The diagnosis of cerebral palsy in two Danish national registries: a validation study.

AIMS: To determine the quality of prospectively collected data from the highly specialized Danish Cerebral Palsy Follow-up Program (CPOP), and to establish the validity of a reported cerebral palsy (CP) diagnosis in the Danish National Patient Registry (NPR), regularly used as a proxy for neurodevelopmental disorders in epidemiological research. METHODS: We compared data from the two registries on children with registered CP, born in Denmark between 2008 and 2009, with information from medical records verified by two experienced physicians specializing in pediatric neurology. Data accuracy was estimated by completeness, correctness, and reliability. Completeness was calculated as the number of cases with correctly registered CP diagnoses divided by the total number of true CP diagnoses (similar to sensitivity). Correctness was calculated as the number of cases with correct registrations divided by the total number of cases (similar to positive predictive value). Reliability was estimated using kappa statistics. RESULTS: Registered CP diagnoses in the CPOP had high accuracy, with 94% correctness and 91% completeness. Furthermore, most key variables in the CPOP showed excellent reliability, especially variables defining the severity of the condition. In the Danish NPR, only 225 of 348 children with a noted CP diagnosis fulfilled the diagnostic criteria for CP, resulting in 65% correctness. CONCLUSIONS: Danish CPOP data are a valid source for epidemiological research. Conversely, a noted CP diagnosis in the Danish NPR was, at best, correct in only two out of three patients.

Children in Denmark with cerebral palsy rarely complete elementary school.

AIM: To investigate how children with cerebral palsy (CP) perform in the Danish school system and which factors are associated with school performance. METHOD: This was a population-based cohort study including 463 126 children born from 1997 to 2003. Data were extracted from seven national registries. The study encompassed 818 children with CP (483 [59.0%] males, 335 [41.0%] females) and 417 731 without CP (214 535 [51.4%] males, 203 196 [48.6%] females). We evaluated two primary outcomes: not completing 10 years of elementary school, defined as attending fewer than eight final mandatory exams; and grade point averages (GPAs). Mann-Whitney U tests were used to analyse differences in GPAs and logistic regressions were used to calculate odds ratios (ORs). RESULTS: Among children with and without CP, 62.6% and 12.4% did not complete elementary school respectively (OR = 11.85 [10.28-13.66]). Additionally, children with CP who attended all final exams achieved lower overall GPAs than children without CP (6.6 vs 7.3, p = 0.001). In children with CP, comorbidities, maternal education, severity of motor impairments, and intellectual deficits were associated with increased odds of not completing elementary school. Notably, one-third of children with CP with apparent normal intelligence did not complete school, despite special educational measures. INTERPRETATION: Danish children with CP rarely complete elementary school despite initiatives for a more supportive educational system. The complexity of individual needs in children with CP may be challenging for an inclusive school environment. WHAT THIS PAPER ADDS: Children with cerebral palsy (CP) have a high risk of not completing elementary school. Children with CP achieve lower overall grades than children without CP. Motor impairment, comorbidities, and maternal education are associated with poor school performance. Intellectual impairment is the most important predictor of poor school performance.

The effect of gestational age on major neurodevelopmental disorders in preterm infants.

BACKGROUND: Preterm infants have an increased risk of neurodevelopmental disorders. We established a direct quantitative comparison of the association between the degree of prematurity and three different neurodevelopmental disorders. METHODS: In this cohort study, we combined data from 995,498 children in the Danish Medical Birth Register, from birth years 1997-2013, with information on cerebral palsy, epilepsy, and special educational needs. We estimated the gestational week-specific prevalence and risk for each of the disorders. RESULTS: The risk ratio of cerebral palsy at gestational weeks 21-24, compared to term birth, was more than ten times higher than for the two other disorders. The prevalence of epilepsy and special educational needs declined almost parallel, with 9.2% (4.6%-13.5%) and 12.5% (11.2%-13.7%), respectively, per week of gestation toward term birth. Cerebral palsy did not decline similarly: from gestational weeks 21-24 until week 29 the prevalence declined insignificantly by 0.6% (-11.1%-11.0%) per week; whereas from week 29 until term, the prevalence declined markedly by 36.7% (25.9%-45.9%) per week. CONCLUSIONS: The prevalence and risk of cerebral palsy are affected differently by the degree of prematurity compared with epilepsy and special educational needs, possibly reflecting important differences in cerebral pathophysiology. IMPACT: For each week of gestation toward term birth, there was a clear log-linear decline in the prevalence of early childhood epilepsy and special educational needs. In contrast, the risk of cerebral palsy was high at the earliest gestational age, and the prevalence did not decline significantly until gestational week 29, from where it declined notably by nearly 40% for each week of gestation until term birth. Our results indicate important differences in the pathophysiological processes that associate preterm birth with these three neurodevelopmental disorders.

Declining prevalence of cerebral palsy in children born at term in Denmark.

AIM: To investigate reasons for the declining prevalence of cerebral palsy (CP) in children born at term in Denmark by evaluating obstetric and neonatal factors associated with CP, and their changes over time. METHOD: In this cohort study, we included 987 495 children (504 600 [51.1%] males and 482 895 [48.9%] females) born after 37 completed gestational weeks during birth years 1997 to 2013. Risk ratios of CP for each factor were calculated with log-binominal regression analyses. Significant factors were evaluated concerning their development in prevalence over time. RESULTS: In the antenatal period, there were significant associations with an increased risk of CP and high maternal body mass index (BMI), smoking during pregnancy, nulliparity, male sex, gestational age, and low birthweight. In the study period, fewer females smoked during pregnancy and fewer children were born post-term, dropping from 22.6% to 11.4% and 9.4% to 2.5% respectively. Conversely, the proportion of females with high BMI increased. Most significant risk factors were found in the neonatal period, with an increase in children with diagnosed birth defects and children admitted to neonatal care. INTERPRETATION: Reasons for the declining prevalence of CP appear to be multifactorial and likely include the decline in maternal smoking and children born post-term along with centralization and advances in neonatal treatment.

Platelet microRNA expression and association with platelet maturity and function in patients with essential thrombocythemia.

Essential thrombocythemia (ET) is characterized by persistently elevated platelet counts and an increased risk of thromboembolic events. Dysregulated expression of small noncoding microRNAs (miRNAs) have been shown in ET and may influence platelet maturity and function in ET patients. In this study, we included 22 ET patients and 19 healthy controls to investigate the expression of 12 platelet miRNAs previously reported to be dysregulated in ET. Further, we investigated the correlation between the expression of selected miRNAs and platelet maturity and platelet function. Total RNA was isolated from platelets, and expression analyses were performed using TaqMan quantitative PCR (qPCR). Mean platelet volume (MPV) and immature platelet count and -fraction (IPC and IPF) were measured using the Sysmex XE-5000 automated haematology system. Platelet function was investigated by multiple electrode aggregometry (agonists: arachidonic acid (AA), thrombin-receptor-activating-peptide (TRAP) and adenosine diphosphate (ADP)), while platelet activation was determined by multi-colour flow cytometry (antibodies: bound-fibrinogen, CD63 and P-selectin (CD62p), agonists: AA, TRAP and ADP). We showed that miR-9 and miR-490 were significantly upregulated in ET patients compared with healthy controls (p-values < 0.01), while miR-10a, miR-28, miR-126, miR-155, miR-221, miR-222, miR-223 and miR-431 were significantly downregulated in ET patients (all p-values < 0.001). A significant positive correlation was observed between miR-431 and MPV, IPC and IPF (all p-values < 0.05). The expression of miR-126 was negatively correlated with platelet aggregation induced by AA and TRAP (p < 0.05). In addition, we found the expression of miR-9 and miR-490 to be negatively correlated with the percentage of fibrinogen-, CD63- and P-selectin- positive platelets using TRAP as agonist (p < 0.05). In conclusion, our data indicate that platelet microRNAs may play a role in ET and that specific microRNAs are correlated with platelet maturity and platelet function.

Children with dyskinetic cerebral palsy are severely affected as compared to bilateral spastic cerebral palsy.

AIM: We aimed at describing clinical findings in children with dyskinetic as compared to bilateral spastic cerebral palsy (CP). METHODS: Data were extracted from the Danish nationwide CP register. Participants were born in 1999-2007 and were 5-6 years at ascertainment. RESULTS: The total number of CP cases was 1165 of which 92 had dyskinetic and 540 bilateral spastic CP. Prevalence of dyskinetic CP was 0.16 per 1000 live births. In participants with dyskinetic compared to bilateral spastic CP, there was more frequently an Apgar level less than five at five minutes (22.7% vs. 11.2%) and neonatal seizures (43.5% vs. 28.5%), but less respiratory deficiency, hyperbilirubinaemia and sepsis. Impairment based on gross motor function classification was more severe in dyskinetic CP (level III-V 90.0% vs. 66.0%). In dyskinetic CP, there was a high rate of reduced developmental quotient (68.1%), visual impairment (39.3%) and epilepsy (51.6%). Basal ganglia lesions were more prevalent in dyskinetic compared to bilateral spastic CP (27.7% vs. 12.8%). CONCLUSION: Cases of dyskinetic CP had overlapping clinical features with cases of bilateral spastic CP, but differed significantly in several perinatal risk factors. The children with dyskinetic CP had experienced more peri- or neonatal adverse events, and neurodevelopmental impairment was severe.