Dm. Mirvis et Mj. Graney, The cumulative effects of historical and physical examination findings on the prognostic value of the electrocardiogram, J ELCARDIOL, 34(3), 2001, pp. 215-223
The electrocardiogram has been shown in epidemiologic studies to be an inde
pendent predictor of survival. These studies have adjusted for selected cov
ariates simultaneously. This article assesses the value of the electrocardi
ogram as a predictor of survival when introduced at progressive stages of t
he common clinical encounter. Data collected from 4,518 patients ages of 60
to 96 years with isolated systolic hypertension who were followed-up for u
p to 6 years as part of the Systolic Hypertension in the Elderly Project we
re analyzed. Survival curves and 3- and 5-year survival races (Cox regressi
on methods) of groups with normal and abnormal resting electrocardiograms w
ere compared. Blocks of covariates representing demographic information, ri
sk factors for cardiovascular disease, clinical history, and physical exami
nation findings were added to the survival models sequentially to mimic the
sequence of the common clinical encounter, and the independent significanc
e of the electrocardiogram as a predictor of survival was assessed at each
step. An abnormal electrocardiogram was associated with reduced survival wh
en no adjustment for covariates is made. Survival was also significantly (P
< .05) different for groups with normal and abnormal electrocardiograms wh
en demographic and risk factor variables were included in the statistical m
odels, but not after findings from the clinical history and physical examin
ation were added. The prognostic value of the electrocardiogram varies with
the stage in the clinical encounter in which it is introduced.