Validation of an Electronic Medical Record-Based Algorithm for Identifying Posttraumatic Stress Disorder in U.S. Veterans

We developed an algorithm for identifying U.S. veterans with a history of posttraumatic stress disorder (PTSD), using the Department of Veterans Affairs (VA) electronic medical record (EMR) system. This work was motivated by the need to create a valid EMR-based phenotype to identify thousands of cases and controls for a genome-wide association study of PTSD in veterans. We used manual chart review (n = 500) as the gold standard. For both the algorithm and chart review, three classifications were possible: likely PTSD, possible PTSD, and likely not PTSD. We used Lasso regression with cross-validation to select statistically significant predictors of PTSD from the EMR and then generate a predicted probability score of being a PTSD case for every participant in the study population (range: 0-1.00). Comparing the performance of our probabilistic approach (Lasso algorithm) to a rule-based approach (International Classification of Diseases [ICD] algorithm), the Lasso algorithm showed modestly higher overall percent agreement with chart review than the ICD algorithm (80% vs. 75%), higher sensitivity (0.95 vs. 0.84), and higher accuracy (AUC = 0.95 vs. 0.90). We applied a 0.7 probability cut-point to the Lasso results to determine final PTSD case-control status for the VA population. The final algorithm had a 0.99 sensitivity, 0.99 specificity, 0.95 positive predictive value, and 1.00 negative predictive value for PTSD classification (grouping possible PTSD and likely not PTSD) as determined by chart review. This algorithm may be useful for other research and quality improvement endeavors within the VA.

Serial sodium values and adverse outcomes in heart failure with preserved ejection fraction

OBJECTIVE

The purpose of our study is to examine whether serial measurements of serum sodium values after diagnosis identify a higher-risk subset of patients with heart failure with preserved ejection fraction.

METHODS

We identified 50,932 subjects with HFpEF with 759,577 recorded sNa measurements (mean age 72 ± 11 years) using a validated algorithm in the VA national database from 2002 to 2012. We examined the association of repeated measures of sNa with mortality using a multivariable Cox proportional hazards model.

RESULTS

After a median follow-up of 2.9 years (IQR: 1.2-5.4), 19,011 deaths occurred. After adjusting for age, sex, race, BMI, glomerular filtration rate, potassium, coronary artery disease, hypertension, hyperlipidemia, atrial fibrillation, pulmonary disease, diabetes, anemia, and medications, we found J-shaped associations of serum sodium with mortality. HRs for all-cause mortality were 2.48 (95% CI: 2.38-2.60) for the sNA 115.00-133.99 category; and 1.40 (95% CI: 1.35-1.46) for the sNA 143.00-175.00 category compared to the 137.01-140.99 category (ref). We used generalized estimating equation-based negative binomial regression to compute the incidence density ratios (IDR) to examine days hospitalized for heart failure and for all causes. There were a total of 1,275,614 days of all-cause hospitalization and 104,006 days of heart-failure hospitalization. The IDRs for the lowest sNA group were 2.03 (95% CI: 1.90-2.18) for all-cause hospitalization and 1.73 (95% CI: 1.39-2.16) for heart-failure hospitalization.

CONCLUSIONS

Our findings suggest that monitoring of serum sodium values during longitudinal follow-up can identify HFpEF patients at risk of adverse outcomes.

The Association Between Social Engagement, Mild Cognitive Impairment, and Falls Among Older Primary Care Patients

OBJECTIVES

To examine associations between mild cognitive impairment (MCI) and falls among primary care patients, and to investigate whether social engagement (SE) modifies these associations.

DESIGN

Cross sectional analysis using baseline data from an observational cohort study.

SETTING

Primary care.

PARTICIPANTS

Community-dwelling older adults (N=430) at risk of mobility decline with a mean age of 76.6 years (range 65-96y).

MAIN OUTCOME MEASURES

The number of falls in the past year was reported at the baseline interview. MCI was identified using a cutoff of 1.5 SD below the age-adjusted mean on at least 2 of the standardized cognitive performance tests. SE (eg, keeping in touch with friends and family, volunteering, participating social activities…) was assessed with the Late Life Function and Disability Instrument, and required a score above the median value 49.5 out of 100.

RESULTS

MCI was present among 42% of participants and 42% reported at least 1 fall in the preceding year. Using generalized estimating equations, MCI was associated with a 77% greater rate of falls (P<.05). There was a statistically significant interaction between SE and MCI on the rate of falls (P<.01), such that at a high level of SE, MCI was not statistically associated with falls (P=.83). In participants with lower levels of SE, MCI is associated with 1.3 times greater rate of falls (P<.01).

CONCLUSIONS

While MCI is associated with a greater risk for falls, higher levels of SE may play a protective role.

Association of statin therapy with incidence of type 2 diabetes among US Veterans

Aims

While some but not all trial data have suggested an elevated risk of type 2 diabetes with statin use, limited data are available on the relation of statin treatment with glycaemia and risk of type 2 diabetes among Veterans. We examined whether statin use was associated with a higher incidence of type 2 diabetes and secondarily, if statin use was associated with high plasma glucose.

Methods

Prospective analysis based on electronic health records of 3,390,799 US Veterans from 2000 to 2012. We used the Veteran Administration Corporate Data Warehouse to obtain information on random plasma glucose. Statin use was captured using the pharmacy database. type 2 diabetes was defined as having at least one inpatient diagnosis or at least two outpatient diagnoses of type 2 diabetes using International Classification of Disease version 9 codes 250.xx, or the use of hypoglycemic agents. We used multi-level derived propensity score and inverse probability weighting to address confounding by indication and Cox regression to estimate relative risk of type 2 diabetes.

Results

The mean age was 62±11.9 years; 93.3% were men and 82.7% were white. During a median follow-up of 3.0 years, 443,104 new cases of type 2 diabetes occurred. Compared to no statin use, multivariable adjusted hazard ratio (95% CI) for type 2 diabetes was 1.21 (1.19-1.24) for low statin potency, 1.22 (1.21-1.23) for medium statin potency, and 1.34 (1.32-1.36) for high statin potency (p linear trend <0.0001). In secondary analysis, statin use was not associated with higher plasma glucose.

Conclusions

Our data show a positive association between statin use and incidence of type 2 diabetes among US Veterans.

Abstract WP221: Relation Between Blood Pressure and Stroke Mortality in the United States Veteran Population

Introduction: Improved control of hypertension is largely credited for declines in stroke incidence and mortality. Previous studies have reported worse outcomes after ischemic stroke with lower blood pressures prior to the stroke. We investigated the relationship between pre-stroke systolic blood pressure (SBP) and mortality after ischemic stroke among U.S. Veterans.

Methods: This longitudinal analysis assessed mortality risk after incident stroke in a national sample of Veterans Health Administration hospitalizations between 2002 and 2007. We included patients who had admission ICD-9 codes for ischemic stroke (433.x1, 434, and 436, excluding 434.x0) and ≥1 outpatient blood pressure measurements 1 to 18 months prior to stroke. We defined 6 categories of average baseline SBP: <120, 120-129, 130-139, 140-149, 150-159, and ≥160 mm Hg. Multivariable Cox analyses were used to relate baseline SBP to all-cause and vascular mortality determined using the National Death Index.

Results: There were 29,458 hospitalizations (mean age 67±12 years, 98% male) for incident stroke. During 4.1±3.3 years mean follow-up, there were 15,489 deaths (54%). There were 6,629 vascular deaths (23%). In a fully adjusted model, with high normal pre-stroke SBP (130-139) as the reference, risk of all-cause mortality was increased for patients with very low-to-normal SBP (<120), normal SBP (120-129), and very high SBP (≥160) (Table 1A). The risk of vascular mortality increased with very low (<120) and very high (≥160) SBP levels, but was not increased with normal SBP (120-129) (Table 1B).

Conclusions: In U.S. Veterans hospitalized with first-ever stroke, very low and very high pre-stroke systolic blood pressure levels increased risk of all-cause and vascular mortality. Optimal SBP targets after stroke, particularly in patients with low pre-stroke SBP, merit further investigation.

A phenotyping algorithm to identify acute ischemic stroke accurately from a national biobank: the Million Veteran Program

Background

Large databases provide an efficient way to analyze patient data. A challenge with these databases is the inconsistency of ICD codes and a potential for inaccurate ascertainment of cases. The purpose of this study was to develop and validate a reliable protocol to identify cases of acute ischemic stroke (AIS) from a large national database.

Methods

Using the national Veterans Affairs electronic health-record system, Center for Medicare and Medicaid Services, and National Death Index data, we developed an algorithm to identify cases of AIS. Using a combination of inpatient and outpatient ICD9 codes, we selected cases of AIS and controls from 1992 to 2014. Diagnoses determined after medical-chart review were considered the gold standard. We used a machine-learning algorithm and a neural network approach to identify AIS from ICD9 codes and electronic health-record information and compared it with a previous rule-based stroke-classification algorithm.

Results

We reviewed administrative hospital data, ICD9 codes, and medical records of 268 patients in detail. Compared with the gold standard, this AIS algorithm had a sensitivity of 91%, specificity of 95%, and positive predictive value of 88%. A total of 80,508 highly likely cases of AIS were identified using the algorithm in the Veterans Affairs national cardiovascular disease-risk cohort (n=2,114,458).

Conclusion

Our algorithm had high specificity for identifying AIS in a nationwide electronic health-record system. This approach may be utilized in other electronic health databases to accurately identify patients with AIS.

Genetics of blood lipids among ~300,000 multi-ethnic participants of the Million Veteran Program

The Million Veteran Program (MVP) was established in 2011 as a national research initiative to determine how genetic variation influences the health of U.S. military veterans. We genotyped 312,571 MVP participants using a custom biobank array and linked the genetic data to laboratory and clinical phenotypes extracted from electronic health records covering a median of 10.0 years of follow-up. Among 297,626 veterans with at least 1 blood lipid measurement including 57,332 blacks and 24,743 Hispanics, we tested up to ~32 million variants for association with lipid levels and identified 118 novel genome-wide significant loci after meta-analysis with data from the Global Lipids Genetics Consortium (total N > 600,000). Through a focus on mutations predicted to result in a loss of gene function and a phenome-wide association study, we propose novel indications for pharmaceutical inhibitors targeting PCSK9 (abdominal aortic aneurysm), ANGPTL4 (type 2 diabetes), and PDE3B (triglycerides and coronary disease).

Development and validation of a heart failure with preserved ejection fraction cohort using electronic medical records

Background

Heart failure (HF) with preserved ejection fraction (HFpEF) comprises nearly half of prevalent HF, yet is challenging to curate in a large database of electronic medical records (EMR) since it requires both accurate HF diagnosis and left ventricular ejection fraction (EF) values to be consistently ≥50%.

Methods

We used the national Veterans Affairs EMR to curate a cohort of HFpEF patients from 2002 to 2014. EF values were extracted from clinical documents utilizing natural language processing and an iterative approach was used to refine the algorithm for verification of clinical HFpEF. The final algorithm utilized the following inclusion criteria: any International Classification of Diseases-9 (ICD-9) code of HF (428.xx); all recorded EF ≥50%; and either B-type natriuretic peptide (BNP) or aminoterminal pro-BNP (NT-proBNP) values recorded OR diuretic use within one month of diagnosis of HF. Validation of the algorithm was performed by 3 independent reviewers doing manual chart review of 100 HFpEF cases and 100 controls.

Results

We established a HFpEF cohort of 80,248 patients (out of a total 1,155,376 patients with the ICD-9 diagnosis of HF). Mean age was 72 years; 96% were males and 12% were African-Americans. Validation analysis of the HFpEF algorithm had a sensitivity of 88%, specificity of 96%, positive predictive value of 96%, and a negative predictive value of 87% to identify HFpEF cases.

Conclusion

We developed a sensitive, highly specific algorithm for detecting HFpEF in a large national database. This approach may be applicable to other large EMR databases to identify HFpEF patients.

Prognostic Significance of Baseline Serum Sodium in Heart Failure With Preserved Ejection Fraction

BACKGROUND

The purpose of this study was to evaluate the relationship between serum sodium at the time of diagnosis and long term clinical outcomes in a large national cohort of patients with heart failure with preserved ejection fraction.

METHODS AND RESULTS

We studied 25 440 patients with heart failure with preserved ejection fraction treated at Veterans Affairs medical centers across the United States between 2002 and 2012. Serum sodium at the time of heart failure diagnosis was analyzed as a continuous variable and in categories as follows: low (115.00-134.99 mmol/L), low-normal (135.00-137.99 mmol/L), referent group (138.00-140.99 mmol/L), high normal (141.00-143.99 mmol/L), and high (144.00-160.00 mmol/L). Multivariable Cox regression and negative binomial regression were performed to estimate hazard ratios (95% confidence interval [CI]) and incidence density ratios (95% CI) for the associations of serum sodium with mortality and hospitalizations (heart failure and all-cause), respectively. The average age of patients was 70.8 years, 96.2% were male, and 14% were black. Compared with the referent group, low, low-normal, and high sodium values were associated with 36% (95% CI, 28%-44%), 6% (95% CI, 1%-12%), and 9% (95% CI, 1%-17%) higher risk of all-cause mortality, respectively. Low and low-normal serum sodium were associated with 48% (95% CI, 10%-100%) and 38% (95% CI, 8%-77%) higher risk of number of days of heart failure hospitalizations per year, and with 44% (95% CI, 32%-56%) and 18% (95% CI, 10%-27%) higher risk of number of days of all-cause hospitalizations per year, respectively.

CONCLUSIONS

Both elevated and reduced serum sodium, including values currently considered within normal range, are associated with adverse outcomes in patients with heart failure with preserved ejection fraction.

DASH Score and Subsequent Risk of Coronary Artery Disease: The Findings From Million Veteran Program

BACKGROUND

While adherence to healthful dietary patterns has been associated with a lower risk of coronary artery disease (CAD) in the general population, limited data are available among US veterans. We tested the hypothesis that adherence to Dietary Approach to Stop Hypertension (DASH) food pattern is associated with a lower risk of developing CAD among veterans.

METHODS AND RESULTS

We analyzed data on 153 802 participants of the Million Veteran Program enrolled between 2011 and 2016. Information on dietary habits was obtained using a food frequency questionnaire at enrollment. We used electronic health records to assess the development of CAD during follow-up. Of the 153 802 veterans who provided information on diet and were free of CAD at baseline, the mean age was 64.0 (SD=11.8) years and 90.4% were men. During a mean follow-up of 2.8 years, 5451 CAD cases occurred. The crude incidence rate of CAD was 14.0, 13.1, 12.6, 12.3, and 11.1 cases per 1000 person-years across consecutive quintiles of Dietary Approach to Stop Hypertension score. Hazard ratios (95% confidence interval) for CAD were 1.0 (ref), 0.91 (0.84-0.99), 0.87 (0.80-0.95), 0.86 (0.79-0.94), and 0.80 (0.73-0.87) from the lowest to highest quintile of Dietary Approach to Stop Hypertension score controlling for age, sex, body mass index, race, smoking, exercise, alcohol intake, and statin use (P linear trend, <0.0001).

CONCLUSIONS

Our data are consistent with an inverse association between Dietary Approach to Stop Hypertension diet score and incidence of CAD among US veterans.

Posttraumatic stress disorder and mortality in VA patients with implantable cardioverter-defibrillators

BACKGROUND

The association between posttraumatic stress disorder (PTSD) and mortality in patients undergoing implantable cardioverter-defibrillator (ICD) placement has not been evaluated in US veterans.

HYPOTHESIS

PTSD in veterans with ICD is associated with increased mortality.

METHODS

We studied a retrospective cohort of 25 678 veterans who underwent ICD implantation between September 30, 2002, and December 31, 2011. Of these subjects, 3280 carried the diagnosis of PTSD prior to ICD implantation. Primary outcome was all-cause mortality between date of ICD implantation and end of follow-up (September 30, 2013). We used Cox proportional hazard models to compute multivariable adjusted hazard ratios with corresponding 95% confidence intervals for the relation between PTSD diagnosis and death following ICD placement.

RESULTS

During a mean follow-up of 4.21 ± 2.62 years, 11 015 deaths were reported. The crude incidence rate of death was 87.8 and 103.9/1000 person-years for people with and without PTSD, respectively. We did not find an association between presence of PTSD before or after ICD implantation and incident death when adjusted for multiple risk factors (hazard ratio: 1.003, 95% confidence interval: 0.948-1.061). In secondary analysis, no statistically significant association was found.

CONCLUSIONS

In this retrospective cohort study among more than 25 000 veterans undergoing ICD implantation, almost 13% had a diagnosis of PTSD. Subjects with PTSD were significantly younger, yet they had a higher incidence of coronary heart disease, major cardiac comorbidities, cancer, and mental health conditions. We found no association between presence of PTSD before or after ICD implantation and incident death when adjusting for all covariates.

Yield and bias in defining a cohort study baseline from electronic health record data

AIMS

Despite growing interest in using electronic health records (EHR) to create longitudinal cohort studies, the distribution and missingness of EHR data might introduce selection bias and information bias to such analyses. We aimed to examine the yield and potential for these healthcare process biases in defining a study baseline using EHR data, using the example of cholesterol and blood pressure (BP) measurements.

METHODS

We created a virtual cohort study of cardiovascular disease (CVD) from patients with eligible cholesterol profiles in the New England (NE) and Southeast (SE) networks of the Veterans Health Administration in the United States. Using clinical data from the EHR, we plotted the yield of patients with BP measurements within an expanding timeframe around an index date of cholesterol testing. We compared three groups: (1) patients with BP from the exact index date; (2) patients with BP not on the index date but within the network-specific 90th percentile around the index date; and (3) patients with no BP within the network-specific 90th percentile.

RESULTS

Among 589,361 total patients in the two networks, 146,636 (61.0%) of 240,479 patients from NE and 289,906 (83.1%) of 348,882 patients from SE had BP measurements on the index date. Ninety percent had BP measured within 11 days of the index date in NE and within 5 days of the index date in SE. Group 3 in both networks had fewer available race data, fewer comorbidities and CVD medications, and fewer health system encounters.

CONCLUSIONS

Requiring same-day risk factor measurement in the creation of a virtual CVD cohort study from EHR data might exclude 40% of eligible patients, but including patients with infrequent visits might introduce bias. Data visualization can inform study-specific strategies to address these challenges for the research use of EHR data.

Baseline Characterization and Annual Trends of Body Mass Index for a Mega-Biobank Cohort of US Veterans 2011-2017

AIM

Million Veteran Program (MVP) is the largest ongoing mega-cohort biobank program in the US with 570,131 enrollees as of May 2017. The primary aim is to describe demographics, military service, and major diseases and comorbidities of the MVP cohort. Our secondary aim is to examine body mass index (BMI), a proxy for general health, among enrollees.

MATERIALS AND METHOD

The study population consists of Veterans who actively use the Veterans Health Administration in the US. Data evaluated in this paper combine health information from multiple sources to provide the most comprehensive demographic profile and information on height and weight of MVP enrollees. A standardized cleaning algorithm was used to curate the demographic variables for each participant in MVP. For height and weight, we derived a final data point for each participant to evaluate BMI.

STATISTICAL ANALYSIS USED

Multivariable logistic regression was used to compare the differences in BMI categories across enrollment years adjusting for gender, race, and age. P < 0.05 was considered statistically significant. All analyses were conducted using Statistical Analysis System 9.2.

RESULTS

The MVP cohort consists of 90.4% of males with an average age of 61.9 years (standard deviation [SD] = 13.9). MVP is the largest multiethnic biobank cohort within the Veteran population with 73.9% White, 19.0% Black, and 6.5% Hispanic. The most common self-reported disease was hypertension (62.6%) for males and depression (47.5%) for females. Mean BMI was 29.7 kg/m² (SD = 5.8) with 38.2% obese and 42.3% overweight.

CONCLUSIONS

Our findings suggest that demographic representation in MVP is similar to the Veterans Health Administration population and contrasts with the overall National Health and Nutrition Examination Survey US population. The prevalence of overweight and obese is high among US Veterans, and future studies will examine the role of BMI and disease risk in the Veteran population.

Metformin vs sulfonylurea use and risk of dementia in US veterans aged ≥65 years with diabetes

OBJECTIVE

To determine whether metformin is associated with a lower incidence of dementia than sulfonylureas.

METHODS

This was a retrospective cohort study of US veterans ≥65 years of age with type 2 diabetes who were new users of metformin or a sulfonylurea and had no dementia. Follow-up began after 2 years of therapy. To account for confounding by indication, we developed a propensity score (PS) and used inverse probability of treatment weighting (IPTW) methods. Cox proportional hazards models estimated the hazard ratio (HR) of incident dementia.

RESULTS

We identified 17,200 new users of metformin and 11,440 new users of sulfonylureas. Mean age was 73.5 years and mean HbA1c was 6.8%. Over an average follow-up of 5 years, 4,906 cases of dementia were diagnosed. Due to effect modification by age, all analyses were conducted using a piecewise model for age. Crude hazard ratio [HR] for any dementia in metformin vs sulfonylurea users was 0.67 (95% confidence interval [CI] 0.61-0.73) and 0.78 (95% CI 0.72-0.83) for those <75 years of age and ≥75 years of age, respectively. After PS IPTW adjustment, results remained significant in veterans <75 years of age (HR 0.89; 95% CI 0.79-0.99), but not for those ≥75 years of age (HR 0.96; 95% CI 0.87-1.05). A lower risk of dementia was also seen in the subset of younger veterans who had HbA1C values ≥7% (HR 0.76; 95% CI 0.63-0.91), had good renal function (HR 0.86; 95% CI 0.76-0.97), and were white (HR 0.87; 95% CI 0.77-0.99).

CONCLUSIONS

After accounting for confounding by indication, metformin was associated with a lower risk of subsequent dementia than sulfonylurea use in veterans <75 years of age. Further work is needed to identify which patients may benefit from metformin for the prevention of dementia.

A Team-Based Online Game Improves Blood Glucose Control in Veterans With Type 2 Diabetes: A Randomized Controlled Trial

OBJECTIVE

Rigorous evidence is lacking whether online games can improve patients' longer-term health outcomes. We investigated whether an online team-based game delivering diabetes self-management education (DSME) to patients via e-mail or mobile application (app) can generate longer-term improvements in hemoglobin A_1c (HbA_1c).

RESEARCH DESIGN AND METHODS

Patients (n = 456) on oral diabetes medications with HbA_1c ≥58 mmol/mol were randomly assigned between a DSME game (with a civics booklet) and a civics game (with a DSME booklet). The 6-month games sent two questions twice weekly via e-mail or mobile app. Participants accrued points based on performance, with scores posted on leaderboards. Winning teams and individuals received modest financial rewards. Our primary outcome measure was HbA_1c change over 12 months.

RESULTS

DSME game patients had significantly greater HbA_1c reductions over 12 months than civics game patients (-8 mmol/mol [95% CI -10 to -7] and -5 mmol/mol [95% CI -7 to -3], respectively; P = 0.048). HbA_1c reductions were greater among patients with baseline HbA_1c >75 mmol/mol: -16 mmol/mol [95% CI -21 to -12] and -9 mmol/mol [95% CI -14 to -5] for DSME and civics game patients, respectively; P = 0.031.

CONCLUSIONS

Patients with diabetes who were randomized to an online game delivering DSME demonstrated sustained and meaningful HbA_1c improvements. Among patients with poorly controlled diabetes, the DSME game reduced HbA_1c by a magnitude comparable to starting a new diabetes medication. Online games may be a scalable approach to improve outcomes among geographically dispersed patients with diabetes and other chronic diseases.

Promoting physical activity in COPD: Insights from a randomized trial of a web-based intervention and pedometer use

RATIONALE

Low physical activity is highly prevalent among COPD patients and is associated with increased healthcare utilization and mortality and reduced HRQL. The addition of a website to pedometer use is effective at increasing physical activity; however, the timeline of change and impact of environmental factors on efficacy is unknown.

METHODS

U.S. Veterans with COPD were randomized (1:1) to receive either (1) a pedometer and website which provided goal-setting, feedback, disease-specific education, and an online community forum or (2) pedometer alone for 3 months. Primary outcome was change in daily step count. Secondary outcomes included 6MWT distance, HRQL, dyspnea, depression, COPD knowledge, exercise self-efficacy, social support, motivation, and confidence to exercise. Generalized linear mixed-effects models evaluated the effect of the pedometer plus website compared to pedometer alone.

RESULTS

Data from 109 subjects (98.5% male, mean age 68.6 ± 8.3 years) were analyzed. At 13 weeks, subjects in the pedometer plus website group had significant increases daily step count from baseline relative to the pedometer alone group (804 ± 356.5 steps per day, p = 0.02). The pedometer plus website group had significant improvements in daily step count from baseline beginning in week 3 which were sustained until week 13. In subgroup analyses, the pedometer plus website attenuated declines in daily step count during the transition from summer to fall. No significant differences in secondary outcomes were noted between groups.

CONCLUSIONS

A website added to pedometer use improves daily step counts, sustains walking over 3 months, and attenuates declines in physical activity due to season.

Wheelchair use and lipophilic statin medications may influence bone loss in chronic spinal cord injury: findings from the FRASCI-bone loss study

We identified a protective bone effect at the knee with lipophilic statin use in individuals with chronic spinal cord injury. Lipophilic statin users gained bone at the knee compared to non-users and wheelchair users lost bone compared to walkers. Ambulation and or statins may be effective osteogenic interventions in chronic spinal cord injury (SCI).

INTRODUCTION

SCI increases the risk of osteoporosis and low-impact fractures, particularly at the knee. However, during the chronic phase of SCI, the natural history and factors associated with longitudinal change in bone density remain poorly characterized. In this study, we prospectively assessed factors associated with change in bone density over a mean of 21 months in 152 men and women with chronic SCI.

METHODS

A mixed model procedure with repeated measures was used to assess predictors of change in bone mineral density (PROC MIXED) at the distal femur and proximal tibia. Factors with a p value of <0.10 in the univariate mixed models, as well as factors that were deemed clinically significant (gender, age, and walking status), were assessed in multivariable models. Factors with a p value of ≤0.05 were included in the final model.

RESULTS

We found no association between bone loss and traditional osteoporosis risk factors, including age, gender, body composition, or vitamin D level or status (normal or deficient). In both crude and fully adjusted models, wheelchair users lost bone compared to walkers. Similarly, statin users gained bone compared to nonusers.

CONCLUSIONS

The statin finding is supported by reports in the general population where statin use has been associated with a reduction in bone loss and fracture risk. Our results suggest that both walking and statins may be effective osteogenic therapies to mitigate bone loss and prevent osteoporosis in chronic SCI. Our findings also suggest that loss of mechanical loading and/or neuronal factors contribute more to disuse osteoporosis than traditional osteoporosis risk factors.

Long-term outcomes in patients with acute coronary syndromes related to prolonging dual antiplatelet therapy more than 12 months after coronary stenting

OBJECTIVES

To assess the impact of stent type on the risk of death or myocardial infarction (MI) related to dual antiplatelet therapy (DAPT) more than 12 months (prolonged DAPT) versus 12 or less months after PCI for an acute coronary syndrome (ACS).

BACKGROUND

The recent DAPT study reported lower recurrent ischemic events from prolonged DAPT in patients treated with PCI for an ACS, but was underpowered to determine the impact of stent type.

METHODS

We determined clinical outcomes after PCI for an ACS (median follow-up: DES = 26 months, BMS = 46 months) in 18,484 patients in the Veterans Affairs system treated with first generation drug-eluting stents (DES) or bare-metal stents (BMS). We used landmark analyses starting 1 year after the index PCI to assess the risk of prolonged DAPT on the primary endpoint of death or MI. Multivariable and propensity models adjusted for confounding.

RESULTS

There was a significant interaction between stent type and prolonged DAPT for death and MI (P = 0.0036), death (P = 0.054), and major bleeding (P = 0.0013). Patients treated with prolonged DAPT had lower risks of death or MI (HR = 0.71, 95% CI = 0.61, 0.82) and death (HR = 0.74, 95%CI = 0.62, 0.89) with DES, but not BMS, and higher risks of major bleeding, particularly with BMS (HR = 1.67, P < 0.001) than DES (HR = 1.24, p = 0.01).

CONCLUSIONS

Prolonging DAPT more than 12 months after PCI for ACS only associated with a lower risk of ischemic events in the 1-4 years after PCI in those receiving first generation DES. Stent type may influence the benefit of prolonged DAPT. © 2016 Wiley Periodicals, Inc.

A comparison of time dependent Cox regression, pooled logistic regression and cross sectional pooling with simulations and an application to the Framingham Heart Study

Background

Typical survival studies follow individuals to an event and measure explanatory variables for that event, sometimes repeatedly over the course of follow up. The Cox regression model has been used widely in the analyses of time to diagnosis or death from disease. The associations between the survival outcome and time dependent measures may be biased unless they are modeled appropriately.

Methods

In this paper we explore the Time Dependent Cox Regression Model (TDCM), which quantifies the effect of repeated measures of covariates in the analysis of time to event data. This model is commonly used in biomedical research but sometimes does not explicitly adjust for the times at which time dependent explanatory variables are measured. This approach can yield different estimates of association compared to a model that adjusts for these times. In order to address the question of how different these estimates are from a statistical perspective, we compare the TDCM to Pooled Logistic Regression (PLR) and Cross Sectional Pooling (CSP), considering models that adjust and do not adjust for time in PLR and CSP.

Results

In a series of simulations we found that time adjusted CSP provided identical results to the TDCM while the PLR showed larger parameter estimates compared to the time adjusted CSP and the TDCM in scenarios with high event rates. We also observed upwardly biased estimates in the unadjusted CSP and unadjusted PLR methods. The time adjusted PLR had a positive bias in the time dependent Age effect with reduced bias when the event rate is low. The PLR methods showed a negative bias in the Sex effect, a subject level covariate, when compared to the other methods. The Cox models yielded reliable estimates for the Sex effect in all scenarios considered.

Conclusions

We conclude that survival analyses that explicitly account in the statistical model for the times at which time dependent covariates are measured provide more reliable estimates compared to unadjusted analyses. We present results from the Framingham Heart Study in which lipid measurements and myocardial infarction data events were collected over a period of 26 years.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-016-0248-6) contains supplementary material, which is available to authorized users.

Occurrence of hepatotoxicity with pazopanib and other anti-VEGF treatments for renal cell carcinoma: an observational study utilizing a distributed database network

PURPOSE

To quantify the hepatic safety of pazopanib and comparator anti-vascular endothelial growth factor (VEGF) therapies in clinical practice among renal cell carcinoma (RCC) patients.

METHODS

A population-based cohort study of new anti-VEGF users was conducted in two US healthcare databases, Department of Veterans Affairs (VA) and an oncology practice network (Altos), and the PHARMO Database Network in The Netherlands. A common protocol was used to collect liver chemistry (LC) data from anti-VEGF initiation through 4 years of follow-up. In the VA population, suspected drug-induced liver injury (DILI) outcomes were investigated via chart review, with adjudication by hepatologists.

RESULTS

In Altos and VA, respectively, the total RCC patients were: pazopanib (156, 243), bevacizumab (122, 99), sorafenib (82, 249) and sunitinib (285, 751). PHARMO contained too few patients to be included. Few cases of alanine aminotransferase (ALT) ≥8× the upper limit of normal were seen across the anti-VEGF cohorts; incidence rates (per 100 person-years) ranged from 0 (sunitinib) to 8.2 (pazopanib) in Altos and from 0 (bevacizumab and sorafenib) to 2.1 (pazopanib) among VA patients. No cases of Hy's law identified by combination LC elevations were seen in patients treated with pazopanib or bevacizumab; one case was observed in those treated with sorafenib, and two cases were found among sunitinib users. One case of adjudicated DILI was observed in a sunitinib-treated patient; none were found among patients treated with pazopanib, bevacizumab or sorafenib.

CONCLUSIONS

Severe liver injury occurred infrequently during exposure to pazopanib and other anti-VEGF therapies in a population-based setting.

Incidence and Determinants of Traumatic Intracranial Bleeding Among Older Veterans Receiving Warfarin for Atrial Fibrillation

IMPORTANCE

Traumatic intracranial bleeding, which is most commonly attributable to falls, is a common concern among health care professionals, who are hesitant to prescribe oral anticoagulants to older adults with atrial fibrillation.

OBJECTIVE

To describe the incidence of and risk factors for traumatic intracranial bleeding in a large cohort of older adults who were newly prescribed warfarin sodium.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study at the US Department of Veterans Affairs (VA). Participants included 31 951 veterans with atrial fibrillation 75 years or older who were new referrals to VA anticoagulation clinics (for warfarin therapy) between January 1, 2002, and December 31, 2012. The dates of the core analysis were March 2014 through May 2015, and subsequent ad hoc analyses were performed through December 2015. Patients with comorbid conditions requiring warfarin were excluded.

MAIN OUTCOMES AND MEASURES

The primary outcome was hospitalization for traumatic intracranial bleeding. Secondary outcomes included hospitalization for any intracranial bleeding or ischemic stroke. We used International Classification of Diseases, Ninth Revision, Clinical Modification codes to identify the incidence rates of these outcomes after warfarin initiation using VA administrative data (in-system hospitalizations) and Medicare fee-for-service claims data (out-of-system hospitalizations). Clinical characteristics, laboratory results, and pharmacy data were extracted from the VA electronic medical record. For traumatic intracranial bleeding, Cox proportional hazards regression was used to determine predictors of interest selected a priori based on prior known associations.

RESULTS

The study population comprised 31 951 participants. The mean (SD) patient age was 81.1 (4.1) years, and 98.1% were male. Comorbidities were common, including hypertension (82.5%), coronary artery disease (42.6%), and diabetes mellitus (33.8%). During the study period, the incidence rate of hospitalization for traumatic intracranial bleeding was 4.80 per 1000 person-years. In unadjusted models, significant predictors of traumatic intracranial bleeding included dementia, fall within the past year, anemia, depression, abnormal renal or liver function, anticonvulsant use, labile international normalized ratio, and antihypertensive use. After adjusting for potential confounders, the remaining significant predictors for traumatic intracranial bleeding were dementia (hazard ratio [HR], 1.76; 95% CI, 1.26-2.46), anemia (HR, 1.23; 95% CI, 1.00-1.52), depression (HR, 1.30; 95% CI, 1.05-1.61), anticonvulsant use (HR, 1.35; 95% CI, 1.04-1.75), and labile international normalized ratio (HR, 1.33; 95% CI, 1.04-1.72). The incidence rates of hospitalization for any intracranial bleeding and ischemic stroke were 14.58 and 13.44, respectively, per 1000 person-years.

CONCLUSIONS AND RELEVANCE

Among patients 75 years or older with atrial fibrillation initiating warfarin therapy, the risk factors for traumatic intracranial bleeding are unique from those for ischemic stroke. The high overall rate of intracranial bleeding in our sample supports the need to more systematically evaluate the benefits and harms of warfarin therapy in older adults.

Long-Term Outcomes in Patients With Diabetes Mellitus Related to Prolonging Clopidogrel More Than 12 Months After Coronary Stenting

BACKGROUND

Recent large clinical trials show lower rates of late cardiovascular events by extending clopidogrel >12 months after percutaneous coronary revascularization (PCI). However, concerns of increased bleeding have elicited support for limiting prolonged treatment to high-risk patients.

OBJECTIVES

The aim of this analysis was to determine the effect of prolonging clopidogrel therapy >12 months versus ≤12 months after PCI on very late outcomes in patients with diabetes mellitus (DM).

METHODS

Using the Veterans Health Administration, 28,849 patients undergoing PCI between 2002 and 2006 were categorized into 3 groups: 1) 16,332 without DM; 2) 9,905 with DM treated with oral medications or diet; and 3) 2,612 with DM treated with insulin. Clinical outcomes, stratified by stent type, ≤4 years after PCI were determined from the Veterans Health Administration and Medicare databases and risk was assessed by multivariable and propensity score analyses using a landmark analysis starting 1 year after the index PCI. The primary endpoint of the study was the risk of all-cause death or myocardial infarction (MI).

RESULTS

In patients with DM treated with insulin who received drug-eluting stents (DES), prolonged clopidogrel treatment was associated with a decreased risk of death (hazard ratio [HR]: 0.59; 95% confidence interval [CI]: 0.42 to 0.82) and death or MI (HR: 0.67; 95% CI: 0.49 to 0.92). Similarly, in patients with noninsulin-treated DM receiving DES, prolonged clopidogrel treatment was associated with less death (HR: 0.61; 95% CI: 0.48 to 0.77) and death or MI (HR: 0.61; 95% CI: 0.5 to 0.75). Prolonged clopidogrel treatment was not associated with a lower risk in patients without DM or in any group receiving bare-metal stents.

CONCLUSIONS

Extending the duration of clopidogrel treatment >12 months may decrease very late death or MI only in patients with DM receiving first-generation DES. Future studies should address this question in patients receiving second-generation DES.

Outcomes with prolonged clopidogrel therapy after coronary stenting in patients with chronic kidney disease

OBJECTIVES

Patients with chronic kidney disease (CKD) are at high risk of death or myocardial infarction (MI) after percutaneous coronary interventions (PCI). We assessed whether prolonged dual antiplatelet therapy beyond the recommended 12 months may prevent adverse outcomes in patients with CKD receiving drug-eluting stents (DES) or bare-metal stents (BMS).

METHODS

We studied all Veterans receiving PCI with BMS or first-generation DES in the Veterans Affairs (VA) Healthcare System between 2002 and 2006, classified by CKD (estimated glomerular filtration rate <60 mL/min) or normal renal function. We used landmark analyses from 12 months after PCI with Cox proportional hazards multivariable and propensity-adjusted models to assess the effect of prolonged clopidogrel (more than 12  months) versus 12 months or less after PCI on clinical outcomes from 1 year to 4 years after PCI.

RESULTS

Of 23 042 eligible subjects receiving PCI, 4880 (21%) had CKD. Compared with normal renal function, patients with CKD had higher risks of death or MI 1-4 years after DES (21% vs 12%, HR=1.75; 95% CI 1.51 to 2.04) or BMS (28% vs 15%, HR=2.10; 95% CI 1.90 to 2.32). In patients with CKD receiving DES, clopidogrel use of more than 12 months after PCI was associated with lower risks of death or MI (18% vs 24%, HR=0.74; 95% CI 0.58 to 0.95), and death (15% vs 23%, HR=0.61; 95% CI 0.47 to 0.80), but had no effect on repeat revascularisation 1-4 years after PCI.

CONCLUSIONS

In patients with CKD, prolonging clopidogrel beyond 12 months after PCI may decrease the risk of death or MI only in patients receiving first-generation DES. These results support a patient-tailored approach to prolonging clopidogrel after PCI.