Bariatric Surgery and the Long-Term Risk of Venous Thromboembolism: A Population-Based Cohort Study

PURPOSE

Bariatric surgery is associated with a greater venous thromboembolism (VTE) risk in the weeks following surgery, but the long-term risk of VTE is incompletely characterized. We evaluated bariatric surgery in relation to long-term VTE risk.

MATERIALS AND METHODS

This population-based retrospective matched cohort study within three United States-based integrated health care systems included adults with body mass index (BMI) ≥ 35 kg/m2 who underwent bariatric surgery between January 2005 and September 2015 (n = 30,171), matched to nonsurgical patients on site, age, sex, BMI, diabetes, insulin use, race/ethnicity, comorbidity score, and health care utilization (n = 218,961). Follow-up for incident VTE ended September 2015 (median 9.3, max 10.7 years).

RESULTS

Our population included 30,171 bariatric surgery patients and 218,961 controls; we identified 4068 VTE events. At 30 days post-index date, bariatric surgery was associated with a fivefold greater VTE risk (HRadj = 5.01; 95% CI = 4.14, 6.05) and a nearly fourfold greater PE risk (HRadj = 3.93; 95% CI = 2.87, 5.38) than no bariatric surgery. At 1 year post-index date, bariatric surgery was associated with a 48% lower VTE risk and a 70% lower PE risk (HRadj = 0.52; 95% CI = 0.41, 0.66 and HRadj = 0.30; 95% CI = 0.21, 0.44, respectively). At 5 years post-index date, lower VTE risks persisted, with bariatric surgery associated with a 41% lower VTE risk and a 55% lower PE risk (HRadj = 0.59; 95% CI = 0.48, 0.73 and HRadj = 0.45; 95% CI = 0.32, 0.64, respectively).

CONCLUSION

Although in the short-term bariatric surgery is associated with a greater VTE risk, in the long-term, it is associated with a substantially lower risk.

Levels of procoagulant factors and peak thrombin generation in relation to dementia risk in older adults: The Cardiovascular Health Study

INTRODUCTION

Markers of hemostasis such as procoagulant factors and peak thrombin generation are associated with cardiovascular outcomes, but their associations with dementia risk are unclear. We aimed to evaluate prospective associations of selected procoagulant factors and peak thrombin generation with dementia risk.

METHODS

We measured levels of 7 hemostatic factors (fibrinogen, factor VII coagulant activity [FVIIc], activated factor VII [FVIIa], factor VIIa-antithrombin [FVIIa-AT], factor XI antigen [FXI], peak thrombin generation, and platelet count) among participants in the Cardiovascular Health Study, a cohort of older adults free of dementia in 1992/1993 (n = 3185). Dementia was adjudicated and classified by DSM-IV criteria through 1998/1999. Cox proportional hazards models estimated hazard ratios (HRs) for any dementia associated with 1-standard deviation (SD) differences, adjusting for sociodemographic and clinical factors and APOE genotype. Secondary analyses separately evaluated the risk of vascular dementia, Alzheimer's disease, and mixed dementia.

RESULTS

At baseline, participants had a median age of 73 years. Over 5.4 years of follow-up, we identified 448 dementia cases. There was no evidence of linear associations between levels of these hemostatic factors with any dementia risk (HRs per 1-SD difference ranged from 1.0 to 1.1; 95 % confidence intervals included 1.0). Results of secondary analyses by dementia subtype were similar.

CONCLUSIONS

In this prospective study, there was no strong evidence of linear associations between levels of fibrinogen, FVIIc, FVIIa, FVIIa-AT, FXI, peak thrombin generation, or platelet count with dementia risk. Despite their associations with cardiovascular disease, higher levels of these biomarkers measured among older adults may not reflect dementia risk.

Risk of Arterial and Venous Thrombotic Events Among Patients with COVID-19: A Multi-National Collaboration of Regulatory Agencies from Canada, Europe, and United States

Purpose

Few studies have examined how the absolute risk of thromboembolism with COVID-19 has evolved over time across different countries. Researchers from the European Medicines Agency, Health Canada, and the United States (US) Food and Drug Administration established a collaboration to evaluate the absolute risk of arterial (ATE) and venous thromboembolism (VTE) in the 90 days after diagnosis of COVID-19 in the ambulatory (eg, outpatient, emergency department, nursing facility) setting from seven countries across North America (Canada, US) and Europe (England, Germany, Italy, Netherlands, and Spain) within periods before and during COVID-19 vaccine availability.

Patients and Methods

We conducted cohort studies of patients initially diagnosed with COVID-19 in the ambulatory setting from the seven specified countries. Patients were followed for 90 days after COVID-19 diagnosis. The primary outcomes were ATE and VTE over 90 days from diagnosis date. We measured country-level estimates of 90-day absolute risk (with 95% confidence intervals) of ATE and VTE.

Results

The seven cohorts included 1,061,565 patients initially diagnosed with COVID-19 in the ambulatory setting before COVID-19 vaccines were available (through November 2020). The 90-day absolute risk of ATE during this period ranged from 0.11% (0.09-0.13%) in Canada to 1.01% (0.97-1.05%) in the US, and the 90-day absolute risk of VTE ranged from 0.23% (0.21-0.26%) in Canada to 0.84% (0.80-0.89%) in England. The seven cohorts included 3,544,062 patients with COVID-19 during vaccine availability (beginning December 2020). The 90-day absolute risk of ATE during this period ranged from 0.06% (0.06-0.07%) in England to 1.04% (1.01-1.06%) in the US, and the 90-day absolute risk of VTE ranged from 0.25% (0.24-0.26%) in England to 1.02% (0.99-1.04%) in the US.

Conclusion

There was heterogeneity by country in 90-day absolute risk of ATE and VTE after ambulatory COVID-19 diagnosis both before and during COVID-19 vaccine availability.

Risk of admission to hospital with arterial or venous thromboembolism among patients diagnosed in the ambulatory setting with covid-19 compared with influenza: retrospective cohort study

Objective

To measure the 90 day risk of arterial thromboembolism and venous thromboembolism among patients diagnosed with covid-19 in the ambulatory (ie, outpatient, emergency department, or institutional) setting during periods before and during covid-19 vaccine availability and compare results to patients with ambulatory diagnosed influenza.

Design

Retrospective cohort study.

Setting

Four integrated health systems and two national health insurers in the US Food and Drug Administration's Sentinel System.

Participants

Patients with ambulatory diagnosed covid-19 when vaccines were unavailable in the US (period 1, 1 April-30 November 2020; n=272 065) and when vaccines were available in the US (period 2, 1 December 2020-31 May 2021; n=342 103), and patients with ambulatory diagnosed influenza (1 October 2018-30 April 2019; n=118 618).

Main outcome measures

Arterial thromboembolism (hospital diagnosis of acute myocardial infarction or ischemic stroke) and venous thromboembolism (hospital diagnosis of acute deep venous thrombosis or pulmonary embolism) within 90 days after ambulatory covid-19 or influenza diagnosis. We developed propensity scores to account for differences between the cohorts and used weighted Cox regression to estimate adjusted hazard ratios of outcomes with 95% confidence intervals for covid-19 during periods 1 and 2 versus influenza.

Results

90 day absolute risk of arterial thromboembolism with covid-19 was 1.01% (95% confidence interval 0.97% to 1.05%) during period 1, 1.06% (1.03% to 1.10%) during period 2, and with influenza was 0.45% (0.41% to 0.49%). The risk of arterial thromboembolism was higher for patients with covid-19 during period 1 (adjusted hazard ratio 1.53 (95% confidence interval 1.38 to 1.69)) and period 2 (1.69 (1.53 to 1.86)) than for patients with influenza. 90 day absolute risk of venous thromboembolism with covid-19 was 0.73% (0.70% to 0.77%) during period 1, 0.88% (0.84 to 0.91%) during period 2, and with influenza was 0.18% (0.16% to 0.21%). Risk of venous thromboembolism was higher with covid-19 during period 1 (adjusted hazard ratio 2.86 (2.46 to 3.32)) and period 2 (3.56 (3.08 to 4.12)) than with influenza.

Conclusions

Patients diagnosed with covid-19 in the ambulatory setting had a higher 90 day risk of admission to hospital with arterial thromboembolism and venous thromboembolism both before and after covid-19 vaccine availability compared with patients with influenza.

Association Between Diabetes Severity and Risks of COVID-19 Infection and Outcomes

BACKGROUND

Little is known about whether diabetes increases the risk of COVID-19 infection and whether measures of diabetes severity are related to COVID-19 outcomes.

OBJECTIVE

Investigate diabetes severity measures as potential risk factors for COVID-19 infection and COVID-19 outcomes.

DESIGN, PARTICIPANTS, MEASURES

In integrated healthcare systems in Colorado, Oregon, and Washington, we identified a cohort of adults on February 29, 2020 (n = 1,086,918) and conducted follow-up through February 28, 2021. Electronic health data and death certificates were used to identify markers of diabetes severity, covariates, and outcomes. Outcomes were COVID-19 infection (positive nucleic acid antigen test, COVID-19 hospitalization, or COVID-19 death) and severe COVID-19 (invasive mechanical ventilation or COVID-19 death). Individuals with diabetes (n = 142,340) and categories of diabetes severity measures were compared with a referent group with no diabetes (n = 944,578), adjusting for demographic variables, neighborhood deprivation index, body mass index, and comorbidities.

RESULTS

Of 30,935 patients with COVID-19 infection, 996 met the criteria for severe COVID-19. Type 1 (odds ratio [OR] 1.41, 95% CI 1.27-1.57) and type 2 diabetes (OR 1.27, 95% CI 1.23-1.31) were associated with increased risk of COVID-19 infection. Insulin treatment was associated with greater COVID-19 infection risk (OR 1.43, 95% CI 1.34-1.52) than treatment with non-insulin drugs (OR 1.26, 95% 1.20-1.33) or no treatment (OR 1.24; 1.18-1.29). The relationship between glycemic control and COVID-19 infection risk was dose-dependent: from an OR of 1.21 (95% CI 1.15-1.26) for hemoglobin A1c (HbA1c) < 7% to an OR of 1.62 (95% CI 1.51-1.75) for HbA1c ≥ 9%. Risk factors for severe COVID-19 were type 1 diabetes (OR 2.87; 95% CI 1.99-4.15), type 2 diabetes (OR 1.80; 95% CI 1.55-2.09), insulin treatment (OR 2.65; 95% CI 2.13-3.28), and HbA1c ≥ 9% (OR 2.61; 95% CI 1.94-3.52).

CONCLUSIONS

Diabetes and greater diabetes severity were associated with increased risks of COVID-19 infection and worse COVID-19 outcomes.

Increased COVID-19 Infection Risk Drives Racial and Ethnic Disparities in Severe COVID-19 Outcomes

COVID-19 inequities have been well-documented. We evaluated whether higher rates of severe COVID-19 in racial and ethnic minority groups were driven by higher infection rates by evaluating if disparities remained when analyses were restricted to people with infection. We conducted a retrospective cohort study of adults insured through Kaiser Permanente (Colorado, Northwest, Washington), follow-up in March-September 2020. Laboratory results and hospitalization diagnosis codes identified individuals with COVID-19. Severe COVID-19 was defined as invasive mechanical ventilation or mortality. Self-reported race and ethnicity, demographics, and medical comorbidities were extracted from health records. Modified Poisson regression estimated adjusted relative risks (aRRs) of severe COVID-19 in full cohort and among individuals with infection. Our cohort included 1,052,774 individuals, representing diverse racial and ethnic minority groups (e.g., 68,887 Asian, 41,243 Black/African American, 93,580 Hispanic or Latino/a individuals). Among 7,399 infections, 442 individuals experienced severe COVID-19. In the full cohort, severe COVID-19 aRRs for Asian, Black/African American, and Hispanic individuals were 2.09 (95% CI: 1.36, 3.21), 2.02 (1.39, 2.93), and 2.09 (1.57, 2.78), respectively, compared to non-Hispanic Whites. In analyses restricted to individuals with COVID-19, all aRRs were near 1, except among Asian Americans (aRR 1.82 [1.23, 2.68]). These results indicate increased incidence of severe COVID-19 among Black/African American and Hispanic individuals is due to higher infection rates, not increased susceptibility to progression. COVID-19 disparities most likely result from social, not biological, factors. Future work should explore reasons for increased severe COVID-19 risk among Asian Americans. Our findings highlight the importance of equity in vaccine distribution.

Association of COVID-19 vs Influenza With Risk of Arterial and Venous Thrombotic Events Among Hospitalized Patients

IMPORTANCE

The incidence of arterial thromboembolism and venous thromboembolism in persons with COVID-19 remains unclear.

OBJECTIVE

To measure the 90-day risk of arterial thromboembolism and venous thromboembolism in patients hospitalized with COVID-19 before or during COVID-19 vaccine availability vs patients hospitalized with influenza.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of 41 443 patients hospitalized with COVID-19 before vaccine availability (April-November 2020), 44 194 patients hospitalized with COVID-19 during vaccine availability (December 2020-May 2021), and 8269 patients hospitalized with influenza (October 2018-April 2019) in the US Food and Drug Administration Sentinel System (data from 2 national health insurers and 4 regional integrated health systems).

EXPOSURES

COVID-19 or influenza (identified by hospital diagnosis or nucleic acid test).

MAIN OUTCOMES AND MEASURES

Hospital diagnosis of arterial thromboembolism (acute myocardial infarction or ischemic stroke) and venous thromboembolism (deep vein thrombosis or pulmonary embolism) within 90 days. Outcomes were ascertained through July 2019 for patients with influenza and through August 2021 for patients with COVID-19. Propensity scores with fine stratification were developed to account for differences between the influenza and COVID-19 cohorts. Weighted Cox regression was used to estimate the adjusted hazard ratios (HRs) for outcomes during each COVID-19 vaccine availability period vs the influenza period.

RESULTS

A total of 85 637 patients with COVID-19 (mean age, 72 [SD, 13.0] years; 50.5% were male) and 8269 with influenza (mean age, 72 [SD, 13.3] years; 45.0% were male) were included. The 90-day absolute risk of arterial thromboembolism was 14.4% (95% CI, 13.6%-15.2%) in patients with influenza vs 15.8% (95% CI, 15.5%-16.2%) in patients with COVID-19 before vaccine availability (risk difference, 1.4% [95% CI, 1.0%-2.3%]) and 16.3% (95% CI, 16.0%-16.6%) in patients with COVID-19 during vaccine availability (risk difference, 1.9% [95% CI, 1.1%-2.7%]). Compared with patients with influenza, the risk of arterial thromboembolism was not significantly higher among patients with COVID-19 before vaccine availability (adjusted HR, 1.04 [95% CI, 0.97-1.11]) or during vaccine availability (adjusted HR, 1.07 [95% CI, 1.00-1.14]). The 90-day absolute risk of venous thromboembolism was 5.3% (95% CI, 4.9%-5.8%) in patients with influenza vs 9.5% (95% CI, 9.2%-9.7%) in patients with COVID-19 before vaccine availability (risk difference, 4.1% [95% CI, 3.6%-4.7%]) and 10.9% (95% CI, 10.6%-11.1%) in patients with COVID-19 during vaccine availability (risk difference, 5.5% [95% CI, 5.0%-6.1%]). Compared with patients with influenza, the risk of venous thromboembolism was significantly higher among patients with COVID-19 before vaccine availability (adjusted HR, 1.60 [95% CI, 1.43-1.79]) and during vaccine availability (adjusted HR, 1.89 [95% CI, 1.68-2.12]).

CONCLUSIONS AND RELEVANCE

Based on data from a US public health surveillance system, hospitalization with COVID-19 before and during vaccine availability, vs hospitalization with influenza in 2018-2019, was significantly associated with a higher risk of venous thromboembolism within 90 days, but there was no significant difference in the risk of arterial thromboembolism within 90 days.

Incident thrombus location and predicting risk of recurrent venous thromboembolism

Background

Understanding venous thromboembolism (VTE) recurrence risk is central to determining the appropriate treatment course. Whether this risk varies after discontinuing anticoagulation or overall by type of incident event (pulmonary embolism [PE] vs deep vein thrombosis [DVT]) and by the detailed location of the DVT needs further clarification.

Methods

In this population‐based inception cohort of incident VTE cases with follow‐up by electronic health record review, incident DVT was categorized as distal, popliteal, or iliofemoral. We used the Fine‐Gray regression model to describe the predictive association of the thrombus location with the risk of recurrence before death.

Results

Among 2766 participants with an incident event from 2002 to 2010, 1713 (62%) ceased anticoagulation and were followed for recurrent events; 301 events were observed during the 4.5 years of follow‐up. Relative to participants with an incident thrombus in an iliofemoral location and no PE, those with a thrombus in a popliteal location and no PE had a similar risk of recurrence (adjusted subdistribution hazard ratio [aSHR], 0.82 [95% confidence interval (CI), 0.57–1.19]), while those with a thrombus in a distal location and no PE and those with a thrombus that included a PE had lower risk of recurrence: aSHR, 0.34 (95% CI, 0.20‐0.57); and aSHR, 0.58 (95% CI 0.45‐0.76), respectively.

Conclusions

The findings of this population‐based inception cohort confirm that the risk of recurrent VTE after discontinuing anticoagulants is similar after iliofemoral and popliteal DVT but is lower after distal DVT. Recurrence may be lower after PE than proximal DVT.

Comparative venous thromboembolic safety of oral and transdermal postmenopausal hormone therapies among women Veterans

OBJECTIVE

Hormone therapy (HT) is used by menopausal women to treat vasomotor symptoms. Venous thromboembolism (VTE) is an important risk of HT use, and more knowledge on the comparative safety of different estrogenic compounds is useful for women who use HT for these symptoms. The objective was to compare the risk of VTE among users of oral conjugated equine estrogen (CEE), oral estradiol (E2), and transdermal E2, in a cohort of women veterans.

METHODS

This retrospective cohort study included all women veterans aged 40 to 89 years, using CEE or E2, without prior VTE, between 2003 and 2011. All incident VTE events were adjudicated. Time-to-event analyses using a time-varying HT exposure evaluated the relative VTE risk between estrogen subtypes, with adjustment for age, race, and body mass index, with stratification for prevalent versus incident use of HT.

RESULTS

Among 51,571 users of HT (74.5% CEE, 12.6% oral, and 12.9% transdermal E2 at cohort entry), with a mean age of 54.0 years, the incidence of VTE was 1.9/1,000 person-years. Compared with CEE use, in the multivariable regression model, there was no difference in the risk of incident VTE associated with oral E2 use (hazard ratio 0.96, 95% CI 0.64-1.46) or with transdermal E2 use (hazard ratio 0.95, 95% CI 0.60-1.49). Results were unchanged when restricting to incident users of HT.

CONCLUSIONS

Among women veterans, the risk of VTE was similar in users of oral CEE, oral E2, and transdermal E2. These findings do not confirm the previously observed greater safety of transdermal and oral E2 over CEE.

Hemostatic factor levels and cognitive decline in older adults: The Cardiovascular Health Study

BACKGROUND

Hemostasis is a key factor in cerebrovascular disease, but the association of hemostatic factors with cognitive decline is unclear.

OBJECTIVE

To prospectively evaluate associations of 20 hemostatic factor levels with changes in cognition during ≥8 years of follow-up in the Cardiovascular Health Study (CHS) of older adults.

METHODS

We included participants of an existing CHS cross-sectional substudy (n = 400) with hemostatic factors measured in 1989-1990. Between 1989-1990 and 1998-1999, cognitive function was measured using the Modified Mini-Mental State Examination (3MSE) and Digit Symbol Substitution Tests. Mixed-effects linear regression models estimated change in cognitive function over time, adjusting for sociodemographic and clinical factors and APOE genotype, using Bonferroni adjustment. We also derived principal components to account for the interrelationship among factors.

RESULTS

Of 20 factors evaluated individually, only higher levels of plasmin-α2 -antiplasmin complex (PAP), tissue factor pathway inhibitor (TFPI), and lower factor X (FXc) levels were associated with faster cognitive decline, estimated by annual change in 3MSE points (1 standard deviation PAP β = -0.65, 95% confidence interval [CI]: -1.08 to -0.21; TFPI β = -0.55, 95% CI: -0.90 to -0.19; FXc β = 0.52, 95% CI: 0.21-0.84). One of four principal components, loading positively on D-dimer, prothrombin fragment 1.2 (F1.2), and PAP was significantly associated with change in 3MSE.

CONCLUSIONS

Levels of PAP, TPFI, and FXc and a combination of factors driven by PAP, D-dimer, and F1.2 were associated with cognitive decline. Whether these findings can be used to improve dementia prevention or prediction requires further study.

Renin-Angiotensin-Aldosterone System Inhibitors and COVID-19 Infection or Hospitalization: A Cohort Study

Background

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) may increase the risk of coronavirus disease 2019 (COVID-19) infection or affect disease severity. Prior studies have not examined risks by medication dose.

Methods

This retrospective cohort study included people aged ≥18 years enrolled in a US integrated healthcare system for at least 4 months as of 2/29/2020. Current ACEI and ARB use was identified from pharmacy data, and the estimated daily dose was calculated and standardized across medications. COVID-19 infections and hospitalizations were identified through 6/14/2020 from laboratory and hospitalization data. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for race/ethnicity, obesity, and other covariates.

Results

Among 322,044 individuals, 826 developed COVID-19 infection. Among people using ACEI/ARBs, 204/56,105 developed COVID-19 (3.6 per 1,000 individuals) compared with 622/265,939 without ACEI/ARB use (2.3 per 1,000), yielding an adjusted OR of 0.91 (95% CI 0.74–1.12). For use of <1 defined daily dose (DDD) vs. nonuse, the adjusted OR for infection was 0.92 (95% CI 0.66–1.28); for 1 to <2 DDDs, 0.89 (95% CI 0.66–1.19); and for ≥2 DDDs, 0.92 (95% CI 0.72–1.18). The OR was similar for ACEIs and ARBs and in subgroups by age and sex. 26% of people with COVID-19 infection were hospitalized; the adjusted OR for hospitalization in relation to ACEI/ARB use was 0.98 (95% CI 0.63–1.54), and there was no association with dose.

Conclusions

These findings support current recommendations that individuals on these medications continue their use.

Renin-angiotensin-aldosterone system inhibitors and COVID-19 infection or hospitalization: a cohort study

There are plausible mechanisms by which angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) may increase the risk of COVID-19 infection or affect disease severity. To examine the association between these medications and COVID-19 infection or hospitalization, we conducted a retrospective cohort study within a US integrated healthcare system. Among people aged ≥18 years enrolled in the health plan for at least 4 months as of 2/29/2020, current ACEI and ARB use was identified from pharmacy data, and the estimated daily dose was calculated and standardized across medications. COVID-19 infections were identified through 6/14/2020 from laboratory and hospitalization data. We used logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals. Among 322,044 individuals, 720 developed COVID-19 infection. Among people using ACEI/ARBs, 183/56,105 developed COVID-19 (3.3 per 1000 individuals) compared with 537/265,939 without ACEI/ARB use (2.0 per 1000), yielding an adjusted OR of 0.94 (95% CI 0.75-1.16). For use of < 1 defined daily dose vs. nonuse, the adjusted OR for infection was 0.89 (95% CI 0.62-1.26); for 1 to < 2 defined daily doses, 0.97 (95% CI 0.71-1.31); and for ≥2 defined daily doses, 0.94 (95% CI 0.72-1.23). The OR was similar for ACEIs and ARBs and in subgroups by age and sex. 29% of people with COVID-19 infection were hospitalized; the adjusted OR for hospitalization in relation to ACEI/ARB use was 0.92 (95% CI 0.54-1.57), and there was no association with dose. These findings support current recommendations that individuals on these medications continue their use.

People taking angiotensin converting enzyme inhibitors and angiotensin receptor blockers, including those using high doses, can continue to take them without concern about higher risk of COVID 19 infection.

Adiposity throughout the life course and risk of venous thromboembolism

OBJECTIVE

Adult body mass index (BMI) is strongly associated with venous thromboembolism (VTE), however whether earlier-life adiposity or other measures of adult adiposity are associated with VTE risk remains largely unknown.

MATERIALS AND METHODS

We evaluated associations of childhood somatotype, BMI in early adulthood, adult adiposity, and change in weight since early adulthood with incident VTE risk over ≥20 years of follow-up among 205,935 participants from Nurses' Health Studies (NHS/NHS II) and Health Professionals Follow-Up Study (HPFS), ages 29-76 at baseline. We estimated multivariable-adjusted hazard ratios for VTE using Cox proportional hazards models.

RESULTS AND CONCLUSIONS

Somatotype in childhood and young adulthood BMI were not significantly associated with VTE risk, after accounting for adult BMI. Adult BMI was strongly associated with VTE in all three cohorts (e.g., multivariable-adjusted HRs comparing ≥35 kg/m² vs. <22.5 kg/m²: NHS:3.03[95% CI: 2.58, 3.56], NHS II:3.82[95% CI: 3.24, 4.51], HPFS:2.81 [95% CI: 2.08, 3.80]; all p-trends < 0.01). Adult waist circumference was associated with greater VTE risk, even after adjusting for adult BMI (all p-trends < 0.01). Increasing weight gain from young adulthood was significantly associated with VTE after adjusting for current BMI among women (HR comparing gain ≥20 kg vs. no change: NHS:1.36[95% CI: 1.13, 1.65], NHS II:1.48[95% CI: 1.17, 1.87]) and not men (HPFS:1.20[95% CI: 0.97, 1.50]). These results indicate that BMI and adiposity are likely more important acutely than cumulatively over time in the etiology and prevention of VTE. Clinically, encouraging weight loss in individuals who are overweight or obese could help reduce VTE risk.

Reduction in physical function in women after venous thromboembolism

Essentials The association of venous thromboembolism (VTE) with subsequent physical function remains unclear. We prospectively evaluated this relationship among women from the Nurses' Health Studies. We found a decline in physical function over four years in women with incident VTE. This decline was somewhat greater among women specifically reporting a pulmonary embolism.

SUMMARY

Background Physical function is integral to healthy aging; however, limited research has examined the association of venous thromboembolism(VTE) with subsequent physical function. Objectives To prospectively evaluate the relationship between VTE and decline in physical function among 80 836 women from the Nurses' Health Study(NHS), ages 46-72 in 1992, and 84 304 women from the Nurses' Health Study II(NHS II), ages 29-48 in 1993. Methods Physical function was measured by the Medical Outcomes Short Form-36 physical function scale, administered every 4 years. We compared change in physical function for women with vs. without an incident VTE in each 4-year follow-up period using multivariable linear regression. Results We observed a decline in physical function over 4 years when comparing women with vs. those without incident VTE in both older (NHS) and younger (NHS II) women (multivariable-adjusted mean difference NHS, -6.5 points [95% CI -7.4, -5.6] per 4 years; NHS II, -3.8 [95% CI -5.6, -2.0]). This difference appeared greater among women specifically reporting a pulmonary embolism (NHS, -7.4 [95% CI -8.7, -6.1]; NHS II, -4.8 [95% CI -6.8, -2.8]), and was equivalent to 6.2 years of aging. Whereas longer-term slopes of physical function decline following a VTE were not different from the slopes of decline in women without a VTE, the absolute level of physical function of women with VTE was worse at the end of follow-up compared to women without VTE. Conclusions In this prospective cohort, incident VTE was strongly associated with an acute decline in physical function. These results suggest it may be clinically important to consider approaches to ameliorating functional deficits shortly after VTE diagnosis.

Vasomotor symptoms and the risk of incident venous thrombosis in postmenopausal women

Essentials Vasomotor symptoms have been proposed as markers of changing cardiovascular risk. In this cohort study, we evaluated these symptoms as markers of venous thrombosis (VT) risk. We found no evidence that vasomotor symptom presence or severity were associated with VT risk. Among these postmenopausal women, vasomotor symptoms are not a useful marker of VT risk.

SUMMARY

Background Vasomotor symptoms may be markers of changes in cardiovascular risk, but it is unknown whether these symptoms are associated with the risk of venous thrombosis (VT). Objective To evaluate the association of vasomotor symptom presence and severity with incident VT risk among postmenopausal women, independent of potential explanatory variables. Methods This cohort study included participants of the Women's Health Initiative (WHI) Hormone Therapy Trials (n = 24 508) and Observational Study (n = 87 783), analyzed separately. At baseline, women reported whether hot flashes or night sweats were present and, if so, their severity. Using Cox proportional hazards models, we estimated the VT risk associated with vasomotor symptom presence and severity, adjusted for potential explanatory variables: age, body mass index, smoking status, race/ethnicity, and time-varying current hormone therapy use. Results At baseline, WHI Hormone Therapy Trial participants were aged 64 years and WHI Observational Study participants were aged 63 years, on average. In the WHI Hormone Therapy Trials over a median of 8.2 years of follow-up, 522 women experienced a VT event. In the WHI Observational Study, over 7.9 years of follow-up, 1103 women experienced a VT event. In adjusted analyses, we found no evidence of an association between vasomotor symptom presence (hazard ratio [HR]adj  0.91, 95% confidence interval [CI] 0.75-1.1 in the WHI Hormone Therapy Trials; HRadj  1.1, 95% CI 0.99-1.3 in the WHI Observational Study) or severity (HRadj for severe versus mild 0.99, 95% CI 0.53-1.9 in the WHI Hormone Therapy Trials; HRadj  1.3, 95% CI 0.89-2.0) in the WHI Observational Study) and the risk of incident VT. Conclusions Although vasomotor symptoms have been associated with the risk of other cardiovascular events in published studies, our findings do not suggest that vasomotor symptoms constitute a marker of VT risk.

Interaction of a genetic risk score with physical activity, physical inactivity, and body mass index in relation to venous thromboembolism risk

INTRODUCTION

Venous thromboembolism (VTE) is highly heritable. Physical activity, physical inactivity and body mass index (BMI) are also risk factors, but evidence of interaction between genetic and environmental risk factors is limited.

METHODS

Data on 2,134 VTE cases and 3,890 matched controls were obtained from the Nurses' Health Study (NHS), Nurses' Health Study II (NHS II), and Health Professionals Follow-up Study (HPFS). We calculated a weighted genetic risk score (wGRS) using 16 single nucleotide polymorphisms associated with VTE risk in published genome-wide association studies (GWAS). Data on three risk factors, physical activity (metabolic equivalent [MET] hours per week), physical inactivity (sitting hours per week) and BMI, were obtained from biennial questionnaires. VTE cases were incident since cohort inception; controls were matched to cases on age, cohort, and genotype array. Using conditional logistic regression, we assessed joint effects and interaction effects on both additive and multiplicative scales. We also ran models using continuous wGRS stratified by risk-factor categories.

RESULTS

We observed a supra-additive interaction between wGRS and BMI. Having both high wGRS and high BMI was associated with a 3.4-fold greater risk of VTE (relative excess risk due to interaction = 0.69, p = 0.046). However, we did not find evidence for a multiplicative interaction with BMI. No interactions were observed for physical activity or inactivity.

CONCLUSION

We found a synergetic effect between a genetic risk score and high BMI on the risk of VTE. Intervention efforts lowering BMI to decrease VTE risk may have particularly large beneficial effects among individuals with high genetic risk.

Cross-sectional association of endogenous steroid hormone, sex hormone-binding globulin, and precursor steroid levels with hemostatic factor levels in postmenopausal women

Essentials Endogenous hormone levels' influence on hemostatic factor levels is not fully characterized. We tested for associations of endogenous hormone with hemostatic factor levels in postmenopause. Estrone levels were inversely associated with the natural anticoagulant, protein S antigen. Dehydroepiandrosterone sulfate levels were inversely associated with thrombin generation.

SUMMARY

Background Oral use of exogenous estrogen/progestin alters hemostatic factor levels. The influence of endogenous hormones on these levels is incompletely characterized. Objectives Our study aimed to test whether, among postmenopausal women, high levels of estradiol (E2), estrone (E1), testosterone (T), dehydroepiandrosterone sulfate (DHEAS), dehydroepiandrosterone (DHEA), and androstenedione, and low levels of sex hormone-binding globulin (SHBG), are positively associated with measures of thrombin generation (TG), a normalized activated protein C sensitivity ratio (nAPCsr), and factor VII activity (FVIIc), and negatively associated with antithrombin activity (ATc) and total protein S antigen (PSAg). Methods This Heart and Vascular Health study cross-sectional analysis included 131 postmenopausal women without a prior venous thrombosis who were not currently using hormone therapy. Adjusted mean differences in TG, nAPCsr, FVIIc, ATc and PSAg levels associated with differences in hormone levels were estimated using multiple linear regression. We measured E2, E1, total T, DHEAS, DHEA and androstenedione levels by mass spectrometry, SHBG levels by immunoassay, and calculated the level of free T. Results One picogram per milliliter higher E1 levels were associated with 0.24% lower PSAg levels (95% Confidence Interval [CI]: -0.35, -0.12) and 1 μg mL-1 higher DHEAS levels were associated with 40.8 nm lower TG peak values (95% CI: -59.5, -22.2) and 140.7 nm×min lower TG endogenous thrombin potential (ETP) (95% CI: -212.1, -69.4). After multiple comparisons correction, there was no evidence for other associations. Conclusions As hypothesized, higher E1 levels were associated with lower levels of the natural anticoagulant PSAg. Contrary to hypotheses, higher DHEAS levels were associated with differences in TG peak and ETP that suggest less generation of thrombin.

Environmental and Genetic Risk Factors Associated with Venous Thromboembolism

Venous thromboembolism (VTE) includes deep vein thrombosis and pulmonary embolism, and a combination of environmental and genetic risk factors contributes to VTE risk. Within environmental risk factors, some are provoking (e.g., cancer, surgery, trauma or fracture, immobilization, pregnancy and the postpartum period, long-distance travel, hospitalization, catheterization, and acute infection) and others are nonprovoking (e.g., age, sex, race/ethnicity, body mass index and obesity, oral contraceptive or hormone therapy use, corticosteroid use, statin use, diet, physical activity, sedentary time, and air pollution). Additionally, VTE has a strong genetic basis, with approximately 50 to 60% of the variance in VTE incidence attributed to genetic effects. Some genetic susceptibility variants that contribute to risk have been identified in candidate genes, mostly related to the clotting system and responsible for inherited hypercoagulable states (e.g., factor V Leiden, prothrombin, fibrinogen gamma, or blood group non-O). Other susceptibility single-nucleotide polymorphisms have been identified from genome-wide association studies, such as the two new loci in TSPAN15 (rs78707713) and SCL44A2 (rs2288904) genes. Risk factors are not always associated with VTE in isolation; however, and an understanding of how environmental and genetic factors interact may provide insight into the pathophysiology of VTE, possibly identifying opportunities for targeted prevention and treatment.

The association of statin therapy with the risk of recurrent venous thrombosis

Essentials A lowered risk of recurrent venous thrombosis (VT) with statin treatment is controversial. Among observational inception cohort of 2,798 adults with incident VT, 457 had recurrent VT. Time-to-event models with time-varying statin use and adjustment for potential confounders was used for analysis. Compared to nonuse, current statin use was associated with 26% lower risk of recurrent VT. Click to hear Prof. Büller's perspective on Anticoagulant Therapy in the Treatment of Venous Thromboembolism

SUMMARY

Background Meta-analyses of randomized controlled trials suggest that treatment with hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) lowers the risk of incident venous thrombosis (VT), particularly among those without prevalent clinical cardiovascular disease (CVD). Whether this is true for the prevention of recurrent VT is debated. We used an observational inception cohort to estimate the association of current statin use with the risk of recurrent VT. Methods and Results The study setting was a large healthcare organization with detailed medical record and pharmacy information at cohort entry and throughout follow-up. We followed 2798 subjects 18-89 years of age who experienced a validated incident VT between January 1, 2002, and December 31, 2010, for a first recurrent VT, validated by medical record review. During follow-up, 457 (16%) developed a first recurrent VT. In time-to-event models incorporating time-varying statin use and adjusting for potential confounders, current statin use was associated with a 26% lower risk of recurrent VT: hazard ratio 0.74, 95% confidence interval 0.59-0.94. Among cohort members free of CVD (n = 2134), current statin use was also associated with a lower risk (38%) of recurrent VT: hazard ratio 0.62, 95% confidence interval 0.45-0.85. We found similar results when restricting to new users of statins and in subgroups of different statin types and doses. Conclusions In a population-based cohort of subjects who had experienced an incident VT, statin use, compared with nonuse, was associated with a clinically relevant lower risk of recurrent VT. These findings suggest a potential secondary benefit of statins among patients who have experienced an incident VT.

Pre-pregnancy BMI, delivery BMI, gestational weight gain and the risk of postpartum venous thrombosis

OBJECTIVE

To characterize the risk of postpartum venous thromboembolism (VTE) associated with body-mass-index (BMI) in both pre-pregnancy and at delivery, and with gestational weight gain (GWG).

METHODS

In a population-based, case-control study, we identified all women in Washington State with ICD-9 codes for VTE in the postpartum period between 2003 and 2011. Controls were women without VTE in the postpartum period, matched by delivery year to cases. Pre-pregnancy BMI, delivery BMI, and covariates were abstracted from birth certificates. Adjusted logistic regression models separately estimated postpartum VTE risk associated with categories of BMI in pre-pregnancy and at delivery.

RESULTS

Cases (n=289) had a higher mean BMI than controls (n=4208) pre-pregnancy (29.9kg/m(2) and 26.3kg/m(2), respectively) and at delivery (34.8kg/m(2) vs. 31.4kg/m(2), respectively), with similar gestational weight gains. Compared with women with a normal pre-pregnancy BMI (18.5-24.9kg/m(2)), overweight (BMI 25-29.9kg/m(2)) and obese (BMI≥30kg/m(2)) women were at a 1.5-fold and 1.8-4 fold greater risk of postpartum VTE, respectively, with greatest risks in women with class III obesity (BMI≥40kg/m(2): OR 4.0, 95%CI 2.7-6.3). Observed associations of delivery BMI with postpartum VTE were less strong than those of pre-pregnancy BMI. Large weight gains during pregnancy (>22kg) also contributed to greater VTE risks (OR 1.5, 95%CI 1.0-2.2).

CONCLUSION

Maternal BMI is an important risk factor for postpartum VTE, grading from weak in overweight women to very strong in women with class III obesity. Care providers may prefer to use pre-pregnancy BMI, along gestational weight gain, when stratifying the risk of postpartum VTE at delivery.

Hysterectomy and Bilateral Salpingo-Oophorectomy: Variations by History of Military Service and Birth Cohort

INTRODUCTION

Little is known about hysterectomy and bilateral salpingo-oophorectomy (BSO), which are associated with both health risks and benefits, among women Veterans.

PURPOSE OF THE STUDY

To compare the prevalence of hysterectomy with or without BSO, and early hysterectomy, between postmenopausal Veterans and non-Veterans.

DESIGN AND METHODS

We used baseline data from the Women's Health Initiative Clinical Trial and Observational Study. Multinomial logistic regression models examined differences in the prevalence of hysterectomy (neither hysterectomy nor BSO, hysterectomy without BSO, and hysterectomy with BSO) between Veterans and non-Veterans. Generalized linear models were used to determine whether early hysterectomy (before age 40) differed between Veterans and non-Veterans. Analyses were stratified by birth cohort (<65, ≥65 years at enrollment).

RESULTS

The unadjusted prevalence of hysterectomy without BSO was similar among Veterans and non-Veterans in both birth cohorts (<65: 22% vs 21%; ≥65: 22% vs 21%). The unadjusted prevalence of hysterectomy with BSO was equivalent among Veterans and non-Veterans in the >65 cohort (21%), but higher among Veterans in the <65 cohort (22% vs 19%). In adjusted analyses, although no differences were observed in the >65 cohort, Veterans in the <65 cohort had higher odds of hysterectomy without BSO (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.03, 1.36) and with BSO (OR 1.26, 95% CI 1.10, 1.45), as well as elevated risk of early hysterectomy (relative risk 1.32, 95% CI 1.19, 1.47), compared with non-Veterans.

IMPLICATIONS

Aging women Veterans may have higher prevalence of hysterectomy and BSO than non-Veterans. This information contributes to understanding the health needs and risks of women Veterans and can inform clinical practice and policy for this population.

The association of F11 genetic variants with the risk of incident venous thrombosis among women, by statin use

Supplementary Material to this article is available online at www.thrombosis-online.com.

Association between newborn birth weight and the risk of postpartum maternal venous thromboembolism: a population-based case-control study

BACKGROUND

Postpartum venous thromboembolism (VTE) is a potentially fatal and preventable event leading to substantial short- and long-term morbidity. We sought to evaluate whether the delivery of term newborns of low or high birth weight was associated with greater risks of VTE.

METHODS AND RESULTS

In a population-based case-control study conducted in Washington State from 1987 through 2011, cases of hospitalized VTE within 3 months of delivery were identified by using selected International Classification of Diseases, Ninth Revision, Clinical Modification codes. Controls were randomly selected postpartum women without VTE, matched on birth year. Birth weight and other maternal and pregnancy characteristics were extracted from birth certificate data. Among term live singleton deliveries, we compared the risk of VTE for mothers of newborns of low and high birth weights (<2500 g and >4000 g, respectively) versus mothers of newborns of normal birth weight (2500-4000 g). Logistic regression models were adjusted for maternal age, race, education, body mass index, parity, delivery methods, gestational length, smoking, gestational diabetes mellitus, and preeclampsia. Patients with VTE (n=547) were older, had a higher body mass index, and experienced more pregnancy-related complications than controls (n=9482). In comparison with mothers of newborns with normal birth weight, mothers of newborns with low birth weight had a 3-fold increased risk of VTE, which persisted after multivariable adjustment (odds ratio, 2.98; 95% confidence interval, 1.80-4.93). Mothers of newborns with high birth weight had only a slightly increased risk of VTE, which was attenuated after multivariable adjustment (odds ratio, 1.26; 95% confidence interval, 0.99-1.61).

CONCLUSIONS

The delivery of a newborn with low birth weight is associated with a 3-fold increased risk of maternal postpartum VTE. This should be considered when assessing VTE risk at delivery.

Racial and ethnic differences in the risk of postpartum venous thromboembolism: a population-based, case-control study

BACKGROUND

Venous thromboembolism (VTE) is a major contributor of maternal morbidity and mortality. Whether maternal race/ethnicity is associated with the risk of postpartum VTE remains unclear.

METHODS AND RESULTS

We conducted a population-based, case-control study in Washington State, from 1987 through 2011. Cases comprised all women with selected International Classification of Diseases, Ninth Edition, Clinical Modification codes for hospitalized VTE within 3 months post-delivery. Controls were randomly selected postpartum women who did not experience a VTE. Characteristics of women and their deliveries were abstracted from birth certificates. Using logistic regression models, we compared the risk of postpartum VTE in black, Asian, and Hispanic women with that in non-Hispanic white women, after adjustment for maternal characteristics (age, body mass index, parity, education), pregnancy complications, and delivery methods.

RESULTS

Our study comprised 688 cases and 10 246 controls. Among controls, the mean age and body mass index were 27.5 years and 26.3 kg m(-2) , respectively. Compared with white women, black and Asian women had a greater and lower risk of postpartum VTE (adjusted odds ratio [OR] 1.50, 95% confidence interval [CI] 1.10-2.04 and OR 0.67, 95%CI 0.48-0.94, respectively). A lower risk was present in Hispanic women (adjusted OR 0.80, 95% CI 0.61-1.06) but was not statistically significant. In subgroup analyses, we observed an increased risk for black compared with white women among women who delivered via cesarean section (OR 2.03, 95% CI 1.34-3.07) but not among vaginal deliveries (OR 1.03, 95% CI 0.61-1.74).

CONCLUSIONS

Maternal race/ethnicity is associated with the risk of postpartum VTE, independently of other risk factors, and should be considered when assessing the use of thromboprophylaxis after delivery.

Age-specific strategies for immunization reminders and recalls: a registry-based randomized trial

BACKGROUND

Although previous studies have found reminder/recall to be effective in increasing immunization rates, little guidance exists regarding the specific ages at which it is optimal to send reminder/recall notices.

PURPOSE

To assess the relative effectiveness of centralized reminder/recall strategies targeting age-specific vaccination milestones among children in urban areas during June 2008-June 2009.

METHODS

Three reminder/recall strategies used capabilities of the Michigan Care Improvement Registry (MCIR), a statewide immunization information system: a 7-month recall strategy, a 12-month reminder strategy, and a 19-month recall strategy. Eligible children were randomized to notification (intervention) or no notification groups (control). Primary study outcomes included MCIR-recorded immunization activity (administration of ≥1 new dose, entry of ≥1 historic dose, entry of immunization waiver) within 60 days following each notification cycle.

RESULTS

A total of 10,175 children were included: 2,072 for the 7-month recall, 3,502 for the 12-month reminder, and 4,601 for the 19-month recall. Immunization activity was similar between notification versus no notification groups at both 7 and 12 months. Significantly more 19-month-old children in the recall group (26%) had immunization activity compared to their counterparts who did not receive a recall notification (19%).

CONCLUSIONS

Although recall notifications can positively affect immunization activity, the effect may vary by targeted age group. Many 7- and 12-month-olds had immunization activity following reminder/recall; however, levels of activity were similar irrespective of notification, suggesting that these groups were likely to receive medical care or immunization services without prompting.

Differential associations of oral estradiol and conjugated equine estrogen with hemostatic biomarkers

BACKGROUND

The risk of venous thrombosis (VT) associated with oral hormone therapy (HT) may differ by type of estrogen compound.

OBJECTIVE

To compare the thrombotic profile of women using oral conjugated equine estrogens (CEE) with that of women using oral estradiol (E2).

METHODS

In postmenopausal, female, health maintenance organization (HMO) members with no history of VT, we measured thrombin generation, levels of factor VII activity, antithrombin activity and total protein S antigen. Mean levels of hemostasis biomarkers were cross-sectionally compared by use and type of estrogen using multiple linear regressions. The type of estrogen used was determined primarily by the HMO formulary, which changed its preferred estrogen from CEE to E2 during the study period.

RESULTS

The sample included 92 E2 users and 48 CEE users, with a mean age of 64.1 years and mean BMI of 29.1 kg m(-2) . Twenty-seven per cent of HT contained medroxyprogesterone acetate. Compared with E2 users, CEE users had greater thrombin generation peak values and endogenous thrombin potential, and lower total protein S (multivariate adjusted differences of 49.8 nm (95% CI, 21.0, 78.6), 175.0 nm × Min (95% CI, 54.4, 295.7) and -13.4% (95% CI, -19.8, -6.9), respectively). Factor VII and antithrombin levels were not different between E2 and CEE users. Results were similar in subgroups of users of unopposed HT, opposed HT, low-dose estrogen and standard dose estrogen.

CONCLUSION

The hemostatic profile of women using CEE is more prothrombotic than that of women using E2. These findings provide further evidence for a different thrombotic risk for oral CEE and oral E2.

Lower risk of cardiovascular events in postmenopausal women taking oral estradiol compared with oral conjugated equine estrogens

IMPORTANCE

Little is known about the comparative cardiovascular safety of oral hormone therapy products, which impedes women from making informed safety decisions about hormone therapy to treat menopausal symptoms.

OBJECTIVE

To compare the relative clinical cardiovascular safety of 2 commonly used oral estrogen drugs-conjugated equine estrogens (CEEs) and estradiol.

DESIGN, SETTING, AND PARTICIPANTS

Population-based, case-control study from January 1, 2003, to December 31, 2009, comparing cardiovascular event risk associated with current CEEs and estradiol use in a large health maintenance organization in which the preferred formulary estrogen changed from CEEs to estradiol during the course of data collection. Participants were 384 postmenopausal women aged 30 to 79 years using oral hormone therapy.

MAIN OUTCOMES AND MEASURES

Incident venous thrombosis was the primary clinical outcome, and incident myocardial infarction and ischemic stroke were secondary outcomes. As validation, an intermediate clotting phenotype, the endogenous thrombin potential-based normalized activated protein C sensitivity ratio, was measured in plasma of controls.

RESULTS

We studied 68 venous thrombosis, 67 myocardial infarction, and 48 ischemic stroke cases, with 201 matched controls; all participants were current users of oral CEEs or estradiol. In adjusted analyses, current oral CEEs use compared with current oral estradiol use was associated with an increased venous thrombosis risk (odds ratio, 2.08; 95% CI, 1.02-4.27; P = .045) and an increased myocardial infarction risk that did not reach statistical significance (odds ratio, 1.87; 95% CI, 0.91-3.84; P = .09) and was not associated with ischemic stroke risk (odds ratio, 1.13; 95% CI, 0.55-2.31; P = .74). Among 140 controls, CEEs users compared with estradiol users had higher endogenous thrombin potential-based normalized activated protein C sensitivity ratios (P < .001), indicating a stronger clotting propensity.

CONCLUSIONS AND RELEVANCE

In an observational study of oral hormone therapy users, CEEs use was associated with a higher risk of incident venous thrombosis and possibly myocardial infarction than estradiol use. This risk differential was supported by biologic data. These findings need replication and suggest that various oral estrogen drugs may be associated with different levels of cardiovascular risk.

Feasibility of initiating and sustaining registry-based immunization recall in private practices

OBJECTIVE

To assess the feasibility of initiating and sustaining immunization recall by private practices, including the barriers and costs, using a statewide immunization information system (IIS).

METHODS

Private practices in southeast Michigan were recruited in 2007 to perform IIS-based immunization recalls. Enrolled practices were provided with training and asked to conduct 4 recalls during the course of 12 months of children 19 to 35 months of age. Each practice recorded the time they spent performing recall-related activities; labor costs were estimated. Formative and summative evaluations with semistructured interviews were conducted to identify barriers.

RESULTS

Of 97 eligible pediatric and family medicine practices, 44 declined to participate, 32 did not respond to repeated contacts, and 20 agreed to enroll in the study (21%). A total of 56 recalls were conducted during the study period, with 9 practices completing at least 4 recalls and 7 practices completing 1 to 3 recalls; 4 practices conducted no recalls. Common barriers reported included time constraints and executing all steps of the recalls. Practice costs per patient recalled ranged from $0.05 to more than $6 and were primarily driven by the type of personnel who performed recalls. The costs of creating a roster of current patients comprised nearly one-half of total labor costs.

CONCLUSIONS

Few private provider practices that we contacted were willing to participate in this study of IIS-based recall, and less than one-half of enrolled practices completed the desired 4 recall cycles in 12 months. Time constraints and other real-world problems should not be underestimated in determining the feasibility of practice-based immunization recall. Efforts to increase the use of a statewide IIS for recall in private practice settings should emphasize ongoing training and technical support to practice staff. Improved interoperability with electronic health record systems may foster practice-based recall by reducing the labor intensity of roster building and other recall activities.

Seasonal influenza vaccination reminders for children with high-risk conditions: a registry-based randomized trial

BACKGROUND

Children with chronic conditions have an increased risk of complications from influenza and have low influenza vaccination rates.

PURPOSE

To assess the feasibility and effectiveness of using a statewide immunization information system (IIS) for seasonal influenza vaccine reminders from local health departments (LHDs) targeting children with high-risk conditions.

DESIGN

A randomized community intervention.

SETTING/PARTICIPANTS

The study was conducted in a population of 3618 children aged 24-60 months with a high-risk condition residing in three Michigan counties. Children were identified using a statewide IIS in October 2008.

INTERVENTION

Children were randomized to intervention (reminder) or control (no reminder) groups. Reminders for seasonal influenza vaccination were mailed by LHDs in November 2008.

MAIN OUTCOME MEASURES

Feasibility of notification (address validity, address deliverability) was assessed (November 2008-February 2009), and frequencies of notification feasibility measures were determined (analyses conducted in 2010). Effectiveness of notification (seasonal influenza vaccine receipt) was assessed using bivariate logistic regression.

RESULTS

Among 3618 children with a high-risk condition, 2730 (75.5%) had not received a 2008-2009 influenza vaccination and were eligible at the time of notification. Among children assigned to the reminder group (n=1374), 42.6% had an address determined to be either invalid, undeliverable, or both. Among those with valid addresses (n=2001), a greater percentage of children with deliverable reminders received at least one influenza vaccination (30.8%) during the outcome observation period than did children assigned to no reminder (24.3%, OR=1.39, 95% CI=1.13, 1.72); children with an undeliverable reminder had an influenza vaccination rate (22.8%) similar to children assigned to no reminder.

CONCLUSIONS

Receipt of a reminder was positively associated with seasonal influenza vaccination. However, more than 40% of children assigned to receive a reminder were determined to have an invalid or undeliverable address, emphasizing the need for increased quality of IIS contact information.

TRIAL REGISTRATION

This study is registered at www.ClinicalTrials.gov NCT01431183.