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1.  Comparative effectiveness of fish oil versus fenofibrate, gemfibrozil, and atorvastatin on lowering triglyceride levels among HIV-infected patients in routine clinical care 
The goal of this study was to compare the effectiveness of fish oil, fenofibrate, gemfibrozil, and atorvastatin on reducing triglyceride (TG) levels among a large cohort of HIV-infected patients in clinical care.
Retrospective observational cohort study
The primary endpoint was absolute change in TG levels measured using the last TG value pre-treatment and the first TG value post-treatment. A pre-post quasi-experimental design was used to estimate the change in TG due to initiating fish oil. Linear regression models examined the comparative effectiveness of treatment with fish oil versus gemfibrozil, fenofibrate, or atorvastatin for TG reduction. Models were adjusted for baseline differences in age, sex, race, CD4+ cell count, diabetes, body mass index, protease inhibitor use, and time between TG measures.
A total of 493 patients (mean age 46 years; 95% male) were included (46 receiving gemfibrozil, 80 fenofibrate, 291 atorvastatin, 76 fish oil) with a mean baseline TG of 347 mg/dL. New use of fish oil decreased TG (ΔTG -45 mg/dL 95% Confidence interval (CI):-80 to -11) in the pre-post study. Compared with fish oil (reference), fibrates were more effective (ΔTG -66; 95% CI:-120 to -12) in reducing TG levels, whereas atorvastatin was not (ΔTG -39; 95% CI:-86 to 9).
In HIV-infected patients in routine clinical care, fish oil is less effective than fibrates (but not atorvastatin) at lowering triglyceride values. Fish oil may still represent an attractive alternative for patients with moderately elevated triglycerides particularly among patients who may not want or tolerate fibrates.
PMCID: PMC4112457  PMID: 23892238
fish oil; triglycerides; dyslipidemia; fibrates; HIV
2.  Anti-diabetic drug utilization of pregnant diabetic women in us managed care 
With the increasing prevalence of type 2 diabetes in young adulthood, treatment of diabetes in pregnancy faces new challenges. Anti-diabetic drug utilization patterns of pregnant women with pre-existing diabetes are poorly described. We aim to describe anti-diabetic (AD) agent utilization among diabetic pregnant women.
We utilized IMS LifeLink, including administrative claims data of patients in US managed care plans, to establish a retrospective cohort of women, age 18–46 years (N = 96,740) with billed procedures for a live birth, and a 12 month eligibility period before and 3 month after delivery. Diabetes mellitus was identified from ≥2 in- or outpatient claims with diagnoses (ICD-9-CM 250.XX) before pregnancy. We estimated the prevalence of AD drugs before, during and after pregnancy, and secular trends across the study period (1999–2009), using linear regression. A sensitivity analysis was conducted to identify the extent of misclassification of trimesters.
Almost six percent (n = 5,581) of the live birth cohort had diabetes mellitus. Throughout the study, 48% (1999) and 78% (2009) (p < 0.0001) of diabetic women received AD drugs during pregnancy. The most common AD drugs during pregnancy were insulin, metformin, sulfonylureas, thiazolidinediones (TZD), and combination AD. The annual prevalence of insulin use increased by only 1% from 39% (1999) to 40% (2009) (p = 0.589) during pregnancy, while use of sulfonylureas and metformin increased from 2.5% and 4.2% (1999) to 17.3% and 15.3% (2009) (p < 0.0001), respectively. Insulin and sulfonylurea use steadily increased in prevalence from the 1st to 3rd trimester (16.5% and 3.3% to 33.0% and 7.5%), while metformin and TZD use decreased (11.4% and 1.6% to 3.8% and 0.2%).
AD use during pregnancy demonstrates the need for additional investigation regarding safety and efficacy of AD drugs on maternal outcomes.
PMCID: PMC3898248  PMID: 24438493
Pharmacoepidemiology; Drug utilization; Pregnancy; Managed care
3.  Comparing marginal structural models to standard methods for estimating treatment effects of antihypertensive combination therapy 
Due to time-dependent confounding by blood pressure and differential loss to follow-up, it is difficult to estimate the effectiveness of aggressive versus conventional antihypertensive combination therapies in non-randomized comparisons.
We utilized data from 22,576 hypertensive coronary artery disease patients, prospectively enrolled in the INternational VErapamil-Trandolapril STudy (INVEST). Our post-hoc analyses did not consider the randomized treatment strategies, but instead defined exposure time-dependently as aggressive treatment (≥3 concomitantly used antihypertensive medications) versus conventional treatment (≤2 concomitantly used antihypertensive medications). Study outcome was defined as time to first serious cardiovascular event (non-fatal myocardial infarction, non-fatal stroke, or all-cause death). We compared hazard ratio (HR) estimates for aggressive vs. conventional treatment from a Marginal Structural Cox Model (MSCM) to estimates from a standard Cox model. Both models included exposure to antihypertensive treatment at each follow-up visit, demographics, and baseline cardiovascular risk factors, including blood pressure. The MSCM further adjusted for systolic blood pressure at each follow-up visit, through inverse probability of treatment weights.
2,269 (10.1%) patients experienced a cardiovascular event over a total follow-up of 60,939 person-years. The HR for aggressive treatment estimated by the standard Cox model was 0.96 (95% confidence interval 0.87-1.07). The equivalent MSCM, which was able to account for changes in systolic blood pressure during follow-up, estimated a HR of 0.81 (95% CI 0.71-0.92).
Using a MSCM, aggressive treatment was associated with a lower risk for serious cardiovascular outcomes compared to conventional treatment. In contrast, a standard Cox model estimated similar risks for aggressive and conventional treatments.
Trial registration Identifier: NCT00133692
PMCID: PMC3573973  PMID: 22866767
Blood pressure; Hypertension; Time-dependent confounding; Marginal structural models
4.  Trends in the prevalence of thrombocytopenia among individuals iInfected with hepatitis C Virus in the United States, 1999-2008 
BMC Research Notes  2012;5:142.
Thrombocytopenia is associated with the natural history of hepatitis C virus (HCV) infection and anti-viral therapy. Recent, national estimates of the clinical burden of thrombocytopenia among HCV-infected individuals in the United States are unavailable. Bi-yearly data from the 1999-2000 to 2007-2008 National Health and Nutrition Examination Surveys (NHANES) were used to examine the prevalence of thrombocytopenia among HCV-infected individuals in the United States.
Among 467 HCV-infected individuals in the survey (weighted population = 3,597,039), mean weighted age was 46.7 years (standard deviation = 15.5) and 61.7% were male. Overall, 7.6% met the study definition of TCP at the 150 × 109/L threshold; 4.5%, 2.0%, and 0.8% had platelet counts below 125, 100, and 75 × 109/L, respectively. The 2-year weighted prevalences of thrombocytopenia (150 × 109/L threshold) from 1999-2008 were 4.9%, 8.6%, 6.5%, 4.1%, and 12.9%. The unadjusted biannual time trend (odds ratio) was 1.16 (95% confidence interval = 0.82-1.64). In the two adjusted models, the odds by time ranged from 1.24-1.40, depending on whether the model included demographic or laboratory variables or both, but did not reach statistical significance. Age was positively and significantly related to thrombocytopenia status.
As the HCV-infected population ages, the prevalence of thrombocytopenia is expected to rise. This study provides limited evidence of such an effect at the national level.
PMCID: PMC3392739  PMID: 22414142
Thrombocytopenia; Hepatitis C; Platelets; NHANES
5.  The association between drospirenone and hyperkalemia: a comparative-safety study 
Drospirenone/ethinyl-estradiol is an oral contraceptive (OC) that possesses unique antimineralocorticoid activity. It is conjectured that drospirenone, taken alone or concomitantly with spironolactone, may be associated with an increased risk of hyperkalemia.
A retrospective cohort study was conducted evaluating women between 18-46 years of age in the Lifelink™ Health Plan Claims Database. The study was restricted to new users of OCs between 1997-2009. Cox proportional hazards models were used to estimate the time to first occurrence of hyperkalemia diagnosis. The main analysis compared OCs containing drospirenone with OCs containing levonorgestrel, a second generation OC not known to impact potassium homeostasis. Logistic regression evaluated concomitant prescribing of drospirenone and spironolactone
The cohort included 1,148,183 women, averaging 28.8 years of age and 280 days of OC therapy. 2325 cases of hyperkalemia were identified. The adjusted hazard ratio (HR) for hyperkalemia with drospirenone compared to levonorgestrel was 1.10 (95%CI 0.95-1.26). There was an increased risk of hyperkalemia with norethindrone HR 1.15 (95%CI: 1.00-1.33) and norgestimate HR 1.27 (95%CI: 1.11-1.46). Other OCs were unassociated with hyperkalemia. The odds of receiving spironolactone while taking drospirenone were 2.66 (95%CI 2.53-2.80) times higher than the odds of receiving spironolactone and levonorgestrel. Only 6.5% of patients taking drospirenone and spironolactone had a serum potassium assay within 180 days of starting concomitant therapy.
A clinically significant signal for hyperkalemia with drospirenone was not demonstrated in the current study. Despite the bolded warning for hyperkalemia with joint drospirenone and spironolactone administration, physicians are actually using them together preferentially, and are not following the recommended potassium monitoring requirements in the package insert.
PMCID: PMC3265420  PMID: 22208934
6.  Lifestyle variables and the risk of myocardial infarction in the General Practice Research Database 
The primary objective of this study is to estimate the association between body mass index (BMI) and the risk of first acute myocardial infarction (AMI). As a secondary objective, we considered the association between other lifestyle variables, smoking and heavy alcohol use, and AMI risk.
This study was conducted in the general practice research database (GPRD) which is a database based on general practitioner records and is a representative sample of the United Kingdom population. We matched cases of first AMI as identified by diagnostic codes with up to 10 controls between January 1st, 2001 and December 31st, 2005 using incidence density sampling. We used multiple imputation to account for missing data.
We identified 19,353 cases of first AMI which were matched on index date, GPRD practice and age to 192,821 controls. There was a modest amount of missing data in the database, and the patients with missing data had different risks than those with recorded values. We adjusted our analysis for each lifestyle variable jointly and also for age, sex, and number of hospitalizations in the past year. Although a record of underweight (BMI <18.0 kg/m2) did not alter the risk for AMI (adjusted odds ratio (OR): 1.00; 95% confidence interval (CI): 0.87–1.11) when compared with normal BMI (18.0–24.9 kg/m2), obesity (BMI ≥30 kg/m2) predicted an increased risk (adjusted OR: 1.41; 95% CI: 1.35–1.47). A history of smoking also predicted an increased risk of AMI (adjusted OR: 1.81; 95% CI: 1.75–1.87) as did heavy alcohol use (adjusted OR: 1.15; 95% CI: 1.06–1.26).
This study illustrates that obesity, smoking and heavy alcohol use, as recorded during routine care by a general practitioner, are important predictors of an increased risk of a first AMI. In contrast, low BMI does not increase the risk of a first AMI.
PMCID: PMC2241637  PMID: 18088433

Results 1-6 (6)