Objective
To determine the relation between age and troponin
level and its prognostic implication.
Design
Retrospective cohort study.
Setting
Five cardiovascular centres in the UK National Institute
for Health Research Health Informatics Collaborative
(UK-NIHR HIC).
Participants
257948 consecutive patients undergoing troponin
testing for any clinical reason between 2010 and
2017.
Main outcome measure
All cause mortality.
Results
257948 patients had troponin measured during the
study period. Analyses on troponin were performed
using the peak troponin level, which was the highest
troponin level measured during the patient’s hospital
stay. Troponin levels were standardised as a multiple
of each laboratory’s 99th centile of the upper limit
of normal (ULN). During a median follow-up of 1198
days (interquartile range 514-1866 days), 55850
(21.7%) deaths occurred. A positive troponin result
(that is, higher than the upper limit of normal)
signified an overall 3.2-fold higher mortality hazard
(95% confidence interval 3.1-fold to 3.2-fold) over
three years. The mortality hazard varied markedly with
age, from 10.6-fold (8.5-fold to 13.3-fold) in 18-29
year olds to 1.5 (1.4 to 1.6) in those older than 90.
A positive troponin result was associated with an
approximately 15 percentage points higher absolute
three year mortality across all age groups. The excess
mortality with a positive troponin result was heavily
concentrated in the first few weeks. Results were
analysed using multivariable adjusted restricted
cubic spline Cox regression. A direct relation was
seen between troponin level and mortality in patients
without acute coronary syndrome (ACS, n=120049),
whereas an inverted U shaped relation was found
in patients with ACS (n=14468), with a paradoxical
decline in mortality at peak troponin levels >70xULN.
In the group with ACS, the inverted U shaped relation
persisted after multivariable adjustment in those who
were managed invasively; however, a direct positive
relation was found between troponin level and
mortality in patients managed non-invasively.
Conclusions
A positive troponin result was associated with a
clinically important increased mortality, regardless of
age, even if the level was only slightly above normal.
The excess mortality with a raised troponin was
heavily concentrated in the first few weeks.