Context.— A large number of epidemiologic studies have reported on associations
between various "inflammatory" factors and coronary heart disease (CHD).
Objective.— To assess the associations of blood levels of fibrinogen, C-reactive
protein (CRP), and albumin and leukocyte count with the subsequent risk of
Data Sources.— Meta-analyses of any long-term prospective studies of CHD published
before 1998 on any of these 4 factors. Studies were identified by MEDLINE
searches, scanning of relevant reference lists, hand searching of cardiology,
epidemiology, and other relevant journals, and discussions with authors of
Study Selection.— All relevant studies identified were included.
Data Extraction.— The following information was abstracted from published reports (supplemented,
in several cases, by the authors): size and type of cohort, mean age, mean
duration of follow-up, assay methods, degree of adjustment for confounders,
and relationship of CHD risk to the baseline assay results.
Data Synthesis.— For fibrinogen, with 4018 CHD cases in 18 studies, comparison of individuals
in the top third with those in the bottom third of the baseline measurements
yielded a combined risk ratio of 1.8 (95% confidence interval [CI], 1.6-2.0)
associated with a difference in long-term usual mean fibrinogen levels of
2.9 µmol/L (0.1 g/dL) between the top and bottom thirds (10.3 vs 7.4
µmol/L [0.35 vs 0.25 g/dL]). For CRP, with 1053 CHD cases in 7 studies,
the combined risk ratio of 1.7 (95% CI, 1.4-2.1) was associated with a difference
of 1.4 mg/L (2.4 vs 1.0 mg/L). For albumin, with 3770 CHD cases in 8 studies,
the combined risk ratio of 1.5 (95% CI, 1.3-1.7) was associated with a difference
of 4 g/L (38 vs 42 g/L, ie, an inverse association). For leukocyte count,
with 5337 CHD cases in the 7 largest studies, the combined risk ratio of 1.4
(95% CI, 1.3-1.5) was associated with a difference of 2.8×109/L
(8.4 vs 5.6×109/L). Each of these overall results was highly
Conclusions.— The published results from these prospective studies are remarkably
consistent for each factor, indicating moderate but highly statistically significant
associations with CHD. Hence, even though mechanisms that might account for
these associations are not clear, further study of the relevance of these
factors to the causation of CHD is warranted.