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ObjectiveTo examine the effect of sex on risk of bloodstream infections (BSI) and BSI mortality and to assess to what extent known risk factors for BSI mediate this association in the general population.ParticipantsThe prospective, population-based HUNT2 Survey (1995-97) in Norway invited 93,898 inhabitants ≥20 years in the Nord-Trøndelag region, whereof 65,237 (69.5%) participated. 46.8% of the participants were men.ExposuresSex and potential mediators between sex and BSI; health behaviours (smoking, alcohol consumption), education attainment, cardiovascular risk factors (systolic blood pressure, non-HDL cholesterol, body mass index) and previous or current comorbidities.Main outcome measuresSex differences in risk of first-time BSI, BSI mortality (death within first 30 days after a BSI), BSI caused by the most frequent bacteria, and the impact of known BSI risk factors as mediators.ResultsWe documented a first-time BSI for 1,840 (2.9%) participants (51.3% men) during a median follow-up of 14.8 years. Of these, 396 (0.6%) died (56.6% men). Men had 41% higher risk of any first-time BSI (95% confidence interval (CI), 28 to 54%) than women. An estimated 34% of the excess risk of BSI in men was mediated by known BSI risk factors. The hazard ratio (HR) with 95% CI for BSI due to S. aureus was 2.09 (1.28 to 2.54), S. pneumoniae 1.36 (1.05 to 1.76), and E. coli 0.97 (0.84 to 1.13) in men vs women. BSI related mortality was higher in men compared to women with HR 1.87 (1.53 to 2.28).ConclusionsThis large population-based study show that men have higher risk of BSI than women. One-third of this effect was mediated by known risk factors for BSI. This raises important questions regarding sex specific approaches to reduce the burden of BSI.

Objective We examined whether anxiety and depression symptoms constitute increased risk of bloodstream infection (BSI), as a proxy for sepsis. Methods A general population with self-reported anxiety and depression symptoms was followed prospectively for hospital-verified BSI. Using multivariable Cox regression analysis, we estimated hazard ratios (HR) with 95% confidence intervals (CI) of BSI and BSI mortality, with and without statistical adjustment for comorbidities, BMI, and life-style factors that may confound or mediate the associations. Results During 14.8 years median follow-up of 59,301 individuals, 1578 (2.7%) experienced BSI and 328 (0.55%) participants died within 30 days after a BSI. Severe depression symptoms were associated with a 38% increased risk of BSI, adjusted for age, sex, and education (HR = 1.38, 95% CI = 1.10-1.73). The HR was attenuated to 1.23 (0.96-1.59) after adjustment for comorbidities and to 1.15 (0.86-1.53) after additional adjustment for BMI and life-style factors. For severe anxiety symptoms, the corresponding HRs were 1.48 (1.20-1.83), 1.35 (1.07-1.70), and 1.28 (0.99-1.64). Moderate symptoms of depression and anxiety were not associated with increased BSI risk. The analysis of BSI mortality yielded imprecise results but suggested an increased risk of BSI mortality in participants with moderate depression symptoms. Conclusions Severe depression and anxiety symptoms were associated with a moderately increased risk of BSI. The association may, at least in part, be confounded or mediated by comorbidities, BMI, and life-style. Future research should investigate whether interventions targeting improved BMI and life-style may reduce the risk of BSI and sepsis in people with depression and anxiety symptoms.

Background: Bloodstream infections (BSI) cause considerable morbidity and mortality, and primary prevention should be a priority. Lifestyle factors are of particular interest since they represent a modifiable target. Methods: We conducted a prospective cohort study among participants in the population-based Norwegian HUNT2 Survey, where 64 027 participants were followed from 1995–97 through 2011 by linkage to prospectively recorded information on BSI at local and regional hospitals. The exposures were: baseline body mass index (BMI) measurements; and self-reported smoking habits, leisure time physical activity and alcohol intake. The outcomes were hazard ratios (HR) of BSI and BSI mortality. Results: During 810 453 person-years and median follow-up of 14.8 years, 1844 (2.9%) participants experienced at least one BSI and 396 (0.62%) died from BSI. Compared with normal weight participants (BMI 18.5–24.9 kg/m2), the age- and sex-adjusted risk of a first-time BSI was 31% [95% confidence interval (CI) 14–51%] higher at BMI 30.0–34.9 kg/m2, 87% (95% CI 50–135%) higher at BMI 35.0–39.9 kg/m2 and 210% (95% CI 117–341%) higher at BMI ≥ 40.0 kg/m2. The risk of BSI mortality was similarly increased. Compared with never-smokers, current smokers had 51% (95% CI 34–70%) and 75% (95% CI 34–129%) higher risks of BSI and BSI mortality, respectively. Physically inactive participants had 71% (95% CI 42–107%) and 108% (95% CI 37–216%) higher risks of BSI and BSI mortality, respectively, compared with the most physically active. © The Author 2017; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association. This is the authors' accepted and refereed manuscript to the article. Locked until 15 June 2018 due to copyright restrictions