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Papers by Simon Hambidge

Research paper thumbnail of United States Epidemiology of Pediatric Injury—Related Primary Care Office Visits in the

Research paper thumbnail of Idiopathic Thrombocytopenic Purpura in Children A Population-Based, Multisite Cohort Study of the Predictors of Chronic

OBJECTIVE. The objective of this study was to identify risk factors for developing chronic idiopa... more OBJECTIVE. The objective of this study was to identify risk factors for developing chronic idiopathic thrombocytopenic purpura in a cohort of pediatric patients with idiopathic thrombocytopenic purpura.

Research paper thumbnail of Strategies to Improve Immunization Rates and Well-Child Care in a Disadvantaged Population A Cluster Randomized Controlled Trial

To measure the effect of a multimodal intervention on well-child care visit (WCV) and immunizatio... more To measure the effect of a multimodal intervention on well-child care visit (WCV) and immunization rates in an inner-city population. Cluster randomized controlled trial. One-year cohort of 2843 infants born at a hospital in an integrated inner-city health care system. Eleven clinics were randomly allocated to 1 of 3 study arms: WCV intervention (n = 3), immunization intervention (n = 4), and controls (n = 4). Interventions to improve immunization and WCV rates included both patient-based and clinic-based activities. Up-to-date status with childhood immunizations and WCVs by age 12 months (primary) and health care utilization and charges (secondary). Compared with the control arm, the WCV and immunization arms had 5% to 6% higher immunization rates and 7% to 8% higher WCV rates. In multivariate analyses that accounted for the clustered nature of the data, the number of immunizations received was greater in the WCV arm than in controls. However, neither the WCV nor the immunization intervention increased WCV or immunization up-to-date rates. The WCV arm had slightly higher health care charges. Neither intervention affected emergency, urgent care or inpatient utilization. This multimodal intervention produced a small increase in the number of childhood immunizations delivered. However, patient- and clinic-based methods did not lead to significant increases in WCV or immunization up-to-date rates after controlling for other factors. Methods found in some settings to increase immunization up-to-date rates may not be as effective in a population of inner-city socioeconomically disadvantaged children.

Research paper thumbnail of Disparities in Pediatric Preventive Care in the United States, 1993-2002

To quantify physician-reported preventive counseling and screening during well-child visits (WCVs... more To quantify physician-reported preventive counseling and screening during well-child visits (WCVs) and to examine racial and ethnic disparities in these activities. Cross-sectional study using the National Ambulatory Medical Care Survey, January 1993 through December 2002. Office-based physician practices. Children from birth to 18 years old who were seen by a physician for a WCV. Preventive counseling and screening. Well-child visits were shorter for Latino children than for white or black children. At WCVs, white children were more likely to receive preventive counseling than were black or Latino children (72% vs 61% vs 61%, respectively; P = .01) but not more likely to receive screening for elevated blood pressure, anemia, vision and hearing acuity, or lead toxicity. There were no differences in secondary diagnoses made at WCVs for white, black, or Latino children (15% vs 17% vs 14%, respectively; P = .65). The children who received the least counseling were Latino children in the public sector non-health maintenance organization setting (counseled at 39% of visits) and Latino children who self-paid for the visits (counseled at 26% of visits). After adjusting for possible confounders, including medications prescribed at the visit, black and Latino children were less likely to receive counseling than were white children (odds ratios, 0.68 and 0.63; 95% confidence interval, 0.48-0.97 and 0.44-0.90, respectively), and black children were less likely to receive preventive screening services (odds ratios, 0.65; 95% confidence interval, 0.45-0.93). By physician report in a nationally representative sample, black and Latino children received less counseling at WCVs than did white children. These disparities were unexplained by the competing demands of other secondary diagnoses or medications prescribed or dispensed.

Research paper thumbnail of Epidemiology of Pediatric Injury-Related Primary Care Office Visits in the United States

ABSTRACT. Objectives. Unintentional injuries are a major cause of childhood mortality and morbidi... more ABSTRACT. Objectives. Unintentional injuries are a major cause of childhood mortality and morbidity in the

Research paper thumbnail of Influencing the Home Food and Activity Environment of Families of Preschool Children Receiving Home-Based Treatment for Obesity

Clinical pediatrics, Jan 12, 2015

Research paper thumbnail of Emergency department visits among pediatric patients for sports-related injury: basic epidemiology and impact of race/ethnicity and insurance status

Pediatric emergency care, 2006

(1) To characterize the demographics and external causes of pediatric sports injury-related visit... more (1) To characterize the demographics and external causes of pediatric sports injury-related visits (SIRVs) to emergency departments (EDs). (2) To analyze the effect of race/ethnicity and insurance on SIRVs to EDs. A stratified random-sample cross-sectional survey of EDs in the National Hospital Ambulatory Medical Care Survey was conducted from 1997-2001; for patients younger than 19 years, we used all visits [n = 33,654; injury-related visits (IRVs) = 13,496, SIRVs = 2990]. We examined both the external cause codes and the actual verbatim text of all IRVs. National estimates of pediatric IRVs were obtained using the assigned patient visit weights in the National Hospital Ambulatory Medical Care Survey databases and SUDAAN 9.1 software (SAS Institute, Inc., Cary, NC). Sports injuries resulted in 2.5 million visits annually, or 23% of ED IRVs. Male sex, older age (6-18 years), and white race/ethnicity are associated with higher rates of SIRVs. Cycling, basketball, playground injuries, and football resulted in the largest numbers of ED SIRVs. Leading diagnoses for SIRVs included fractures and dislocations, sprains and strains, open wounds, and contusions. Hispanic race/ethnicity was associated with lower rates of SIRVs across all insurance types. After controlling for demographic factors and insurance, Hispanic children were less likely to have an SIRV than white children (odds ratio, 0.7; 95% confidence interval, 0.6-0.9). Sports and recreation are the leading causes of pediatric ED IRVs. Hispanic children, regardless of insurance status, had lower rates of SIRVs than white children, which helps explain the lower rate of nonfatal IRVs to EDs among Hispanic youth.

Research paper thumbnail of Safety of measles-containing vaccines in 1-year-old children

Pediatrics, 2015

All measles-containing vaccines are associated with several types of adverse events, including se... more All measles-containing vaccines are associated with several types of adverse events, including seizure, fever, and immune thrombocytopenia purpura (ITP). Because the measles-mumps-rubella-varicella (MMRV) vaccine compared with the separate measles-mumps-rubella (MMR) and varicella (MMR + V) vaccine increases a toddler's risk for febrile seizures, we investigated whether MMRV is riskier than MMR + V and whether either vaccine elevates the risk for additional safety outcomes. Study children were aged 12 to 23 months in the Vaccine Safety Datalink from 2000 to 2012. Nine study outcomes were investigated: 7 main outcomes (anaphylaxis, ITP, ataxia, arthritis, meningitis/encephalitis, acute disseminated encephalomyelitis, and Kawasaki disease), seizure, and fever. Comparing MMRV with MMR + V, relative risk was estimated by using stratified exact binomial tests. Secondary analyses examined post-MMRV or MMR + V risk versus comparison intervals; risk and comparison intervals were then co...

Research paper thumbnail of Parental decline of pneumococcal vaccination and risk of pneumococcal related disease in children

Vaccine, 2011

Background-An increasing number of parents are choosing to decline immunizations for their childr... more Background-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.

Research paper thumbnail of Trivalent inactivated influenza vaccine is not associated with sickle cell hospitalizations in adults from a large cohort

Vaccine, 2011

We evaluated the risk of hospitalization for sickle cell crisis (SCC) following influenza vaccina... more We evaluated the risk of hospitalization for sickle cell crisis (SCC) following influenza vaccination (trivalent inactivated vaccine, TIV) in adults with sickle cell disease. The cohort consisted of all adults aged 18years and older who had a diagnosis of sickle cell disease in the Vaccine Safety Datalink from 1991 to 2006. The outcome measure was any hospitalization for SCC with

Research paper thumbnail of Burden of acute gastroenteritis hospitalizations and emergency department visits in US children that is potentially preventable by rotavirus vaccination: a probe study using the now-withdrawn rotashield vaccine

Pediatrics, 2009

With the implementation of a new rotavirus immunization program in the United States in 2006, det... more With the implementation of a new rotavirus immunization program in the United States in 2006, determining the potential health benefits of rotavirus vaccination is important. We estimated the burden of acute gastroenteritis hospitalizations and emergency department visits in US children that are potentially preventable by rotavirus vaccination. We conducted a retrospective cohort analysis of children who in 1998-1999 were eligible to receive a now-withdrawn rotavirus vaccine (RotaShield) and were continuously enrolled in 1 of 6 managed care organizations in the Vaccine Safety Datalink. Estimates of vaccine effectiveness against all-cause gastroenteritis hospitalizations and emergency department visits adjusted according to month of birth, gender, and managed care organizations were calculated as 1 minus the risk ratio of outcomes among children in different dose groups. The burden of acute gastroenteritis prevented by vaccination was compared with the rotavirus burden estimated by 2...

Research paper thumbnail of Population-Level Obesity Surveillance: Monitoring Childhood Body Mass Index z-Score in a Safety-Net System

Academic Pediatrics, 2014

To determine the utility of repeated patient-level body mass index (BMI) measurements among highe... more To determine the utility of repeated patient-level body mass index (BMI) measurements among higher-risk patients seen at safety-net clinics as a community-level monitoring tool for overweight and obesity population trends. Data from a network of urban, federally qualified community health centers with computerized tracking of BMI at sequential outpatient visits were analyzed. We performed a longitudinal observational study over 8 years (2005-2012) with children stratified by weight status groups on the basis of BMI. Changes in BMI z-scores were used to estimate population trends among children 2 to 11 years old, with at least 2 visits (at least 1 year apart), for whom weight and height were measured. Among children (n = 33,542), the rate of overweight was 16% and rate of obesity was 18% at their last visit. Children were followed for an average of 3.24 ± 1.76 years to measure trends and change in weight status from earlier to later childhood. Children who were obese at first visit had increased odds (adjusted odds ratio 27.8, 95% confidence interval 25.6-30.2) of being obese by last visit. Mean change in BMI z-score per person-year of observation was 0.10 ± 0.38, with a differing rate of change based on weight status category at last visit (not overweight = 0.06 ± 0.39; overweight = 0.17 ± 0.34; obese = 0.19 ± 0.36). Change in BMI z-score per person-year decreased for 40% of obese children; however, their weight status group remained unchanged. Childhood obesity prevalence was high, with substantial progression to overweight and obesity from first to last visit. Clinically derived BMI z-score per person-year measures can effectively show population trends not observed using standard weight status categories.

Research paper thumbnail of What Can Providers Learn From Childhood Body Mass Index Trajectories: A Study of a Large, Safety-Net Clinical Population

Academic Pediatrics, 2014

To describe childhood weight gain using body mass index (BMI) z-score trajectories in a low-incom... more To describe childhood weight gain using body mass index (BMI) z-score trajectories in a low-income urban safety-net population and identify among gender- and race/ethnicity-specific groups any trends for increased risk. A retrospective cohort study was conducted among 2- to 12-year-old patients (2006-2013) visiting a safety-net provider. BMI z-score trajectories were calculated overall, for gender- and race/ethnicity-specific groups, and for peak BMI percentile subgroups to describe weight gain longitudinally. From 2006 to 2013, a total of 26,234 eligible children were followed for an average of 3.7 years. At baseline (mean age, 4.2 years), 74% of patients were at a normal weight compared to 65% at most recent observation (mean age, 7.8 years). All gender and race/ethnicity subgroups showed increasing average BMI z-scores during childhood. Children consistently under the 50th percentile and those of white race had the most stable BMI z-score trajectories. BMI z-score increased with increasing age in all subgroups. Hispanic boys and black girls had the most significant increase in BMI z-score during this observation period. Children observed in early childhood and whose BMI exceeded the 95th percentile at any time were often already overweight (20%) or obese (36%) by 3 years of age. The entire population demonstrated an upward trend in BMI z-score trajectory. This trend was most notable among black girls and Hispanic boys. Many obese children were already overweight by age 3, and persistence of obesity after 3 years of age was high, suggesting that intervention before age 3 may be essential to curbing unhealthy weight trajectories.

Research paper thumbnail of School-Located Influenza Vaccination With Third-Party Billing: What Do Parents Think?

Academic Pediatrics, 2014

To assess rates of immunization; costs of conducting clinics; and reimbursements for a school-loc... more To assess rates of immunization; costs of conducting clinics; and reimbursements for a school-located influenza vaccination (SLIV) program that billed third-party payers. SLIV clinics were conducted in 19 elementary schools in the Denver Public School district (September 2010 to February 2011). School personnel obtained parental consent, and a community vaccinator conducted clinics and performed billing. Vaccines For Children vaccine was available for eligible students. Parents were not billed for any fees. Data were collected regarding implementation costs and vaccine cost was calculated using published private sector prices. Reimbursement amounts were compared to costs. Overall, 30% of students (2784 of 9295) received ≥1 influenza vaccine; 39% (1079 of 2784) needed 2 doses and 80% received both. Excluding vaccine costs, implementation costs were $24.69 per vaccination. The percentage of vaccine costs reimbursed was 62% overall (82% from State Child Health Insurance Program (SCHIP), 50% from private insurance). The percentage of implementation costs reimbursed was 19% overall (23% from private, 27% from Medicaid, 29% from SCHIP and 0% among uninsured). Overall, 25% of total costs (implementation plus vaccine) were reimbursed. A SLIV program resulted in vaccination of nearly one third of elementary students. Reimbursement rates were limited by 1) school restrictions on charging parents fees, 2) low payments for vaccine administration from public payers and 3) high rates of denials from private insurers. Some of these problems might be reduced by provisions in the Affordable Care Act.

Research paper thumbnail of Safety of Trivalent Inactivated Influenza Vaccine in Children 6 to 23 Months Old

Research paper thumbnail of Childhood vaccines and Kawasaki disease, Vaccine Safety Datalink, 1996-2006

Vaccine, 2015

Kawasaki disease is a childhood vascular disorder of unknown etiology. Concerns have been raised ... more Kawasaki disease is a childhood vascular disorder of unknown etiology. Concerns have been raised about vaccinations being a potential risk factor for Kawasaki disease. Data from the Vaccine Safety Datalink were collected on children aged 0-6 years at seven managed care organizations across the United States. Defining exposure as one of several time periods up to 42 days after vaccination, we conducted Poisson regressions controlling for age, sex, season, and managed care organization to determine if rates of physician-diagnosed and verified Kawasaki disease were elevated following vaccination compared to rates during all unexposed periods. We also performed case-crossover analyses to control for unmeasured confounding. A total of 1,721,186 children aged 0-6 years from seven managed care organizations were followed for a combined 4,417,766 person-years. The rate of verified Kawasaki disease was significantly lower during the 1-42 days after vaccination (rate ratio=0.50, 95% CL=0.27-0.92) and 8-42 days after vaccination (rate ratio=0.45, 95% CL=0.22-0.90) compared to rates during unexposed periods. Breaking down the analysis by vaccination category did not identify a subset of vaccines which was solely responsible for this association. The case-crossover analyses revealed that children with Kawasaki disease had lower rates of vaccination in the 42 days prior to symptom onset for both physician-diagnosed Kawasaki disease (rate ratio=0.79, 95% CL=0.64-0.97) and verified Kawasaki disease (rate ratio=0.38, 95% CL=0.20-0.75). Childhood vaccinations' studied did not increase the risk of Kawasaki disease; conversely, vaccination was associated with a transient decrease in Kawasaki disease incidence. Verifying and understanding this potential protective effect could yield clues to the underlying etiology of Kawasaki disease.

Research paper thumbnail of Receipt of pertussis vaccine during pregnancy across 7 Vaccine Safety Datalink Sites

In response to widespread pertussis outbreaks and infant deaths, in 2010, the California Departme... more In response to widespread pertussis outbreaks and infant deaths, in 2010, the California Department of Health (CDPH) and in 2011 the Advisory Committee on Immunization Practices (ACIP) advised that the tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine be administered during pregnancy. The goals of this study were to describe Tdap coverage among pregnant women following these recommendations. In this observational cohort study, we utilized electronic medical record and claims data from seven Vaccine Safety Datalink sites to identify pregnancies and Tdap administrations. All Tdap doses were classified as pre-pregnancy, during pregnancy or post-pregnancy/postpartum. For pregnancies ending in a live birth, we evaluated factors associated with Tdap vaccination. Among 289,141 live births at the California VSD sites, receipt of Tdap during pregnancy increased substantially in the years 2010, 2011, and 2012, when coverage was 15.9, 30.0 and 19.5%, respectively. Among 82,398 women with live births at the Oregon, Washington, Colorado, Wisconsin and Minnesota VSD sites, receipt of Tdap during pregnancy first increased in 2012, at 16.0%. Women receiving early prenatal care and other vaccine(s) during pregnancy had higher Tdap coverage. We observed substantial increases in Tdap coverage during pregnancy following CDPH and ACIP recommendations.

Research paper thumbnail of Latino Parents' Perceptions of Weight Terminology Used in Pediatric Weight Counseling

Academic pediatrics, Jan 20, 2014

To identify which English and Spanish terms Latino parents consider motivating, as well as cultur... more To identify which English and Spanish terms Latino parents consider motivating, as well as culturally and linguistically appropriate, for provider use during weight counseling of overweight and obese Latino youth. Latino parent perceptions of common Spanish and English terms for overweight were discussed with 54 parents in 6 focus groups (3 English, 3 Spanish). Atlas.ti software was used for qualitative analysis. An initial codebook was used to code passages for English and Spanish terminology separately. Subsequent changes to the coded passages and creation of new codes were made by team consensus. "Demasiado peso para su salud" (too much weight for his/her health) was the only phrase for excess weight that was consistently identified as motivating and inoffensive by Spanish-speaking parents. "Sobrepeso" (overweight), a commonly used term among health care providers, was motivating to some parents but offensive to others. English-speaking parents had mixed react...

Research paper thumbnail of Evaluation of the association of maternal pertussis vaccination with obstetric events and birth outcomes

JAMA, Jan 12, 2014

In 2010, due to a pertussis outbreak and neonatal deaths, the California Department of Health rec... more In 2010, due to a pertussis outbreak and neonatal deaths, the California Department of Health recommended that the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) be administered during pregnancy. Tdap is now recommended by the Advisory Committee on Immunization Practices for all pregnant women, preferably between 27 and 36 weeks' gestation. Limited data exist on Tdap safety during pregnancy. To evaluate whether maternal Tdap vaccination during pregnancy is associated with increased risks of adverse obstetric events or adverse birth outcomes. Retrospective, observational cohort study using administrative health care databases from 2 California Vaccine Safety Datalink sites. Of 123,494 women with singleton pregnancies ending in a live birth between January 1, 2010, and November 15, 2012, 26,229 (21%) received Tdap during pregnancy and 97,265 did not. Risks of small-for-gestational-age (SGA) births (<10th percentile), chorioamnionitis, preterm ...

Research paper thumbnail of School-Located Influenza Vaccination With Third-Party Billing: Outcomes, Cost, and Reimbursement

Academic Pediatrics, 2014

Research paper thumbnail of United States Epidemiology of Pediatric Injury—Related Primary Care Office Visits in the

Research paper thumbnail of Idiopathic Thrombocytopenic Purpura in Children A Population-Based, Multisite Cohort Study of the Predictors of Chronic

OBJECTIVE. The objective of this study was to identify risk factors for developing chronic idiopa... more OBJECTIVE. The objective of this study was to identify risk factors for developing chronic idiopathic thrombocytopenic purpura in a cohort of pediatric patients with idiopathic thrombocytopenic purpura.

Research paper thumbnail of Strategies to Improve Immunization Rates and Well-Child Care in a Disadvantaged Population A Cluster Randomized Controlled Trial

To measure the effect of a multimodal intervention on well-child care visit (WCV) and immunizatio... more To measure the effect of a multimodal intervention on well-child care visit (WCV) and immunization rates in an inner-city population. Cluster randomized controlled trial. One-year cohort of 2843 infants born at a hospital in an integrated inner-city health care system. Eleven clinics were randomly allocated to 1 of 3 study arms: WCV intervention (n = 3), immunization intervention (n = 4), and controls (n = 4). Interventions to improve immunization and WCV rates included both patient-based and clinic-based activities. Up-to-date status with childhood immunizations and WCVs by age 12 months (primary) and health care utilization and charges (secondary). Compared with the control arm, the WCV and immunization arms had 5% to 6% higher immunization rates and 7% to 8% higher WCV rates. In multivariate analyses that accounted for the clustered nature of the data, the number of immunizations received was greater in the WCV arm than in controls. However, neither the WCV nor the immunization intervention increased WCV or immunization up-to-date rates. The WCV arm had slightly higher health care charges. Neither intervention affected emergency, urgent care or inpatient utilization. This multimodal intervention produced a small increase in the number of childhood immunizations delivered. However, patient- and clinic-based methods did not lead to significant increases in WCV or immunization up-to-date rates after controlling for other factors. Methods found in some settings to increase immunization up-to-date rates may not be as effective in a population of inner-city socioeconomically disadvantaged children.

Research paper thumbnail of Disparities in Pediatric Preventive Care in the United States, 1993-2002

To quantify physician-reported preventive counseling and screening during well-child visits (WCVs... more To quantify physician-reported preventive counseling and screening during well-child visits (WCVs) and to examine racial and ethnic disparities in these activities. Cross-sectional study using the National Ambulatory Medical Care Survey, January 1993 through December 2002. Office-based physician practices. Children from birth to 18 years old who were seen by a physician for a WCV. Preventive counseling and screening. Well-child visits were shorter for Latino children than for white or black children. At WCVs, white children were more likely to receive preventive counseling than were black or Latino children (72% vs 61% vs 61%, respectively; P = .01) but not more likely to receive screening for elevated blood pressure, anemia, vision and hearing acuity, or lead toxicity. There were no differences in secondary diagnoses made at WCVs for white, black, or Latino children (15% vs 17% vs 14%, respectively; P = .65). The children who received the least counseling were Latino children in the public sector non-health maintenance organization setting (counseled at 39% of visits) and Latino children who self-paid for the visits (counseled at 26% of visits). After adjusting for possible confounders, including medications prescribed at the visit, black and Latino children were less likely to receive counseling than were white children (odds ratios, 0.68 and 0.63; 95% confidence interval, 0.48-0.97 and 0.44-0.90, respectively), and black children were less likely to receive preventive screening services (odds ratios, 0.65; 95% confidence interval, 0.45-0.93). By physician report in a nationally representative sample, black and Latino children received less counseling at WCVs than did white children. These disparities were unexplained by the competing demands of other secondary diagnoses or medications prescribed or dispensed.

Research paper thumbnail of Epidemiology of Pediatric Injury-Related Primary Care Office Visits in the United States

ABSTRACT. Objectives. Unintentional injuries are a major cause of childhood mortality and morbidi... more ABSTRACT. Objectives. Unintentional injuries are a major cause of childhood mortality and morbidity in the

Research paper thumbnail of Influencing the Home Food and Activity Environment of Families of Preschool Children Receiving Home-Based Treatment for Obesity

Clinical pediatrics, Jan 12, 2015

Research paper thumbnail of Emergency department visits among pediatric patients for sports-related injury: basic epidemiology and impact of race/ethnicity and insurance status

Pediatric emergency care, 2006

(1) To characterize the demographics and external causes of pediatric sports injury-related visit... more (1) To characterize the demographics and external causes of pediatric sports injury-related visits (SIRVs) to emergency departments (EDs). (2) To analyze the effect of race/ethnicity and insurance on SIRVs to EDs. A stratified random-sample cross-sectional survey of EDs in the National Hospital Ambulatory Medical Care Survey was conducted from 1997-2001; for patients younger than 19 years, we used all visits [n = 33,654; injury-related visits (IRVs) = 13,496, SIRVs = 2990]. We examined both the external cause codes and the actual verbatim text of all IRVs. National estimates of pediatric IRVs were obtained using the assigned patient visit weights in the National Hospital Ambulatory Medical Care Survey databases and SUDAAN 9.1 software (SAS Institute, Inc., Cary, NC). Sports injuries resulted in 2.5 million visits annually, or 23% of ED IRVs. Male sex, older age (6-18 years), and white race/ethnicity are associated with higher rates of SIRVs. Cycling, basketball, playground injuries, and football resulted in the largest numbers of ED SIRVs. Leading diagnoses for SIRVs included fractures and dislocations, sprains and strains, open wounds, and contusions. Hispanic race/ethnicity was associated with lower rates of SIRVs across all insurance types. After controlling for demographic factors and insurance, Hispanic children were less likely to have an SIRV than white children (odds ratio, 0.7; 95% confidence interval, 0.6-0.9). Sports and recreation are the leading causes of pediatric ED IRVs. Hispanic children, regardless of insurance status, had lower rates of SIRVs than white children, which helps explain the lower rate of nonfatal IRVs to EDs among Hispanic youth.

Research paper thumbnail of Safety of measles-containing vaccines in 1-year-old children

Pediatrics, 2015

All measles-containing vaccines are associated with several types of adverse events, including se... more All measles-containing vaccines are associated with several types of adverse events, including seizure, fever, and immune thrombocytopenia purpura (ITP). Because the measles-mumps-rubella-varicella (MMRV) vaccine compared with the separate measles-mumps-rubella (MMR) and varicella (MMR + V) vaccine increases a toddler's risk for febrile seizures, we investigated whether MMRV is riskier than MMR + V and whether either vaccine elevates the risk for additional safety outcomes. Study children were aged 12 to 23 months in the Vaccine Safety Datalink from 2000 to 2012. Nine study outcomes were investigated: 7 main outcomes (anaphylaxis, ITP, ataxia, arthritis, meningitis/encephalitis, acute disseminated encephalomyelitis, and Kawasaki disease), seizure, and fever. Comparing MMRV with MMR + V, relative risk was estimated by using stratified exact binomial tests. Secondary analyses examined post-MMRV or MMR + V risk versus comparison intervals; risk and comparison intervals were then co...

Research paper thumbnail of Parental decline of pneumococcal vaccination and risk of pneumococcal related disease in children

Vaccine, 2011

Background-An increasing number of parents are choosing to decline immunizations for their childr... more Background-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.

Research paper thumbnail of Trivalent inactivated influenza vaccine is not associated with sickle cell hospitalizations in adults from a large cohort

Vaccine, 2011

We evaluated the risk of hospitalization for sickle cell crisis (SCC) following influenza vaccina... more We evaluated the risk of hospitalization for sickle cell crisis (SCC) following influenza vaccination (trivalent inactivated vaccine, TIV) in adults with sickle cell disease. The cohort consisted of all adults aged 18years and older who had a diagnosis of sickle cell disease in the Vaccine Safety Datalink from 1991 to 2006. The outcome measure was any hospitalization for SCC with

Research paper thumbnail of Burden of acute gastroenteritis hospitalizations and emergency department visits in US children that is potentially preventable by rotavirus vaccination: a probe study using the now-withdrawn rotashield vaccine

Pediatrics, 2009

With the implementation of a new rotavirus immunization program in the United States in 2006, det... more With the implementation of a new rotavirus immunization program in the United States in 2006, determining the potential health benefits of rotavirus vaccination is important. We estimated the burden of acute gastroenteritis hospitalizations and emergency department visits in US children that are potentially preventable by rotavirus vaccination. We conducted a retrospective cohort analysis of children who in 1998-1999 were eligible to receive a now-withdrawn rotavirus vaccine (RotaShield) and were continuously enrolled in 1 of 6 managed care organizations in the Vaccine Safety Datalink. Estimates of vaccine effectiveness against all-cause gastroenteritis hospitalizations and emergency department visits adjusted according to month of birth, gender, and managed care organizations were calculated as 1 minus the risk ratio of outcomes among children in different dose groups. The burden of acute gastroenteritis prevented by vaccination was compared with the rotavirus burden estimated by 2...

Research paper thumbnail of Population-Level Obesity Surveillance: Monitoring Childhood Body Mass Index z-Score in a Safety-Net System

Academic Pediatrics, 2014

To determine the utility of repeated patient-level body mass index (BMI) measurements among highe... more To determine the utility of repeated patient-level body mass index (BMI) measurements among higher-risk patients seen at safety-net clinics as a community-level monitoring tool for overweight and obesity population trends. Data from a network of urban, federally qualified community health centers with computerized tracking of BMI at sequential outpatient visits were analyzed. We performed a longitudinal observational study over 8 years (2005-2012) with children stratified by weight status groups on the basis of BMI. Changes in BMI z-scores were used to estimate population trends among children 2 to 11 years old, with at least 2 visits (at least 1 year apart), for whom weight and height were measured. Among children (n = 33,542), the rate of overweight was 16% and rate of obesity was 18% at their last visit. Children were followed for an average of 3.24 ± 1.76 years to measure trends and change in weight status from earlier to later childhood. Children who were obese at first visit had increased odds (adjusted odds ratio 27.8, 95% confidence interval 25.6-30.2) of being obese by last visit. Mean change in BMI z-score per person-year of observation was 0.10 ± 0.38, with a differing rate of change based on weight status category at last visit (not overweight = 0.06 ± 0.39; overweight = 0.17 ± 0.34; obese = 0.19 ± 0.36). Change in BMI z-score per person-year decreased for 40% of obese children; however, their weight status group remained unchanged. Childhood obesity prevalence was high, with substantial progression to overweight and obesity from first to last visit. Clinically derived BMI z-score per person-year measures can effectively show population trends not observed using standard weight status categories.

Research paper thumbnail of What Can Providers Learn From Childhood Body Mass Index Trajectories: A Study of a Large, Safety-Net Clinical Population

Academic Pediatrics, 2014

To describe childhood weight gain using body mass index (BMI) z-score trajectories in a low-incom... more To describe childhood weight gain using body mass index (BMI) z-score trajectories in a low-income urban safety-net population and identify among gender- and race/ethnicity-specific groups any trends for increased risk. A retrospective cohort study was conducted among 2- to 12-year-old patients (2006-2013) visiting a safety-net provider. BMI z-score trajectories were calculated overall, for gender- and race/ethnicity-specific groups, and for peak BMI percentile subgroups to describe weight gain longitudinally. From 2006 to 2013, a total of 26,234 eligible children were followed for an average of 3.7 years. At baseline (mean age, 4.2 years), 74% of patients were at a normal weight compared to 65% at most recent observation (mean age, 7.8 years). All gender and race/ethnicity subgroups showed increasing average BMI z-scores during childhood. Children consistently under the 50th percentile and those of white race had the most stable BMI z-score trajectories. BMI z-score increased with increasing age in all subgroups. Hispanic boys and black girls had the most significant increase in BMI z-score during this observation period. Children observed in early childhood and whose BMI exceeded the 95th percentile at any time were often already overweight (20%) or obese (36%) by 3 years of age. The entire population demonstrated an upward trend in BMI z-score trajectory. This trend was most notable among black girls and Hispanic boys. Many obese children were already overweight by age 3, and persistence of obesity after 3 years of age was high, suggesting that intervention before age 3 may be essential to curbing unhealthy weight trajectories.

Research paper thumbnail of School-Located Influenza Vaccination With Third-Party Billing: What Do Parents Think?

Academic Pediatrics, 2014

To assess rates of immunization; costs of conducting clinics; and reimbursements for a school-loc... more To assess rates of immunization; costs of conducting clinics; and reimbursements for a school-located influenza vaccination (SLIV) program that billed third-party payers. SLIV clinics were conducted in 19 elementary schools in the Denver Public School district (September 2010 to February 2011). School personnel obtained parental consent, and a community vaccinator conducted clinics and performed billing. Vaccines For Children vaccine was available for eligible students. Parents were not billed for any fees. Data were collected regarding implementation costs and vaccine cost was calculated using published private sector prices. Reimbursement amounts were compared to costs. Overall, 30% of students (2784 of 9295) received ≥1 influenza vaccine; 39% (1079 of 2784) needed 2 doses and 80% received both. Excluding vaccine costs, implementation costs were $24.69 per vaccination. The percentage of vaccine costs reimbursed was 62% overall (82% from State Child Health Insurance Program (SCHIP), 50% from private insurance). The percentage of implementation costs reimbursed was 19% overall (23% from private, 27% from Medicaid, 29% from SCHIP and 0% among uninsured). Overall, 25% of total costs (implementation plus vaccine) were reimbursed. A SLIV program resulted in vaccination of nearly one third of elementary students. Reimbursement rates were limited by 1) school restrictions on charging parents fees, 2) low payments for vaccine administration from public payers and 3) high rates of denials from private insurers. Some of these problems might be reduced by provisions in the Affordable Care Act.

Research paper thumbnail of Safety of Trivalent Inactivated Influenza Vaccine in Children 6 to 23 Months Old

Research paper thumbnail of Childhood vaccines and Kawasaki disease, Vaccine Safety Datalink, 1996-2006

Vaccine, 2015

Kawasaki disease is a childhood vascular disorder of unknown etiology. Concerns have been raised ... more Kawasaki disease is a childhood vascular disorder of unknown etiology. Concerns have been raised about vaccinations being a potential risk factor for Kawasaki disease. Data from the Vaccine Safety Datalink were collected on children aged 0-6 years at seven managed care organizations across the United States. Defining exposure as one of several time periods up to 42 days after vaccination, we conducted Poisson regressions controlling for age, sex, season, and managed care organization to determine if rates of physician-diagnosed and verified Kawasaki disease were elevated following vaccination compared to rates during all unexposed periods. We also performed case-crossover analyses to control for unmeasured confounding. A total of 1,721,186 children aged 0-6 years from seven managed care organizations were followed for a combined 4,417,766 person-years. The rate of verified Kawasaki disease was significantly lower during the 1-42 days after vaccination (rate ratio=0.50, 95% CL=0.27-0.92) and 8-42 days after vaccination (rate ratio=0.45, 95% CL=0.22-0.90) compared to rates during unexposed periods. Breaking down the analysis by vaccination category did not identify a subset of vaccines which was solely responsible for this association. The case-crossover analyses revealed that children with Kawasaki disease had lower rates of vaccination in the 42 days prior to symptom onset for both physician-diagnosed Kawasaki disease (rate ratio=0.79, 95% CL=0.64-0.97) and verified Kawasaki disease (rate ratio=0.38, 95% CL=0.20-0.75). Childhood vaccinations&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; studied did not increase the risk of Kawasaki disease; conversely, vaccination was associated with a transient decrease in Kawasaki disease incidence. Verifying and understanding this potential protective effect could yield clues to the underlying etiology of Kawasaki disease.

Research paper thumbnail of Receipt of pertussis vaccine during pregnancy across 7 Vaccine Safety Datalink Sites

In response to widespread pertussis outbreaks and infant deaths, in 2010, the California Departme... more In response to widespread pertussis outbreaks and infant deaths, in 2010, the California Department of Health (CDPH) and in 2011 the Advisory Committee on Immunization Practices (ACIP) advised that the tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine be administered during pregnancy. The goals of this study were to describe Tdap coverage among pregnant women following these recommendations. In this observational cohort study, we utilized electronic medical record and claims data from seven Vaccine Safety Datalink sites to identify pregnancies and Tdap administrations. All Tdap doses were classified as pre-pregnancy, during pregnancy or post-pregnancy/postpartum. For pregnancies ending in a live birth, we evaluated factors associated with Tdap vaccination. Among 289,141 live births at the California VSD sites, receipt of Tdap during pregnancy increased substantially in the years 2010, 2011, and 2012, when coverage was 15.9, 30.0 and 19.5%, respectively. Among 82,398 women with live births at the Oregon, Washington, Colorado, Wisconsin and Minnesota VSD sites, receipt of Tdap during pregnancy first increased in 2012, at 16.0%. Women receiving early prenatal care and other vaccine(s) during pregnancy had higher Tdap coverage. We observed substantial increases in Tdap coverage during pregnancy following CDPH and ACIP recommendations.

Research paper thumbnail of Latino Parents' Perceptions of Weight Terminology Used in Pediatric Weight Counseling

Academic pediatrics, Jan 20, 2014

To identify which English and Spanish terms Latino parents consider motivating, as well as cultur... more To identify which English and Spanish terms Latino parents consider motivating, as well as culturally and linguistically appropriate, for provider use during weight counseling of overweight and obese Latino youth. Latino parent perceptions of common Spanish and English terms for overweight were discussed with 54 parents in 6 focus groups (3 English, 3 Spanish). Atlas.ti software was used for qualitative analysis. An initial codebook was used to code passages for English and Spanish terminology separately. Subsequent changes to the coded passages and creation of new codes were made by team consensus. "Demasiado peso para su salud" (too much weight for his/her health) was the only phrase for excess weight that was consistently identified as motivating and inoffensive by Spanish-speaking parents. "Sobrepeso" (overweight), a commonly used term among health care providers, was motivating to some parents but offensive to others. English-speaking parents had mixed react...

Research paper thumbnail of Evaluation of the association of maternal pertussis vaccination with obstetric events and birth outcomes

JAMA, Jan 12, 2014

In 2010, due to a pertussis outbreak and neonatal deaths, the California Department of Health rec... more In 2010, due to a pertussis outbreak and neonatal deaths, the California Department of Health recommended that the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) be administered during pregnancy. Tdap is now recommended by the Advisory Committee on Immunization Practices for all pregnant women, preferably between 27 and 36 weeks' gestation. Limited data exist on Tdap safety during pregnancy. To evaluate whether maternal Tdap vaccination during pregnancy is associated with increased risks of adverse obstetric events or adverse birth outcomes. Retrospective, observational cohort study using administrative health care databases from 2 California Vaccine Safety Datalink sites. Of 123,494 women with singleton pregnancies ending in a live birth between January 1, 2010, and November 15, 2012, 26,229 (21%) received Tdap during pregnancy and 97,265 did not. Risks of small-for-gestational-age (SGA) births (<10th percentile), chorioamnionitis, preterm ...

Research paper thumbnail of School-Located Influenza Vaccination With Third-Party Billing: Outcomes, Cost, and Reimbursement

Academic Pediatrics, 2014