Mortality risk after COVID-19 vaccination: A self-controlled case series study

BACKGROUND

Although previous studies found no-increased mortality risk after COVID-19 vaccination, residual confounding bias might have impacted the findings. Using a modified self-controlled case series (SCCS) design, we assessed the risk of non-COVID-19 mortality, all-cause mortality, and four cardiac-related death outcomes after primary series COVID-19 vaccination.

METHODS

We analyzed all deaths between December 14, 2020, and August 11, 2021, among individuals from eight Vaccine Safety Datalink sites. Demographic characteristics of deaths in recipients of COVID-19 vaccines and unvaccinated individuals were reported. We conducted SCCS analyses by vaccine type and death outcomes and reported relative incidences (RI). The observation period for death spanned from the dates of emergency use authorization to the end of the study period (August 11, 2021) without censoring the observation period upon death. We pre-specified a primary risk interval of 28-day and a secondary risk interval of 14-day after each vaccination dose. Adjusting for seasonality in mortality analyses is crucial because death rates vary over time. Deaths among unvaccinated individuals were included in SCCS analyses to account for seasonality by incorporating calendar month in the models.

RESULTS

For Pfizer-BioNTech (BNT162b2), RIs of non-COVID-19 mortality, all-cause mortality, and four cardiac-related death outcomes were below 1 and 95 % confidence intervals (CIs) excluded 1 across both doses and both risk intervals. For Moderna (mRNA-1273), RI point estimates of all outcomes were below 1, although the 95 % CIs of two RI estimates included 1: cardiac-related (RI = 0.78, 95 % CI, 0.58-1.04) and non-COVID-19 cardiac-related mortality (RI = 0.80, 95 % CI, 0.60-1.08) 14 days after the second dose in individuals without pre-existing cancer and heart disease. For Janssen (Ad26.COV2.S), RIs of four cardiac-related death outcomes ranged from 0.94 to 0.98 for the 14-day risk interval, and 0.68 to 0.72 for the 28-day risk interval and 95 % CIs included 1.

CONCLUSION

Using a modified SCCS design and adjusting for temporal trends, no-increased risk was found for non-COVID-19 mortality, all-cause mortality, and four cardiac-related death outcomes among recipients of the three COVID-19 vaccines used in the US.

An individual segmented trajectory approach for identifying opioid use patterns using longitudinal dispensing data

PURPOSE

The aim of this study is to use electronic opioid dispensing data to develop an individual segmented trajectory approach for identifying opioid use patterns. The resulting opioid use patterns can be used for examining the association between opioid use and drug overdose.

METHODS

We retrospectively assembled a cohort of members on long-term opioid therapy (LTOT) between January 1, 2006 and June 30, 2019 who were 18 years and older and enrolled in one of three health care systems in the US. We have developed an individual segmented trajectory analysis for identifying various opioid use patterns by scanning over the follow-up and finding distinct opioid use patterns based on variability measured with coefficient of variation and trends of milligram morphine equivalents levels.

RESULTS

Among 31, 865 members who were on LTOT between January 1, 2006 and June 30, 2019, 58.3% were female, and the average age was 55.4 years (STD = 15.4). The study population had 152 557 person-years of follow-up, with an average follow-up of 4.4 years per enrollment per person (STD = 3.4). This novel approach identified up to 13 distinct patterns including 88 756 episodes of "stable" pattern (42.1%) with an average follow-up of 11.2 months, 29 140 episodes of "increasing" pattern (13.8%) with an average follow-up of 6.0 months, 13 201 episodes of ≤10% dose reduction (6.3%) with an average follow-up of 10.4 months, 7286 episodes of 11%-20% dose reduction (3.5%) with an average follow-up of 5.3 months, 4457 episodes of 21%-30% dose reduction (2.1%) with an average follow-up of 4.0 months, and 9903 episodes of >30% dose reduction (4.7%) with an average follow-up of 2.6 months.

CONCLUSIONS

A novel approach was developed to identify 13 distinct opioid use patterns using each individual's longitudinal dispensing data and these patterns can be used in examining overdose risk during the time that these patterns are ongoing.

Long-term Neutralizing Antibody Levels Against Measles and Rubella Viruses Among Adults With 3 Doses of Measles-Mumps-Rubella Vaccine

Background

A third dose of measles-mumps-rubella vaccine (MMR) may be administered for various reasons, but data on long-term immunity are limited. We assessed neutralizing antibody levels against measles and rubella among adults up to 11 years after receipt of a third MMR dose.

Methods

In this longitudinal study, healthy adults who received a third MMR dose as young adults (ages 18-28 years) were recalled around 5 years and 9-11 years after the third dose. Measles and rubella antibody levels were assessed by plaque-reduction and immunocolorimetric neutralization assays, respectively. Antibody concentrations <120 mIU/mL and <10 U/mL were considered potentially susceptible to measles and rubella, respectively. Geometric mean concentrations (GMCs) and 95% confidence intervals (CIs) over time were estimated from generalized estimating equation models.

Results

Approximately 5 and 9-11 years after receipt of the third dose, 405 and 304 adults were assessed, respectively. Measles GMC was 428 mIU/mL (95% CI, 392-468 mIU/mL) 5 years postvaccination, declining to 381 mIU/mL (95% CI, 339-428 mIU/mL) 11 years postvaccination. At the last follow-up visit (9-11 years postvaccination), 10% of participants were potentially susceptible to measles infection. Rubella GMCs were stable throughout the follow-up period (63 U/mL to 65 U/mL); none of the participants was susceptible to rubella at the last follow-up visit.

Conclusions

Eleven years after receiving a third MMR dose, measles and rubella neutralizing antibody levels remained high in adults. However, on the basis of waning antibody levels, some adults may become susceptible to measles infection over time despite receipt of 3 vaccine doses.

Safety signal identification for COVID-19 bivalent booster vaccination using tree-based scan statistics in the Vaccine Safety Datalink

BACKGROUND

Traditional active vaccine safety monitoring involves pre-specifying health outcomes and biologically plausible outcome-specific time windows of concern, limiting the adverse events that can be evaluated. In this study, we used tree-based scan statistics to look broadly for >60,000 possible adverse events after bivalent COVID-19 vaccination.

METHODS

Vaccine Safety Datalink enrollees aged ≥5 years receiving Moderna or Pfizer-BioNTech bivalent COVID-19 vaccine through November 2022 were followed for 56 days post-vaccination. Incident diagnoses in inpatient or emergency department settings were analyzed for clustering within the hierarchical ICD-10-CM diagnosis code "tree" and temporally within post-vaccination follow-up. The conditional self-controlled tree-temporal scan statistic was used, conditioning on total number of cases of each diagnosis and total number of cases of any diagnosis occurring during the scanning risk window across the entire tree. P = 0.01 was the pre-specified cut-off for statistical significance.

RESULTS

Analysis included 352,509 doses of Moderna and 979,189 doses of Pfizer-BioNTech bivalent vaccines. After Moderna vaccination, no statistically significant clusters were found. After Pfizer-BioNTech, there were clusters of unspecified adverse events (Days 1-3, p = 0.0001-0.0007), influenza (Days 35-56, p = 0.0001), cough (Days 44-55, p = 0.0002), and COVID-19 (Days 52-56, p = 0.0004).

CONCLUSIONS

For Pfizer-BioNTech only, we detected clusters of: (1) unspecified adverse effects, as have been observed in other vaccine studies using this method, and (2) respiratory disease toward the end of follow-up. The respiratory clusters were likely due to overlap of follow-up with the spread of respiratory syncytial virus, influenza, and COVID-19, i.e., confounding by seasonality. The untargeted nature of the method and its inherent adjustment for the many diagnoses and risk intervals evaluated are unique advantages. Limitations include susceptibility to time-varying confounding, lower statistical power for assessing risks of specific outcomes than in traditional studies targeting fewer outcomes, and the possibility of missing adverse events not strongly clustered in time or within the "tree."

Association Between Opioid Dose Reduction Rates and Overdose Among Patients Prescribed Long-Term Opioid Therapy

BACKGROUND

Tapering long-term opioid therapy is an increasingly common practice, yet rapid opioid dose reductions may increase the risk of overdose. The objective of this study was to compare overdose risk following opioid dose reduction rates of ≤10%, 11% to 20%, 21% to 30%, and >30% per month to stable dosing.

METHODS

We conducted a retrospective cohort study in three health systems in Colorado and Wisconsin. Participants were patients ≥18 years of age prescribed long-term opioid therapy between January 1, 2006, and June 30, 2019. Five opioid dosing patterns and drug overdoses (fatal and nonfatal) were identified using electronic health records, pharmacy records, and the National Death Index. Cox proportional hazard regression was conducted on a propensity score-weighted cohort to estimate adjusted hazard ratios (aHRs) for follow-up periods of 1, 3, 6, 9, and 12 months after a dose reduction.

RESULTS

In a cohort of 17 540 patients receiving long-term opioid therapy, 42.7% of patients experienced a dose reduction. Relative to stable dosing, a dose reduction rate of >30% was associated with an increased risk of overdose and the aHR estimates decreased as the follow-up increased; the aHRs for the 1-, 6- and 12-month follow-ups were 5.33 (95% CI, 1.98-14.34), 1.81 (95% CI,1.08-3.03), and 1.49 (95% CI, 0.97-2.27), respectively. The slower tapering rates were not associated with overdose risk.

CONCLUSIONS

Patients receiving long-term opioid therapy exposed to dose reduction rates of >30% per month had increased overdose risk relative to patients exposed to stable dosing. Results support the use of slow dose reductions to minimize the risk of overdose.

Effectiveness of first and second COVID-19 mRNA vaccine monovalent booster doses during a period of circulation of Omicron variant sublineages: December 2021-July 2022

Background

US recommendations for COVID-19 vaccine boosters have expanded in terms of age groups covered and numbers of doses recommended, whereas evolution of Omicron sublineages raises questions about ongoing vaccine effectiveness.

Methods

We estimated effectiveness of monovalent COVID-19 mRNA booster vaccination versus two-dose primary series during a period of Omicron variant virus circulation in a community cohort with active illness surveillance. Hazard ratios comparing SARS-CoV-2 infection between booster versus primary series vaccinated individuals were estimated using Cox proportional hazards models with time-varying booster status. Models were adjusted for age and prior SARS-CoV-2 infection. The effectiveness of a second booster among adults ≥50 years of age was similarly estimated.

Results

The analysis included 883 participants ranging in age, from 5 to >90 years. Relative effectiveness was 51% (95% CI: 34%, 64%) favoring the booster compared with primary series vaccination and did not vary by prior infection status. Relative effectiveness was 74% (95% CI: 57%, 84%) at 15 to 90 days after booster receipt, but declined to 42% (95% CI: 16%, 61%) after 91 to 180 days, and to 36% (95% CI: 3%, 58%) after 180 days. The relative effectiveness of a second booster compared to a single booster was 24% (95% CI: -40% to 61%).

Conclusions

An mRNA vaccine booster dose added significant protection against SARS-CoV-2 infection, but protection decreased over time. A second booster did not add significant protection for adults ≥50 years of age. Uptake of recommended bivalent boosters should be encouraged to increase protection against Omicron BA.4/BA.5 sublineages.

Association Between Aluminum Exposure From Vaccines Before Age 24 Months and Persistent Asthma at Age 24 to 59 Months

OBJECTIVE

To assess the association between cumulative aluminum exposure from vaccines before age 24 months and persistent asthma at age 24 to 59 months.

METHODS

A retrospective cohort study was conducted in the Vaccine Safety Datalink (VSD). Vaccination histories were used to calculate cumulative vaccine-associated aluminum in milligrams (mg). The persistent asthma definition required one inpatient or 2 outpatient asthma encounters, and ≥2 long-term asthma control medication dispenses. Cox proportional hazard models were used to evaluate the association between aluminum exposure and asthma incidence, stratified by eczema presence/absence. Adjusted hazard ratios (aHR) and 95% confidence intervals (CI) per 1 mg increase in aluminum exposure were calculated, adjusted for birth month/year, sex, race/ethnicity, VSD site, prematurity, medical complexity, food allergy, severe bronchiolitis, and health care utilization.

RESULTS

The cohort comprised 326,991 children, among whom 14,337 (4.4%) had eczema. For children with and without eczema, the mean (standard deviation [SD]) vaccine-associated aluminum exposure was 4.07 mg (SD 0.60) and 3.98 mg (SD 0.72), respectively. Among children with and without eczema, 6.0% and 2.1%, respectively, developed persistent asthma. Among children with eczema, vaccine-associated aluminum was positively associated with persistent asthma (aHR 1.26 per 1 mg increase in aluminum, 95% CI 1.07, 1.49); a positive association was also detected among children without eczema (aHR 1.19, 95% CI 1.14, 1.25).

CONCLUSION

In a large observational study, a positive association was found between vaccine-related aluminum exposure and persistent asthma. While recognizing the small effect sizes identified and the potential for residual confounding, additional investigation of this hypothesis appears warranted.

Opioid Dose Trajectories and Associations With Mortality, Opioid Use Disorder, Continued Opioid Therapy, and Health Plan Disenrollment

IMPORTANCE

Uncertainty remains about the longer-term benefits and harms of different opioid management strategies, such as tapering and dose escalation. For instance, opioid tapering could help patients reduce opioid exposure to prevent opioid use disorder, but patients may also seek care elsewhere and engage in nonprescribed opioid use.

OBJECTIVE

To evaluate the association between opioid dose trajectories observed in practice and patient outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study was conducted in 3 health systems in Colorado and Wisconsin. The study population included patients receiving long-term opioid therapy between 50 and 200 morphine milligram equivalents between August 1, 2014, and July 31, 2017. Follow-up ended on December 31, 2019. Data were analyzed from January 2020 to August 2022.

EXPOSURES

Group-based trajectory modeling identified 5 dosing trajectories over 1 year: 1 decreasing, 1 high-dose increasing, and 3 stable.

MAIN OUTCOMES AND MEASURES

Primary outcomes assessed after the trajectory period were 1-year all-cause mortality, incident opioid use disorder, continued opioid therapy at 1 year, and health plan disenrollment. Associations were tested using Cox proportional hazards regression and log-binomial models, adjusting for baseline covariates.

RESULTS

A total of 3913 patients (mean [SD] age, 59.2 [14.4] years; 2767 White non-Hispanic [70.7%]; 2237 female patients [57.2%]) were included in the study. Compared with stable trajectories, the decreasing dose trajectory was negatively associated with opioid use disorder (adjusted hazard ratio [aHR], 0.40; 95% CI, 0.29-0.55) and continued opioid therapy (site 1: adjusted relative risk [aRR], 0.39; 95% CI, 0.34-0.44), but was positively associated with health plan disenrollment (aHR, 1.66; 95% CI, 1.24-2.22). The decreasing trajectory was not associated with mortality (aHR, 1.28; 95% CI, 0.87-1.86). In contrast, the high-dose increasing trajectory was positively associated with mortality (aHR, 2.19; 95% CI, 1.44-3.32) and opioid use disorder (aHR, 1.81; 95% CI, 1.39-2.37) but was not associated with disenrollment (aHR, 0.90; 95% CI, 0.56-1.42) or continued opioid therapy (site 1: aRR, 0.98; 95% CI, 0.94-1.03).

CONCLUSIONS AND RELEVANCE

In this cohort study, decreasing opioid dose was associated with reduced risk of opioid use disorder and continued opioid therapy but increased risk of disenrollment compared with stable dosing, whereas the high-dose increasing trajectory was associated with an increased risk of mortality and opioid use disorder. These findings can inform opioid management decision-making.

mRNA COVID-19 vaccine effectiveness against SARS-CoV-2 infection in a prospective community cohort, rural Wisconsin, November 2020 to December 2021

Reduced COVID‐19 vaccine effectiveness (VE) has been observed with increasing predominance of SARS‐CoV‐2 Delta (B.1.617.2) variant. Two‐dose VE against laboratory‐confirmed SARS‐CoV‐2 infection (symptomatic and asymptomatic) was estimated using Cox proportional hazards models with time‐varying vaccination status in a prospective rural community cohort of 1266 participants aged ≥12 years. Between November 3, 2020 and December 7, 2021, VE was 56% for mRNA COVID‐19 vaccines overall, 65% for Moderna, and 50% for Pfizer‐BioNTech. VE when Delta predominated (June to December 2021) was 54% for mRNA COVID‐19 vaccines overall, 59% for Moderna, and 52% for Pfizer‐BioNTech.

The Childhood Vaccination Schedule and the Lack of Association With Type 1 Diabetes

OBJECTIVES

Safety studies assessing the association between the entire recommended childhood immunization schedule and autoimmune diseases, such as type 1 diabetes mellitus (T1DM), are lacking. To examine the association between the recommended immunization schedule and T1DM, we conducted a retrospective cohort study of children born between 2004 and 2014 in 8 US health care organizations that participate in the Vaccine Safety Datalink.

METHODS

Three measures of the immunization schedule were assessed: average days undervaccinated (ADU), cumulative antigen exposure, and cumulative aluminum exposure. T1DM incidence was identified by International Classification of Disease codes. Cox proportional hazards models were used to analyze associations between the 3 exposure measures and T1DM incidence. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were calculated. Models were adjusted for sex, race and ethnicity, birth year, mother's age, birth weight, gestational age, number of well-child visits, and study site.

RESULTS

In a cohort of 584 171 children, the mean ADU was 38 days, the mean cumulative antigen exposure was 263 antigens (SD = 54), and the mean cumulative aluminum exposure was 4.11 mg (SD = 0.73). There were 1132 incident cases of T1DM. ADU (aHR = 1.01; 95% CI, 0.99-1.02) and cumulative antigen exposure (aHR = 0.98; 95% CI, 0.97-1.00) were not associated with T1DM. Cumulative aluminum exposure >3.00 mg was inversely associated with T1DM (aHR = 0.77; 95% CI, 0.60-0.99).

CONCLUSIONS

The recommended schedule is not positively associated with the incidence of T1DM in children. These results support the safety of the recommended childhood immunization schedule.

Trends in Mortality at a Level II Rural Trauma Center

BACKGROUND

Most studies of deaths from traumatic injury are from urban trauma centers. In contrast, rural areas have higher incidence of traumatic fatal injuries than urban areas. The objective of this research was to describe trends of injuries and mortality from a trauma center serving a largely rural population and compare results with reports from the National Trauma Data Bank (NTDB).

METHODS

We conducted a retrospective study of patients admitted to a rural Wisconsin level II trauma center from 2000 through 2018. Details on injuries and deaths prior to discharge were obtained from the trauma registry. Event counts and fatality ratios were described by year, sex, age, mechanism of injury, and injury severity score (ISS). Trends were analyzed across 2000-2005, 2006-2011, and 2012-2018 calendar year eras.

RESULTS

During 2000-2018, there were 17,334 injury events among 16,495 patients included in the trauma registry. Across the 3 eras, the proportion of injuries related to falls increased (35.6%, 40.6%, and 51.5%, respectively), and the proportion from on-road motor vehicle events decreased (37.0 %, 32.8, and 22.5%, respectively), similar to the trends from 3 corresponding NTDB reports for 2004, 2010, and 2016. There was a statistically significant decreasing trend (P < 0.001) in overall fatality ratios across the 3 eras, 5.3% (95% CI, 4.7%-6.0%), 4.1% (95% CI, 3.7%-4.6%), and 3.9 (95% CI, 3.4%-4.4%), respectively. The fatality ratios point estimates were similar to overall fatality ratios from the NTDB reports (4.7%, 4.0%, 4.3%, respectively). The median patient age increased significantly from 42, 45, and 55 years across the 3 eras (test for trend P <  0.0001).

CONCLUSION

Long-term trends of traumatic injuries and mortality were generally similar to national trends, particularly in the shift to older patients and in the increasing proportion of injury events due to falls. Further research on traumatic injuries and deaths in rural populations is needed, particularly regarding immediate deaths at the scene and longer-term deaths after discharge.

Vaccine Safety Datalink infrastructure enhancements for evaluating the safety of maternal vaccination

BACKGROUND

Identifying pregnancy episodes and accurately estimating their beginning and end dates are imperative for observational maternal vaccine safety studies using electronic health record (EHR) data.

METHODS

We modified the Vaccine Safety Datalink (VSD) Pregnancy Episode Algorithm (PEA) to include both the International Classification of Disease, ninth revision (ICD-9 system) and ICD-10 diagnosis codes, incorporated additional gestational age data, and validated this enhanced algorithm with manual medical record review. We also developed the new Dynamic Pregnancy Algorithm (DPA) to identify pregnancy episodes in real time.

RESULTS

Around 75% of the pregnancy episodes identified by the enhanced VSD PEA were live births, 12% were spontaneous abortions (SABs), 10% were induced abortions (IABs), and 0.4% were stillbirths (SBs). Gestational age was identified for 99% of live births, 89% of SBs, 69% of SABs, and 42% of IABs. Agreement between the PEA-assigned and abstractor-identified pregnancy outcome and outcome date was 100% for live births, but was lower for pregnancy losses. When gestational age was available in the medical record, the agreement was higher for live births (97%), but lower for pregnancy losses (75%). The DPA demonstrated strong concordance with the PEA and identified pregnancy episodes ⩾6 months prior to the outcome date for 89% of live births.

CONCLUSION

The enhanced VSD PEA is a useful tool for identifying pregnancy episodes in EHR databases. The DPA improves the timeliness of pregnancy identification and can be used for near real-time maternal vaccine safety studies.

PLAIN LANGUAGE SUMMARY

Improving identification of pregnancies in the Vaccine Safety Datalink electronic medical record databases to allow for better and faster monitoring of vaccination safety during pregnancy Introduction: It is important to monitor of the safety of vaccines after they have been approved and licensed by the Food and Drug Administration, especially among women vaccinated during pregnancy. The Vaccine Safety Datalink (VSD) monitors vaccine safety through observational studies within large databases of electronic medical records. Since 2012, VSD researchers have used an algorithm called the Pregnancy Episode Algorithm (PEA) to identify the medical records of women who have been pregnant. Researchers then use these medical records to study whether receiving a particular vaccine is linked to any negative outcomes for the woman or her child.Methods: The goal of this study was to update and enhance the PEA to include the full set of medical record diagnostic codes [both from the older International Classification of Disease, ninth revision (ICD-9 system) and the newer ICD-10 system] and to incorporate additional sources of data about gestational age. To ensure the validity of the PEA following these enhancements, we manually reviewed medical records and compared the results with the algorithm. We also developed a new algorithm, the Dynamic Pregnancy Algorithm (DPA), to identify women earlier in pregnancy, allowing us to conduct more timely vaccine safety assessments.Results: The new version of the PEA identified 2,485,410 pregnancies in the VSD database. The enhanced algorithm more precisely estimated the beginning of pregnancies, especially those that did not result in live births, due to the new sources of gestational age data.Conclusion: Our new algorithm, the DPA, was successful at identifying pregnancies earlier in gestation than the PEA. The enhanced PEA and the new DPA will allow us to better evaluate the safety of current and future vaccinations administered during or around the time of pregnancy.

Prediction of serious RSV-related outcomes in older adults with outpatient RSV respiratory illness during 12 consecutive seasons

We developed and evaluated a model to predict serious outcomes among 243 adults ≥60 years old with medically attended respiratory illness and laboratory‐confirmed respiratory syncytial virus (RSV); 47 patients had a serious outcome defined as hospital admission, emergency department (ED) visit, or pneumonia diagnosis. The model used logistic regression with penalized maximum likelihood estimation. The reduced penalized model included age ≥ 75 years, ≥1 ED visit in prior year, crackles/rales, tachypnea, wheezing, new/increased sputum, and new/increased dyspnea. The optimal score cutoff yielded sensitivity and specificity of 66.0% and 81.6%. This prediction model provided moderate utility for identifying older adults with elevated risk of complicated RSV illness.

Association Between Rotavirus Vaccination and Type 1 Diabetes in Children

IMPORTANCE

Because rotavirus infection is a hypothesized risk factor for type 1 diabetes, live attenuated rotavirus vaccination could increase or decrease the risk of type 1 diabetes in children.

OBJECTIVE

To examine whether there is an association between rotavirus vaccination and incidence of type 1 diabetes in children aged 8 months to 11 years.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study of 386 937 children born between January 1, 2006, and December 31, 2014, was conducted in 7 US health care organizations of the Vaccine Safety Datalink. Eligible children were followed up until a diagnosis of type 1 diabetes, disenrollment, or December 31, 2017.

EXPOSURES

Rotavirus vaccination for children aged 2 to 8 months. Three exposure groups were created. The first group included children who received all recommended doses of rotavirus vaccine by 8 months of age (fully exposed to rotavirus vaccination). The second group had received some, but not all, recommended rotavirus vaccines (partially exposed to rotavirus vaccination). The third group did not receive any doses of rotavirus vaccines (unexposed to rotavirus vaccination).

MAIN OUTCOMES AND MEASURES

Incidence of type 1 diabetes among children aged 8 months to 11 years. Type 1 diabetes was identified by International Classification of Diseases codes: 250.x1, 250.x3, or E10.xx in the outpatient setting. Cox proportional hazards regression models were used to analyze time to type 1 diabetes incidence from 8 months to 11 years. Hazard ratios and 95% CIs were calculated. Models were adjusted for sex, race/ethnicity, birth year, mother's age, birth weight, gestational age, number of well-child visits, and Vaccine Safety Datalink site.

RESULTS

In a cohort of 386 937 children (51.1% boys and 41.9% non-Hispanic white), 360 169 (93.1%) were fully exposed to rotavirus vaccination, 15 765 (4.1%) were partially exposed to rotavirus vaccination, and 11 003 (2.8%) were unexposed to rotavirus vaccination. Children were followed up a median of 5.4 years (interquartile range, 3.8-7.8 years). The total person-time follow-up in the cohort was 2 253 879 years. There were 464 cases of type 1 diabetes in the cohort, with an incidence rate of 20.6 cases per 100 000 person-years. Compared with children unexposed to rotavirus vaccination, the adjusted hazard ratio was 1.03 (95% CI, 0.62-1.72) for children fully exposed to rotavirus vaccination and 1.50 (95% CI, 0.81-2.77) for children partially exposed to rotavirus vaccination.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that rotavirus vaccination does not appear to be associated with type 1 diabetes in children.

Near Real-Time Surveillance to Assess the Safety of the 9-Valent Human Papillomavirus Vaccine

BACKGROUND AND OBJECTIVES

Human papillomavirus is the most common sexually transmitted infection in the United States and causes certain anogenital and oropharyngeal cancers. The 9-valent human papillomavirus vaccine (9vHPV) provides protection against additional types not included in the quadrivalent vaccine. We conducted near real-time vaccine safety surveillance for 24 months after the vaccine became available in the Vaccine Safety Datalink.

METHODS

Immunizations and adverse events were extracted weekly from October 2015 to October 2017 from standardized data files for persons 9 to 26 years old at 6 Vaccine Safety Datalink sites. Prespecified adverse events included anaphylaxis, allergic reaction, appendicitis, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, injection site reaction, pancreatitis, seizure, stroke, syncope, and venous thromboembolism. The observed and expected numbers of events after 9vHPV were compared weekly by using sequential methods. Both historical and concurrent comparison groups were used to identify statistical signals for adverse events. Unexpected signals were investigated by medical record review and/or additional analyses.

RESULTS

During 105 weeks of surveillance, 838 991 doses of 9vHPV were administered. We identified unexpected statistical signals for 4 adverse events: appendicitis among boys 9 to 17 years old after dose 3; pancreatitis among men 18 to 26 years old; and allergic reactions among girls 9 to 17 years old and women 18 to 26 years old after dose 2. On further evaluation, which included medical record review, temporal scan analysis, and additional epidemiological analyses, we did not confirm signals for any adverse events.

CONCLUSIONS

After 2 years of near real-time surveillance of 9vHPV and several prespecified adverse events, no new safety concerns were identified.

Inactivated influenza vaccine and spontaneous abortion in the Vaccine Safety Datalink in 2012-13, 2013-14, and 2014-15

Introduction:

A recent study reported an association between inactivated influenza vaccine (IIV) and spontaneous abortion (SAB), but only among women who had also been vaccinated in the previous influenza season. We sought to estimate the association between IIV administered in three recent influenza seasons and SAB among women who were and were not vaccinated in the previous influenza season.

Methods:

We conducted a case-control study over three influenza seasons (2012–13, 2013–14, 2014–15) in the Vaccine Safety Datalink (VSD). Cases (women with SAB) and controls (women with live births) were matched on VSD site, date of last menstrual period, age group, and influenza vaccination status in the previous influenza season. Of 1908 presumptive cases identified from the electronic record, 1236 were included in the main analysis. Administration of IIV was documented in several risk windows, including 1–28, 29–56, and >56 days before the SAB date.

Results:

Among 627 matched pairs vaccinated in the previous season, no association was found between vaccination in the 1–28 day risk window and SAB (adjusted odds ratio (aOR) 0.9; 95% confidence interval (CI) 0.6–1.5). The season-specific aOR ranged from 0.5 to 1.7 with all CIs including the null value of 1.0. Similarly, no association was found among women who were not vaccinated in the previous season; the season-specific aOR in the 1–28 day risk window ranged from 0.6 to 0.7 and the 95% CI included 1.0 in each season. There was no association found between SAB and influenza vaccination in the other risk windows, or when vaccine receipt was analyzed relative to date of conception.

Conclusion:

During these seasons we found no association between IIV and SAB, including among women vaccinated in the previous season. These findings lend support to current recommendations for influenza vaccination at any time during pregnancy, including the first trimester.

Similar relative risks of seizures following measles containing vaccination in children born preterm compared to full-term without previous seizures or seizure-related disorders

BACKGROUND

Febrile seizures are associated with the first dose of measles-containing vaccines and the risk increases with chronologic age during the second year of life. We used the Vaccine Safety Datalink (VSD) to determine if the relative increase in risk of seizures following receipt of measles-containing vaccine differs by gestational age at birth.

METHODS

Children were eligible if they received their first dose of measles-containing vaccine at age 12 through 23 months from January 2003 through September 2015. Children were excluded if they had a history of seizure or conditions strongly related to seizure prior to 12 months of age. Seizures were identified by diagnostic codes in the inpatient or emergency department settings. Using risk-interval analysis, we estimated the incidence rate ratio (IRR) for seizures in the 7 through 10 days (risk period) vs 15 through 42 days (control period) following receipt of measles-containing vaccines in children born preterm (<37 weeks gestation age) and those born full-term (≥37 weeks).

RESULTS

There were 532,375 children (45,343 preterm and 487,032 full-term) who received their first dose of measles-containing vaccine at age 12 through 23 months. The IRRs of febrile seizures 7 through 10 days compared with 15 through 42 days after receipt of measles-containing vaccine were 3.9 (95% CI: 2.5-6.0) in preterm children and 3.2 (2.7-3.7) in full-term children; the ratio of IRRs: was 1.2 (0.76-1.9), p = 0.41. IRRs were also similar across gestational age groups, by vaccine type received (measles-mumps-rubella [MMR] or measles-mumps-rubella-varicella [MMRV]) and age at vaccination (12-15 or 16-23 months).

CONCLUSION

Vaccination with a measles-containing vaccine in the second year of life is associated with a similar relative risk of a first seizure in children born preterm as in those who were born full-term.

Association Between Estimated Cumulative Vaccine Antigen Exposure Through the First 23 Months of Life and Non-Vaccine-Targeted Infections From 24 Through 47 Months of Age

IMPORTANCE

Some parents are concerned that multiple vaccines in early childhood could weaken their child's immune system. Biological data suggest that increased vaccine antigen exposure could increase the risk for infections not targeted by vaccines.

OBJECTIVE

To examine estimated cumulative vaccine antigen exposure through the first 23 months of life in children with and without non-vaccine-targeted infections from 24 through 47 months of age.

DESIGN, SETTING, AND PARTICIPANTS

A nested case-control study was conducted in 6 US health care organizations participating in the Vaccine Safety Datalink. Cases were identified by International Classification of Diseases codes for infectious diseases in the emergency department and inpatient medical settings and then validated by medical record review. Cases of non-vaccine-targeted infection were matched to controls by age, sex, health care organization site, and chronic disease status. Participants were children ages 24 through 47 months, born between January 1, 2003, and September 31, 2013, followed up until December 31, 2015.

EXPOSURES

Cumulative vaccine antigen exposure, estimated by summing the number of antigens in each vaccine dose received from birth through age 23 months.

MAIN OUTCOMES AND MEASURES

Non-vaccine-targeted infections, including upper and lower respiratory infections and gastrointestinal infections, from 24 through 47 months of age, and the association between these infections and estimated cumulative vaccine exposure from birth through 23 months. Conditional logistic regression was used to estimate matched odds ratios representing the odds of non-vaccine-targeted infections for every 30-unit increase in estimated cumulative number of antigens received.

RESULTS

Among the 944 patients (193 cases and 751 controls), the mean (SD) age was 32.5 (6.3) months, 422 (45%) were female, and 61 (7%) had a complex chronic condition. Through the first 23 months, the estimated mean (SD) cumulative vaccine antigen exposure was 240.6 (48.3) for cases and 242.9 (51.1) for controls. The between-group difference for estimated cumulative antigen exposure was -2.3 (95% CI, -10.1 to 5.4; P = .55). Among children with vs without non-vaccine-targeted infections from 24 through 47 months of age, the matched odds ratio for estimated cumulative antigen exposure through age 23 months was not significant (matched odds ratio, 0.94; 95% CI, 0.84 to 1.07).

CONCLUSIONS AND RELEVANCE

Among children from 24 through 47 months of age with emergency department and inpatient visits for infectious diseases not targeted by vaccines, compared with children without such visits, there was no significant difference in estimated cumulative vaccine antigen exposure through the first 23 months of life.

Infant Hospitalizations and Mortality After Maternal Vaccination

BACKGROUND

The Advisory Committee on Immunization Practices currently recommends pregnant women receive influenza and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines. There are limited studies of the long-term safety in infants for vaccines administered during pregnancy. We evaluate whether maternal receipt of influenza and Tdap vaccines increases the risk of infant hospitalization or death in the first 6 months of life.

METHODS

We included singleton, live birth pregnancies in the Vaccine Safety Datalink between 2004 and 2014. Outcomes were infant hospitalizations and mortality in the first 6 months of life. We performed a case-control study matching case patients and controls 1:1 and used conditional logistic regression to estimate odds ratios for maternal exposure to influenza and/or Tdap vaccines in pregnancy.

RESULTS

There were 413 034 live births in our population. Of these, 25 222 infants had hospitalizations and 157 infants died in the first 6 months of life. We found no association between infant hospitalization and maternal influenza (adjusted odds ratio: 1.00; 95% confidence interval [CI]: 0.96-1.04) or Tdap (adjusted odds ratio: 0.94; 95% CI: 0.88-1.01) vaccinations. We found no association between infant mortality and maternal influenza (adjusted odds ratio: 0.96; 95% CI: 0.54-1.69) or Tdap (adjusted odds ratio: 0.44; 95% CI: 0.17-1.13) vaccinations.

CONCLUSIONS

We found no association between vaccination during pregnancy and risk of infant hospitalization or death in the first 6 months of life. These findings support the safety of current recommendations for influenza and Tdap vaccination during pregnancy.

Risk of venous thromboembolism following influenza vaccination in adults aged 50years and older in the Vaccine Safety Datalink

BACKGROUND

Influenza-like illness and inflammation are known risk factors for venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE). However, few studies have characterized the risk of VTE following influenza vaccination. We examined VTE risk after vaccination in adults 50years old and older within the Vaccine Safety Datalink (VSD).

METHODS

We used the self-controlled case series method to determine the risk of VTE among age-eligible adults who received influenza vaccine (with or without pandemic H1N1) and experienced a VTE during the months of September through December in 2007 through 2012. Presumptive VTE cases were identified among VSD participants using diagnostic codes, diagnostic tests, and oral anticoagulant prescription. Potential cases were validated by medical record review. The VTE incidence rate ratio was calculated among confirmed cases for the risk window 1 to 10days after vaccination relative to all other person-time from September through December.

RESULTS

Of the 1,488 presumptive cases identified, 508 were reviewed, of which 492 (97%) were confirmed cases of VTE. The analysis included 396 incident, confirmed cases. Overall, there was no increased risk of VTE in the 1 to 10days after influenza vaccination (IRR=0.89, 95% CI 0.69-1.17) compared to the control period. Results were similar when all person-time was censored before vaccination. A post hoc analysis showed an increased risk among current tobacco smokers (IRR=2.57, 95% CI 1.06-6.23). No clustering of VTE was observed in the 1-42days after vaccination.

DISCUSSION

Overall, there was no evidence that inactivated influenza vaccine was associated with VTE in adults ≥50years old. An increased risk was found among current smokers in a post hoc analysis. These findings are consistent with previous research and support the safety of annual vaccination in this population.

Frequency of Serum Creatinine Monitoring During Allopurinol Therapy in Ambulatory Patients

Background:

Allopurinol dosage reduction is recommended in patients with renal dysfunction because drug toxicity risk is increased. Little information is available about serum creatinine (SCr) monitoring in ambulatory patients taking allopurinol.

Objective:

To evaluate SCr monitoring among patients prescribed allopurinol, identify associated factors, and evaluate administrative data in assessing monitoring.

Methods:

Information for this retrospective cohort study was drawn from a dataset of 2 020 037 individuals; approximately 200 000 members from each of 10 organizations. Study patients had received at least one year of ongoing allopurinol prescription dispensings. Patient variables analyzed included age, gender, chronic diseases, outpatient visits, hospitalizations, gout diagnosis, and SCr monitoring. A random sample of medical records was reviewed to assess the accuracy of the automated data. Statistical analysis included descriptive and logistic regression techniques.

Results:

Overall, 1139 (26%) of 4357 patients did not have SCr monitoring. For individuals without recent hospitalization, factors protective against lack of monitoring were increasing age (OR 0.77 per 10 y; 95% CI 0.74 to 0.79), more chronic diseases (OR 0.81; 95% CI 0.78 to 0.83), more outpatient visits (OR 0.87 per 5 visits; 95% CI 0.83 to 0.91), and gout diagnosis (OR 0.74; 95% CI 0.65 to 0.85). The sensitivity and specificity of administrative data compared with medical records for SCr monitoring were 92% and 65%, respectively.

Conclusions:

More than one-fourth of patients dispensed allopurinol did not have SCr monitoring during one year of therapy. Lack of monitoring and lack of subsequent possible dosage adjustment put patients at increased risk of allopurinol toxicity.

Incidence of Medically Attended Respiratory Syncytial Virus and Influenza Illnesses in Children 6-59 Months Old During Four Seasons

RSV was the most common viral agent causing acute respiratory illness in children 6 to 59 months old during the influenza season. Children in the 6-23 month age range had a higher incidence of RSV compared to those aged 24-59 months.

Background. Respiratory syncytial virus (RSV) and influenza are significant causes of seasonal respiratory illness in children. The incidence of influenza and RSV hospitalization is well documented, but the incidence of medically attended, laboratory-confirmed illness has not been assessed in a well defined community cohort.

Methods. Children aged 6–59 months with medically attended acute respiratory illness were prospectively enrolled during the 2006–2007 through 2009–2010 influenza seasons in a Wisconsin community cohort. Nasal swabs were tested for RSV and influenza by multiplex reverse-transcription polymerase chain reaction. The population incidence of medically attended RSV and influenza was estimated separately and standardized to weeks 40 through 18 of each season.

Results. The cohort included 2800–3073 children each season. There were 2384 children enrolled with acute respiratory illness; 627 (26%) were positive for RSV and 314 (13%) for influenza. The mean age was 28 months (standard deviation [SD] = 15) for RSV-positive and 38 months (SD = 16) for influenza-positive children. Seasonal incidence (cases per 10 000) was 1718 (95% confidence interval [CI], 1602–1843) for RSV and 768 (95% CI, 696–848) for influenza. Respiratory syncytial virus incidence was highest among children 6–11 (2927) and 12–23 months old (2377). Influenza incidence was highest (850) in children 24–59 months old. The incidence of RSV was higher than influenza across all seasons and age groups.

Conclusions. The incidence of medically attended RSV was highest in children 6–23 months old, and it was consistently higher than influenza. The burden of RSV remains high throughout the first 2 years of life.

Validation of Health Event Capture in the Marshfield Epidemiologic Study Area

OBJECTIVE

In this study, health event capture is broadly defined as the degree to which a group of people use a particular provider network as their primary source of health care services. The Marshfield Epidemiologic Study Area (MESA) is a valuable resource for population-based health research, but the completeness of health event capture has not been validated in recent years. Our objective was to determine the current level of outpatient and inpatient health event capture by Marshfield Clinic (MC) facilities and affiliated hospitals for people living within MESA.

DESIGN

A stratified sample survey with strata defined by MESA region (Central or North) and age group (<18 years or ≥18 years).

SETTING

24 ZIP codes in central and northern Wisconsin, USA.

PARTICIPANTS

2,485 individuals participated of the 4,313 sampled cohort members residing in MESA Central (N=61,041) and MESA North (N=25,906) on February 22, 2011.

METHODS

A health care utilization survey was mailed to a random sample stratified by age group and MESA region. Telephone interviews were attempted for nonrespondents. The survey requested information on sources of outpatient care and overnight hospital admissions. Population proportions representing health event capture metrics and corresponding 95% confidence intervals (CI) were estimated with analytic weights applied to account for the survey design.

RESULTS

Among those with an outpatient visit during the past 24 months, the most recent visit of an estimated 93% (95% CI, 91% - 94%) was at a MC facility. The most recent admission of an estimated 93% (95% CI, 90% - 96%) of those hospitalized in the past 24 months was at a hospital affiliated with MC. The proportion admitted to MC affiliated hospitals was higher for residents of MESA Central (97%) compared to MESA North (83%).

CONCLUSION

A high proportion of outpatient visits and inpatient admissions in MESA Central and MESA North are accessible in the MC electronic health record. This pattern of high health event capture has been demonstrated since the inception of MESA in 1991. The results from this study validate and support the continued use of MESA for population-based epidemiologic and clinical research.

Impact of repeated vaccination on vaccine effectiveness against influenza A(H3N2) and B during 8 seasons

The effect of prior influenza vaccination history on vaccine effectiveness was assessed in a community cohort over 8 seasons. Current- and previous-season vaccination generated similar levels of protection; vaccine-induced protection was greatest for individuals with no recent vaccination history.

Background. Recent studies suggest that influenza vaccination in the previous season may influence the effectiveness of current-season vaccination, but this has not been assessed in a single population over multiple years.

Methods. Patients presenting with acute respiratory illness were prospectively enrolled during the 2004–2005 through 2012–2013 influenza seasons. Respiratory swabs were tested for influenza and vaccination dates obtained from a validated registry. Vaccination status was determined for the current, previous, and prior 5 seasons. Vaccine effectiveness (VE) was calculated for participants aged ≥9 years using logistic regression models with an interaction term for vaccination history.

Results. There were 7315 enrollments during 8 seasons; 1056 (14%) and 650 (9%) were positive for influenza A(H3N2) and B, respectively. Vaccination during current only, previous only, or both seasons yielded similar protection against H3N2 (adjusted VE range, 31%–36%) and B (52%–66%). In the analysis using 5 years of historical vaccination data, current season VE against H3N2 was significantly higher among vaccinated individuals with no prior vaccination history (65%; 95% confidence interval [CI], 36%–80%) compared with vaccinated individuals with a frequent vaccination history (24%; 95% CI, 3%–41%; P = .01). VE against B was 75% (95% CI, 50%–87%) and 48% (95% CI, 29%–62%), respectively (P = .05). Similar findings were observed when analysis was restricted to adults 18–49 years.

Conclusions. Current- and previous-season vaccination generated similar levels of protection, and vaccine-induced protection was greatest for individuals not vaccinated during the prior 5 years. Additional studies are needed to understand the long-term effects of annual vaccination.

Seasonal incidence of medically attended respiratory syncytial virus infection in a community cohort of adults ≥50 years old

BACKGROUND

Diagnostic testing for respiratory syncytial virus (RSV) is not routinely performed in adults. We estimated medically attended RSV seasonal incidence in a community cohort of adults ≥50 years old during four influenza seasons (2006-07 through 2009-10).

METHODS

Patients seeking care for acute respiratory illness (ARI) were prospectively enrolled and tested for RSV by multiplex RT-PCR. Results from enrolled patients were used to estimate projected cases among non-enrolled patients with ARI. The seasonal incidence of medically attended RSV was the sum of actual and projected cases divided by the community cohort denominator. Since each enrollment period did not include the entire RSV season, incidence estimates were adjusted to account for the statewide proportion of RSV occurring outside the study enrollment period.

RESULTS

There were 16,088 to 17,694 adults in the cohort each season and 164 RSV cases in all 4 seasons. The overall seasonal incidence of medically attended RSV was 154 episodes (95% CI, 132-180) per 10,000 persons; the incidence was highest in 2007-08 (179) and lowest in 2006-07 (110). Among persons 50-59, 60-69, and ≥70 years old, RSV incidence was 124 (95% CI, 99-156), 147 (95% CI, 110-196), and 199 (95% CI, 153-258), respectively.

CONCLUSIONS

The incidence of medically attended RSV increased with age and was similar during four seasons.

Waning vaccine protection against influenza A (H3N2) illness in children and older adults during a single season

BACKGROUND

Recent studies have suggested that vaccine-induced protection against influenza may decline within one season. We reanalyzed data from a study of influenza vaccine effectiveness to determine if time since vaccination was an independent predictor of influenza A (H3N2).

METHODS

Patients with acute respiratory illness were actively recruited during the 2007-2008 season. Respiratory swabs were tested for influenza, and vaccination dates were determined by a validated immunization registry. The association between influenza RT-PCR result and vaccination interval (days) was examined using multivariable logistic regression, adjusting for calendar time, age and other confounders.

RESULTS

There were 629 vaccinated participants, including 177 influenza A (H3N2) cases and 452 test negative controls. The mean (SD) interval from vaccination to illness onset was 101.7 (25.9) days for influenza cases and 93.0 (29.9) days for controls. There was a significant association between vaccination interval and influenza result in the main effects model. The adjusted odds ratio (aOR) for influenza was 1.12 (CI 1.01, 1.26) for every 14 day increase in the vaccination interval. Age modified the association between vaccination interval and influenza (p=0.005 for interaction). Influenza was associated with increasing vaccination interval in young children and older adults, but not in adolescents or non-elderly adults. Similar results were found when calendar week of vaccine receipt was assessed as the primary exposure variable.

CONCLUSIONS

Identification of influenza A (H3N2) was associated with increasing time since vaccination among young children and older adults during a single influenza season.

Influenza vaccination is not associated with detection of noninfluenza respiratory viruses in seasonal studies of influenza vaccine effectiveness

BACKGROUND

 The test-negative control study design is the basis for observational studies of influenza vaccine effectiveness (VE). Recent studies have suggested that influenza vaccination increases the risk of noninfluenza respiratory virus infection. Such an effect could create bias in VE studies using influenza-negative controls. We investigated the association between influenza infection, vaccination, and detection of other respiratory viruses among children <5 years old and adults ≥50 years old with acute respiratory illness who participated in seasonal studies of influenza vaccine effectiveness.

METHODS

 Nasal/nasopharyngeal samples collected from 2004–2005 through 2009–2010 were tested for 19 respiratory virus targets using a multiplex reverse-transcription polymerase chain reaction (RT-PCR) platform. Vaccination status was determined using a validated registry. Adjusted odds ratios for influenza and vaccination status were calculated using three different control groups: influenza-negative, other respiratory virus positive, and pan-negative.

RESULTS

 Influenza was detected in 12% of 2010 children and 20% of 1738 adults. Noninfluenza respiratory viruses were detected in 70% of children and 38% of adults without influenza. The proportion vaccinated did not vary between virus-positive controls and pan-negative controls in children (P = .62) or adults (P = .33). Influenza infection was associated with reduced odds of vaccination, but adjusted odds ratios differed by no more than 0.02 when the analysis used influenza-negative or virus-positive controls.

CONCLUSIONS

 Influenza vaccination was not associated with detection of noninfluenza respiratory viruses. Use of influenza-negative controls did not generate a biased estimate of vaccine effectiveness due to an effect of vaccination on other respiratory virus infections.

A population-based cohort study of undervaccination in 8 managed care organizations across the United States

OBJECTIVES To examine patterns and trends of undervaccination in children aged 2 to 24 months and to compare health care utilization rates between undervaccinated and age-appropriately vaccinated children. DESIGN Retrospective matched cohort study. SETTING Eight managed care organizations of the Vaccine Safety Datalink. PARTICIPANTS Children born between 2004 and 2008. MAIN EXPOSURE Immunization records were used to calculate the average number of days undervaccinated. Two matched cohorts were created: 1 with children who were undervaccinated for any reason and 1 with children who were undervaccinated because of parental choice. For both cohorts, undervaccinated children were matched to age-appropriately vaccinated children by birth date, managed care organization, and sex. MAIN OUTCOME MEASURES Rates of undervaccination, specific patterns of undervaccination, and health care utilization rates. RESULTS Of 323 247 children born between 2004 and 2008, 48.7% were undervaccinated for at least 1 day before age 24 months. The prevalence of undervaccination and specific patterns of undervaccination increased over time (P &lt; .001). In a matched cohort analysis, undervaccinated children had lower outpatient visit rates compared with children who were age-appropriately vaccinated (incidence rate ratio [IRR], 0.89; 95% CI, 0.89- 0.90). In contrast, undervaccinated children had increased inpatient admission rates compared with age-appropriately vaccinated children (IRR, 1.21; 95% CI, 1.18-1.23). In a second matched cohort analysis, children who were undervaccinated because of parental choice had lower rates of outpatient visits (IRR, 0.94; 95% CI, 0.93-0.95) and emergency department encounters (IRR, 0.91; 95% CI, 0.88-0.94) than age-appropriately vaccinated children. CONCLUSIONS Undervaccination appears to be an increasing trend. Undervaccinated children appear to have different health care utilization patterns compared with age-appropriately vaccinated children.

A scan statistic for identifying optimal risk windows in vaccine safety studies using self-controlled case series design

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.

A mixed methods study of parental vaccine decision making and parent-provider trust

OBJECTIVE

To describe parental vaccine decision making behaviors and characterize trust in physician advice among parents with varying childhood vaccination behaviors.

METHODS

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. On the basis of 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 by chi-square tests and multivariable logistic regression.

RESULTS

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 reevaluate their vaccine decisions than parents who accepted all vaccines. Although 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.

CONCLUSIONS

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) and often (pregnancy through infancy), and cover both the risks and benefits of vaccination.

The risk of immune thrombocytopenic purpura after vaccination in children and adolescents

BACKGROUND

The risk of immune thrombocytopenic purpura (ITP) after childhood vaccines other than measles-mumps-rubella vaccine (MMR) is unknown.

METHODS

Using data from 5 managed care organizations for 2000 to 2009, we identified a cohort of 1.8 million children ages 6 weeks to 17 years. Potential ITP cases were identified by using diagnostic codes and platelet counts. All cases were verified by chart review. Incidence rate ratios were calculated comparing the risk of ITP in risk (1 to 42 days after vaccination) and control periods.

RESULTS

There were 197 chart-confirmed ITP cases out of 1.8 million children in the cohort. There was no elevated risk of ITP after any vaccine in early childhood other than MMR in the 12- to 19-month age group. There was a significantly elevated risk of ITP after hepatitis A vaccine at 7 to 17 years of age, and for varicella vaccine and tetanus-diphtheria-acellular pertussis vaccine at 11 to 17 years of age. For hepatitis A, varicella, and tetanus-diphtheria-acellular pertussis vaccines, elevated risks were based on one to two vaccine-exposed cases. Most cases were acute and mild with no long-term sequelae.

CONCLUSIONS

ITP is unlikely after early childhood vaccines other than MMR. Because of the small number of exposed cases and potential confounding, the possible association of ITP with hepatitis A, varicella, and tetanus-diphtheria-acellular pertussis vaccines in older children requires further investigation.

Parental decline of pneumococcal vaccination and risk of pneumococcal related disease in children

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Parental refusal of varicella vaccination and the associated risk of varicella infection in children

OBJECTIVE

To quantify both the individual-level and attributable risk of varicella infection requiring medical care in children whose parents refuse varicella immunizations.

DESIGN

Matched case-control study with conditional logistic regression analysis.

SETTING

Kaiser Permanente of Colorado (KPCO) health plan between 1998 and 2008.

PARTICIPANTS

Each pediatric physician-diagnosed case of varicella (n = 133) was matched to 4 randomly selected controls (n = 493). Cases were matched by age, sex, and length of enrollment in KPCO. Main Exposures Varicella vaccine refusal.

OUTCOME MEASURES

Varicella infection.

RESULTS

There were 7 varicella vaccine refusers (5%) among the cases and 3 (0.6%) among the controls. Children of parents who refused varicella immunizations were at a greatly increased risk of varicella infection requiring medical care (odds ratio, 8.6; 95% confidence interval, 2.2-33.3) compared with children of parents who accepted vaccinations (P = .004). In the entire KPCO pediatric population, 5% of varicella cases were attributed to parental vaccine refusal.

CONCLUSIONS

Children of parents who refuse varicella immunizations are at high risk of varicella infection relative to vaccinated children. These results will be helpful to health care providers and parents when making decisions about immunizing children.

Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children

OBJECTIVE

The objective of this study was to determine if children who contracted pertussis infection were more likely to have parents who refused pertussis vaccinations than a similar group of children who did not develop pertussis infection.

METHODS

We conducted a case-control study of children enrolled in the Kaiser Permanente of Colorado health plan between 1996 and 2007. Each pertussis case was matched to 4 randomly selected controls. Pertussis case status and vaccination status were ascertained by medical chart review.

RESULTS

We identified 156 laboratory-confirmed pertussis cases and 595 matched controls. There were 18 (12%) pertussis vaccine refusers among the cases and 3 (0.5%) pertussis vaccine refusers among the controls. Children of parents who refused pertussis immunizations were at an increased risk for pertussis compared with children of parents who accepted vaccinations. In a secondary case-control analysis of children continuously enrolled in Kaiser Permanente of Colorado from 2 to 20 months of age, vaccine refusal was associated with a similarly increased risk of pertussis. In the entire Kaiser Permanente of Colorado pediatric population, 11% of all pertussis cases were attributed to parental vaccine refusal.

CONCLUSIONS

Children of parents who refuse pertussis immunizations are at high risk for pertussis infection relative to vaccinated children. Herd immunity does not seem to completely protect unvaccinated children from pertussis. These findings stress the need to further understand why parents refuse immunizations and to develop strategies for conveying the risks and benefits of immunizations to parents more effectively.

Statin and statin-fibrate use was significantly associated with increased myositis risk in a managed care population

OBJECTIVE

We quantified the risk of myositis associated with statin and fibrate drug use with other covariates within a managed care organization (MCO) population.

STUDY DESIGN AND SETTING

The study spanned the years 1999-2003. Myositis cases had creatine kinase (CK) >or=10x upper limit of normal and a myopathy diagnosis. Exposures of statins, fibrates, and other drugs were assessed with age, gender, and indicators of suspected myopathy risk. Exposures were first analyzed within a cohort with CK monitoring and then within a more general secondary cohort. Adjusted relative risks (RRs) and incidence rates of myositis were generated by Poisson regression.

RESULTS

Myositis was significantly associated with statin monotherapy (RR 2.8 [95% confidence interval, CI=1.3-5.9]), statin-fibrate combination therapy (9.1 [95% CI=3.5-23]), comorbid liver disease (4.3 [95% CI=1.5-13], and/or renal disease (2.5 [95% CI=1.3-5.0]). Myositis rates per covariate pattern ranged from 33 to 6,400 per 100,000 person-years. The mean time to event was 1.7 years for statin-fibrate use, 2.0 years for statins alone, and 2.1 years for unexposed. Within the secondary cohort, RRs increased up to 10 times further away from the null.

CONCLUSION

Statins, with or without fibrates, and liver and renal disease were significantly associated with increased myositis risk in an MCO population.

Laboratory evaluation of potassium and creatinine among ambulatory patients prescribed spironolactone: are we monitoring for hyperkalemia?

BACKGROUND

Serum potassium and creatinine evaluation is recommended in patients prescribed spironolactone, yet the proportion of ambulatory patients chronically dispensed spironolactone receiving evaluation is not well understood.

OBJECTIVE

To estimate the rate of potassium and creatinine evaluation and identify factors associated with conducting these tests among ambulatory patients dispensed spironolactone.

METHODS

A retrospective cohort study was designed to evaluate patients at 10 health maintenance organizations with ongoing spironolactone dispensing for one year (N = 2257). Potassium and creatinine evaluation were determined from administrative data. Associations between patient characteristics and laboratory testing were assessed, using logistic regression modeling.

RESULTS

Serum creatinine and potassium were evaluated in 72.3% of patients during a 13 month period. The likelihood of potassium and creatinine monitoring was greater among patients who were older (OR 1.28; 95% CI 1.17 to 1.41 per decade of life); male (OR 1.25; 95% CI 1.01 to 1.54); had diabetes (OR 1.63; 95% CI 1.31 to 2.03); received concomitant therapy with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (OR 2.23; 95% CI 1.74 to 2.87), potassium supplements (OR 1.96; 95% CI 1.51 to 2.54), or digoxin (OR 2.10 95% CI 1.48 to 2.98); or had more outpatient visits (OR 1.31; 95% CI 1.19 to 1.44). Among patients with heart failure (n = 790), factors associated with the incidence of laboratory testing were diabetes (OR 1.64, 95% CI 1.14 to 2.34), outpatient visits (OR 1.20; 95% CI 1.02 to 1.41), and digoxin therapy (OR 2.26; 95% CI 1.38 to 3.69).

CONCLUSIONS

Three-fourths of ambulatory patients dispensed spironolactone receive recommended laboratory evaluation, with monitoring more likely to be completed in patients prescribed concomitant therapy with drugs that increase hyperkalemia risk, older patients, and those with diabetes.

Systematic review and meta-analysis of clinically relevant adverse events from HMG CoA reductase inhibitor trials worldwide from 1982 to present

PURPOSE

Our objective was to determine the association of clinically relevant adverse events from a systematic review and meta-analysis of statin randomized controlled trials (RCT).

METHODS

We performed the meta-analysis in the manner of a Cochrane Collaboration systematic review. Outcomes were discontinuances of therapy or muscle-related symptoms due to adverse events. We searched for articles from 1982 through June 2006 in MEDLINE and other databases. The main inclusion criteria were double blind, placebo controlled RCTs with a monotherapy intervention of any marketed statin and active surveillance of adverse events. We excluded studies of drug interactions, organ transplants, or exercise, or those not meeting all of the study quality criteria. The primary analysis was a statin formulation stratified fixed-effect model using Peto odds-ratios (POR). Secondary analyses explored the stability of the primary results.

RESULTS

Over 86,000 study participants from 119 studies were included. Available statins were associated with a lower POR of discontinuance (overall: 0.88 [0.84, 0.93], largest effect with pravastatin: 0.79 [0.74, 0.84]), an elevated POR of rhabdomyolysis (1.59 [0.54, 4.70]) and myositis (2.56 [1.12, 5.85]), and null odds of myalgia (1.09 [0.97, 1.23]). Cerivastatin by comparison demonstrated larger PORs for discontinuances and muscle-related adverse events. Secondary analyses demonstrated the stability of the results.

CONCLUSIONS

Overall, discontinuation of statin therapy due to adverse events was no worse than placebo. The risks of muscle-related adverse events were in general agreement with the known risks of statins.

Adherence to cardioprotective medications and mortality among patients with diabetes and ischemic heart disease

BACKGROUND

Patients with diabetes and ischemic heart disease (IHD) are at high risk for adverse cardiac outcomes. Clinical practice guidelines recommend multiple cardioprotective medications to reduce recurrent events. We evaluated the association between cardioprotective medication adherence and mortality among patients with diabetes and IHD.

METHODS

In a retrospective cohort study of 3,998 patients with diabetes and IHD, we evaluated use of ACE inhibitors or angiotensin receptor blockers, beta-blockers, and statin medications. Receipt of cardioprotective medications was based on filled prescriptions. Medication adherence was calculated as the proportion of days covered (PDC) for filled prescriptions. The primary outcome of interest was all-cause mortality.

RESULTS

The majority of patients (92.8%) received at least 1 cardioprotective medication. Patients receiving any medications had lower unadjusted mortality rates compared to patients not receiving any medications (7.9% vs. 11.5%; p = 0.03). In multivariable analysis, receipt of any cardioprotective medication remained associated with lower all-cause mortality (OR 0.65; 95% CI 0.43-0.99). Among patients receiving cardioprotective medications, the majority (80.3%) were adherent (PDC > or = 0.80). Adherent patients had lower unadjusted mortality rates (6.7% vs. 12.1%; p < 0.01). In multivariable analysis, medication adherence remained associated with lower all-cause mortality (OR 0.52; 95% CI 0.39-0.69) compared to non-adherence. In contrast, there was no mortality difference between patients receiving cardioprotective medications who were non-adherent compared to patients not receiving any medications (OR 1.01; 95% CI 0.64-1.61).

CONCLUSION

In conclusion, medication adherence is associated with improved outcomes among patients with diabetes and IHD. Quality improvement interventions are needed to increase medication adherence in order for patients to maximize the benefit of cardioprotective medications.

Effect of medication nonadherence on hospitalization and mortality among patients with diabetes mellitus

BACKGROUND

Medication nonadherence may reduce the effectiveness of therapies. To our knowledge, the association between medication nonadherence and mortality remains unexplored outside the context of clinical trials.

METHODS

A retrospective cohort study of 11 532 patients with diabetes mellitus in a managed care organization. Medication adherence was calculated as the proportion of days covered for filled prescriptions of oral hypoglycemics, antihypertensives, and statin medications. The primary outcomes of interest were all-cause hospitalization and all-cause mortality. Multivariable regression analyses were performed to assess the independent association between medication adherence and outcomes.

RESULTS

Nonadherent patients (proportion of days covered, <80%; prevalence, 21.3%) were younger and had fewer comorbidities compared with adherent patients. During follow-up, nonadherent patients had higher glycosylated hemoglobin, systolic and diastolic blood pressure, and low-density lipoprotein cholesterol levels. In unadjusted analyses, nonadherent patients had higher all-cause hospitalization (23.2% vs 19.2%, P<.001) and higher all-cause mortality (5.9% vs 4.0%, P<.001). In multivariable analyses, medication nonadherence remained significantly associated with increased risks for all-cause hospitalization (odds ratio, 1.58; 95% confidence interval, 1.38-1.81; P<.001) and for all-cause mortality (odds ratio, 1.81; 95% confidence interval, 1.46-2.23; P<.001). The findings were consistent across patient subgroups and using different cutoffs for the proportion of days covered.

CONCLUSIONS

Medication nonadherence is prevalent among patients with diabetes mellitus and is associated with adverse outcomes. Interventions are needed to increase medication adherence so that patients can realize the full benefit of prescribed therapies.

Four different study designs to evaluate vaccine safety were equally validated with contrasting limitations

OBJECTIVE

We conducted a simulation study to empirically compare four study designs [cohort, case-control, risk-interval, self-controlled case series (SCCS)] used to assess vaccine safety.

STUDY DESIGN AND METHODS

Using Vaccine Safety Datalink data (a Centers for Disease Control and Prevention-funded project), we simulated 250 case sets of an acute illness within a cohort of vaccinated and unvaccinated children. We constructed the other three study designs from the cohort at three different incident rate ratios (IRRs, 2.00, 3.00, and 4.00), 15 levels of decreasing disease incidence, and two confounding levels (20%, 40%) for both fixed and seasonal confounding. Each of the design-specific study samples was analyzed with a regression model. The design-specific beta; estimates were compared.

RESULTS

The beta; estimates of the case-control, risk-interval, and SCCS designs were within 5% of the true risk parameters or cohort estimates. However, the case-control's estimates were less precise, less powerful, and biased by fixed confounding. The estimates of SCCS and risk-interval designs were biased by unadjusted seasonal confounding.

CONCLUSIONS

All the methods were valid designs, with contrasting strengths and weaknesses. In particular, the SCCS method proved to be an efficient and valid alternative to the cohort method.

Laboratory monitoring of potassium and creatinine in ambulatory patients receiving angiotensin converting enzyme inhibitors and angiotensin receptor blockers

PURPOSE

Serum potassium and creatinine monitoring is recommended for patients prescribed angiotensin converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB). Much has been written about hyperkalemia associated with these drugs; little is known about laboratory monitoring patterns. The purpose of this retrospective cohort study was to assess creatinine and potassium monitoring and characteristics associated with monitoring among patients dispensed ACEi or ARB.

METHODS

This study was conducted in 10 United States health maintenance organizations. Study patients (n = 52 906) were aged 18 or older with dispensings of ACEi or ARB for at least 1 year. Serum potassium and creatinine monitoring were assessed from administrative data and medical records.

RESULTS

More than two-thirds (68.4%) of patients received laboratory monitoring. Likelihood of monitoring increased with age (adjusted odds ratio [OR] 2.10; 95% confidence interval [95%CI] 1.93, 2.28 [individuals >or= 80 compared to <50 years]), >9 outpatient visits (OR 1.46; 95%CI 1.39, 1.54), hospitalization (OR 1.15; 95%CI 1.06, 1.25), concomitant medications (potassium [OR 2.01; 95%CI 1.84, 2.20], diuretics [OR 1.54; 95%CI 1.47, 1.61], digoxin [OR 1.15; 95%CI 1.01, 1.30]), and comorbidities (diabetes [OR 1.68; 95%CI 1.61, 1.75], heart failure [OR 1.73; 95%CI 1.57, 1.90], chronic kidney disease [OR 2.95; 95%CI 2.48. 3.51]).

CONCLUSIONS

Nearly one-third of patients dispensed ACEi or ARB did not undergo laboratory monitoring at least yearly. Though patients at increased risk of hyperkalemia were more likely to be monitored, many remained unmonitored.

Evaluation of cases of severe statin-related transaminitis within a large health maintenance organization

PURPOSE

To describe the rate, potential causes, symptoms, time to onset, and time to resolution of severe transaminitis associated with increased 3-hydroxy-3-methylglutaryl coenzyme reductase inhibitor ("statin") usage in a large group model health maintenance organization.

SUBJECTS AND METHODS

Health plan members 18 years of age and older, not receiving chemotherapy, who had received at least 1 statin prescription between January 1, 1997, and December 31, 2001 were eligible. All eligible patients with an alanine aminotransferase greater than 10 times the upper limit of normal at any time during the study period were identified using computerized laboratory records. Medical records were subsequently reviewed in order to determine whether the elevation was attributable to statin therapy.

RESULTS

Alanine aminotransferase had never been measured in 2334 of 25334 (9%) of eligible patients. In the remaining 23000 patients, 62 (0.3%) were identified with an alanine aminotransferase greater than 10 times the upper limit of normal during the 5-year study period. Of these, 17 (0.1% of 23000 patients) had severe transaminitis deemed directly attributable to statin use. All except 4 of these 17 cases were associated with drug interactions. In 16 cases, transaminitis resolved upon statin discontinuation.

CONCLUSIONS

In the observed study sample, statin-related severe transaminitis occurred infrequently. These findings support less frequent liver enzyme monitoring for most patients on statins. Continued monitoring remains warranted for patients on concomitant medications or those with comorbid conditions.

Relationships between self-reported asthma utilization and patient characteristics

BACKGROUND

Identifying asthmatic individuals most likely to utilize medical care in the future will help to direct intervention and medical resources; however, there are currently limited models for future utilization.

OBJECTIVE

This study investigated the relationship between patient characteristics and medical utilization, using an asthma disease management patient population.

METHODS

We analyzed a sample of 1412 adults, enrolled for 6 months in an asthma disease management program, for relationships with utilization. Individuals answered demographic, socioeconomic, and medical questions via telephonic contact upon enrollment. Follow-up regarding medical utilization occurred during the subsequent 6 months. Relationships between utilization and enrollment answers were statistically modeled.

RESULTS

Oral steroid bursts, day and night symptom frequencies, age, gender, education level, and employment status all had a significant relationship to medical utilization. Those individuals who had used oral steroids 6 months prior to enrollment, patients with more than five night-time asthma symptoms per month, and those with "continuous" day symptoms were more likely to report utilization. Those patients under 44 years old, females, those who were not high school graduates, and patients who defined themselves as unemployed because of their asthma were also more likely to report utilization. While those unemployed because of asthma were already more likely to report utilization, individuals in the 45+ age category were more likely than those 18-44.

CONCLUSIONS

Identifying asthma patients likely to utilize medical care is feasible, although more investigation is needed to demonstrate applicability to a general asthma population.