Inflammatory dispositions: a population-based study of the association between hostility and peripheral leukocyte counts

This study tests the hypothesis that high hostility is associated with increased peripheral blood leukocyte count. Hostility and peripheral blood leukocyte count have been independently associated with cardiovascular and all cause mortality but their association has not been reported in a population-based sample. Participants in the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk), aged 40–80 years, were identified through age–sex general practice registers. White blood cell counts and a measure of hostility were available from 11,367 participants and, after a mean interval of 44 months, from 11,857 at a second health check. The measure of hostility was completed between health checks. Ageadjusted associations were found between hostility and lymphocyte counts assessed at both health checks. Sex differences in these associations were not observed. There was an incremental elevation in mean lymphocyte cell counts with increasing hostility such that there was a 4.6% difference between top and bottom quintiles of hostility at the first (P<0.0001) and 5.0% difference at the second health check (P<0.0001). While half of this association was explained in terms of smoking behaviour, these results support an association between hostility and lymphocyte count, independent of age, sex, smoking history, alcohol intake and social class (1.9% difference, P=0.02 and 2.9% difference, P=0.0007 at the first and second health checks, respectively). If these findings can be replicated, study of inflammation as a plausible pathway linking hostility to health endpoints would be warranted.