Subclinical and overt thyroid dysfunction and risk of all-cause mortality and cardiovascular events: a large
Christian Selmer1, Jonas Bjerring Olesen, Morten Lock Hansen
1Department of Cardiology (C.S., J.B.O., M.L.H., P.R.H., G.H.G.), Gentofte University Hospital, DK-2900 Hellerup, Denmark; Department of Endocrinology (C.S., J.F.), Herlev University Hospital, DK-2730 Herlev, Denmark; Copenhagen General Practitioners Laboratory (J.C.M.), DK-2100 Copenhagen, Denmark; Faculty of Health and Medical Sciences (J.F., G.H.G.), University of Copenhagen, DK-2200 Copenhagen, Denmark; Department of Cardiology (O.D.P.), Roskilde University Hospital, DK-4000 Roskilde, Denmark; Institute of Health, Science, and Technology (C.T.-P.), Aalborg University, DK-9220 Aalborg, Denmark; and National Institute of Public Health (L.M.v.K., G.H.G.), University of Southern Denmark, DK-1353 Copenhagen, Denmark.
Context:
Thyroid dysfunction has been associated with both increased all-cause and cardiovascular mortality, but limited data are available on mild thyroid dysfunction and cause-specific mortality.
Objective:
The objective of the study was to examine the risk of all-cause mortality, major adverse cardiovascular events (MACEs), and cause-specific events in subjects with overt and subclinical thyroid dysfunction.
Design:
This was a retrospective cohort study.
Setting And Participants:
Participants in the study were subjects who underwent thyroid blood tests, without prior thyroid disease, consulting their general practitioner in 2000-2009 in Copenhagen, Denmark.
Main Outcome Measure:
All-cause mortality, MACEs, and cause-specific events identified in nationwide registries were measured.
Results:
A total of 47 327 (8.4%) deaths occurred among 563 700 included subjects [mean age 48.6 (SD ± 18.2) y; 39% males]. All-cause mortality was increased in overt and subclinical hyperthyroidism [age adjusted incidence rates of 16 and 15 per 1000 person-years, respectively; incidence rate ratios (IRRs) 1.25 [95% confidence interval (CI) 1.15-1.36] and 1.23 (95% CI 1.16-1.30)] compared with euthyroid (incidence rate of 12 per 1000 person-years). Risk of MACEs was elevated in overt and subclinical hyperthyroidism [IRRs 1.16 (95% CI 1.05-1.27) and 1.09 (95% CI 1.02-1.16)] driven by heart failure [IRRs 1.14 (95% CI 0.99-1.32) and 1.20 (95% CI 1.10-1.31)]. A reduction of all-cause mortality was observed in subclinical hypothyroidism with TSH of 5-10 mIU/L [IRR 0.92 (95% CI 0.86-0.98)].
Conclusions:
Heart failure is the leading cause of an increased cardiovascular mortality in both overt and subclinical hyperthyroidism. Subclinical hypothyroidism with TSH 5-10 mIU/L might be associated with a lower risk of all-cause mortality.
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