title: Cardiovascular morbidity and mortality in surgically treated hyperthyroidism - a nation-wide cohort study with a long-term follow-up.
abstract: OBJECTIVE
  Previous studies suggest that patients with hyperthyroidism remain at an increased risk of cardiovascular morbidity even after restoring euthyroidism. The mechanisms of the increased risk and its dependency on the different treatment modalities of hyperthyroidism remain unclear. The aim of this long-term follow-up study was to compare the rate of hospitalizations for cardiovascular causes and the mortality in hyperthyroid patients treated surgically with an age- and gender-matched reference population.
  
  
  METHODS
  A population-based cohort study was conducted among 4334 hyperthyroid patients (median age 46 years) treated with thyroidectomy in 1986-2007 in Finland and among 12,991 reference subjects. Firstly, the hospitalizations due to cardiovascular diseases (CVD) were analysed until thyroidectomy. Secondly, the hazard ratios for any new hospitalization due to CVDs after the thyroidectomy were calculated in Cox regression analysis adjusted with the prevalent CVDs at the time of thyroidectomy.
  
  
  RESULTS
  The risk of hospitalization due to all CVDs started to increase already 5 years before the thyroidectomy, and by the time of the operation, it was 50% higher in the hyperthyroid patients compared to the controls (P < 0·001). After the thyroidectomy, the hospitalizations due to all CVDs (HR 1·15), hypertension (HR 1·23), heart failure (HR 1·17) and valvular diseases or cardiomyopathies (HR 1·55) remained more frequent among the patients than among the controls for 20 years after thyroidectomy. The increased morbidity was not clearly related to the aetiology of hyperthyroidism. Despite the increased CVD morbidity among the patients, there was no difference in cardiovascular mortality.
  
  
  CONCLUSIONS
  The present study shows that hyperthyroidism increases the risk of hospitalization due to CVDs and the risk is sustained up to two decades after effective surgical treatment. However, there was no excess CVD mortality in the middle-aged patient cohort studied.
authors.affiliation: Heart Center Co., Tampere University Hospital, Tampere, Finland; School of Medicine, University of Tampere, Tampere, Finland.
authors.forename: Essi
authors.initials: E
authors.lastname: Ryödi
authors.forename: Jorma
authors.initials: J
authors.lastname: Salmi
authors.forename: Pia
authors.initials: P
authors.lastname: Jaatinen
authors.forename: Heini
authors.initials: H
authors.lastname: Huhtala
authors.forename: Rauni
authors.initials: R
authors.lastname: Saaristo
authors.forename: Matti
authors.initials: M
authors.lastname: Välimäki
authors.forename: Anssi
authors.initials: A
authors.lastname: Auvinen
authors.forename: Saara
authors.initials: S
authors.lastname: Metso
mesh_terms: D000328:Adult; D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality*; D015331:Cohort Studies; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D006760:Hospitalization; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010343:Patient Admission; D016016:Proportional Hazards Models; D012016:Reference Values; D012042:Registries; D012307:Risk Factors; D013965:Thyroidectomy / Q000379:methods*; D016896:Treatment Outcome