'No independent link' between diabetes and poor outcomes after CABG/PTCA
'No independent link' between diabetes and poor outcomes after CABG/PTCA
Medwire
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ArticleHistory
ArticleContext
:
Joanna Lyford,Aff1
Corresponding Affiliation: Aff1
Diabetes, outcome, revascularization
Context
An investigation into why diabetic patients have worse outcomes than nondiabetics after cardiac
catheterization reveals that the discrepancy can be entirely explained by adverse clinical variables that
are associated with diabetes. Contradicting previous studies, Canadian researchers identified no
'independent diabetes factor' - such as an increased tendency towards thrombosis - that was
independently associated with worse mortality following revascularization procedures.
Significant findings
The team reports that unadjusted 1-year mortality was 7.6% for patients with diabetes versus 4.1% for
those without diabetes (odds ratio 1.9, 95% confidence interval [CI] 1.6-2.3). However, after adjusting
for potential confounders including comorbid conditions, previous cardiac history, coronary anatomy
and renal function, the odds ratio was reduced to 1.1 (95% CI 0.8-1.3). Similarly, the adjusted hazard
ratio for longer term mortality was 1.2 (95% CI 1.0-1.4, mean follow-up 702 days).
Comments
The team suggests various reasons for the discrepancy between their findings and those of prior
epidemiological studies, which have reported relative risks ranging from 1.3 to 2.5 - even after adjusting
for other prognostic factors such as left ventricular ejection fraction and renal disease. 'Prior studies
either focused on selected patient samples or failed to measure potential confounders. The rich clinical
detail of the APPROACH database may have allowed us to adjust more fully for the clinical status of
our patients. Duration of follow-up may also affect the prognostic importance of diabetes', they note. As
the hazard ratio at 3 years was greater than that at 1 year, Ghali et al postulate an atherogenic
mechanism for long-term risk associated with diabetes, noting that this is consistent with our current
understanding of the pathophysiology of glucose metabolism. They also admit that their study focused
only on survival, although other outcomes (such as quality of life, severity of angina, readmission to
hospital) are important and deserve attention. 'When physicians are considering the short- to
intermediate-term prognosis of diabetic patients who have undergone diagnostic cardiac catheterization,
they should be evaluated mainly on the presence or absence of other clinical variables associated with
poor prognosis', the team concludes.
Methods
A multicenter team analyzed data from a prospective cohort study (APPROACH) that captured
detailed clinical information and longitudinal outcomes for 11,468 patients (17% of whom were
diabetic) undergoing cardiac catheterization in Alberta, Canada. They used logistic regression to model
predictors of 1-year mortality, while proportional hazards analysis was used to model predictors of
survival up to 3 years after cardiac catheterization.
Additional information
This PDF file was created after publication.
1. Ghali WA , Quan H , Norris CM , Dzavik V , Naylor CD , Mitchell LB , Brant R , Knudtson ML : Prognostic significance of diabetes as a predictor of survival after cardiac catheterization . Am J Med . 2000 , 109 : 543 - 548 . (...truncated)