Simon J Hambidge

Kaiser Permanente, Oakland, California, United States

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Publications (83)344 Total impact

  • BMC Public Health 12/2015; 15(1). DOI:10.1186/s12889-015-1833-z · 2.32 Impact Factor
  • Clinical Pediatrics 02/2015; DOI:10.1177/0009922815570614 · 1.26 Impact Factor
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    ABSTRACT: 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 contrasted for MMRV versus MMR+V. We evaluated 123 200 MMRV and 584 987 MMR + V doses. Comparing MMRV with MMR + V, risks for the 7 main outcomes were not significantly different. Several outcomes had few or zero postvaccination events. Comparing risk versus comparison intervals, ITP risk was higher after MMRV (odds ratio [OR]: 11.3 [95% confidence interval (CI): 1.9 to 68.2]) and MMR + V (OR: 10 [95% CI: 4.5 to 22.5]) and ataxia risk was lower after both vaccines (MMRV OR: 0.8 [95% CI: 0.5 to 1]; MMR + V OR: 0.8 [95% CI: 0.7 to 0.9]). Compared with MMR + V, MMRV increased risk of seizure and fever 7 to 10 days after vaccination. This study did not identify any new safety concerns comparing MMRV with MMR + V or after either the MMRV or the MMR + V vaccine. This study provides reassurance that these outcomes are unlikely after either vaccine. Copyright © 2015 by the American Academy of Pediatrics.
    Pediatrics 01/2015; 135(2). DOI:10.1542/peds.2014-1822 · 5.30 Impact Factor
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    ABSTRACT: 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 reactions to "unhealthy weight," "weight problem," and "overweight," finding them motivating, confusing, or insulting. Parents found "fat" "gordo" and "obese" "obeso" consistently offensive. Most participants found growth charts and the term "BMI" confusing. Parents consistently reported that providers could enhance motivation and avoid offending families by linking a child's weight to health risks, particularly diabetes. "Demasiado peso para su salud" (too much weight for his/her health) was motivating to many Spanish-speaking Latino parents. Among English-speaking Latino parents, no single English term emerged as motivating, well-understood, and inoffensive. Linking a child's excess weight with increased health risks was motivating and valuable to many parents regardless of language spoken. Copyright © 2014 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.
    Academic Pediatrics 12/2014; 15(2). DOI:10.1016/j.acap.2014.11.003 · 2.23 Impact Factor
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    ABSTRACT: 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.
    JAMA The Journal of the American Medical Association 11/2014; 312(18):1897-904. DOI:10.1001/jama.2014.14825 · 30.39 Impact Factor
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    ABSTRACT: 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. Copyright © 2014. Published by Elsevier Ltd.
    Vaccine 11/2014; 33(2). DOI:10.1016/j.vaccine.2014.10.044 · 3.49 Impact Factor
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    ABSTRACT: 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. Copyright © 2014 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.
    Academic Pediatrics 11/2014; 14(6):632-8. DOI:10.1016/j.acap.2014.06.007 · 2.23 Impact Factor
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    ABSTRACT: 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.
    Academic Pediatrics 08/2014; DOI:10.1016/j.acap.2014.06.009 · 2.23 Impact Factor
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    ABSTRACT: Objective. 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. Methods. 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. Results. 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. Conclusion. We observed substantial increases in Tdap coverage during pregnancy following CDPH and ACIP recommendations.
    Preventive Medicine 06/2014; 67. DOI:10.1016/j.ypmed.2014.05.025 · 2.93 Impact Factor
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    ABSTRACT: Little is known regarding the timing of childhood vaccination and postvaccination seizures.METHODS: In a cohort of 323 247 US children from the Vaccine Safety Datalink born from 2004 to 2008, we analyzed the association between the timing of childhood vaccination and the first occurrence of seizure with a self-controlled case series analysis of the first doses of individual vaccines received in the first 2 years of life.RESULTS: In infants, there was no association between the timing of infant vaccination and postvaccination seizures. In the second year of life, the incident rate ratio (IRR) for seizures after receipt of the first measles-mumps-rubella vaccine (MMR) dose at 12 to 15 months was 2.65 (95% confidence interval [CI] 1.99-3.55); the IRR after an MMR dose at 16 to 23 months was 6.53 (95% CI 3.15-13.53). The IRR for seizures after receipt of the first measles-mumps-rubella-varicella vaccine (MMRV) dose at 12 to 15 months was 4.95 (95% CI 3.68-6.66); the IRR after an MMRV dose at 16 to 23 months was 9.80 (95% CI 4.35 -22.06).CONCLUSIONS: There is no increased risk of postvaccination seizure in infants regardless of timing of vaccination. In year 2, delaying MMR vaccine past 15 months of age results in a higher risk of seizures. The strength of the association is doubled with MMRV vaccine. These findings suggest that on-time vaccination is as safe with regard to seizures as delayed vaccination in the first year of life, and that delayed vaccination in the second year of life is associated with more postvaccination seizures than on-time vaccination.
    Pediatrics 05/2014; 133(6). DOI:10.1542/peds.2013-3429 · 5.30 Impact Factor
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    ABSTRACT: School-located influenza vaccination (SLIV) may be instrumental in achieving high vaccination rates among children. Sustainability of SLIV programs may require third-party billing. This study assessed, among parents of elementary school students, the attitudes about SLIV and billing at school, as well as factors associated with being supportive of SLIV. We conducted a survey (April 2010 to June 2010) of parents of 1000 randomly selected primarily low-income children at 20 elementary schools at which SLIV with billing had occurred. Response rate was 70% (n = 699). Eighty-one percent agreed (61% strongly) they "would be okay" with SLIV for their child. Many agreed it was better to get vaccinated at their child's doctor's office because they could take care of other health issues (72%) and the doctor knows the child's medical history (65%). However, an equal percentage (47%) thought the best place for influenza vaccination was the child's doctor's office and the child's school. Twenty-five percent did not want to give health insurance information necessary for billing at school. Factors independently associated with strongly supporting SLIV included parental education of high school or less (relative risk 1.30; 95% confidence interval 1.09-1.58), Hispanic ethnicity (1.25; 1.08-1.45); believing the vaccine is efficacious (1.49; 1.23-1.84); and finding school delivery more convenient (2.37; 1.82-3.45). Having concerns about the safety of influenza vaccine (0.80; 0.72-0.88) and not wanting their child to be vaccinated without a parent (0.74; 0.64-0.83) were negatively associated. The majority of parents were supportive of SLIV, although parental concerns about not being present for vaccination and about the safety and efficacy of the vaccine will need to be addressed.
    Academic pediatrics 05/2014; 14(3):241-8. DOI:10.1016/j.acap.2014.01.006 · 2.23 Impact Factor
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    ABSTRACT: 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.
    Academic pediatrics 05/2014; 14(3):234-40. DOI:10.1016/j.acap.2014.01.005 · 2.23 Impact Factor
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    ABSTRACT: In 2008, a diphtheria, tetanus, acellular pertussis, and inactivated poliovirus combined vaccine (DTaP-IPV) was licensed for use in children 4 through 6 years of age. While pre-licensure studies did not demonstrate significant safety concerns, the number vaccinated in these studies was not sufficient to examine the risk of uncommon but serious adverse events. To assess the risk of serious adverse events following DTaP-IPV vaccination. The study was conducted from January 2009 through September 2012 in the Vaccine Safety Datalink (VSD) project. In the VSD, electronic vaccination and encounter data are updated and aggregated weekly as part of ongoing surveillance activities. Based on previous reports and biologic plausibility, eight potential adverse events were monitored: meningitis/encephalitis; seizures; stroke; Guillain-Barré syndrome; Stevens-Johnson syndrome; anaphylaxis; serious allergic reactions other than anaphylaxis; and serious local reactions. Adverse event rates in DTaP-IPV recipients were compared to historical incidence rates in the VSD population prior to 2009. Sequential probability ratio testing was used to analyze the data on a weekly basis. During the study period, 201,116 children received DTaP-IPV vaccine. Ninety-seven percent of DTaP-IPV recipients also received other vaccines on the same day, typically measles-mumps-rubella and varicella vaccines. There was no statistically significant increased risk of any of the eight pre-specified adverse events among DTaP-IPV recipients when compared to historical incidence rates. In this safety surveillance study of more than 200,000 DTaP-IPV vaccine recipients, there was no evidence of increased risk for any of the pre-specified adverse events monitored. Continued surveillance of DTaP-IPV vaccine safety may be warranted to monitor for rare adverse events, such as Guillain-Barré syndrome.
    Vaccine 03/2014; 32(25). DOI:10.1016/j.vaccine.2014.03.063 · 3.49 Impact Factor
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    ABSTRACT: A number of studies have described influenza vaccination coverage during pregnancy but few publications have described rates of other vaccinations. To describe vaccination rates during pregnancy in the Vaccine Safety Datalink (VSD), with particular focus on vaccinations contraindicated during pregnancy. Pregnancies ending in 2002 through 2009 and vaccinations administered during these pregnancies were identified in the VSD. Vaccination rates per 1000 pregnancies during the study period were calculated by vaccine type, recommendation category, pregnancy year, maternal age, and trimester. Analyses were conducted in 2012-2013. In the VSD, 669,695 pregnancies and 141,389 vaccinations were identified. Trivalent inactivated influenza (TIV) was the most commonly administered vaccination (174.1 doses per 1000 pregnancies) and was most often administered during the 2nd and 3rd trimesters. The most common vaccines in the "consider if indicated" category were tetanus-diphtheria (6.1 per 1000) and hepatitis B (3.7 per 1000). Contraindicated vaccination was infrequent, and the majority of these were measles-mumps-rubella (MMR) (1.2 per 1000); varicella (1.0 per 1000); and live-attenuated influenza vaccine (LAIV) (0.3 per 1000). Both "consider if indicated" and contraindicated vaccines were more frequently administered during early pregnancy. TIV was the most commonly administered vaccine. With the exception of TIV, other vaccines were most frequently administered during early pregnancy and among younger women, suggesting that vaccination may occur when the woman and/or provider are unaware of the pregnancy. Contraindicated vaccines were infrequently administered during pregnancy; however, given that some women received contraindicated vaccines later in pregnancy, clearer recommendations and improved provider education may be needed.
    American journal of preventive medicine 02/2014; 46(2):150-7. DOI:10.1016/j.amepre.2013.10.010 · 4.28 Impact Factor
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    ABSTRACT: The self-controlled case series (SCCS) method is often used to examine the temporal association between vaccination and adverse events using only data from patients who experienced such events. Conditional Poisson regression models are used to estimate incidence rate ratios, and these models perform well with large or medium-sized case samples. However, in some vaccine safety studies, the adverse events studied are rare and the maximum likelihood estimates may be biased. Several bias correction methods have been examined in case-control studies using conditional logistic regression, but none of these methods have been evaluated in studies using the SCCS design. In this study, we used simulations to evaluate 2 bias correction approaches-the Firth penalized maximum likelihood method and Cordeiro and McCullagh's bias reduction after maximum likelihood estimation-with small sample sizes in studies using the SCCS design. The simulations showed that the bias under the SCCS design with a small number of cases can be large and is also sensitive to a short risk period. The Firth correction method provides finite and less biased estimates than the maximum likelihood method and Cordeiro and McCullagh's method. However, limitations still exist when the risk period in the SCCS design is short relative to the entire observation period.
    American journal of epidemiology 12/2013; 178(12):1750-9. DOI:10.1093/aje/kwt211 · 4.98 Impact Factor
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    ABSTRACT: Background: Caries, a common childhood disease, is preventable, yet access to preventive dental care (PDC) is limited for disadvantaged children. Objective: To examine the provision of PDC by medical providers after participation in an oral health promotion program (OHPP). Design/Methods: We implemented a staged intervention in an urban safety-net health system with 8 federally-qualified health centers (FQHCs). Four FQHCs received the OHPP in 2009 (intervention) and 4 in 2011 (controls). OHPP consisted of an oral health training regarding PDC (including fluoride varnish application (FVA)) and quarterly practice coaching. We measured OHPP adoption by 1) comparing FVA in children receiving care in the intervention vs. control FQHCs in 2011 and 2) FVA in children 18-, 30- and 42-months of age in 2013. Descriptive statistics, Wilcoxon rank-sum and Chi-square tests were used. Results: 1) A random sample of 421 children receiving care in the 4 intervention/4 control FQHCs were recruited. They were 40.6 months old, Hispanic (91.2% intervention/86.4% control, p=0.14) and insured by Medicaid/SCHIP (90.2% intervention/85.6% control, p=0.17). Children from intervention FQHCs were more likely to have received a FVA (mean=1.4 FVA (N=296, Range=0 to 7) than children from control FQHCs (mean= 0.4 FVA (N=124, Range=0 to 4)) (p<0.0001). 2) 79% of 18-month old children receiving care in any FQHCs had received at ≥ 1 FVA; 62% of 30-month old children had received ≥ 2; and 38% of 42-month old children had received ≥ 3. Conclusions: A structured OHPP program effectively engaged medical providers in the provision of PDC to children.
    141st APHA Annual Meeting and Exposition 2013; 11/2013
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    ABSTRACT: IMPORTANCE The first dose of live attenuated measles-containing vaccines is associated with an increased risk of febrile seizures 7 to 10 days following immunization among 12- to 23-month-old children. The combination measles, mumps, rubella, and varicella vaccine is associated with a 2-fold increased risk of febrile seizures 7 to 10 days following immunization compared with the separately administered measles, mumps, and rubella and varicella vaccines. It is unknown whether the magnitude of these increased risks depends on age at immunization. OBJECTIVE To examine the potential modifying effect of age on the risk of fever and seizures following immunization with measles-containing vaccines. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study at 8 Vaccine Safety Datalink sites of a total of 840 348 children 12 to 23 months of age who had received a measles-containing vaccine from 2001 through 2011. EXPOSURES Any measles-containing vaccines and measles-containing vaccines by type. MAIN OUTCOMES AND MEASURES Fever and seizure events occurring during a 42-day postimmunization observation period. RESULTS In the analysis of any measles-containing vaccines, the increased risk of seizures during the 7- to 10-day risk interval, using the remainder of the observation period as the control interval, was significantly greater among older children (relative risk, 6.5; 95% CI, 5.3-8.1; attributable risk, 9.5 excess cases per 10 000 doses; 95% CI, 7.6-11.5) than among younger children (relative risk, 3.4; 95% CI, 3.0-3.9; attributable risk = 4.0 excess cases per 10 000 doses; 95% CI, 3.4-4.6). The relative risk of postimmunization fever was significantly greater among older children than among younger children; however, its attributable risk was not. In the analysis of vaccine type, measles, mumps, rubella, and varicella vaccine was associated with a 1.4-fold increase in the risk of fever and 2-fold increase in the risk of seizures compared with measles, mumps, and rubella vaccine administered with or without varicella vaccine in both younger and older children. CONCLUSIONS AND RELEVANCE Measles-containing vaccines are associated with a lower increased risk of seizures when administered at 12 to 15 months of age. Findings of this study that focused on safety outcomes highlight the importance of timely immunization of children with the first dose of measles-containing vaccines.
    10/2013; 167(12). DOI:10.1001/jamapediatrics.2013.2745
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    ABSTRACT: Background: Among toddlers, measles-containing vaccines increase risk of seizure and fever during 7-10 days after immunization. We evaluated risk of 7 additional outcomes following combination measles-mumps-rubella-varicella (MMRV) and separately administered MMR and varicella (MMR+V) vaccines. Methods: In children aged 12-23 months who were part of the Vaccine Safety Datalink from 2000-2012, we examined pre-specified post-vaccination risk intervals for anaphylaxis (day 0), immune thrombocytopenia purpura (ITP; days 14-28, 1-42), ataxia (days 14-28, 1-42), arthritis (days 1-42), encephalitis/meningitis/encephalopathy (days 3-21, 1-42), acute disseminated encephalomyelitis (ADEM; days 3-21, 1-42), and Kawasaki Disease (days 1-28, 1-56). We compared outcomes during the risk intervals post-MMRV with those post-MMR+V; we also compared outcomes during each risk interval with those during a later control interval using case centered logistic regression. Case centered analyses estimate the odds ratio (OR) by dividing the observed odds of an outcome in the risk interval by the expected odds. The expected odds were derived from similar vaccinees at risk when the outcome occurred. Results: We evaluated 123,200 MMRV doses and 584,987 MMR+V doses. Difference in risk between MMRV and MMR + V was not statistically significant during any pre-specified risk interval for any outcome. However, several outcomes had few or zero events in the risk interval after either vaccine (ADEM, arthritis, Kawasaki Disease, encephalitis/meningitis, anaphylaxis). Comparing the risk interval with the control interval (case centered analyses), we detected increased risk of ITP following both MMRV (OR 11.3, 95% confidence interval [CI] 1.9-68.2) and MMR+V (OR 10, CI 4.5-22.5), decreased risk of ataxia after both MMRV (OR 0.8, CI 0.5-1) and MMR+V (OR 0.8, CI 0.7-0.9) and increased risk of anaphylaxis (2 cases) after MMRV (OR 15.3, CI 2.2-108.9). Conclusion: Comparing MMRV with MMR + V, there were no statistically significant differences in risk for all outcomes. The individual elevated risk for ITP after MMRV and MMR + V is consistent with previous studies, while the increased risk for anaphylaxis after MMRV and the reduced risk for ataxia after both MMRV and MMR + V require more investigation. Power was limited and ongoing monitoring of anaphylaxis and other outcomes is warranted.
    IDWeek 2013 Meeting of the Infectious Diseases Society of America; 10/2013
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    ABSTRACT: IMPORTANCE Undervaccination is an increasing trend that potentially places children and their communities at an increased risk for serious infectious diseases. OBJECTIVE To examine the association between undervaccination and pertussis in children 3 to 36 months of age. DESIGN Matched case-control study with conditional logistic regression analysis. SETTING Eight managed care organizations of the Vaccine Safety Datalink between 2004 and 2010. PARTICIPANTS Each laboratory-confirmed case of pertussis (72 patients) was matched to 4 randomly selected controls (for a total of 288 controls). The case patients were matched to controls by managed care organization site, sex, and age at the index date. The index date was defined as the date of pertussis diagnosis for the case patients. EXPOSURE Undervaccination for the diphtheria, tetanus toxoids, and acellular pertussis (DTaP) vaccine. Undervaccination was defined as the number of doses of DTaP vaccine that was either missing or delayed by the index date. Case patients and controls could be undervaccinated by 0, 1, 2, 3, or 4 doses of DTaP vaccine. Children undervaccinated by 0 doses were considered age-appropriately vaccinated by the index date. MAIN OUTCOME AND MEASURE Pertussis. RESULTS Of the 72 case patients with pertussis, 12 (16.67%) were hospitalized, and 34 (47.22%) were undervaccinated for DTaP vaccine by the date of pertussis diagnosis. Of the 288 matched controls, 64 (22.22%) were undervaccinated for DTaP vaccine. Undervaccination was strongly associated with pertussis. Children undervaccinated for 3 or 4 doses of DTaP vaccine were 18.56 (95% CI, 4.92-69.95) and 28.38 (95% CI, 3.19-252.63) times more likely, respectively, to have received a diagnosis of pertussis than children who were age-appropriately vaccinated. CONCLUSIONS AND RELEVANCE Undervaccination with DTaP vaccine increases the risk of pertussis among children 3 to 36 months of age.
    09/2013; 167(11). DOI:10.1001/jamapediatrics.2013.2353
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    ABSTRACT: In the examination of the association between vaccines and rare adverse events after vaccination in postlicensure observational studies, it is challenging to define appropriate risk windows because prelicensure RCTs provide little insight on the timing of specific adverse events. Past vaccine safety studies have often used prespecified 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. Copyright © 2013 John Wiley & Sons, Ltd.
    Statistics in Medicine 08/2013; 32(19). DOI:10.1002/sim.5733 · 2.04 Impact Factor

Publication Stats

1k Citations
344.00 Total Impact Points


  • 2008–2015
    • Kaiser Permanente
      • Center for Health Research (Oregon, Hawaii, and Georgia)
      Oakland, California, United States
  • 2004–2014
    • University of Colorado
      • • Department of Pediatrics
      • • Department of Family Medicine
      Denver, Colorado, United States
  • 2002–2010
    • Denver Health and Hospital Authority
      Denver, Colorado, United States
  • 2009
    • Community College of Denver
      Denver, Colorado, United States
  • 2006
    • University of Utah
      • Division of Pediatric Inpatient Medicine
      Salt Lake City, UT, United States
    • University of Colorado Hospital
      • Department of Pediatrics
      Denver, Colorado, United States