Body mass index and risk of dying from a bloodstream infection: A Mendelian randomization study.

BACKGROUND: In observational studies of the general population, higher body mass index (BMI) has been associated with increased incidence of and mortality from bloodstream infection (BSI) and sepsis. On the other hand, higher BMI has been observed to be apparently protective among patients with infection and sepsis. We aimed to evaluate the causal association of BMI with risk of and mortality from BSI. METHODS AND FINDINGS: We used a population-based cohort in Norway followed from 1995 to 2017 (the Trøndelag Health Study [HUNT]), and carried out linear and nonlinear Mendelian randomization analyses. Among 55,908 participants, the mean age at enrollment was 48.3 years, 26,324 (47.1%) were men, and mean BMI was 26.3 kg/m2. During a median 21 years of follow-up, 2,547 (4.6%) participants experienced a BSI, and 451 (0.8%) died from BSI. Compared with a genetically predicted BMI of 25 kg/m2, a genetically predicted BMI of 30 kg/m2 was associated with a hazard ratio for BSI incidence of 1.78 (95% CI: 1.40 to 2.27; p < 0.001) and for BSI mortality of 2.56 (95% CI: 1.31 to 4.99; p = 0.006) in the general population, and a hazard ratio for BSI mortality of 2.34 (95% CI: 1.11 to 4.94; p = 0.025) in an inverse-probability-weighted analysis of patients with BSI. Limitations of this study include a risk of pleiotropic effects that may affect causal inference, and that only participants of European ancestry were considered. CONCLUSIONS: Supportive of a causal relationship, genetically predicted BMI was positively associated with BSI incidence and mortality in this cohort. Our findings contradict the "obesity paradox," where previous traditional epidemiological studies have found increased BMI to be apparently protective in terms of mortality for patients with BSI or sepsis

Association of Genetically Predicted Insomnia With Risk of Sepsis: A Mendelian Randomization Study.

IMPORTANCE: Insomnia has been associated with altered inflammatory response as well as increased risk of infections and sepsis in observational studies. However, these studies are prone to bias, such as residual confounding. To further understand the potential causal association between insomnia and sepsis risk, a 2-sample Mendelian randomization (MR) approach should be explored. OBJECTIVE: To evaluate whether genetically predicted insomnia is associated with risk of sepsis. DESIGN, SETTING, AND PARTICIPANTS: Two-sample MR was performed to estimate the association between genetically predicted insomnia and sepsis risk. Data were obtained from a genome-wide association study identifying 555 independent genetic variants (R2 < 0.01) strongly associated with insomnia (P < 5 × 10-8). Sensitivity analyses were conducted to address bias due to pleiotropy and sample overlap, along with mediation analyses and sex-stratified analyses. The insomnia data set included 2.4 million individuals of European ancestry from the UK Biobank and 23andMe. For sepsis, 462 918 individuals of European ancestry from the UK Biobank were included. Data were extracted between February and December 2022 and analyzed between March 2022 and March 2023. EXPOSURE: Genetically predicted insomnia. MAIN OUTCOME AND MEASURE: Sepsis. RESULTS: There were 593 724 individuals with insomnia and 10 154 cases of sepsis. A doubling in the population prevalence of genetically predicted insomnia was associated with an odds ratio of 1.37 (95% CI, 1.19-1.57; P = 7.6 × 10-6) for sepsis. Sensitivity analyses supported this observation. One-third of the association between genetically predicted insomnia and risk of sepsis was mediated through a combination of cardiometabolic risk factors for sepsis (body mass index, type 2 diabetes, smoking, or cardiovascular disease; overall proportion, 35.2%; 95% CI, 5.1-76.9). The association between insomnia and sepsis was more pronounced among women compared with men (women: odds ratio, 1.44; 95% CI, 1.24-1.68; men: OR, 1.10; 95% CI, 0.86-1.40). CONCLUSIONS AND RELEVANCE: The concordance between these findings and previous observational studies supports that insomnia is potentially causally associated with the risk of sepsis. Thus, insomnia is a potential preventable risk factor of sepsis that should be further investigated, also in non-European populations

Body mass index and risk of dying from a bloodstream infection: A Mendelian randomization study.

BACKGROUND: In observational studies of the general population, higher body mass index (BMI) has been associated with increased incidence of and mortality from bloodstream infection (BSI) and sepsis. On the other hand, higher BMI has been observed to be apparently protective among patients with infection and sepsis. We aimed to evaluate the causal association of BMI with risk of and mortality from BSI. METHODS AND FINDINGS: We used a population-based cohort in Norway followed from 1995 to 2017 (the Trøndelag Health Study [HUNT]), and carried out linear and nonlinear Mendelian randomization analyses. Among 55,908 participants, the mean age at enrollment was 48.3 years, 26,324 (47.1%) were men, and mean BMI was 26.3 kg/m2. During a median 21 years of follow-up, 2,547 (4.6%) participants experienced a BSI, and 451 (0.8%) died from BSI. Compared with a genetically predicted BMI of 25 kg/m2, a genetically predicted BMI of 30 kg/m2 was associated with a hazard ratio for BSI incidence of 1.78 (95% CI: 1.40 to 2.27; p < 0.001) and for BSI mortality of 2.56 (95% CI: 1.31 to 4.99; p = 0.006) in the general population, and a hazard ratio for BSI mortality of 2.34 (95% CI: 1.11 to 4.94; p = 0.025) in an inverse-probability-weighted analysis of patients with BSI. Limitations of this study include a risk of pleiotropic effects that may affect causal inference, and that only participants of European ancestry were considered. CONCLUSIONS: Supportive of a causal relationship, genetically predicted BMI was positively associated with BSI incidence and mortality in this cohort. Our findings contradict the "obesity paradox," where previous traditional epidemiological studies have found increased BMI to be apparently protective in terms of mortality for patients with BSI or sepsis

Body mass index and risk of dying from a bloodstream infection: A Mendelian randomization study.

BackgroundIn observational studies of the general population, higher body mass index (BMI) has been associated with increased incidence of and mortality from bloodstream infection (BSI) and sepsis. On the other hand, higher BMI has been observed to be apparently protective among patients with infection and sepsis. We aimed to evaluate the causal association of BMI with risk of and mortality from BSI.Methods and findingsWe used a population-based cohort in Norway followed from 1995 to 2017 (the Trøndelag Health Study [HUNT]), and carried out linear and nonlinear Mendelian randomization analyses. Among 55,908 participants, the mean age at enrollment was 48.3 years, 26,324 (47.1%) were men, and mean BMI was 26.3 kg/m2. During a median 21 years of follow-up, 2,547 (4.6%) participants experienced a BSI, and 451 (0.8%) died from BSI. Compared with a genetically predicted BMI of 25 kg/m2, a genetically predicted BMI of 30 kg/m2 was associated with a hazard ratio for BSI incidence of 1.78 (95% CI: 1.40 to 2.27; p ConclusionsSupportive of a causal relationship, genetically predicted BMI was positively associated with BSI incidence and mortality in this cohort. Our findings contradict the "obesity paradox," where previous traditional epidemiological studies have found increased BMI to be apparently protective in terms of mortality for patients with BSI or sepsis