Identification of individuals with ischemic stroke at particularly high risk of venous thromboembolism (VTE) is crucial for targeted thromboprophylaxis. To guide clinical decision‐making and ...development of risk prediction models, increased knowledge on risk factors and biomarkers is needed. Therefore, we set out to identify risk factors and predictors for VTE in people with ischemic stroke by conducting a systematic review of the literature. Medline and Embase were searched from January 1990 and onwards. Studies investigating demographic, clinical, and/or laboratory factors for stroke‐related VTE were considered. Two reviewers screened all retrieved records, independently and in duplicate. Risk of bias assessments were guided by a structured framework (PROSPERO‐ID: CRD42020176361). Of 4674 identified records, 26 studies were included. Twenty‐six demographic, clinical, and laboratory factors associated with increased risk of stroke‐related VTE after multivariable adjustments were identified. The following factors were reported by ≥2 studies: prior VTE, cancer, prestroke disability, leg weakness, increasing lesion volume of the brain infarct, infection, low Barthel Index, increasing length of hospital stay, biochemical indices of dehydration, as well as elevated levels of D‐dimer, C‐reactive protein, and homocysteine. The majority of the studies were of poor quality with moderate or high risk of bias. In conclusion, this systematic review informs on several potential risk factors and predictors for VTE in people with ischemic stroke. To improve risk stratification and guide development of risk prediction models, further confirmation is needed because there were few high‐quality studies on each factor.
Myocardial infarction (MI) is associated with an increased risk of venous thromboembolism (VTE). Obesity is a recognized risk factor for both MI and VTE. Whether obesity further increases the risk of ...VTE in MI patients is scarcely investigated.
To study the joint effect of MI and obesity on the risk of VTE.
Study participants (n = 29 410) were recruited from three surveys of the Tromsø Study (conducted in 1994–1995, 2001, and 2007–2008) and followed up through 2014. All incident MI and VTE cases during follow‐up were recorded. Cox regression models with MI as a time‐dependent variable were used to estimate hazard ratios (HRs) of VTE (adjusted for age and sex) by combinations of MI exposure and obesity status. Joint effects were assessed by calculating relative excess risk and attributable proportion (AP) due to interaction.
During a median of 19.6 years of follow‐up, 2090 study participants experienced an MI and 784 experienced a VTE. Among those with MI, 55 developed a subsequent VTE, yielding an overall incidence rate (IR) of VTE of 5.3 per 1000 person‐years (95% confidence interval CI: 4.1–6.9). In the combined exposure group (MI+/Obesity+), the IR was 11.3 per 1000 person‐years, and the adjusted HR indicated a 3‐fold increased risk of VTE (HR 3.16, 95% CI: 1.99–4.99) compared to the reference group (MI−/Obesity−). The corresponding AP was 0.46 (95% CI: 0.17–0.74).
The combination of MI and obesity yielded a supra‐additive effect on VTE risk of which 46% of the VTE events were attributed to the interaction.
Patients with ischemic stroke have increased risk of venous thromboembolism (VTE). Obesity is prevalent in stroke patients and a well-established risk factor for VTE. Whether obesity further ...increases the VTE risk in patients with stroke remains unclear.
We investigated the joint effect of ischemic stroke and obesity on the risk of incident VTE in a population-based cohort.
Participants (n = 29,920) were recruited from the fourth to sixth surveys of the Tromsø Study (1994-1995, 2001, and 2007-2008) and followed through 2014. Incident events of ischemic stroke and VTE during follow-up were recorded. Hazard ratios (HRs) of VTE with 95% CIs were estimated according to combined categories of ischemic stroke and obesity (body mass index ≥ 30 kg/m2), with exposure to neither risk factors as reference.
During a median follow-up of 19.6 years, 1388 participants experienced ischemic stroke and 807 participants developed VTE. Among those with stroke, 51 developed VTE, yielding an incidence rate of VTE after stroke of 7.2 per 1000 person-years (95% CI, 5.5-9.5). In subjects without stroke, obesity was associated with a 1.8-fold higher VTE risk (HR, 1.76; 95% CI, 1.47-2.11). In nonobese subjects, stroke was associated with a 1.8-fold higher VTE risk (HR, 1.77; 95% CI, 1.27-2.46). Obese subjects with stroke had a 2-fold increased VTE risk (HR, 2.44; 95% CI, 1.37-4.36).
The combination of obesity and ischemic stroke did not yield an excess risk of VTE. Our findings suggest that obese subjects with ischemic stroke do not have a more than additive risk of VTE.
•Ischemic stroke (IS) is associated with an increased risk of venous thromboembolism (VTE).•Obesity may further increase the VTE risk in patients with IS.•We investigated the combined effect of IS and obesity on VTE risk in a large cohort.•Obesity did not result in an excess risk of VTE in patients with IS.
Obesity is a well-established risk factor for venous thromboembolism (VTE). However, data on the proportion of incident VTEs attributed to overweight and obesity in the general population are ...limited.
To investigate the population attributable fraction (PAF) of VTE due to overweight and obesity in a population-based cohort with repeated measurements of body mass index (BMI).
Participants from the fourth to seventh surveys of the Tromsø Study (enrolment: 1994-2016) were followed through 2020, and all incident VTEs were recorded. In total, 36,341 unique participants were included, and BMI measurements were updated for those attending more than one survey. BMI was categorized as <25 kg/m
, 25-30 kg/m
(overweight), and ≥30 kg/m
(obesity). Time-varying Cox regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). The PAF was estimated based on age- and sex-adjusted HRs and the prevalence of BMI categories in VTE cases.
At baseline, the prevalence of overweight and obesity was 37.9 and 13.8%, respectively. During a median follow-up of 13.9 years, 1,051 VTEs occurred. The age- and sex-adjusted HRs of VTE were 1.40 (95% CI: 1.21-1.61) for overweight and 1.86 (95% CI: 1.58-2.20) for obesity compared with subjects with BMI <25 kg/m
. The PAF of VTE due to overweight and obesity was 24.6% (95% CI: 16.6-32.9), with 12.9% (95% CI: 6.6-19.0) being attributed to overweight and 11.7% (95% CI: 8.5-14.9) to obesity. Similar PAFs were obtained in analyses stratified by sex and VTE subtypes (provoked/unprovoked events, deep vein thrombosis, pulmonary embolism).
Our findings indicate that almost 25% of all VTE events can be attributed to overweight and obesity in a general population from Norway.
