the study subjects compared with controls (OR: 2.09 and 1.85; P<0.001).

Conclusions: We demonstrate that inpatients with hyperthyroidism are at significantly increased risk of re-hospitalisation and morbidity from cardiovascular diseases. The identification of these patients and institution of appropriate management and follow-up plans is likely to alleviate this significant health and financial burden.