Venous thrombosis risk during and after medical and surgical hospitalizations: The medical inpatient thrombosis and hemostasis (MITH) study.

BACKGROUND: Thirty to seventy percent of all venous thromboembolism (VTE) events are associated with hospitalization. The absolute and relative risks during and after hospitalization are poorly characterized. OBJECTIVES: Quantify the absolute rate and relative risk of VTE during and up to 3 months after medical and surgical hospitalizations. PATIENTS/METHODS: We conducted an observational cohort study between 2010 and 2016 of patients cared for by the University of Vermont (UVM) Health Network's primary care population. Cox proportional hazard models with hospitalization modeled as a time-varying covariate were used to estimate VTE risk. RESULTS: Over 4.3 years of follow-up, 55 220 hospitalizations (156 per 1000 person-years) and 713 first venous thromboembolism events (2.0 per 1000 person-years) occurred. Among individuals not recently hospitalized, the rate of venous thromboembolism was 1.4 per 1000 person-years and 71.8 per 1000 person-years during hospitalization. During the first, second, and third months after discharge, the rates of venous thromboembolism were 35.1, 11.3, and 5.2 per 1000 person-years, respectively. Relative to those not recently hospitalized, the age- and sex-adjusted HRs of venous thromboembolism were 38.0 (95% CI 28.0, 51.5) during hospitalization, and 18.4 (95% CI 15.0, 22.6), 6.3 (95% CI 4.3, 9.0), and 3.0 (95% CI 1.7, 5.4) during the first, second, and third months after discharge, respectively. Stratified by medical versus surgical services the rates were similar. CONCLUSION: Hospitalization and up to 3 months after discharge were strongly associated with increased venous thromboembolism risk. These data quantify this risk for use in future studies.

Effects of Thyroid Function on Hemostasis, Coagulation, and Fibrinolysis: A Mendelian Randomization Study.

Background: Untreated hypothyroidism is associated with acquired von Willebrand syndrome, and hyperthyroidism is associated with increased thrombosis risk. However, the causal effects of thyroid function on hemostasis, coagulation, and fibrinolysis are unknown. Methods: In a two-sample Mendelian randomization (MR) study with genome-wide association variants, we assessed causality of genetically predicted hypothyroidism (N = 134,641), normal-range thyrotropin (TSH; N = 54,288) and free thyroxine (fT4) (N = 49,269), hyperthyroidism (N = 51,823), and thyroid peroxidase antibody positivity (N = 25,821) on coagulation (activated partial thromboplastin time, von Willebrand factor [VWF], factor VIII [FVIII], prothrombin time, factor VII, fibrinogen) and fibrinolysis (D-dimer, tissue plasminogen activator [TPA], plasminogen activator inhibitor-1) from the CHARGE Hemostasis Consortium (N = 2583-120,246). Inverse-variance-weighted random effects were the main MR analysis followed by sensitivity analyses. Two-sided p < 0.05 was nominally significant, and p < 0.0011[ = 0.05/(5 exposures × 9 outcomes)] was Bonferroni significant for the main MR analysis. Results: Genetically increased TSH was associated with decreased VWF [ß(SE) = -0.020(0.006), p = 0.001] and with decreased fibrinogen [ß(SE) = -0.008(0.002), p = 0.001]. Genetically increased fT4 was associated with increased VWF [ß(SE) = 0.028(0.011), p = 0.012]. Genetically predicted hyperthyroidism was associated with increased VWF [ß(SE) = 0.012(0.004), p = 0.006] and increased FVIII [ß(SE) = 0.013(0.005), p = 0.007]. Genetically predicted hypothyroidism and hyperthyroidism were associated with decreased TPA [ß(SE) = -0.009(0.024), p = 0.024] and increased TPA [ß(SE) = 0.022(0.008), p = 0.008], respectively. MR sensitivity analyses showed similar direction but lower precision. Other coagulation and fibrinolytic factors were inconclusive. Conclusions: In the largest genetic studies currently available, genetically increased TSH and fT4 may be associated with decreased and increased synthesis of VWF, respectively. Since Bonferroni correction may be too conservative given the correlation between the analyzed traits, we cannot reject nominal associations of thyroid traits with coagulation or fibrinolytic factors.

Physical activity and incident diabetes in American Indians: the Strong Heart Study.

The authors examined the association between total physical activity (leisure-time plus occupational) and incident diabetes among 1,651 American Indians who participated in the Strong Heart Study, a longitudinal study of cardiovascular disease and its risk factors among 13 American Indian communities in 4 states (North Dakota, South Dakota, Oklahoma, and Arizona). Discrete Cox models were used to examine the association between physical activity level (in tertiles), compared with no physical activity, and incident diabetes, after adjustment for potential confounders. During 10 years of follow-up (f1989-1999), 454 incident cases of diabetes were identified. Compared with participants who reported no physical activity, those who reported any physical activity had a lower risk of diabetes: Odds ratios were 0.67 (95% confidence interval (CI): 0.46, 0.99), 0.67 (95% CI: 0.45, 0.99), and 0.67 (95% CI: 0.45, 0.99) for increasing tertile of physical activity, after adjustment for age, sex, study site, education, smoking, alcohol use, and family history of diabetes. Further adjustment for body mass index and other potential mediators attenuated the risk estimates. These data suggest that physical activity is associated with a lower risk of incident diabetes in American Indians. This study identifies physical activity as an important determinant of diabetes among American Indians and suggests the need for physical activity outreach programs that target inactive American Indians.

Cystatin C concentration as a predictor of systolic and diastolic heart failure.

BACKGROUND: Risk factors for heart failure (HF) may differ according to ejection fraction (EF). Higher cystatin C, a marker of kidney dysfunction, is associated with incident HF, but previous studies did not determine EF at diagnosis. We hypothesized that kidney dysfunction would predict diastolic HF (DHF) better than systolic HF (SHF) in the Cardiovascular Health Study. METHODS AND RESULTS: Cystatin C was measured in 4453 participants without HF at baseline. Incident HF was categorized as DHF (EF > or = 50%) or SHF (EF < 50%). We compared the association of cystatin C with the risk for DHF and SHF, after adjustment for age, sex, race, medications, and HF risk factors. During 8 years of follow-up, 167 participants developed DHF and 206 participants developed SHF. After adjustment, sequentially higher quartiles of cystatin C were associated with risk for SHF (competing risks hazard ratios 1.0 [reference], 1.99 [95% confidence interval 1.14-3.48], 2.32 [1.32-4.07], 3.17 [1.82-5.50], P for trend < .001). The risk for DHF was apparent only at the highest cystatin C quartile (hazard ratios 1.0 [reference], 1.09 [0.62-1.89], 1.08 [0.61-1.93], and 1.83 [1.07-3.11]). CONCLUSIONS: Cystatin C levels are linearly associated with the incidence of systolic HF, whereas only the highest concentrations of cystatin C predict diastolic HF.