Determination of age-specific and sex-specific familial risks for the different manifestations of venous thromboembolism: A nationwide family study in Sweden

Epidemiological trends of deep venous thrombosis in HIV-infected subjects (1997-2013): A nationwide population-based study in Spain

BACKGROUND

Chronic infections may be a triggering factor as well as a risk factor of deep venous thrombosis (DVT). The purpose of this study was to analyze the epidemiological trends of hospital admissions related to DVT in human immunodeficiency virus (HIV)-infected patients during the combination antiretroviral therapy (cART) era, in relation to hepatitis C virus (HCV) serological status.

METHODS

We performed a retrospective study using the Spanish Minimum Basic Data Set. We selected HIV-infected subjects over 15years old with a hospital admission and DVT diagnosis (ICD-9-CM codes: 453.4x and 453.8x) between 1997 and 2013. Patients were classified according to HCV serology. We estimated the incidence (events per 100,000 patient-years) in four calendar periods (1997-1999, 2000-2003, 2004-2007, and 2008-2013).

RESULTS

Overall, the incidence of DVT-related hospitalizations had a significant upward trend in all HIV-infected patients (P<0.001), with significant differences between 1997-1999 and 2008-2013 [49.5 vs. 88.1 (P<0.001)]. Moreover, the incidence was higher in HIV-monoinfected patients than in HIV/HCV-coinfected patients during the entire follow-up (P<0.001). However, the incidence had a significant downward trend in HIV-monoinfected patients (P=0.002) and a significant upward trend in HIV/HCV-coinfected patients (P<0.001). Specifically, the incidence of DVT-related hospitalizations in HIV-monoinfected patients significantly decreased from 1997-1999 to 2008-2013 [142.7 vs. 103.1 (P=0.006)], whereas in HIV/HCV-coinfected patients, the incidence increased from 8.4 (1997-1999) to 70.7 (2008-2013) (P<0.001).

CONCLUSIONS

Our findings suggest that DVT is an emerging health problem among HIV-infected patients, with increasing incidence during the first 17years after the introduction of cART, particularly in HIV/HCV-coinfected patients.

Family history of venous thromboembolism as a risk factor and genetic research tool

Familial clustering of venous thromboembolism (VTE) was described as far back as 1905 by Briggs. Although Egeberg discovered inherited deficiency of antithrombin in 1965, it was not until Dahlback discovered resistance to activated protein C in 1993 that it became clear that genetic factors are common risk factors of VTE. Several genes have been linked to familial aggregation of VTE and genome-wide association studies have found several novel gene loci. Still, it has been estimated that much of the heritability for VTE remains to be discovered. Family history (FH) of VTE is therefore still important to determine whether a patient has an increased genetic risk of VTE. FH has the potential to represent the sum of effects and interactions between environmental and genetic factors. In this article the design, methodology, results, clinical and genetic implications of FH studies of VTE are reviewed. FH in first-degree relatives (siblings and/or parents) is associated with a 2–3 times increased familial relative risk (FRR). However, the FRR is dependent on age, number of affected relatives, and presentation of VTE (provoked/unprovoked). Especially high familial risks are observed in individuals with two or more affected siblings (FFR> 50). However, the familial risk for recurrent VTE is much lower or non-significant. Moreover, FH of VTE appears mainly to be important for venous diseases (i. e. VTE and varicose veins). The familial associations with other diseases are weaker. In conclusion, FH of VTE is an important research tool and a clinically potential useful risk factor for VTE.

Association between small intestinal bacterial overgrowth and deep vein thrombosis

Objective: Small intestinal bacterial overgrowth (SIBO) has been associated with several diseases. The association between SIBO and deep vein thrombosis (DVT) has not been investigated. This study was aimed to investigate the frequency and risk factors for the development of DVT in patients tested for SIBO.

Methods: All 321 eligible patients were included from the Cleveland Clinic Gastrointestinal Motility Lab databank from January 2008 to January 2014. Patients who were evaluated with glucose hydrogen/methane breath test as well as Doppler ultrasonography for suspected DVT were included. Patients with catheter-related DVT were excluded. The primary outcomes were the frequency and risk factors (including SIBO) for DVT in this patient population.

Results: Of the 321-case cohort, 144 patients (44.9%) tested positive for SIBO, and 53 (16.5%) had ultrasonographic findings of DVT. SIBO evaluation before the evaluation of DVT occurred in 201 patients (median time from the breath test to ultrasonography: 27 months; interquartile range [IQR]: 11.0–45.0 months), and SIBO evaluation after evaluation for DVT occurred in 120 patients (median time from ultrasonography to the breath test: 30 months; IQR: 11.8–54.3 months). In the univariate analysis, DVT was associated with family history of thromboembolic events (35.8% vs 16.0%, P=0.001), chronic kidney diseases (CKD; 26.4% vs 13.4%, P=0.019) and the presence of SIBO (69.8% vs 39.9%, P<0.001). In the multivariate analysis, family history of thromboembolic events (odds ratio [OR]: 3.39; 95% confidence interval [CI]: 1.67–6.87; P<0.001), CKD (OR: 2.23; 95%CI: 1.04–4.74; P = 0.037), and the presence of SIBO (OR: 3.27; 95% CI: 1.70–6.32; P < 0.001) remained independently associated with DVT.

Conclusion: SIBO was found to be associated with DVT. The nature of this association warrants further investigation.

Venous thromboembolism and varicose veins share familial susceptibility: a nationwide family study in Sweden

Background

Varicose veins (VVs) have been associated with venous thromboembolism (VTE), but whether these diseases share familial susceptibility has not been determined. This nationwide study aimed to determine whether VTE shares familial susceptibility with VVs.

Methods and Results

Swedish Multigeneration Register data for persons aged 0 to 76 years during the period 1964–2008 were linked to the Swedish Inpatient and Outpatient Registers. Familial risks (standardized incidence ratios [SIRs]) of VTE and VVs were examined in 2 ways (ie, bidirectionally): risk of VTE in subjects whose siblings had been diagnosed with VVs and risk of VVs in persons whose siblings had been diagnosed with VTE. The analyses were repeated for spouses to determine the importance of shared adult family environment. In total, 96 810 siblings had VVs and 87 564 had VTE. An increased risk of VTE was observed in persons whose siblings had VVs (SIR 1.30, 95% CI 1.26 to 1.33), whereas persons whose siblings had VTE had an increased risk of VVs (SIR 1.30, 95% CI 1.27 to 1.34). If 2 or more siblings were affected by VTE, the risk for VVs was 1.70 (95% CI 1.53 to 1.88). Conversely, if 2 or more siblings were affected by VVs, the risk for VTE was 1.52 (95% CI 1.38 to 1.67). In spouses of VTE patients, a minor increased risk of VVs was observed (SIR 1.05 for husbands, SIR 1.06 for wives). The risk of VTE in spouses of VV patients was similarly small (SIR 1.01 for husbands, SIR 1.05 for wives).

Conclusions

VVs and VTE share familial susceptibility. This novel finding suggests the existence of shared familial and possibly genetic factors.

Familial Transmission of Venous Thromboembolism

Background—

Venous thromboembolism (VTE) clusters in families, but the familial risk of VTE has not been determined among adoptees. The aim was to disentangle the contributions of genetic and environmental factors to the familial transmission of VTE.

Methods and Results—

The Swedish Multi-Generation Register was used to follow all Swedish-born adoptees born from 1932 to 2004 (n=80,214) between January 1, 1964, and December 31, 2010, for VTE. The risk of VTE was estimated in adoptees with ≥1 biological parent with VTE compared with adoptees without a biological parent with VTE. The risk of VTE was also estimated in adoptees with ≥1 adoptive parent with VTE compared with adoptees without an adoptive parent with VTE. Adoptees with ≥1 biological parent with VTE (n=137) were more likely to have VTE than adoptees without a biological parent with VTE (standardized incidence ratio) 1.51 (95% confidence interval, 1.27–1.79). The standardized incidence ratio for VTE was highest for adoptees with a biological parent diagnosed with VTE before the age of 50 years (standardized incidence ratio=2.03, 1.24–3.14). In contrast, adoptees with ≥1 adoptive parent with VTE (n=156) were not at increased risk of VTE (standardized incidence ratio=1.07, 0.91–1.25).

Conclusions—

These novel findings suggest that genetic factors make a stronger contribution to the familial transmission of VTE from parents to offspring than family environmental factors.

Family history of venous thromboembolism (VTE) and risk of recurrent hospitalization for VTE: a nationwide family study in Sweden

BACKGROUND

Data concerning the importance of a family history of venous thromboembolism (VTE) for the risk of recurrent VTE are sparse. The aim of this nationwide study was to determine whether a family history of VTE is a risk factor for recurrent hospitalization for unprovoked VTE (deep vein thrombosis of the lower extremities or pulmonary embolism).

METHODS

We linked Multigeneration Register data on individuals aged 0-77 years to the Swedish nationwide Hospital Discharge Register data for the period 1987-2009 to compare the risk of hospitalization for unprovoked recurrent VTE among individuals with and without a parental or sibling history of VTE. We calculated hazard ratios (HRs) to determine the familial HR for recurrent hospitalization for VTE.

RESULTS AND CONCLUSIONS

The risk of recurrent VTE hospitalization was 1.20 (95% confidence interval [CI] 1.10-1.32) for individuals with affected parents, and 1.30 (95% CI 1.14-1.49) for those with affected siblings. The risk of recurrent VTE hospitalization in individuals with two affected parents was 1.92 (95% CI 1.44-2.58). There was an interaction between age at diagnosis of VTE and a family history of VTE, with a family history having a stronger effect on VTE risk in younger patients. We conclude that a family history of VTE is a modest risk factor for recurrent VTE hospitalization in Sweden.

Age-and sex-specific seasonal variation of venous thromboembolism in patients with and without family history: a nationwide family study in Sweden

Seasonal variation in venous thromboembolism (VTE) risk in individuals with familial predisposition to VTE has not been explored. This nationwide study aimed to determine whether there are age- and sex-specific seasonal differences in risk of hospitalisation of VTE among individuals with and without a family history of VTE. The Swedish Multi-Generation Register was linked to Hospital Discharge Register data for the period 1964-2010. Seasonal variation in first VTE events in 1987-2010 for individuals with and without a family history of VTE (siblings or parents) was determined by several independent methods. Stratified analyses were performed according to age, sex, and VTE subtype (pulmonary embolism [PE] or deep venous thrombosis [DVT]). Seasonal variation in VTE incidence, mostly with a peak during the winter, was observed in both sexes in individuals with and without family history with overall peak-to-low ratios (PLRs) of 1.15 and 1.21, respectively. The peak day was December 25 and February 1 for those with and without a family history of VTE, respectively. Seasonal variation was strongest among individuals aged >50 years. Among individuals aged 0-25 years with a family history, the peak for VTE was in July (PLR = 1.20). Significant seasonal variation was observed for PE and DVT with the exception of DVT among those with a family history (PLR = 1.01). In conclusion, our data support the presence of a modest seasonal variation of VTE among individuals with and without a family history of VTE. However, young age and family history may modify and attenuate the effect of season on VTE.

Venous thromboembolism does not share strong familial susceptibility with pre-eclampsia/eclampsia: a nationwide family study in Sweden

OBJECTIVE

Genetic variants associated with venous thromboembolism (VTE) have been suggested to be involved in the pathogenesis of pre-eclampsia/eclampsia (PEC/EC). This nationwide study aimed to determine whether VTE shares familial susceptibility with PEC/EC.

DESIGN

Population-based cohort study.

SETTING

Sweden.

SAMPLE

A total of 941 841 Swedish women delivering their first child between 1987 and 2008.

METHODS

Data from the Swedish Multigeneration Register were linked to the Swedish Hospital Discharge Register. The risk of PEC/EC was determined in primiparous women with a family history of VTE (in parents and/or siblings), compared with primiparous women without a family history of VTE. Odds ratios (ORs) were calculated by logistic regression.

MAIN OUTCOME MEASURE

PEC/EC in first pregnancy.

RESULTS

In total, 43 621 women had PEC/EC in association with their first pregnancy. The OR for PEC/EC in women with a family history of VTE was 1.06 (95% CI 1.01-1.11); however, a family history of VTE was associated with higher odds of PEC/EC among women with previous hypertension (OR 1.38, 95% CI 1.25-1.52).

CONCLUSION

A family history of VTE is weakly associated with PEC/EC risk, and is not clinically useful for the prediction of PEC/EC. The results of the present study suggest that it is unlikely that strong disease-causing mutations shared by VTE and PEC/EC are common in the Swedish population. The novel association between family history and PEC/EC among the subgroup with previous hypertension needs further confirmation in future studies.

Familial risk of venous thromboembolism in first-, second- and third-degree relatives: a nationwide family study in Sweden

Venous thromboembolism (VTE) clusters in families, but the familial risk of VTE has only been determined in first-degree relatives. This nationwide study aimed to determine the familial risk of VTE in first-, second- and third-degree relatives of affected individuals. The Swedish Multi-Generation Register was linked to Hospital Discharge Register data for the period 1987-2009. This was a case-cohort study. Odds ratios (ORs) for VTE were calculated for individuals whose relatives were hospitalised for VTE, as determined by the International Classification of Diseases (ICD), and those whose relatives were unaffected by VTE. The familial OR for VTE was 2.49 in siblings (95% confidence interval [CI] 2.40-2.58), 2.65 in children (2.50-2.80), 2.09 in parents (2.03-2.15), 1.52 in maternal half-siblings (1.26-1.85), 2.34 in paternal half-siblings (2.00-2.73), 1.69 in nieces/nephews (1.57-1.82), 1.47 in cousins (1.33-1.64), and 1.14 in spouses of individuals diagnosed with VTE (1.09-1.18). Familial clustering was stronger at young ages. The familial transmission was slightly stronger for males compared with females but was only significant for siblings 1.13 (1.05-1.22) and parents 1.11 (1.05-1.78) of probands. The present data showing an increased VTE risk among not only first-degree relatives but also second- and third-degree relatives indicate that the genetic component of the familial clustering of VTE is strong. Family history is a potentially useful genetic surrogate marker for clinical VTE risk assessment, even in second- and third degree-relatives.

A nationwide family study of pulmonary embolism: identification of high risk families with increased risk of hospitalized and fatal pulmonary embolism

BACKGROUND

Family history is an important risk factor for deep venous thrombosis. However, few studies have determined the importance of family history of pulmonary embolism (PE).

OBJECTIVE

This nationwide study aimed to determine the familial risks of fatal and hospitalized PE.

METHODS

The Swedish Multi-Generation Register for subjects aged 0 to 76 years old born since 1932 were linked to the Hospital Discharge Register and Cause of Death Register for the period 1964-2008. Standardized incidence ratios (SIRs) for first hospitalization or death (without previous hospitalization for PE) with a main diagnosis of PE were calculated for individuals whose parent or siblings were hospitalized with or died from PE, compared to those whose parent or siblings were not affected by PE.

RESULTS

A total of 20,860 individuals were hospitalized for PE and 862 died due to primary fatal PE (without previous hospitalization for PE). The familial SIR for individuals with one sibling with hospitalized PE was 2.49 (95% CI 1.62-3.83). The familial SIR for siblings with two affected probands was 114.29 (95% CI 56.57-223.95). The familial SIRs for individuals with a parent or sibling hospitalized for PE were significantly increased for fatal PE (1.76; 95% CI 1.38-2.21) and hospitalized PE (2.13; 95% CI 2.04-2.23). Spouses had low overall familial risk for PE (1.09; 95% CI, 1.03-1.14).

CONCLUSION

The high familial risk in multiplex sibling families suggests the existence of strong genetic risk factors for PE. Familial factors and possibly genetic factors are important risk factors for primary fatal pulmonary embolism.