Validation study in four health-care databases: upper gastrointestinal bleeding misclassification affects precision but not magnitude of drug-related upper gastrointestinal bleeding risk

ObjectiveTo evaluate the accuracy of disease codes and free text in identifying upper gastrointestinal bleeding (UGIB) from electronic health-care records (EHRs).Study Design and SettingWe conducted a validation study in four European electronic health-care record (EHR) databases such as Integrated Primary Care Information (IPCI), Health Search/CSD Patient Database (HSD), ARS, and Aarhus, in which we identified UGIB cases using free text or disease codes: (1) International Classification of Disease (ICD)-9 (HSD, ARS); (2) ICD-10 (Aarhus); and (3) International Classification of Primary Care (ICPC) (IPCI). From each database, we randomly selected and manually reviewed 200 cases to calculate positive predictive values (PPVs). We employed different case definitions to assess the effect of outcome misclassification on estimation of risk of drug-related UGIB.ResultsPPV was 22% [95% confidence interval (CI): 16, 28] and 21% (95% CI: 16, 28) in IPCI for free text and ICPC codes, respectively. PPV was 91% (95% CI: 86, 95) for ICD-9 codes and 47% (95% CI: 35, 59) for free text in HSD. PPV for ICD-9 codes in ARS was 72% (95% CI: 65, 78) and 77% (95% CI: 69, 83) for ICD-10 codes (Aarhus). More specific definitions did not have significant impact on risk estimation of drug-related UGIB, except for wider CIs.ConclusionsICD-9-CM and ICD-10 disease codes have good PPV in identifying UGIB from EHR; less granular terminology (ICPC) may require additional strategies. Use of more specific UGIB definitions affects precision, but not magnitude, of risk estimates.     

Multicenter study on the value of ICD-9-CM codes for case identification of celiac disease

PurposeTo evaluate the value of ICD-9-CM code for identifying celiac disease (CD).MethodsWe searched administrative data to identify all adults with ICD-9-CM diagnosis code 579.0 (CD) at three teaching hospitals between 2000 and 2010. We then stratified patients according to the presence/absence of relevant serology and endoscopy codes into four groups: None, serology, endoscopy, and both. A diagnostic algorithm was applied to define CD status.ResultsThrough random sampling and appropriate weighting, the 1200 reviewed patients represented a cohort of 8,122 cases. The overall positive predictive value (PPV) of the ICD-9-CM code was 15% (95% confidence interval [CI], 13%–17%). Case identification by a diagnosis code alone had a PPV of 4%, whereas the group with diagnosis code plus both serology and endoscopy testing had a PPV of 49%. Independent predictors of CD were non-Hispanic white, ICD-9-CM–coded patient group, total number of a diagnosis code, and receiving a diagnosis code by a gastroenterologist. The model had an area under the curve of 0.87 (95% CI, 0.84–0.89).ConclusionsThe performance of ICD-9-CM 579.0 alone for identifying CD is extremely poor. Adding other readily available administrative data significantly improves CD case identification. The proposed case finding strategy via administrative databases may facilitate future research on CD.     

Comparison of the use of administrative data and an active system for surveillance of invasive aspergillosis

BACKGROUND: Administrative data, such as International Classification of Diseases, Ninth Revision (ICD-9) codes, are readily available and are an attractive option for surveillance and quality assessment within a single institution or for interinstitutional comparisons. To understand the usefulness of administrative data for the surveillance of invasive aspergillosis, we compared information obtained from a system based on ICD-9 codes with information obtained from an active, prospective surveillance system, which used more extensive case-finding methods (Transplant Associated Infection Surveillance Network). METHODS: Patients with suspected invasive aspergillosis were identified by aspergillosis-related ICD-9 codes assigned to hematopoietic stem cell transplant recipients and solid organ transplant recipients at a single hospital from April 1, 2001, through January 31, 2005. Suspected cases were classified as proven or probable invasive aspergillosis by medical record review using standard definitions. We calculated the sensitivity and positive predictive value (PPV) of identifying invasive aspergillosis by individual ICD-9 codes and by combinations of codes. RESULTS: The sensitivity of code 117.3 was modest (63% [95% confidence interval {CI}, 38%-84%]), as was the PPV (71% [95% CI, 44%-90%]); the sensitivity of code 117.9 was poor (32% [95% CI, 13%-57%]), as was the PPV (15% [95% CI, 6%-31%]). The sensitivity of codes 117.3 and 117.9 combined was 84% (95% CI, 60%-97%); the PPV of the combined codes was 30% (95% CI, 18%-44%). Overall, ICD-9 codes triggered a review of medical records for 64 medical patients, only 16 (25%) of whom had proven or probable invasive aspergillosis. CONCLUSIONS: A surveillance system that involved multiple ICD-9 codes was sufficiently sensitive to identify most cases of invasive aspergillosis; however, the poor PPV of ICD-9 codes means that this approach is not adequate as the sole tool used to classify cases. Screening ICD-9 codes to trigger a medical record review might be a useful method of surveillance for invasive aspergillosis and quality assessment, although more investigation is needed.     

ICD-9-CM codes poorly indentified venous thromboembolism during pregnancy

OBJECTIVE: There is little data regarding the accuracy of pregnancy-specific ICD-9-CM codes used to identify patients with venous thromboembolism (VTE). STUDY DESIGN AND SETTING: We identified a large cohort of pregnant patients in whom there were one or more pregnancy-specific (600 codes) or standard ICD-9-CM codes (400 codes) for VTE. Charts of these cases were abstracted to determine the presence of objectively documented VTE. RESULTS: A total of 214 cases had a code for VTE either during pregnancy or the 6-week postpartum period; 82% had a pregnancy-specific code and 18% a standard code. Overall, 84 (39%, 95% CI=33-46%) had objectively documented VTE. A pregnancy-specific ICD-9-CM for VTE had a positive predictive value (PPV) of 54/174=31% (95% CI=24-38%), whereas standard VTE codes had a PPV of 30 of 38=80% (95% CI=63-99%). A PPV in the range of 95-100% could be attained using other criteria, at the expense of detecting only 28 to 45% of all VTE cases. CONCLUSIONS: Pregnancy-specific ICD-9-CM codes for VTE have low PPV. Other criteria must be applied to select cases with a high probability of having objectively documented VTE.     

Positive predictive value of primary inpatient discharge diagnoses of infection among cancer patients in the Danish National Registry of Patients

PurposePharmacovigilance studies of cancer treatment frequently monitor infections. Predictive values of algorithms identifying disease depend on prevalence of the disease in the population under study. We therefore estimated the positive predictive value (PPV) of primary inpatient diagnosis of infection among cancer patients in the Danish National Registry of Patients (DNRP).MethodsThe algorithm to identify infections in the DNPR was based on International Classification of Diseases, 10th revision (ICD-10) codes. A physician blinded to the type of sampled infection reviewed the medical charts and assessed the presence and type of infection. Using the physician global assessment as gold standard, we computed PPVs with and without requiring agreement on infection type.ResultsWe retrieved 266 of 272 medical charts (98%). Presence of infection was confirmed in 261 patients, resulting in an overall PPV of 98% (95% confidence interval, 96%–99%). When requiring agreement on infection type, overall PPV was 77%. For skin infections, pneumonia, and sepsis, PPVs were 79%, 93% and 84%, respectively. For these infections, we additionally calculated PPVs using evidence-based criteria as the gold standard. PPV was similar for pneumonia, but lower for skin infections and sepsis.ConclusionsThe Danish National Registry of Patients is suitable for monitoring infections requiring hospitalization among cancer patients.     

The risk of febrile seizures following influenza and 13-valent pneumococcal conjugate vaccines

BackgroundEvidence on the risk of febrile seizures after inactivated influenza vaccine (IIV) and 13-valent pneumococcal conjugate vaccine (PCV13) is mixed. In the FDA-sponsored Sentinel Initiative, we examined risk of febrile seizures after IIV and PCV13 in children 6–23 months of age during the 2013–14 and 2014–15 influenza seasons.MethodsUsing claims data and a self-controlled risk interval design, we compared the febrile seizure rate in a risk interval (0–1 days) versus control interval (14–20 days). In exploratory analyses, we assessed whether the effect of IIV was modified by concomitant PCV13 administration.ResultsAdjusted for age, calendar time and concomitant administration of the other vaccine, the incidence rate ratio (IRR) for risk of febrile seizures following IIV was 1.12 (95% CI 0.80, 1.56) and following PCV13 was 1.80 (95% CI 1.29, 2.52). The attributable risk for febrile seizures following PCV13 ranged from 0.33 to 5.16 per 100,000 doses by week of age.The age and calendar-time adjusted IRR comparing exposed to unexposed time was numerically larger for concomitant IIV and PCV13 (IRR 2.80, 95% CI 1.63, 4.83), as compared to PCV13 without concomitant IIV (IRR 1.54, 95% CI 1.04, 2.28), and the IRR for IIV without concomitant PCV13 suggested no independent effects of IIV (IRR 0.94, 95% CI 0.63, 1.42). Taken together, this suggests a possible interaction between IIV and PCV13, though our study was not sufficiently powered to provide a precise estimate of the interaction.ConclusionsWe found an elevated risk of febrile seizures after PCV13 vaccine but not after IIV. The risk of febrile seizures after PCV13 is low compared to the overall risk in this population of children, and the risk should be interpreted in the context of the importance of preventing pneumococcal infections.     

ICD-10 anaphylaxis algorithm and the estimate of vaccine-attributable anaphylaxis incidence in Medicare

BackgroundAnaphylaxis is a rare, serious allergic reaction. Its identification in large healthcare databases can help better characterize this risk.ObjectiveTo create an ICD-10 anaphylaxis algorithm, estimate its positive predictive values (PPVs) in a post-vaccination risk window, and estimate vaccination-attributable anaphylaxis rates in the Medicare Fee For Service (FFS) population.MethodsAn anaphylaxis algorithm with core and extended portions was constructed analyzing ICD-10 anaphylaxis claims data in Medicare FFS from 2015 to 2017. Cases of post-vaccination anaphylaxis among Medicare FFS beneficiaries were then identified from October 1, 2015 to February 28, 2019 utilizing vaccine relevant anaphylaxis ICD-10 codes. Information from medical records was used to determine true anaphylaxis cases based on the Brighton Collaboration’s anaphylaxis case definition. PPVs were estimated for incident anaphylaxis and the subset of vaccine-attributable anaphylaxis within a 2-day post-vaccination risk window. Vaccine-attributable anaphylaxis rates in Medicare FFS were also estimated.ResultsThe study recorded 66,572,128 vaccinations among 21,685,119 unique Medicare FFS beneficiaries. The algorithm identified a total of 190 suspected anaphylaxis cases within the 2-day post-vaccination window; of these 117 (62%) satisfied the core algorithm, and 73 (38%) additional cases satisfied the extended algorithm. The core algorithm’s PPV was 66% (95% CI [56%, 76%]) for identifying incident anaphylaxis and 44% (95% CI [34%, 56%]) for vaccine-attributable anaphylaxis. The vaccine-attributable anaphylaxis incidence rate after any vaccination was 0.88 per million doses (95% CI [0.67, 1.16]).ConclusionThe ICD-10 claims algorithm for anaphylaxis allows the assessment of anaphylaxis risk in real-world data. The algorithm revealed vaccine-attributable anaphylaxis is rare among vaccinated Medicare FFS beneficiaries.     

Risk factors and familial clustering for fever 7–10 days after the first dose of measles vaccines

BackgroundSeven to ten days after a first dose of a measles-containing vaccine (MCV; i.e., MMR or MMRV), children have elevated fever risk which can be associated with febrile seizures. This study investigated individual and familial factors associated with fever 7–10 days after MCV.MethodsRetrospective cohort study among children who were <36 months of age at receipt of MCV in six sites of the Vaccine Safety Datalink from 1/1/2000 to 12/31/2012. We evaluated medically-attended clinic or emergency department visits with a code for fever 7–10 days after any MCV (“MCV- associated”). We evaluated factors associated with MCV-associated fever using χ² and multivariable logistic regression analyses.ResultsAmong 946,806 children vaccinated with MCV, we identified 7480 (0.8%) MCV-associated fever visits. Compared with children without fever after MCV, children with MCV-associated fever were more likely to have received MMRV than MMR (OR 1.3 95% CI 1.2, 1.5), have had medically attended fever both following previous vaccines (OR 1.3 95% CI 1.1, 1.6) and at any other previous time (OR 1.7 95% CI 1.6, 1.8), have had at least 1 prior seizure (OR 2.2 95% CI 1.7, 2.7), and have had >3 medical visits within the 6 months before MCV (OR 1.7 95% CI 1.6, 1.8). In families with multiple MCV-immunized children, after adjusting for healthcare seeking behavior care for fever, those whose siblings had MCV-associated fever were more likely to also have MCV-associated fever (OR 3.5 95% CI 2.5, 4.8).DiscussionChildren who received MMRV vaccine or who had prior medically-attended fevers and seizures during the first year of life had increased risk of fever after a first dose of measles vaccine. After adjusting for familial propensity to seek care, MCV-associated fever still clustered within families, suggesting a possible genetic basis for susceptibility to developing fever due to measles vaccines.     

Administrative codes combined with medical records based criteria accurately identified bacterial infections among rheumatoid arthritis patients

ObjectiveTo evaluate diagnostic properties of International Classification of Diseases, Version 9 (ICD-9) diagnosis codes and infection criteria to identify bacterial infections among rheumatoid arthritis (RA) patients.Study Design and SettingWe performed a cross-sectional study of RA patients with and without ICD-9 codes for bacterial infections. Sixteen bacterial infection criteria were developed. Diagnostic properties of comprehensive and restrictive sets of ICD-9 codes and the infection criteria were tested against an adjudicated review of medical records.ResultsRecords on 162 RA patients with and 50 without purported bacterial infections were reviewed. Positive and negative predictive values of ICD-9 codes ranged from 54%–85% and 84%–100%, respectively. Positive predictive values of the medical records based criteria were 84% and 89% for “definite” and “definite or empirically treated” infections, respectively. Positive predictive value of infection criteria increased by 50% as disease prevalence increased using ICD-9 codes to enhance infection likelihood.ConclusionICD-9 codes alone may misclassify bacterial infections in hospitalized RA patients. Misclassification varies with the specificity of the codes used and strength of evidence required to confirm infections. Combining ICD-9 codes with infection criteria identified infections with greatest accuracy. Novel infection criteria may limit the requirement to review medical records.     

Safety of measles and pertussis-containing vaccines in children with autism spectrum disorders

ObjectivesTo determine whether children aged 4–7 years with a diagnosis of autism spectrum disorders (ASD) were at increased risk of fever, febrile seizures, or emergency department (ED) visits following measles- or pertussis-containing vaccines compared with children without ASD.MethodsThe study included children born between 1995–2012, aged 4–7 years at vaccination, and members of six healthcare delivery systems within Vaccine Safety Datalink. We conducted self-controlled risk interval analyses comparing rates of outcomes in risk and control intervals within each group defined by ASD status, and then compared outcome rates between children with and without ASD, in risk and control intervals, by estimating difference-in-differences using logistic regressions.ResultsThe study included 14,947 children with ASD and 1,650,041 children without ASD. After measles- or pertussis-containing vaccination, there were no differences in association between children with and without ASD for fever (ratio of rate ratio for measles-containing vaccine = 1.07, 95% CI 0.58–1.96; for pertussis-containing vaccine = 1.16, 95% CI 0.63–2.15) or ED visits (ratio of rate ratio for measles-containing vaccine = 1.11, 95% CI 0.80–1.54; for pertussis-containing vaccine = 0.87, 95% CI 0.59–1.28). Febrile seizures were rare. Pertussis-containing vaccines were associated with small increased risk of febrile seizures in children without ASD.ConclusionChildren with ASD were not at increased risk for fever or ED visits compared with children without ASD following measles- or pertussis-containing vaccines. These results may provide further reassurance that these vaccines are safe for all children, including those with ASD.     

Hospital discharge diagnoses of ventricular arrhythmias and cardiac arrest were useful for epidemiologic research

OBJECTIVE: We investigated the validity of hospital discharge diagnosis regarding ventricular arrhythmias and cardiac arrest. METHODS: We identified patients whose record in the PHARMO record linkage system database showed a code for ventricular or unspecified cardiac arrhythmias according to codes of the International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM). The validity of ICD codes for ventricular arrhythmias and cardiac arrest (427.1, 427.4, 427.41, 427.42, 427.5, 427.69) and ICD codes for unspecified cardiac arrhythmias (427.2, 427.60, 427.8, 427.89, 427.9) was ascertained through manual review of hospital clinical records. The positive predictive value (PPV) was calculated, and differences between characteristics of true and false positives were evaluated. RESULTS: The PPV of ICD codes for ventricular arrhythmias and cardiac arrest was 82% (95% confidence interval CI = 72-92). True positive results were associated with male gender (P = .09) and younger age (P = .05). Of the unspecified cardiac arrhythmias 10% (95% CI = 2-18) were identified as ventricular arrhythmias or cardiac arrest. CONCLUSION: Hospitalizations for ventricular cardiac arrhythmias and cardiac arrest (coded according to ICD-9-CM as paroxysmal ventricular tachycardia, ventricular fibrillation, ventricular flutter, ventricular premature beats, or cardiac arrest) have a high PPV and are useful for selecting events in epidemiological studies on drug-induced arrhythmias.     

ICD-10 hospital discharge diagnosis codes were sensitive for identifying pulmonary embolism but not deep vein thrombosis

ObjectiveTo estimate the sensitivity of International Classification of Diseases, Tenth revision (ICD-10) hospital discharge diagnosis codes for identifying deep vein thrombosis (DVT) and pulmonary embolism (PE).Study Design and SettingWe compared predefined ICD-10 discharge diagnosis codes with the diagnoses that were prospectively recorded for 1,375 patients with suspected DVT or PE who were enrolled at 25 hospitals in France. Sensitivity was calculated as the percentage of patients identified by predefined ICD-10 codes among positive cases of acute symptomatic DVT or PE confirmed by objective testing.ResultsThe sensitivity of ICD-10 codes was 58.0% (159 of 274; 95% CI: 51.9, 64.1) for isolated DVT and 88.9% (297 of 334; 95% CI: 85.6, 92.2) for PE. Depending on the hospital, the median values for sensitivity were 57.7% for DVT (interquartile range, IQR, 48.6–66.7; intracluster correlation coefficient, 0.02; P = 0.31) and 88.9% for PE (IQR, 83.3–96.3; intracluster correlation coefficient, 0.11; P = 0.03). The sensitivity of ICD-10 codes was lower for surgical patients and for patients who developed PE or DVT while they were hospitalized.ConclusionICD-10 discharge diagnosis codes yield satisfactory sensitivity for identifying objectively confirmed PE. A substantial proportion of DVT cases are missed when using hospital discharge data for complication screening or research purposes.     

The incidence of childhood and adolescent seizures in the UK from 1999 to 2011: A retrospective cohort study using the Clinical Practice Research Datalink

BackgroundIn postmarketing vaccine surveillance, adverse events observed in a vaccinated population are compared to the number expected based on a background incidence rate. The background rate should be accurate and obtained from a population comparable to the one vaccinated. Such rates are often not available.MethodsThe incidence rate of generalised convulsive, febrile and afebrile seizures was estimated in individuals born after 01-January-1998 and aged between 2 months and 15 years of age using the UK Clinical Practice Research Datalink (1999–2011).ResultsThe study population consisted of 1532,992 individuals (4917,369 person years (PY) of follow up). A total of 28,917 generalised convulsive seizure events were identified during follow-up, the overall incidence rate was 5.88 per 1000PY. Age specific rates increased sharply from 4/1000PY at 2 months of age, peaked at 19/1000PY at 16 months and decreased until approximately 6 years of age at which point they became relatively stable at 2/1000PY. 67% of GCSs were categorised as febrile: 56% using Read codes, 11% using free text. Febrile seizures accounted for the age trend in GCS, with rates peaking at 16.1/1000PY at 16 months of age while afebrile seizure rates remained relatively stable across all ages (24 seizures per 1000PY). Analysis by first occurrence of febrile seizure showed a similar pattern, comparable to published studies on the incidence of seizures in childhood.DiscussionThe rates reported in this study could be used in the postmarketing surveillance of infant vaccines. However, given the variation across strata, and the potential underascertainment of seizure events presenting to A&E, care must be taken when interpreting and using these rates.     

Qualité du codage des diagnostics et motifs de prise en charge (principal et associés) dans le recueil d’informations médicalisé en psychiatrie (RIM-P) en 2015 et 2016, France

BackgroundBased on the observation of the misuse of ICD-10 to code the diagnoses in the RIM-P (lack of completeness, conformity and diversity), the Technical Agency for information on Hospital Care (ATIH), which provides tools for collecting medical information, conducted two actions in 2016. First, a chapter devoted to the instructions of coding has been written in the methodological guide of production of the RIM-P, second, a variable “type psy” was added to the ICD-10 nomenclature's file framing ICD-10 coding in the RIM-P. The purpose of this study is to describe the quality of diagnosis coding using ICD-10 in the RIM-P in 2015 and 2016.MethodsThe quality of diagnosis coding using ICD-10 in the summaries of activity of the RIM-P national databases was described in 2015 and 2016. The study focused on the completeness, the conformity and the diversity of coding.ResultsBetween 2015 and 2016, the percentage of summaries without primary diagnosis (“DP”) decreased slightly for full-time (5.2% vs. 3.8%), part-time (6.3% vs. 4.9%) inpatient stays and outpatient care (9.9% vs. 8.9%). ICD-10 codes used to code DP or associated diagnosis (“DA”), while prohibited, mainly belong to Chapter V Mental and behavioral disorders. Per year, only one-third of the summaries and one-half of patients had two or more ICD-10 codes reported for inpatient stays (one-fifth of the summaries and one-fourth of the patients for outpatient care). In addition, per year and per facility, the average number of distinct ICD-10 codes used to fill “DP” or “DA” was approximately half as important in part-time hospitalization, as in full-time hospitalization or for outpatient care. Moreover, 90% of the health facilities used < 550 distinct ICD-10 codes in full-time inpatient stays, < 270 in part-time inpatient stays and < 950 for outpatient care to code the “DP” or the “DA”. The diversity of ICD-10 codes used was low and similar between 2015 and 2016, especially to describe the socio-economic environment, resistance to treatment or non-compliance.ConclusionThis study emphasizes the need for a collective effort to improve the diversity of the diagnoses’ coding in the RIM-P.     

Accuracy of ICD-9-CM codes in identifying infections of pneumonia and herpes simplex virus in administrative data

PurposeClinical epidemiology studies increasingly rely on electronic medical records data. The validity of International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes is crucial as they are often used to identify conditions of interest. We evaluated the use of archived ICD-9-CM codes to identify two representative infection-related conditions, pneumonia and herpes simplex virus (HSV), in a defined health system.MethodsRecords were obtained for a sample of 175 and 179 patients with ICD-9-CM codes for pneumonia and HSV, respectively. An adjudicated case status was assigned for each subject.ResultsThe presence of a single ICD-9-CM code had a positive predictive value of 88% for pneumonia and 86% for HSV. False positives (noncases) accounted for less than 10% of records evaluated for each condition.ConclusionsOur study demonstrates that ICD-9-CM codes for pneumonia and HSV were valid markers of a true history of these conditions, suggesting that ICD-9-CM codes can be used to successfully identify infection-related conditions in epidemiologic studies. However, validation studies for individual conditions may help identify condition-specific strategies to improve the performance of diagnostic codes.     

Prevalence of febrile seizures in Dutch schoolchildren

During a scheduled visit to the school physician, the number of children with a history of febrile seizures was determined in 3570 children attending primary schools in the suburban area of the city of Rotterdam. At the age of 6 years, 140 had experienced at least one febrile seizure (3.9%, 95% confidence interval 3.3% to 4.5%). Of these, 19 (14%) had experienced a recurrent seizure during the same febrile illness. Recurrent seizures in subsequent fever episodes occurred in 26%. The median age at onset was 18 months. One-third of the children had visited the hospital directly after the seizure, and 6% had used anticonvulsant drugs for at least 6 months. Of all the children, 5.4% had a positive first-degree family history of febrile seizures. Children with a positive family history were at a 4.5-fold increased risk of experiencing febrile seizures. Since in this study a generally accepted definition of febrile seizures was used, the estimated prevalence in Dutch school-children may well be compared with prevalence rates found in the United States and Great Britain.     

Prevalence of febrile seizures in Dutch schoolchildren

Summary. During a scheduled visit to the school physician, the number of children with a history of febrile seizures was determined in 3570 children attending primary schools in the suburban area of the city of Rotterdam. At the age of 6 years, 140 had experienced at least one febrile seizure (3.9%, 95% confidence interval 3.3% to4.5%). Of these, 19 (14%) had experienced a recurrent seizure during the same febrile illness. Recurrent seizures in subsequent fever episodes occurred in 26%. The median age at onset was 18 months. One-third of the children had visited the hospital directly after the seizure, and 6% had used anticonvulsant drugs for at least 6 months. Of all the children, 5.4% had a positive first-degree family history of febrile seizures. Children with a positive family history were at a 4.5-fold increased risk of experiencing febrile seizures. Since in this study a generally accepted definition of febrile seizures was used, the estimated prevalence in Dutch schoolchildren may well be compared with prevalence rates found in the United States and Great Britain.     

Revaccination outcomes of children with vaccine proximate seizures

BackgroundSeizures, whether febrile or afebrile, occurring within 14 days following vaccination can be considered as vaccine proximate seizures (VPSs). While the attributable risk and clinical severity of first febrile VPS is well known, the risk and clinical outcomes of VPS recurrence is less well defined.MethodsWe conducted a retrospective review of revaccination management and outcomes in children who experienced a VPS as their first seizure seen in Australian Specialist Immunisation Clinics between 2013 and 2017. Vaccination outcomes were compared between children who had a VPS as their only seizure (VPS only) and children who had further non-vaccine proximate seizures following their initial VPS (VPS+) prior to review at the clinic.ResultsWe identified 119 children with a VPS as their first seizure, of which 61 (51%) went on to have other seizures (VPS+). Children with VPS+ were more likely to present at a younger age (6.2 vs 12.5 months, P = 0.03), with afebrile seizures (42.6% vs 15.5%, P = 0.002) compared to VPS only children. VPS recurrence on revaccination was uncommon in both groups, but more common in VPS+ children (12.5% vs 2.4%, P = 0.07). Having an epilepsy diagnosis, specifically Dravet syndrome, was associated with VPS recurrence (P < 0.001). Of the four children with Dravet syndrome who had VPS recurrence, all had status epilepticus following revaccination.ConclusionIn children who presented with a single VPS as their only seizure, VPS recurrence on revaccination was uncommon. Children who had multiple non-vaccine proximate seizures following their initial VPS (VPS+) were more likely to present with afebrile VPS, at a younger age and have a VPS recurrence with vaccination. In these children, particularly those aged < 12 months, assessment and investigation for diagnosis of Dravet syndrome should be considered and additional precautions for revaccination undertaken as they are at highest risk of VPS recurrence.