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1.  A Mixed Methods Study of Parental Vaccine Decision Making and Parent-Provider Trust 
Academic pediatrics  2013;13(5):481-488.
To describe parental vaccine decision making behaviors and characterize trust in physician advice among parents with varying childhood vaccination behaviors.
Between 2008 and 2011, a mixed methods study was conducted with parents of children aged <4 years who were members of Kaiser Permanente Colorado health plan. Seven focus groups were conducted with vaccine hesitant parents. Based on findings from the focus groups, a survey was developed, pilot tested and mailed to a stratified sample of 854 parents who accepted (n=500), delayed (n=227), or refused (n=127) vaccinations for one of their children. Survey results were analyzed using chi-square tests and multivariable logistic regression.
Several themes emerged from the focus groups, including: 1) the vaccine decision making process begins prenatally, 2) vaccine decision making is an evolving process, and 3) there is overall trust in the pediatrician, but a lack of trust in the information they provided about vaccines. The survey response rate was 52% (n=443). Parents who refused or delayed vaccines were 2-times more likely to report that they began thinking about vaccines before their child was born, and 8-times more likely to report that they constantly re-evaluate their vaccine decisions than parents who accepted all vaccines. While parents tended to report trusting their pediatrician’s advice on nutrition, behavior and the physical examination, they did not believe their pediatrician provided balanced information on both the benefits and risks of vaccination.
These results have implications for future interventions to address parental vaccination concerns. Such interventions may be more effective if they are applied early (during pregnancy), often (pregnancy through infancy), and cover both the risks and benefits of vaccination.
PMCID: PMC3767928  PMID: 24011751
immunization; vaccine refusal; vaccine decision making; mixed methods
2.  A scan statistic for identifying optimal risk windows in vaccine safety studies using self-controlled case series design 
Statistics in medicine  2013;32(19):3290-3299.
In examining the association between vaccines and rare adverse events after vaccination in post-licensure observational studies, it is challenging to define appropriate risk windows because pre-licensure randomized clinical trials provide little insight on the timing of specific adverse events. Past vaccine safety studies have often used pre-specified risk windows based on prior publications, biological understanding of the vaccine, and expert opinion. Recently, a data driven approach was developed to identify appropriate risk windows for vaccine safety studies that use the self-controlled case series design. This approach employs both the maximum incidence rate ratio and the linear relation between the estimated incidence rate ratio and the inverse of average person time at risk, given a specified risk window. In this paper, we present a scan statistic that can identify appropriate risk windows in vaccine safety studies using the self-controlled case series design while taking into account the dependence of time intervals within an individual and while adjusting for time-varying covariates such as age and seasonality. This approach uses the maximum likelihood ratio test based on fixed effects models, which has been used for analyzing data from self-controlled case series design in addition to conditional Poisson models.
PMCID: PMC4004030  PMID: 23303643
self-controlled case series; adverse events after vaccination; fixed effects model; scan statistics; maximum likelihood ratio test
3.  Patterns of Care and Persistence After Incident Elevated Blood Pressure 
Pediatrics  2013;132(2):e349-e355.
Screening for hypertension in children occurs during routine care. When blood pressure (BP) is elevated in the hypertensive range, a repeat measurement within 1 to 2 weeks is recommended. The objective was to assess patterns of care after an incident elevated BP, including timing of repeat BP measurement and likelihood of persistently elevated BP.
This retrospective study was conducted in 3 health care organizations. All children aged 3 through 17 years with an incident elevated BP at an outpatient visit during 2007 through 2010 were identified. Within this group, we assessed the proportion who had a repeat BP measured within 1 month of their incident elevated BP and the proportion who subsequently met the definition of hypertension. Multivariate analyses were used to identify factors associated with follow-up BP within 1 month of initial elevated BP.
Among 72 625 children and adolescents in the population, 6108 (8.4%) had an incident elevated BP during the study period. Among 6108 with an incident elevated BP, 20.9% had a repeat BP measured within 1 month. In multivariate analyses, having a follow-up BP within 1 month was not significantly more likely among individuals with obesity or stage 2 systolic elevation. Among 6108 individuals with an incident elevated BP, 84 (1.4%) had a second and third consecutive elevated BP within 12 months.
Whereas >8% of children and adolescents had an incident elevated BP, the great majority of BPs were not repeated within 1 month. However, relatively few individuals subsequently met the definition of hypertension.
PMCID: PMC3727670  PMID: 23821694
child; adolescent; hypertension; blood pressure; screening; electronic health records
4.  Use of Fixed Effects Models to Analyze Self-Controlled Case Series Data in Vaccine Safety Studies 
Conditional Poisson models have been used to analyze vaccine safety data from self-controlled case series (SCCS) design. In this paper, we derived the likelihood function of fixed effects models in analyzing SCCS data and showed that the likelihoods from fixed effects models and conditional Poisson models were proportional. Thus, the maximum likelihood estimates (MLEs) of time-varying variables including vaccination effect from fixed effects model and conditional Poisson model were equal. We performed a simulation study to compare empirical type I errors, means and standard errors of vaccination effect coefficient, and empirical powers among conditional Poisson models, fixed effects models, and generalized estimating equations (GEE), which has been commonly used for analyzing longitudinal data. Simulation study showed that both fixed effect models and conditional Poisson models generated the same estimates and standard errors for time-varying variables while GEE approach produced different results for some data sets. We also analyzed SCCS data from a vaccine safety study examining the association between measles mumps-rubella (MMR) vaccination and idiopathic thrombocytopenic purpura (ITP). In analyzing MMR-ITP data, likelihood-based statistical tests were employed to test the impact of time-invariant variable on vaccination effect. In addition a complex semi-parametric model was fitted by simply treating unique event days as indicator variables in the fixed effects model. We conclude that theoretically fixed effects models provide identical MLEs as conditional Poisson models. Because fixed effect models are likelihood based, they have potentials to address methodological issues in vaccine safety studies such as how to identify optimal risk window and how to analyze SCCS data with misclassification of adverse events
PMCID: PMC3976179  PMID: 24707443
Self-controlled case series; Adverse events after immunization; Fixed effects model; Longitudinal data; Conditional Poisson model
5.  National Trends in Pharmaceutical Opioid Related Overdose Deaths Compared to other Substance Related Overdose Deaths: 1999-2009 
Drug and alcohol dependence  2013;131(3):263-270.
Pharmaceutical opioid related deaths have increased. This study aimed to place pharmaceutical opioid overdose deaths within the context of heroin, cocaine, psychostimulants, and pharmaceutical sedative hypnotics, examine demographic trends, and describe common combinations of substances involved in opioid related deaths.
We reviewed deaths among 15-64 year olds in the US from 1999-2009 using death certificate data available through the CDC Wide-Ranging Online Data for Epidemiologic Research (WONDER) Database. We identified International Classification of Disease-10 codes describing accidental overdose deaths, including poisonings related to stimulants, pharmaceutical drugs, and heroin. We used crude and age adjusted death rates (deaths/100,000 person years [p-y] and 95% confidence interval [CI] and multivariable Poisson regression models, yielding incident rate ratios (IRRs), for analysis.
The age adjusted death rate related to pharmaceutical opioids increased almost 4-fold from 1999 to 2009 (1.54/100,000 p-y [95% CI 1.49-1.60] to 6.05/100,000 p-y [95% CI 5.95-6.16; p<0.001). From 1999 to 2009, pharmaceutical opioids were responsible for the highest relative increase in overdose death rates (IRR 4.22, 95% CI 3.03-5.87) followed by sedative hypnotics (IRR 3.53, 95% CI 2.11-5.90). Heroin related overdose death rates increased from 2007 to 2009 (1.05/100,000 persons [95% CI 1.00-1.09] to 1.43/100,000 persons [95% CI 1.38-1.48; p<0.001). From 2005-2009 the combination of pharmaceutical opioids and benzodiazepines was the most common cause of polysubstance overdose deaths (1.27/100,000 p-y (95% CI 1.25-1.30).
Strategies, such as wider implementation of naloxone, expanded access to treatment, and development of new interventions are needed to curb the pharmaceutical opioid overdose epidemic.
PMCID: PMC3935414  PMID: 23294765
Overdose; poisoning; pharmaceutical opioids; stimulants; heroin; mortality
6.  A Pragmatic Framework for Single-site and Multisite Data Quality Assessment in Electronic Health Record-based Clinical Research 
Medical care  2012;50(0):10.1097/MLR.0b013e318257dd67.
Answers to clinical and public health research questions increasingly require aggregated data from multiple sites. Data from electronic health records and other clinical sources are useful for such studies, but require stringent quality assessment. Data quality assessment is particularly important in multisite studies to distinguish true variations in care from data quality problems.
We propose a “fit-for-use” conceptual model for data quality assessment and a process model for planning and conducting single-site and multisite data quality assessments. These approaches are illustrated using examples from prior multisite studies.
Critical components of multisite data quality assessment include: thoughtful prioritization of variables and data quality dimensions for assessment; development and use of standardized approaches to data quality assessment that can improve data utility over time; iterative cycles of assessment within and between sites; targeting assessment toward data domains known to be vulnerable to quality problems; and detailed documentation of the rationale and outcomes of data quality assessments to inform data users. The assessment process requires constant communication between site-level data providers, data coordinating centers, and principal investigators.
A conceptually based and systematically executed approach to data quality assessment is essential to achieve the potential of the electronic revolution in health care. High-quality data allow “learning health care organizations” to analyze and act on their own information, to compare their outcomes to peers, and to address critical scientific questions from the population perspective.
PMCID: PMC3833692  PMID: 22692254
data quality; data quality assessment; single-site studies; multisite studies
7.  Parental Decline of Pneumococcal Vaccination and Risk of Pneumococcal Related Disease in Children 
Vaccine  2010;29(5):994-999.
An increasing number of parents are choosing to decline immunizations for their children. This study examined the association between the parental decision to decline pneumococcal conjugate (PCV7) vaccinations and the risk of hospitalization due to pneumococcal disease or lobar pneumonia in children.
We conducted a case-control study nested within a cohort of children enrolled in the Kaiser Permanente Colorado (KPCO) health plan between 2004 and 2009. Each child hospitalized with pneumococcal disease or lobar pneumonia (n=106) was matched to 4 randomly selected controls (n=401). Cases were matched to controls by age, sex, high-risk status, calendar time, and length of enrollment in KPCO. Disease status and parental vaccination decisions were validated with medical record review. Cases and controls were classified as vaccine decliners or vaccine acceptors.
Among 106 cases, there were 6 (6%) PCV7 vaccine decliners; among 401 controls, there were 4 (1%) vaccine decliners. Children of parents who declined PCV7 immunization were 6.5 times (OR=6.5; 95% CI=1.7, 24.5) more likely to be hospitalized for invasive pneumococcal disease or lobar pneumonia than vaccinated children.
Parental decline of pneumococcal vaccination apparently increases the risk for hospitalization due to pneumococcal disease or lobar pneumonia in children. Providers can use this information when helping parents weigh the benefits and risks of immunizing their children.
PMCID: PMC3026079  PMID: 21145372
case control study; pneumococcal vaccine; vaccine decliner; lobar pneumonia; invasive pneumococcal disease
8.  Return to drug use and overdose after release from prison: a qualitative study of risk and protective factors 
Former inmates are at high risk for death from drug overdose, especially in the immediate post-release period. The purpose of the study is to understand the drug use experiences, perceptions of overdose risk, and experiences with overdose among former prisoners.
This qualitative study included former prison inmates (N = 29) who were recruited within two months after their release. Interviewers conducted in-person, semi-structured interviews which explored participants' experiences and perceptions. Transcripts were analyzed utilizing a team-based method of inductive analysis.
The following themes emerged: 1) Relapse to drugs and alcohol occurred in a context of poor social support, medical co-morbidity and inadequate economic resources; 2) former inmates experienced ubiquitous exposure to drugs in their living environments; 3) intentional overdose was considered "a way out" given situational stressors, and accidental overdose was perceived as related to decreased tolerance; and 4) protective factors included structured drug treatment programs, spirituality/religion, community-based resources (including self-help groups), and family.
Former inmates return to environments that strongly trigger relapse to drug use and put them at risk for overdose. Interventions to prevent overdose after release from prison may benefit from including structured treatment with gradual transition to the community, enhanced protective factors, and reductions of environmental triggers to use drugs.
PMCID: PMC3414824  PMID: 22966409
Drug use; Overdose; Prisoners; Relapse; Prison re-entry
9.  Near Real-Time Surveillance for Influenza Vaccine Safety: Proof-of-Concept in the Vaccine Safety Datalink Project 
American Journal of Epidemiology  2009;171(2):177-188.
The emergence of pandemic H1N1 influenza in 2009 has prompted public health responses, including production and licensure of new influenza A (H1N1) 2009 monovalent vaccines. Safety monitoring is a critical component of vaccination programs. As proof-of-concept, the authors mimicked near real-time prospective surveillance for prespecified neurologic and allergic adverse events among enrollees in 8 medical care organizations (the Vaccine Safety Datalink Project) who received seasonal trivalent inactivated influenza vaccine during the 2005/06–2007/08 influenza seasons. In self-controlled case series analysis, the risk of adverse events in a prespecified exposure period following vaccination was compared with the risk in 1 control period for the same individual either before or after vaccination. In difference-in-difference analysis, the relative risk in exposed versus control periods each season was compared with the relative risk in previous seasons since 2000/01. The authors used Poisson-based analysis to compare the risk of Guillian-Barré syndrome following vaccination in each season with that in previous seasons. Maximized sequential probability ratio tests were used to adjust for repeated analyses on weekly data. With administration of 1,195,552 doses to children under age 18 years and 4,773,956 doses to adults, no elevated risk of adverse events was identified. Near real-time surveillance for selected adverse events can be implemented prospectively to rapidly assess seasonal and pandemic influenza vaccine safety.
PMCID: PMC2878099  PMID: 19965887
cohort studies; influenza, human; influenza vaccines; managed care programs; population surveillance; safety; vaccines

Results 1-9 (9)