No evidence linking sleep traits with white blood cell counts: Multivariable-adjusted and Mendelian randomization analyses.

BACKGROUND: Disturbances in habitual sleep have been associated with multiple age-associated diseases. However, the biological mechanisms underpinning these associations remain largely unclear. We assessed the possible involvement of the circulating immune system by determining the associations between sleep traits and white blood cell counts using multivariable-adjusted linear regression and Mendelian randomization. METHODS: Cross-sectional multivariable-adjusted linear regression analyses were done using participants within the normal range of total white blood cell counts (>4.5 × 109 and <11.0 × 109/µL) from UK Biobank. For the sleep traits, we examined (short and long) sleep duration, chronotype, insomnia symptoms and daytime dozing. Two-sample Mendelian randomization analyses were done using instruments for sleep traits derived from European-ancestry participants from UK Biobank (over 410,000 participants) and using SNP-outcome data derived from European-ancestry participants from the Blood Cell Consortium (N = 563,946) to which no data from UK Biobank contributed. RESULTS: Using data from 357,656 participants (mean [standard deviation] age: 56.5 [8.1] years, and 44.4% men), we did not find evidence that disturbances in any of the studied sleep traits were associated with differences in blood cell counts (total, lymphocytes, neutrophiles, eosinophiles and basophiles). Also, we did not find associations between disturbances in any of the studied sleep traits and white blood cell counts using Mendelian Randomization. CONCLUSION: Based on the results from two different methodologies, disturbances in habitual sleep are unlikely to cause changes in blood cell counts and thereby differences in blood cell counts are unlikely to be underlying the observed sleep-disease associations.

Long-term Outcome of Reexploration for Bleeding After Coronary Artery Bypass Grafting.

OBJECTIVES: This study aimed to determine the influence of reexploration for bleeding and blood product requirement after coronary artery bypass grafting (CABG) on long-term mortality. DESIGN: A retrospective cohort study. SETTING: A single-center institution. PARTICIPANTS: All patients who underwent CABG between January 1998 and December 2019 were included. INTERVENTIONS: The parameters were analyzed to assess the association between reexploration for bleeding and long-term mortality. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was all-cause mortality up to the end of follow-up (June 1, 2021). The secondary endpoints were 30-day mortality, duration of admission, blood product transfusion, postoperative use of an intra-aortic balloon pump, deep sternal wound infection, myocardial infarction, and neurologic complications. The Cox proportional hazards model was used to assess the association between reexploration and blood product use and all-cause mortality. Median follow-up was 9.7 years (IQR 5.1-14.6). In total, 576 out of 21,346 (2.7%) patients were reexplored for bleeding. Thirty-day mortality was 6.2% v 1.6% for the reexplored versus not reexplored patients. Reexploration for bleeding was not significantly correlated with long-term mortality (hazard ratio [HR] 1.029; p = 0.068). On the other hand, blood product transfusion (HR = 1.135; p < 0.001), and in particular, packed red blood cell (pRBC) transfusion (HR = 1.139; p < 0.001), was significantly associated with higher long-term mortality. After multivariate Cox regression using ≥5 pRBC transfused as a cut-off point, reexploration for bleeding was not significantly associated with long-term mortality (HR 0.982; p = 0.813). Receiving ≥5 pRBCs was significantly associated with higher long-term mortality (HR 1.249; p < 0.001). CONCLUSION: Reexploration for bleeding was significantly associated with higher 30-day mortality but not with long-term mortality. Poorer long-term mortality was attributed to patient characteristics and higher use of postoperative blood products.