Incidence of Celiac Disease in Down Syndrome: A Longitudinal, Population-Based Birth Cohort Study

American Academy of Pediatrics (AAP) guidelines for children with Down syndrome (DS) include assessment for celiac disease (CD), although data to support this recommendation have been inconsistent. We determined the incidence of CD among children with DS in a population-based birth cohort of children born from 1976 to 2000 in Olmsted County, Minnesota. Individuals with karyotype-confirmed DS and CD (using diagnosis codes, positive serology, and duodenal biopsies) were identified. The incidence of CD in DS was compared with the published incidence of CD for Olmsted County residents (17.4 [95% confidence interval = 15.2-19.6] per 100 000 person-years). Among 45 individuals with DS from the birth cohort, 3 (6.7%) were identified with positive celiac serology and confirmatory biopsies at ages 9, 12, and 23 years, for an incidence of 325 per 100 000 person-years. Thus, individuals with DS have more than 18 times the incidence rate of CD compared with the general population, supporting the AAP guidelines.

Gestational Age, Perinatal Characteristics, and Autism Spectrum Disorder: A Birth Cohort Study

OBJECTIVE

To determine how gestational age relates to research-identified autism spectrum disorder (ASD-R) in the context of perinatal risk factors.

STUDY DESIGN

This is a population-based cohort study using the 1994-2000 Olmsted County Birth Cohort. Children included were born and remained in Olmsted County after age 3 years. ASD-R status was determined from signs and symptoms abstracted from medical and educational records. Cox proportional hazards models were fit to identify associations between perinatal characteristics and ASD-R.

RESULTS

The incidence of preterm birth (<37 weeks' gestation) was 8.6% among 7876 children. The cumulative incidence of ASD-R was 3.8% (95% CI 3.3-4.2) at 21 years of age. Compared with children born at full term, the risk of ASD-R appeared to be increased for children born preterm with unadjusted hazard ratios (HRs) of 2.62 (95% CI 0.65-10.57), 1.68 (95% CI 0.54-5.29), and 1.60 (95% CI 1.06-2.40) for children born extremely preterm, very preterm, and moderate-to-late preterm, respectively. In a multivariable model adjusted for perinatal characteristics, the associations were attenuated with adjusted HRs of 1.75 (95% CI 0.41-7.40), 1.24 (95% CI 0.38-4.01), and 1.42 (95% CI 0.93-2.15), for children born extremely preterm, very preterm, and moderate-to-late preterm, respectively. Among children with maternal history available (N = 6851), maternal psychiatric disorder was associated with ASD-R (adjusted HR 1.73, 95% CI 1.24-2.42).

CONCLUSIONS

The increased risk of ASD-R among children born preterm relative to children born full term was attenuated by infant and maternal characteristics.

Association of Comorbid Mood and Anxiety Disorders With Autism Spectrum Disorder

IMPORTANCE

It is critical to evaluate the risk of comorbid psychiatric diagnoses to meet the needs of individuals with autism spectrum disorder (ASD).

OBJECTIVE

To examine whether individuals with ASD are at greater risk for comorbid diagnoses of depression, anxiety, or bipolar disorder.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from a population-based birth cohort of 31 220 individuals born in Olmsted County, Minnesota, from January 1, 1976, to December 31, 2000. Patients with research-identified ASD were previously identified using a multistep process that evaluated signs and symptoms abstracted from medical and educational records. For each of the 1014 patients with ASD, 2 age- and sex-matched referents who did not meet criteria for ASD were randomly selected from the birth cohort (n = 2028). Diagnosis codes for anxiety, depression, and bipolar disorders were electronically obtained using the Rochester Epidemiological Project records-linkage system. Data analysis was performed from July 1, 2018, to April 1, 2019.

MAIN OUTCOMES AND MEASURES

Cumulative incidence of clinically diagnosed depression, anxiety, and bipolar disorder through early adulthood in individuals with ASD compared with referents.

RESULTS

A total of 1014 patients with ASD (median age at last follow-up, 22.8 years [interquartile range, 18.4-28.0 years]; 747 [73.7%] male; 902 [89.0%] white) and 2028 referents (median age at last follow-up, 22.4 years [interquartile range, 18.8-26.2 years]; 1494 [73.7%] male; 1780 [87.8%] white) participated in the study. Patients with ASD were significantly more likely to have clinically diagnosed bipolar disorder (hazard ratio [HR], 9.34; 95% CI, 4.57-19.06), depression (HR, 2.81; 95% CI, 2.45-3.22), and anxiety (HR, 3.45; 95% CI, 2.96-4.01) compared with referents. Among individuals with ASD, the estimates of cumulative incidence by 30 years of age were 7.3% (95% CI, 4.8%-9.7%) for bipolar disorder, 54.1% (95% CI, 49.8%-58.0%) for depression, and 50.0% (95% CI, 46.0%-53.7%) for anxiety. Among referents, cumulative incidence estimates by 30 years of age were 0.9% (95% CI, 0.1%-1.7%) for bipolar disorder, 28.9% (95% CI, 25.7%-32.0%) for depression, and 22.2% (95% CI, 19.3%-25.0%) for anxiety.

CONCLUSIONS AND RELEVANCE

The findings suggest that individuals with ASD may be at increased risk for clinically diagnosed depression, anxiety, and bipolar disorder compared with age- and sex-matched referents. This study supports the importance of early, ongoing surveillance and targeted treatments to address the psychiatric needs of individuals with ASD.

Psychiatric Comorbidities Modify the Association Between Childhood ADHD and Risk for Suicidality: A Population-Based Longitudinal Study

OBJECTIVE

The objective of this study was to evaluate the effect of psychiatric comorbidities on the association between childhood ADHD and suicidality among adults.

METHOD

Subjects were recruited from a population-based birth cohort. Participating adult subjects with childhood ADHD and non-ADHD controls were administered a structured psychiatric interview to assess suicidality and psychiatric comorbidities. Associations were assessed using logistic regression.

RESULTS

Compared with controls, ADHD cases were significantly more likely to meet criteria for suicidality. Subjects with childhood ADHD who met criteria for generalized anxiety disorder had a higher than expected risk of suicidality with an observed odds ratio of 10.94 (95% confidence interval [4.97, 24.08]) compared with an expected odds ratio of 4.86, consistent with a synergistic interaction effect. Significant synergistic interactions were also observed for hypomanic episode and substance-related disorders.

CONCLUSION

Childhood ADHD is significantly associated with adult suicidal risk. Comorbidity between ADHD and some psychiatric disorders is associated with a higher suicidal risk than expected.

Autism Spectrum Disorder: Incidence and Time Trends Over Two Decades in a Population-Based Birth Cohort

We retrospectively identified autism spectrum disorder (ASD) incident cases among 31,220 individuals in a population-based birth cohort based on signs and symptoms uniformly abstracted from medical and educational records. Inclusive and narrow research definitions of ASD (ASD-R_I and ASD-R_N, respectively) were explored, along with clinical diagnoses of ASD (ASD-C) obtained from the records. The incidence of ASD-R_I, ASD-R_N, and ASD-C increased significantly from 1985 to 1998, then ASD-R_I and ASD-R_N plateaued while the rate of ASD-C continued to increase during 1998-2004. The rising incidence of research-defined ASD may reflect improved recognition and documentation of ASD signs and symptoms. Although the frequency of threshold ASD symptoms stabilized, the rate of ASD-C continued to increase, narrowing the gap between clinical ascertainment and symptom documentation.

Patterns of neuropsychological changes after general anaesthesia in young children: secondary analysis of the Mayo Anesthesia Safety in Kids study

BACKGROUND

We hypothesised that exposure to multiple, but not single, procedures requiring general anaesthesia before age 3 yr is associated with a specific pattern of deficits in processing speed and fine motor skills.

METHODS

A secondary analysis (using factor and cluster analyses) of data from the Mayo Anesthesia Safety in Kids study was conducted, in which unexposed, singly exposed, and multiply exposed children born in Olmsted County, MN, USA from 1994 to 2007 were sampled using a propensity-guided approach and underwent neuropsychological testing at ages 8-12 or 15-20 yr.

RESULTS

In the factor analysis, the data were well fit to a five factor model. For subjects multiply (but not singly) exposed to anaesthesia, a factor reflecting motor skills, visual-motor integration, and processing speed was significantly lower [standardised difference of -0.35 (95% confidence interval {CI} -0.57 to -0.13)] compared with unexposed subjects. No other factor was associated with exposure. Three groups were identified in the cluster analysis, with 106 subjects (10.6%) in Cluster A (lowest performance in most tests), 557 (55.9%) in Cluster B, and 334 (33.5%) in Cluster C (highest performance in most tests). The odds of multiply exposed children belonging to Cluster A was 2.83 (95% CI: 1.49-5.35; P=0.001) compared with belonging to Cluster B; there was no other significant association between exposure status and cluster membership.

CONCLUSIONS

Multiple, but not single, exposures to procedures requiring general anaesthesia before age 3 yr are associated with a specific pattern of deficits in neuropsychological tests. Factors predicting which children develop the most pronounced deficits remain unknown.

Epidemiology of general anesthesia prior to age 3 in a population-based birth cohort

BACKGROUND

Utilization of general anesthesia in children has important policy, economic, and healthcare delivery implications, yet there is little information regarding the epidemiology of these procedures in the United States.

AIMS

The primary objective of this study was to describe in a geographically defined population the incidence of procedures requiring general anesthesia up to the child's third birthday, and the patient characteristics associated with receiving these procedures. A secondary objective was to determine the proportion of children in the population who meet the risk criteria promulgated by the Food and Drug Administration (FDA).

METHODS

A retrospective cohort of children born from 1994 to 2007 in Olmsted County, MN was established. Birth certificate information and receipt of general anesthesia before age 3 were collected. Proportional hazard regressions were performed to evaluate the association between characteristics of children and incidence of general anesthesia.

RESULTS

Among the 20 922 children in the cohort, 3120 (14.9%) underwent at least 1 general anesthesia before age 3. In multivariate regression, factors independently associated with receiving at least 1 procedure included prematurity, male sex, lower birth weight, cesarean delivery, a non-Hispanic mother, and a White mother, controlling for multiple gestation, number of children previously born, age, education, and marital status of the mother. Seven hundred and twenty-three children (3.5%) had at least 1 subsequent procedure. Estimated gestational age <32 weeks and low birth weight were independently associated with receiving repeated anesthesia. Eight hundred and twenty children (3.9%) had a single prolonged exposure above 3 hours, multiple exposures prior to age 3, or both.

CONCLUSION

Approximately 1 in 7 children were exposed to at least 1 episode of general anesthesia before age 3, and approximately 1 in 4 children who received general anesthesia fall within the high-risk category as defined by the recent FDA warning. The apparent disparities in surgical utilization related to race and ethnicity in this study population deserve further exploration.

Clustering and variable selection in the presence of mixed variable types and missing data

We consider the problem of model-based clustering in the presence of many correlated, mixed continuous, and discrete variables, some of which may have missing values. Discrete variables are treated with a latent continuous variable approach, and the Dirichlet process is used to construct a mixture model with an unknown number of components. Variable selection is also performed to identify the variables that are most influential for determining cluster membership. The work is motivated by the need to cluster patients thought to potentially have autism spectrum disorder on the basis of many cognitive and/or behavioral test scores. There are a modest number of patients (486) in the data set along with many (55) test score variables (many of which are discrete valued and/or missing). The goal of the work is to (1) cluster these patients into similar groups to help identify those with similar clinical presentation and (2) identify a sparse subset of tests that inform the clusters in order to eliminate unnecessary testing. The proposed approach compares very favorably with other methods via simulation of problems of this type. The results of the autism spectrum disorder analysis suggested 3 clusters to be most likely, while only 4 test scores had high (>0.5) posterior probability of being informative. This will result in much more efficient and informative testing. The need to cluster observations on the basis of many correlated, continuous/discrete variables with missing values is a common problem in the health sciences as well as in many other disciplines.

Adults With Persistent ADHD: Gender and Psychiatric Comorbidities-A Population-Based Longitudinal Study

OBJECTIVE

The aim of the study was to evaluate associations between ADHD and comorbid psychiatric disorders among adults from a population-based birth cohort.

METHOD

Participants were recruited from all children born between 1976 and 1982 remaining in Rochester, Minnesota, after age 5. Participants with childhood ADHD ( n = 232; M age = 27.0 years; 72% men) and non-ADHD controls ( n = 335; M age = 28.6 years; 63% men) completed a structured interview (M.I.N.I. International Neuropsychiatric Interview) assessing current ADHD status and comorbid psychiatric disorders.

RESULTS

Among 232 with childhood ADHD, 68 (49 men, 19 women) had persistent adult ADHD. Compared with non-ADHD controls and non-persistent ADHD participants, adults with persistent ADHD were significantly more likely to have any or each of 12 psychiatric comorbidities. The associations retained significant or marginally significant when stratified by gender. Externalizing psychiatric disorders were more common in men (74%) and internalizing disorders in women (58%).

CONCLUSION

Persistent ADHD is associated with an increased risk of comorbid psychiatric disorders in adult men and women.

Comparing Methods to Determine Persistence of Childhood ADHD Into Adulthood: A Prospective, Population-Based Study

OBJECTIVE

To compare the rate of persistence of ADHD into adulthood as determined by a norm-referenced versus non-norm-referenced diagnostic interview, and by standardized questionnaires.

METHOD

Adults from a birth cohort, including research-identified childhood ADHD cases ( N = 232; M_age = 27.0 years; 167 males, 65 females) and controls ( N = 335; M_age = 28.6 years; 210 males, 125 females), were administered the M.I.N.I. International Neuropsychiatric Interview, the Murphy-Barkley Symptoms Checklist (MB), and the Wender Utah Rating Scale (WURS) Results: Among the childhood ADHD cases, 29.3% fulfilled criteria for adult ADHD using a norm-referenced approach to M.I.N.I. scoring, versus 13.8% using published M.I.N.I. criteria. Among participants meeting norm-referenced diagnostic criteria, 41.8% and 69.1% were classified as adult ADHD using the MB and WURS, respectively.

CONCLUSION

A non-norm-referenced approach resulted in a significant underestimate of the rate of adult ADHD. Reliance on either of two adult ADHD questionnaires would have further reduced this estimate.

What can large population-based birth cohort study ask about past, present and future of children with disorders of development, learning and behaviour?

A large cohort consisting of all children born to mothers from community provides 'natural' selection into different exposures and is a powerful resource for epidemiological research. A large population-based birth cohort with detailed systematic information already recorded, as part of longitudinal medical care, historical and current school data, detailed birth certificate data and all three resources available for every member of the birth cohort, are extremely rare. Our population-based birth cohort consists of all children born between 1976 and 2000 to mothers residing in Olmsted County, Minnesota, at the time of child's birth (N=39 890). In this paper, we provide a comprehensive report of the method describing the identification, the characteristics and longitudinal follow-up of each child (and family members) from the birth cohort, wealth of complementary resources of data and study measures and designs (retrospective, combined retrospective/prospective). In the last decade or so, we obtained scientific and clinically needed answers for incidence rates, potential risk/protective factors, treatment, comorbidities, outcomes, cost/usage and potential biases (that are always assessed and clinically interpreted) of many developmental learning and behavioural disorders (DLBDs) including learning and attention-deficit/hyperactivity disorders, intellectual disability, speech-language impairment and autism spectrum disorder. Many current and future questions related to DLBDs are remaining to be answered. The Olmsted County Birth Cohort (OCBC) is an example of a comprehensive, contemporary epidemiological research model for the development of similar research infrastructures, and its current and future results are important for replication and comparison with other population-based retrospective and prospective birth cohort studies.

Epidemiology of Pediatric Critical Illness in a Population-Based Birth Cohort in Olmsted County, MN

OBJECTIVES

Investigations of pediatric critical illness typically focus on inpatient cohorts drawn from wide referral areas and diverse healthcare systems. Cohorts amenable to investigating the full spectrum of critical illness as it develops within a community have yet to be studied in the United States. Our objective was to provide the first epidemiologic report of the incidence and presentation of pediatric critical illness within a U.S. population-based birth cohort.

DESIGN

Retrospective cohort study.

SETTING

A geographically defined community (Olmsted, MN) with medical record linkage across all health systems. All ICU services are provided within a single children's hospital.

PATIENTS

A birth cohort of children (n =9,441) born 2003-2007 in Olmsted County, MN.

MEASUREMENTS AND MAIN RESULTS

During the study period, there were a total of 15,277 ICU admissions to Mayo Clinic Children's Hospital. A total of 577 birth cohort children accounted for 824 of these admissions during the 61,770 person-years of follow-up accumulated. Incidence of first-time ICU admission was 9.3 admits per 1,000 person-years. Admission rates were highest in the first year of life and then declined steadily. Respiratory problems were among the most common reasons for admission at any age and diagnoses reflect changes in health risk factors as children grow and develop over time. After 1 year old, a majority of children admitted have preexisting chronic comorbidities and/or prior ICU stays. In-hospital mortality occurred exclusively in children admitted prior to 5 days of age (n = 4). Seven children died after hospital discharge.

CONCLUSIONS

This is the first report characterizing critical illness within a population-based birth cohort of U.S. children. The results demonstrate the changing incidence, presentation, and healthcare requirements associated with critical illness across the developmental spectrum as a population of children ages.

Mediating and Moderating Role of Depression, Conduct Disorder or Attention-Deficit/Hyperactivity Disorder in Developing Adolescent Substance Use Disorders: A Population-Based Study

Objective

To evaluate the mediating/moderating effects of common internalizing /externalizing disorders on the association between ADHD and adolescent substance use disorders (SUD) in a population-based birth cohort.

Methods

Among 5718 children in the birth cohort, 343 ADHD incident cases and 712 matched controls were identified. Psychiatric diagnoses prior to age 19 were classified into DSM-IV categories. The association between ADHD and SUD was summarized (hazard ratios (HR), 95% CI). The effect of depression, CD/ODD, anxiety was evaluated separately.

Results

Assessment of the joint effects of ADHD and each psychiatric disorder did not support a moderating effect of these disorders on SUD on additive scale. However, the association between ADHD and SUD was partially explained by a mediating role of these psychiatric disorders.

Conclusion

For clinicians our results emphasize that depression (or CD/ODD) confers greater risk for SUD than ADHD alone. Early detection/treatment of SUD among adolescents with depression (or CD/ODD) is crucial regardless of ADHD.

Construction and Characterization of a Population-Based Cohort to Study the Association of Anesthesia Exposure with Neurodevelopmental Outcomes

Exposure to general anesthesia at an early age has been associated with adverse neurodevelopmental outcomes in both animal and human studies, but some of these studies employed anesthetic agents that are no longer in clinical use. In this manuscript, we describe the methods used to construct a new population-based study cohort to study the association between early anesthetic exposure and subsequent neurodevelopmental outcomes. A birth cohort of all children born in Olmsted County, MN from January 1, 1996 to December 31, 2000 was identified. For each, school enrollment status in the Independent School District (ISD) 535 at age 5 or 6 and all episodes of anesthetic exposure before age 3 were identified. A study cohort was created by matching children enrolled in ISD 535 based on the propensity of receiving general anesthesia. Three analyses were performed to characterize the study cohort by comparing the birth and parental information, comorbidities, and socioeconomic status. The first analysis compared the characteristics of birth cohort children who were and were not enrolled in ISD 535. The second analysis evaluated the success of the propensity matching schemes in creating groups of children that were similar in measured characteristics except for anesthesia exposure. The third analysis compared the characteristics of children with anesthesia exposures who were and were not included in the final cohort based on propensity matching. Results of these analyses demonstrate only slight differences among the comparison groups, and therefore these are unlikely to compromise our future analysis of anesthetic exposure and neurodevelopmental outcomes.

Childhood Attention-Deficit/Hyperactivity Disorder, Sex, and Obesity: A Longitudinal Population-Based Study

OBJECTIVE

To assess obesity rates during childhood and young adulthood in patients with attention-deficit/hyperactivity disorder (ADHD) and age- and sex-matched controls derived from a population-based birth cohort because cross-sectional studies suggest an association between ADHD and obesity.

PATIENTS AND METHODS

Study subjects included patients with childhood ADHD (n=336) and age- and sex-matched non-ADHD controls (n=665) from a 1976 to 1982 birth cohort (N=5718). Height, weight, and stimulant treatment measurements were abstracted retrospectively from medical records documenting care provided from January 1, 1976, through August 31, 2010. The association between ADHD and obesity in patients with ADHD relative to controls was estimated using Cox models.

RESULTS

Patients with attention-deficit/hyperactivity disorder were 1.23 (95% CI, 1.00-1.50; P<.05) times more likely to be obese during the follow-up period than were non-ADHD controls. This association was not statistically significant in either sex (female participants: hazard ratio [HR], 1.49; 95% CI, 0.98-2.27; P=.06; male participants HR, 1.17, 95% CI, 0.92-1.48; P=.20). Patients with ADHD who were not obese as of the date ADHD research diagnostic criteria were met were 1.56 (95% CI, 1.14-2.13; P<.01) times more likely to be obese during the subsequent follow-up than were controls. This association was statistically significant in female study subjects (HR, 2.02; 95% CI, 1.13-3.60; P=.02), but not in male participants (HR, 1.41; 95% CI, 0.97-2.05; P=.07). A higher proportion of patients with ADHD were obese after the age of 20 years compared with non-ADHD controls (34.4% vs 25.1%; P=.01); this difference was observed only in female patients (41.6% vs 19.2%). There were no differences in obesity rates between stimulant-treated and nontreated patients with ADHD.

CONCLUSION

Childhood ADHD is associated with obesity during childhood and young adulthood in females. Treatment with stimulant medications is not associated with the development of obesity up to young adulthood.

Risk of Asthma in Late Preterm Infants: A Propensity Score Approach

BACKGROUND

The risk of asthma, specifically in former late preterm infants, has not been well defined. Covariate imbalance and lack of controlling for this has led to inconsistent results in prior studies.

OBJECTIVE

The objective of this study was to determine the risk of asthma in former late preterm infants using a propensity score approach.

METHODS

The study was a population-based birth cohort study. Study subjects were all children born in Rochester, Minn, between 1976 and 1982. Asthma status during the first 7 years of life was assessed by applying predetermined criteria. The propensity score was formulated using 15 covariates by fitting a logistic regression model for late preterm birth versus term birth. We applied the propensity score method to match late preterm infants (34 0/7 to 36 6/7 weeks of gestation) to term infants (37 0/7 to 40 6/7 weeks of gestation) within a caliper of 0.2 standard deviation of logit of propensity score.

RESULTS

Of the eligible 7040 infants, 5915 children had complete data. Before propensity score matching, late preterm infants had a higher risk of asthma (20 of 262, 7.6%) compared with full-term infants (272 of 5653, 4.8%) (P = .039). There was significant covariate imbalance between comparison groups. After matching with propensity scores, we found that former late preterm infants had a similar risk of asthma to the matched full-term infants (6.6% vs 7.7%, respectively, P = .61), and the result was consistent with covariate-adjustment Cox regression models controlling for significant covariates (P = .57).

CONCLUSION

A late preterm birth history is not independently associated with childhood asthma, as the reported risk of asthma among former late preterm infants appears to be due to covariate imbalance.

Neurodevelopment of children exposed to anesthesia: design of the Mayo Anesthesia Safety in Kids (MASK) study

There is increasing evidence that exposure of developing brains in animals, including nonhuman primates, to commonly-utilized anesthetic agents may cause adverse effects on cognition and behavior. In this paper, we summarize our methodology for a population-based, propensity-matched study to evaluate possible anesthesia-related sequelae in preschool children when evaluated in elementary or high school. A cohort of all children born in Olmsted County, Minnesota between the years 1994 and 2007 who are currently local residents has been identified. Existing medical records are being used to identify all episodes of exposure to general anesthesia prior to the age of 3 years (i.e., prior to their 3rd birthday). Children with multiple, single, and no anesthesia exposure are sampled for testing between the ages of 8 and 12 years or 15 and 19 years during the period 2012-2016. To match children in different exposure groups as closely as possible, sampling is guided by propensity-matching for the likelihood of receiving anesthesia. Selected children are invited to participate in a single 4-hour session of neuropsychological testing, including the National Center for Toxicological Research-Operant Test Battery, which has been used to study anesthetic neurotoxicity in nonhuman primates. The results of this testing will be compared among children with different anesthetic exposure histories. The expected products of this research will be a detailed phenotype of possible anesthetic-associated neurotoxicity in humans, utilizing a robust patient database and neuropsychological testing battery, and the first comparison of effects of anesthetic exposure in children and nonhuman primates performing nearly identical behavioral tasks.

ADHD, stimulant treatment, and growth: a longitudinal study

BACKGROUND AND OBJECTIVE

There is ongoing concern that stimulant medications may adversely affect growth. In a sample of attention-deficit/hyperactivity disorder (ADHD) cases and controls from a population-based birth cohort, we assessed growth and the association between stimulant treatment and growth.

METHODS

Subjects included childhood ADHD cases (N = 340) and controls (N = 680) from a 1976 to 1982 birth cohort (N = 5718). Height and stimulant treatment information were abstracted from medical records and obtained during a prospective, adult follow-up study. For each subject, a parametric penalized spline smoothing method modeled height over time, and the corresponding height velocity was calculated as the first derivative. Peak height velocity (PHV) age and magnitude were estimated from the velocity curves. Among stimulant-treated ADHD cases, we analyzed height Z scores at the beginning, at the end, and 24 months after the end of treatment.

RESULTS

Neither ADHD itself nor treatment with stimulants was associated with differences in magnitude of PHV or final adult height. Among boys treated with stimulants, there was a positive correlation between duration of stimulant usage before PHV and age at PHV (r = 0.21, P = .01). There was no significant correlation between duration of treatment and change in height Z scores (r = -0.08 for beginning vs end change, r = 0.01 for end vs 24 months later change). Among the 59 ADHD cases treated for ≥3 years, there was a clinically insignificant decrease in mean Z score from beginning (0.48) to end (0.33) of treatment (P = .06).

CONCLUSIONS

Our findings suggest that ADHD treatment with stimulant medication is not associated with differences in adult height or significant changes in growth.

Childhood ADHD and risk for substance dependence in adulthood: a longitudinal, population-based study

Background

Adolescents with attention-deficit/hyperactivity disorder (ADHD) are known to be at significantly greater risk for the development of substance use disorders (SUD) compared to peers. Impulsivity, which could lead to higher levels of drug use, is a known symptom of ADHD and likely accounts, in part, for this relationship. Other factors, such as a biologically increased susceptibility to substance dependence (addiction), may also play a role.

Objective

This report further examines the relationships between childhood ADHD, adolescent- onset SUD, and substance abuse and substance dependence in adulthood.

Method

Individuals with childhood ADHD and non-ADHD controls from the same population-based birth cohort were invited to participate in a prospective outcome study. Participants completed a structured neuropsychiatric interview with modules for SUD and a psychosocial questionnaire. Information on adolescent SUD was obtained retrospectively, in a previous study, from medical and school records. Associations were summarized using odds ratios (OR) and 95% CIs estimated from logistic regression models adjusted for age and gender.

Results

A total of 232 ADHD cases and 335 non-ADHD controls participated (mean age, 27.0 and 28.6 years, respectively). ADHD cases were more likely than controls to have a SUD diagnosed in adolescence and were more likely to have alcohol (adjusted OR 14.38, 95% CI 1.49–138.88) and drug (adjusted OR 3.48, 95% CI 1.38–8.79) dependence in adulthood. The subgroup of participating ADHD cases who did not have SUD during adolescence were no more likely than controls to develop new onset alcohol dependence as adults, although they were significantly more likely to develop new onset drug dependence.

Conclusions

Our study found preliminary evidence that adults with childhood ADHD are more susceptible than peers to developing drug dependence, a disorder associated with neurological changes in the brain. The relationship between ADHD and alcohol dependence appears to be more complex.

ADHD and learning disabilities in former late preterm infants: a population-based birth cohort

BACKGROUND AND OBJECTIVE

Previous studies suggest that former late preterm infants are at increased risk for learning and behavioral problems compared with term infants. These studies have primarily used referred clinical samples of children followed only until early school age. Our objective was to determine the cumulative incidence of attention deficit/hyperactivity disorder (ADHD) and learning disabilities (LD) in former late preterm versus term infants in a population-based birth cohort.

METHODS

Subjects included all children born 1976 to 1982 in Rochester, MN who remained in the community after 5 years. This study focused on the comparison of subjects in 2 subgroups, late preterm (34 to <37 weeks) and term (37 to <42 weeks). School and medical records were available to identify individuals who met research criteria for ADHD and LD in reading, written language, and math. The Kaplan-Meier method was used to estimate the cumulative incidence of each condition by 19 years of age. Cox models were fit to evaluate the association between gestational age group and condition, after adjusting for maternal education and perinatal complications.

RESULTS

We found no statistically significant differences in the cumulative incidence of ADHD or LD between the late preterm (N = 256) versus term (N = 4419) groups: ADHD (cumulative incidence by age 19 years, 7.7% vs 7.2%; P = .84); reading LD (14.2% vs 13.1%; P = .57); written language LD (13.5% vs 15.7%; P = .36), and math LD (16.1% vs 15.5%; P = .89).

CONCLUSIONS

These data from a population-based birth cohort indicate that former late preterm infants have similar rates of LD and ADHD as term infants.

Incidence of enuresis and encopresis among children with attention-deficit/hyperactivity disorder in a population-based birth cohort

OBJECTIVE

This study reports the incidence of enuresis and encopresis among children with attention-deficit/hyperactivity disorder (ADHD) versus those without ADHD.

METHODS

Subjects included 358 children (74.5% boys) with research-identified ADHD from a 1976 to 1982 population-based birth cohort (n = 5718) and 729 (75.2% boys) non-ADHD control subjects from the same birth cohort, matched by gender and age. All subjects were retrospectively followed from birth until a diagnosis of enuresis or encopresis was made or last follow-up before 18 years of age. The complete medical record for each subject was reviewed to obtain information on age of initial diagnosis of an elimination disorder, frequency and duration of symptoms, and identification of exclusionary criteria specified by DSM-IV, with confirmation of the diagnosis by expert consensus.

RESULTS

Children with ADHD were 2.1 (95% confidence interval [CI], 1.3-3.4; P = .002) times more likely to meet DSM-IV criteria for enuresis than non-ADHD controls; they were 1.8 (95% CI, 1.2-2.7; P = .006) times more likely to do so than non-ADHD controls when less stringent criteria for a diagnosis of enuresis were employed. Though not significant, children with ADHD were 1.8 (95% CI, 0.7-4.6; P = .23) times more likely to meet criteria for encopresis than non-ADHD controls. The relative risk was 2.0 (95% CI, 1.0-4.1; P = .05) when a less stringent definition for encopresis was utilized.

CONCLUSIONS

Children with ADHD are more likely than their peers without ADHD to develop enuresis with a similar trend for encopresis.

Mortality, ADHD, and psychosocial adversity in adults with childhood ADHD: a prospective study

OBJECTIVE

We examined long-term outcomes of attention-deficit/hyperactivity disorder (ADHD) in a population-based sample of childhood ADHD cases and controls, prospectively assessed as adults.

METHODS

Adults with childhood ADHD and non-ADHD controls from the same birth cohort (N = 5718) were invited to participate in a prospective outcome study. Vital status was determined for birth cohort members. Standardized mortality ratios (SMRs) were constructed to compare overall and cause-specific mortality between childhood ADHD cases and controls. Incarceration status was determined for childhood ADHD cases. A standardized neuropsychiatric interview was administered.

RESULTS

Vital status for 367 childhood ADHD cases was determined: 7 (1.9%) were deceased, and 10 (2.7%) were currently incarcerated. The SMR for overall survival of childhood ADHD cases versus controls was 1.88 (95% confidence interval [CI], 0.83-4.26; P = .13) and for accidents only was 1.70 (95% CI, 0.49-5.97; P = .41). However, the cause-specific mortality for suicide only was significantly higher among ADHD cases (SMR, 4.83; 95% CI, 1.14-20.46; P = .032). Among the childhood ADHD cases participating in the prospective assessment (N = 232; mean age, 27.0 years), ADHD persisted into adulthood for 29.3% (95% CI, 23.5-35.2). Participating childhood ADHD cases were more likely than controls (N = 335; mean age, 28.6 years) to have ≥1 other psychiatric disorder (56.9% vs 34.9%; odds ratio, 2.6; 95% CI, 1.8-3.8; P < .01).

CONCLUSIONS

Childhood ADHD is a chronic health problem, with significant risk for mortality, persistence of ADHD, and long-term morbidity in adulthood.

Early speech-language impairment and risk for written language disorder: a population-based study

OBJECTIVE

To compare risk of written language disorder (WLD) in children with and without speech-language impairment (S/LI) from a population-based cohort.

METHODS

Subjects included all children born between 1976 and 1982 in Rochester, Minnesota, who remained in the community after age 5 years (n = 5718). Records from public and private schools, medical agencies, and tutoring services were abstracted. S/LI was determined based on eligibility criteria for an individualized education plan. Incident cases of WLD were identified by research criteria using regression-based discrepancy, non-regression-based discrepancy, and low-achievement formulas applied to cognitive and academic achievement tests. Incidence of WLD (with or without reading disorder [RD]) was compared between children with and without S/LI. Associations were summarized using hazard ratios.

RESULTS

Cumulative incidence of WLD by age 19 years was significantly higher in children with S/LI than in children without S/LI. The magnitude of association between S/LI and WLD with RD was significantly higher for girls than for boys. This was not true for the association between S/LI and WLD without RD.

CONCLUSIONS

Risk for WLD is significantly increased among children with S/LI compared with children without S/LI based on this population-based cohort. Early identification and intervention for children at risk for WLD could potentially influence academic outcomes.

Childhood ADHD is strongly associated with a broad range of psychiatric disorders during adolescence: a population-based birth cohort study

BACKGROUND

To evaluate associations between attention-deficit/hyperactivity disorder (ADHD) and comorbid psychiatric disorders using research-identified incident cases of ADHD and population-based controls.

METHODS

Subjects included a birth cohort of all children born 1976-1982 remaining in Rochester, MN after age five (n = 5,718). Among them we identified 379 ADHD incident cases and 758 age-gender matched non-ADHD controls, passively followed to age 19 years. All psychiatric diagnoses were identified and abstracted, but only those confirmed by qualified medical professionals were included in the analysis. For each psychiatric disorder, cumulative incidence rates for subjects with and without ADHD were estimated using the Kaplan-Meier method. Corresponding hazard ratios (HR) were estimated using Cox models adjusted for gender and mother's age and education at the subject's birth. The association between ADHD and the likelihood of having an internalizing or externalizing disorder was summarized by estimating odds ratios (OR).

RESULTS

Attention-deficit/hyperactivity disorder was associated with a significantly increased risk of adjustment disorders (HR = 3.88), conduct/oppositional defiant disorder (HR = 9.54), mood disorders (HR = 3.67), anxiety disorders (HR = 2.94), tic disorders (HR = 6.53), eating disorders (HR = 5.68), personality disorders (HR = 5.80), and substance-related disorders (HR = 4.03). When psychiatric comorbidities were classified on the internalization-externalization dimension, ADHD was strongly associated with coexisting internalizing/externalizing (OR = 10.6), or externalizing-only (OR = 10.0) disorders.

CONCLUSION

This population-based study confirms that children with ADHD are at significantly increased risk for a wide range of psychiatric disorders. Besides treating the ADHD, clinicians should identify and provide appropriate treatment for psychiatric comorbidities.

Evaluation of the ability of neurobiological, neurodevelopmental and socio-economic variables to predict cognitive outcome in premature infants

BACKGROUND

When developed in the 1990s, the Neurobiologic Risk Score (NBRS) and Neurodevelopmental Risk Exam (NRE) correlated well with developmental outcomes in premature infants. Given recent advances in neonatology, we assessed their present ability to predict cognitive outcome, alone and combined with socio-economic factors.

METHODS

One hundred and twenty-nine neonates <32 weeks gestational age were assessed at 6, 12 and/or 24 months corrected age with the Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS). Indices of socio-economic status included maternal education and marital status.

RESULTS

At 24 months corrected age (n= 67), the NBRS (r=-0.5), maternal education (r= 0.46) and marital status (r= 0.37) correlated with the CAT/CLAMS. These correlations increased when NBRS and maternal education were combined (r= 0.63) and when specific NBRS components (intraventricular haemorrhage, periventricular leukomalacia, seizures) and maternal education were combined (r= 0.66).

CONCLUSIONS

In the contemporary neonatal intensive care unit, measures used to predict cognitive outcome should incorporate both neurobiological risk factors and socio-economic variables.

Attention-deficit/hyperactivity disorder after early exposure to procedures requiring general anesthesia

OBJECTIVE

To study the association between exposure to procedures performed under general anesthesia before age 2 years and development of attention-deficit/hyperactivity disorder (ADHD).

PATIENTS AND METHODS

Study patients included all children born between January 1, 1976, and December 31, 1982, in Rochester, MN, who remained in Rochester after age 5. Cases of ADHD diagnosed before age 19 years were identified by applying stringent research criteria. Cox proportional hazards regression assessed exposure to procedures requiring general anesthesia (none, 1, 2 or more) as a predictor of ADHD using a stratified analysis with strata based on a propensity score including comorbid health conditions.

RESULTS

Among the 5357 children analyzed, 341 ADHD cases were identified (estimated cumulative incidence, 7.6%; 95% confidence interval [CI], 6.8%-8.4%). For children with no postnatal exposure to procedures requiring anesthesia before the age of 2 years, the cumulative incidence of ADHD at age 19 years was 7.3% (95% CI, 6.5%-8.1%). For single and 2 or more exposures, the estimates were 10.7% ( 95% CI, 6.8%-14.4%) and 17.9% ( 95% CI, 7.2%-27.4%), respectively. After adjusting for gestational age, sex, birth weight, and comorbid health conditions, exposure to multiple (hazard ratio, 1.95; 95% CI, 1.03-3.71), but not single (hazard ratio,1.18; 95% CI, 0.79-1.77), procedures requiring general anesthesia was associated with an increased risk for ADHD.

CONCLUSION

Children repeatedly exposed to procedures requiring general anesthesia before age 2 years are at increased risk for the later development of ADHD even after adjusting for comorbidities.

Cognitive and behavioral outcomes after early exposure to anesthesia and surgery

BACKGROUND

Annually, millions of children are exposed to anesthetic agents that cause apoptotic neurodegeneration in immature animals. To explore the possible significance of these findings in children, we investigated the association between exposure to anesthesia and subsequent (1) learning disabilities (LDs), (2) receipt of an individualized education program for an emotional/behavior disorder (IEP-EBD), and (3) scores of group-administered achievement tests.

METHODS

This was a matched cohort study in which children (N = 8548) born between January 1, 1976, and December 31, 1982, in Rochester, Minnesota, were the source of cases and controls. Those exposed to anesthesia (n = 350) before the age of 2 were matched to unexposed controls (n = 700) on the basis of known risk factors for LDs. Multivariable analysis adjusted for the burden of illness, and outcomes including LDs, receipt of an IEP-EBD, and the results of group-administered tests of cognition and achievement were outcomes.

RESULTS

Exposure to multiple, but not single, anesthetic/surgery significantly increased the risk of developing LDs (hazard ratio: 2.12 [95% confidence interval: 1.26-3.54]), even when accounting for health status. A similar pattern was observed for decrements in group-administered tests of achievement and cognition. However, exposure did not affect the rate of children receiving an individualized education program.

CONCLUSIONS

Repeated exposure to anesthesia and surgery before the age of 2 was a significant independent risk factor for the later development of LDs but not the need for educational interventions related to emotion/behavior. We cannot exclude the possibility that multiple exposures to anesthesia/surgery at an early age may adversely affect human neurodevelopment with lasting consequence.

Written-language disorder among children with and without ADHD in a population-based birth cohort

OBJECTIVE

We determined the incidence of written-language disorder (WLD) among children with and without attention-deficit/hyperactivity disorder (ADHD) in a population-based birth cohort.

METHODS

Subjects included a birth cohort of all children born in 1976-1982 who remained in Rochester, Minnesota, after 5 years of age (N = 5718). Information from medical, school, and private tutorial records was abstracted. Cumulative incidences of WLD with or without reading disability (RD), identified with any of 3 formulas, among children with and without ADHD and hazard ratios (HRs) were calculated.

RESULTS

For both genders, the cumulative incidence of WLD by 19 years of age was significantly higher for children with ADHD than for children without ADHD (boys: 64.5% vs 16.5%; girls: 57.0% vs 9.4%). The magnitude of association between ADHD and WLD with RD was significantly higher for girls than for boys (adjusted HR: girls: 9.8; boys: 4.2; P < .001). However, this was not true for WLD without RD (adjusted HR: girls: 7.4; boys: 6.6; P = .64).

CONCLUSIONS

ADHD is strongly associated with an increased risk of WLD (with or without RD) for both boys and girls. Girls with ADHD are at higher risk of having WLD with RD compared with boys with ADHD, whereas boys and girls are at the same risk of having WLD without RD.

Is excess folic acid supplementation a risk factor for autism?

BACKGROUND

The objective was to assess the association between increasing autism incidence rates and the increasing dose of folic acid in prescription prenatal and pediatric vitamins.

METHODS

We used published autism incidence rates from the Rochester Epidemiological Project in Rochester, MN, for 1976-1997. Additionally, we used the percent of prescription prenatal vitamins containing 1mg folic acid and the percent of prescription pediatric vitamins with any folic acid from Physicians' Desk References for roughly the same time period.

RESULTS

The Pearson product moment correlation coefficient (r) for the association between the percentage of prescription prenatal vitamins containing 1mg folic acid and research-identified autism incidence in Olmsted County was 0.87 [95% confidence interval (CI)=0.19-0.99]. In contrast, there was a weak association between pediatric vitamins containing any folic acid and autism incidence using the same statistical method (r=0.62, 95% CI=-0.38-0.95).

CONCLUSIONS

If it is true that too little folic acid results in nervous tissue damage, as is accepted by the scientific community in regard to neural tube defects (NTDs), then it seems plausible that too much folic acid may result in nervous tissue damage associated with autism. Although the correlations described here do not provide proof of causation, these data provide an impetus for further study. Children who develop autism may be receiving a massive dose of folic acid in utero, as well as, after birth. It would be of interest to carry out a case-control study using medical record data to document folic acid intake for pregnant women whose offspring were later diagnosed with autism and controls.

Longitudinal direct medical costs associated with constipation in women

BACKGROUND

Although direct medical costs for constipation-related medical visits are thought to be high, to date, there have been no studies examining longitudinal resource utilisation in adults with constipation.

AIM

To estimate the incremental direct medical costs associated with constipation in women.

METHODS

This is a nested case-control study. The study population consisted of all mothers of 5718 children in the population-based birth cohort born during 1976-1982 in a community. The cases presented to the medical facilities with constipation. The controls were randomly selected and matched to cases in a 2:1 ratio. Direct medical costs for constipated women and controls were collected for the years 1987-2002.

RESULTS

We identified 168 women with a diagnosis of constipation. The total direct medical costs over the 15-year period for constipated subjects were more than double those of controls [$63 591 (95% CI: 49 786-81 396) vs. $24 529 (95% CI: 20 667-29 260)]. The overall out-patient costs for constipated women were $38 897 (95% CI: 31 381-48 253) compared to $15 110 (95% CI: 12 904-17 781) for controls. The median of annual out-patient visits for constipated women was 0.16 compared to 0.11 for controls.

CONCLUSION

Women with constipation have significantly higher medical care utilisation and expenditures compared with women without constipation.

Gender, attention-deficit/hyperactivity disorder, and reading disability in a population-based birth cohort

OBJECTIVE

To determine the incidence of reading disability (RD) among children with and without research-identified attention-deficit/hyperactivity disorder (ADHD), separately according to gender, in a population-based birth cohort.

METHOD

Subjects included all children born in 1976-1982 remaining in Rochester, Minnesota, after 5 years of age (n=5718). Information from medical, school, and private tutorial records was abstracted. Cumulative incidence of RD, by any of 3 RD formulas, in children with and without ADHD and corresponding hazard ratios (HRs) were calculated separately according to gender.

RESULTS

Cumulative incidence of RD by the age of 19 years was significantly higher in children with ADHD (51% in boys, 46.7% in girls) compared with those without ADHD (14.5% in boys, 7.7% in girls). Among children with ADHD, the risk for RD was similar in boys versus girls (HR: 1.0). However, among children without ADHD, boys were 2.0 times more likely than girls to meet RD criteria. Among girls, the HR for the risk for RD associated with ADHD (versus those without ADHD) was 8.1 (95% confidence interval: 5.7-11.5), which was significantly higher than the corresponding HR among boys (3.9 [95% confidence interval: 3.2-4.9]).

CONCLUSIONS

The risk for RD is significantly greater among children with ADHD compared with those without ADHD. Among children with ADHD, the risk for RD is the same for boys and girls. However, among children without ADHD, boys are more at risk for RD than girls. Among girls, the magnitude of increased risk for RD associated with ADHD is nearly twice that among boys, because girls without ADHD are less likely to have RD than boys without ADHD.

Neuraxial labor analgesia for vaginal delivery and its effects on childhood learning disabilities

BACKGROUND

In prior work, children born to mothers who received neuraxial anesthesia for cesarean delivery had a lower incidence of subsequent learning disabilities compared with vaginal delivery. The authors speculated that neuraxial anesthesia may reduce stress responses to delivery, which could affect subsequent neurodevelopmental outcomes. To further explore this possibility, we examined the association between the use of neuraxial labor analgesia and development of childhood learning disabilities in a population-based birth cohort of children delivered vaginally.

METHODS

The educational and medical records of all children born to mothers residing in the area of 5 townships of Olmsted County, Minnesota from 1976 to 1982 and remaining in the community at age 5 years were reviewed to identify those with learning disabilities. Cox proportional hazards regression was used to compare the incidence of learning disabilities between children delivered vaginally with and without neuraxial labor analgesia, including analyses adjusted for factors of either potential clinical relevance or that differed between the 2 groups in univariate analysis.

RESULTS

Of the study cohort, 4684 mothers delivered children vaginally, with 1495 receiving neuraxial labor analgesia. The presence of childhood learning disabilities in the cohort was not associated with use of labor neuraxial analgesia (adjusted hazard ratio, 1.05; 95%confidence interval, 0.85-1.31; P = 0.63).

CONCLUSION

The use of neuraxial analgesia during labor and vaginal delivery was not independently associated with learning disabilities diagnosed before age 19 years. Future studies are needed to evaluate potential mechanisms of the previous finding indicating that the incidence of learning disabilities is lower in children born to mothers via cesarean delivery under neuraxial anesthesia compared with vaginal delivery.

Epilepsy in children with attention-deficit/hyperactivity disorder

Previous studies have suggested a higher incidence of symptoms of attention-deficit/hyperactivity disorder (ADHD) in children with epilepsy, but few have investigated epilepsy in children with ADHD. The objective here was to compare the incidence and characteristics of epilepsy among population-based, research identified cohorts of children with (n = 358) and without ADHD (n = 728), based on medical record review to age 20 years. Data abstracted included characteristics of seizures, testing, and treatment. Cases were 2.7 times more likely than controls to have epilepsy (95% CI = 0.94-7.76; P = 0.066), had earlier seizure onset (median age, 5.5 vs 15 years; P = 0.020), and exhibited a trend toward more frequent seizures (more than monthly, 63% vs 17%). Among children who met the research criteria for ADHD, those with epilepsy tended to be less likely to have received a clinical diagnosis of ADHD (63% vs 89%; P = 0.052) or to be treated with stimulants (50% vs 85%; P = 0.025). The findings suggest a strong trend toward a higher incidence of epilepsy among children with ADHD than among children without ADHD. Epilepsy in children with ADHD appears to be more severe than in those without. Finally, there appears to be a reluctance to diagnose and initiate treatment for ADHD in children with epilepsy.

Incidence of gastrointestinal symptoms in children with autism: a population-based study

OBJECTIVE

To determine whether children with autism have an increased incidence of gastrointestinal symptoms compared with matched control subjects in a population-based sample.

DESIGN/METHODS

In a previous study including all of the residents of Olmsted County, Minnesota, aged <21 years between 1976 and 1997, we identified 124 children who fulfilled criteria on the basis of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, for a research diagnosis of autism. Two matched control subjects were identified for each case subject. Through the Rochester Epidemiology Project, all medical diagnoses, are indexed for computerized retrieval. Gastrointestinal diagnoses before 21 years of age were grouped into 5 categories: (1) constipation; (2) diarrhea; (3) abdominal bloating, discomfort, or irritability; (4) gastroesophageal reflux or vomiting; and (5) feeding issues or food selectivity. The cumulative incidence of each category was calculated by using the Kaplan-Meier method. Cox proportional hazards models were fit to estimate the risk ratios (case subjects versus control subjects) and corresponding 95% confidence intervals.

RESULTS

Subjects were followed to median ages of 18.2 (case subjects) and 18.7 (control subjects) years. Significant differences between autism case and control subjects were identified in the cumulative incidence of constipation (33.9% vs 17.6%) and feeding issues/food selectivity (24.5% vs 16.1). No significant associations were found between autism case status and overall incidence of gastrointestinal symptoms or any other gastrointestinal symptom category.

CONCLUSIONS

As constipation and feeding issues/food selectivity often have a behavioral etiology, data suggest that a neurobehavioral rather than a primary organic gastrointestinal etiology may account for the higher incidence of these gastrointestinal symptoms in children with autism.

The forgotten learning disability: epidemiology of written-language disorder in a population-based birth cohort (1976-1982), Rochester, Minnesota

OBJECTIVE

The aim of this study was to report the incidence rates and other epidemiologic characterizations of written-language disorder. There have been no epidemiologic studies on the incidence of written-language disorder in the United States, and the use of a population-based birth cohort, longitudinally followed, is the most powerful method for reaching this objective.

METHODS

In this population-based, retrospective birth cohort study, subjects included 5718 children born between 1976 and 1982 in Rochester, Minnesota, who remained in the community after 5 years of age. Records from all public and nonpublic schools, medical facilities, and private tutorial services were reviewed and results of all individually administered IQ and achievement tests, and extensive medical, educational, and socioeconomic information, were collected. The essential features of writing problems from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision were included in our operationalized definition of written-language disorder. Written-language disorder incident cases were established by using research criteria based on 3 formulas (regression-based discrepancy, nonregression-based discrepancy, and low achievement).

RESULTS

Cumulative incidence rates of written-language disorder varied from 6.9% to 14.7% depending on the formula. Boys were 2 to 3 times more likely to be affected than girls regardless of the formula. Among all written-language disorder cases (N = 806), 25% (n = 203) had written-language disorder without a reading disability. Specifics of the writing problems were identified for 87% (n = 702) of written-language disorder cases.

CONCLUSIONS

In this population-based birth cohort of school-aged children, written-language disorder was at least as frequent as reading disabilities and significantly more frequent among boys than girls.

The incidence of clinically diagnosed versus research-identified autism in Olmsted County, Minnesota, 1976-1997: results from a retrospective, population-based study

Autism prevalence studies have often relied on administrative prevalence or clinical diagnosis as case-identification strategies. We report the incidence of clinical diagnoses of autism spectrum disorders (ASD), versus research-identified autism among residents of Olmsted County, Minnesota, age < or =21 years, from 1976-1997. The incidence of clinically diagnosed ASD (with 95% CI) was 1.5 per 100,000 (0.0-3.7) in 1980-1983 and 33.1 (22.8-43.3) in 1995-1997, a 22.1-fold increase. In contrast, the incidence of research-identified autism increased from 5.5 (1.4-9.5) per 100,000 to 44.9 (32.9-56.9), an 8.2-fold increase. Only 46.8% of research-identified cases received a clinical diagnosis of ASD. These findings demonstrate the potential for misleading interpretation of results from epidemiologic studies that rely on clinical diagnosis of autism to identify cases.

Prevalence, recognition, and treatment of attention-deficit/hyperactivity disorder in a national sample of US children

OBJECTIVE

To determine the US national prevalence of attention-deficit/hyperactivity disorder (ADHD) and whether prevalence, recognition, and treatment vary by socioeconomic group.

DESIGN

Cross-sectional survey.

SETTING

Nationally representative sample of the US population from 2001 to 2004.

PARTICIPANTS

Eight- to 15-year-old children (N = 3082) in the National Health and Nutrition Examination Survey.

MAIN OUTCOME MEASURES

The Diagnostic Interview Schedule for Children (caregiver module) was used to ascertain the presence of ADHD in the past year based on Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV) criteria. Prior diagnosis of ADHD by a health professional and ADHD medication use were assessed by caregiver report.

RESULTS

Of the children, 8.7% met DSM-IV criteria for ADHD. The poorest children (lowest quintile) were more likely than the wealthiest (highest quintile) to fulfill criteria for ADHD (adjusted odds ratio [AOR], 2.3; 95% confidence interval [CI], 1.4-3.9). Among children meeting DSM-IV ADHD criteria, 47.9% had a prior diagnosis of ADHD and 32.0% were treated consistently with ADHD medications during the past year. Girls were less likely than boys to have their disorder identified (AOR, 0.3; 95% CI, 0.1-0.8), and the wealthiest children were more likely than the poorest to receive regular medication treatment (AOR, 3.4; 95% CI, 1.3-9.1).

CONCLUSIONS

Of US children aged 8 to 15 years, 8.7%, an estimated 2.4 million, meet DSM-IV criteria for ADHD. Less than half of children meeting DSM-IV criteria report receiving either a diagnosis of ADHD or regular medication treatment. Poor children are most likely to meet criteria for ADHD yet are least likely to receive consistent pharmacotherapy.

Medical presentation of constipation from childhood to early adulthood: a population-based cohort study

BACKGROUND & AIMS

Constipation is a common disorder in children and adults, but the role of gender and early life risk factors remains undefined. The aims of the study were as follows: (1) to estimate the incidence of medical presentation for constipation in a population-based birth cohort, and (2) to examine factors associated with constipation presentation from childhood to adulthood.

METHODS

A birth cohort of all children born between 1976 and 1982 to mothers who were residents of Rochester, Minnesota, and who remained in the community until age 5 was used for this study. Medical visits for constipation were identified by diagnoses codes and chart review. Subjects were followed up based on their diagnoses accumulated while younger than 21 years old, and 80% of subjects remained in the area until 18 years of age.

RESULTS

Of 5299 birth cohort members without constipation presentation before age 5, the overall age- and sex-adjusted incidence was 3.9 per 1000 person-years. A higher incidence for constipation in females occurred beginning at 13 years to early adulthood (rate ratio, 2.6 for 13-16 y and 4.2 for 17 to <21 y). Children with a diagnosis for constipation at younger than 5 years of age had a significantly higher incidence for subsequent medical visits for constipation through adolescence and early adulthood compared with the incidence rate of children without an early medical presentation (rate ratio, 4.5 for 5-8 y, 2.5 for 9-12 y, and 3.9 for 17-20 y).

CONCLUSIONS

Early medical presentation and female sex influence incident and repeat medical visits for constipation from childhood to early adulthood.

Modifiers of long-term school outcomes for children with attention-deficit/hyperactivity disorder: does treatment with stimulant medication make a difference? Results from a population-based study

OBJECTIVE

The purpose of this study was to describe the significance of potential modifiers of long-term school outcomes among children with attention-deficit/hyperactivity disorder (AD/HD), including treatment with stimulant medication.

METHODS

Subjects included 370 children with research-identified AD/HD from a 1976-1982 population-based birth cohort (N = 5718). In a companion study, the complete school record for each subject was reviewed to obtain information on reading achievement, absenteeism, grade retention, and school dropout. Data on type of stimulant, dose, age at initiation of treatment, and start/stop dates were collected from medical and school records, available for all subjects.

RESULTS

Treatment with stimulants was associated with decreased rates of absenteeism; longer duration of treatment was also associated with decreased absenteeism rates. There was a modest positive correlation (r = .15, p = .012) between average daily stimulant dose and last reading score. Cases treated with stimulants were 1.8 times less likely to subsequently be retained a grade (95% confidence interval: 1.01-3.2; p = .047). The proportion of school dropout was similar between treated and not treated cases (22.2% vs 25.8%, p = .54). Other potential modifiers of school outcomes (sociodemographic risk factors, presence of comorbid learning or psychiatric disorders, and receipt of special educational services) were also examined and found to be associated with poorer outcomes.

CONCLUSIONS

In this birth cohort, stimulant treatment of children with AD/HD was associated with improved reading achievement, decreased school absenteeism, and decreased grade retention. This study provides support for efforts to ensure that children with AD/HD receive appropriate long-term medical treatment.

Long-term school outcomes for children with attention-deficit/hyperactivity disorder: a population-based perspective

OBJECTIVE

The purpose of this study was to compare long-term school outcomes (academic achievement in reading, absenteeism, grade retention, and school dropout) for children with attention-deficit/hyperactivity disorder (AD/HD) versus those without AD/HD.

METHODS

Subjects included 370 children with research-identified AD/HD from a 1976-1982 population-based birth cohort (N = 5718) and 740 non-AD/HD control subjects from the same birth cohort, matched by gender and age. All subjects were retrospectively followed from birth until a median age of 18.4 years (AD/HD cases) or 18.3 years (non-AD/HD controls). The complete school record for each subject was reviewed to obtain information on reading achievement (last available California Achievement Test reading score), absenteeism (number/percentage of school days absent at each grade level), grade retention (having to repeat an entire grade in the subsequent school year), and school dropout (failure to graduate from high school).

RESULTS

Median reading achievement scores at age 12.8 years (expressed as a national percentile) were significantly different for AD/HD cases and non-AD/HD controls (45 vs 73). Results were similar for both boys and girls with AD/HD. Median percentage of days absent was statistically significantly higher for children with AD/HD versus those without AD/HD, although the difference was relatively small in absolute number of days absent. Subjects with AD/HD were three times more likely to be retained a grade. Similarly, subjects with AD/HD were 2.7 times more likely to drop out before high school graduation (22.9%) than non-AD/HD controls (10.0%).

CONCLUSIONS

The results of this population-based study clearly demonstrate the association between AD/HD and poor long-term school outcomes.

Incidence of presentation of common functional gastrointestinal disorders in children from birth to 5 years: a cohort study

BACKGROUND & AIMS

Gastroesophageal reflux disease (GERD), abdominal pain of unknown origin, and constipation are thought to be causes for frequent medical visits during childhood. The aim of this study was to estimate the incidences, repeat presentation, clinical symptoms, and sociodemographic risk factors in children who medically presented for GERD, abdominal pain of unknown origin, and constipation from birth to 5 years.

METHODS

This was a population-based, retrospective birth cohort study of all children born to mothers residing in Rochester, Minnesota who remained in the area until at least age 5 (n = 5718). The medical records of all individuals were searched for relevant diagnostic billing codes for GERD, abdominal pain of unknown origin, and constipation, without another underlying diagnosis, and manually reviewed. Parental sociodemographic factors collected from birth certificate records on patients and matched controls were compared.

RESULTS

The incidence for childhood (age, <5 y) presentation of GERD, abdominal pain of unknown origin, and constipation was .9/1000 person-years, 4.5/1000 person-years, and 6.8/1000 person-years, respectively; there were no significant differences between boys and girls. Three or more medical visits by age 5 occurred in 11%, 19%, and 24% of children who were seen for abdominal pain of unknown origin, constipation, and GERD, respectively. Single parentage, maternal age (<18 y), and maternal education (<high school) were not associated with abdominal pain or constipation presentation.

CONCLUSIONS

The incidences of presentation for GERD, abdominal pain of unknown origin, and constipation are among the highest for pediatric disorders, and a cause for repeated medical consultations.

Autism: a review of the state of the science for pediatric primary health care clinicians

Autism is a complex neurodevelopmental disorder characterized by impaired reciprocal social interaction, impaired communication, and restricted, repetitive, or stereotyped behaviors. Autism seems to affect more children than was previously believed, although this phenomenon may be due to broadening of the diagnostic criteria and increased awareness of the condition. Recent research has clearly indicated the importance of early identification, since early intensive treatment is associated with better long-term outcome. There are many controversies and competing theories about the etiology and treatment of autism, often leaving families confused about the best course of treatment and intervention. Pediatric primary health care clinicians have an important role in both the early identification and ongoing management of children with autism. It is, therefore, essential that primary care clinicians have up-to-date information about the science of autism.

Developmental dissociation, deviance, and delay: Occurrence of attention-deficit-hyperactivity disorder in individuals with and without borderline-to-mild intellectual disability

A neurodevelopmental model for understanding the spectrum of developmental disabilities postulates that developmental delay, dissociation, and deviance reflect underlying central nervous system dysfunction. In this study, we determined the occurrence of the dissociated and developmentally deviant behavioral profile of attention-deficit-hyperactivity disorder (ADHD) among children with and without developmental cognitive delays (borderline-to-mild intellectual disability) in a population-based birth cohort (n = 5718). Among the 70 children identified to have borderline-to-mild intellectual disability, 30% (n = 21; 7 females, 14 males) met research criteria for ADHD, compared to only 6.4% of children without intellectual disability (n = 358; 88 females, 270 males). The odds ratio for comorbid ADHD for children with versus without borderline-to-mild intellectual disability was 6.3 (95% confidence interval: 3.7-10.6; p < 0.001). These data illustrate that developmental dissociation and/or deviance, as represented by ADHD, are more likely to occur in the context of developmental delay, represented by borderline-to-mild intellectual disability.

Emergency department use and costs for youth with attention-deficit/hyperactivity disorder: associations with stimulant treatment

OBJECTIVE

To investigate whether, among youth with attention-deficit/hyperactivity disorder (ADHD), stimulant treatment is associated with reduced emergency department (ED) use and medical costs.

METHODS

We previously reviewed the complete and detailed school and medical records of all individuals born 1976-1982 in Rochester, Minn, to identify those who met criteria for ADHD between age 5 years and emigration from the area. Stimulant treatment (all start/stop dates, dosages) was also abstracted. This study followed birth cohort members with ADHD in provider-linked billing data from January 1, 1987 (billing data first available), to age 18 for outcomes: ED visits, ED costs, and medical costs. For each outcome, we analyzed associations with 1) any stimulants (yes/no), 2) proportion of follow-up time on stimulants, and 3) among those treated with stimulants, periods on versus off stimulants.

RESULTS

Of 313 youth with ADHD, 231 (74%) received any stimulants; treatment duration ranged from 14 days to 11.8 years. Treated and untreated youth were similar with respect to median annual ED visits (0.5 vs 0.5) and medical costs (661 US dollars vs 741 US dollars) (P > .05); however, increasing proportion of follow-up on stimulants was associated with fewer ED visits (P= .02) and higher medical costs (P< .001). The 231 treated youth experienced an average of 3.7 periods on and off stimulants; while receiving stimulants, they exhibited fewer ED visits (P= .02), lower ED costs (P = .03), and higher medical costs (P< .001) compared with periods off stimulants.

CONCLUSIONS

Among youth with ADHD, extended stimulant treatment is associated with decreased ED visits and ED costs, but higher total medical costs.

Long-term stimulant medication treatment of attention-deficit/hyperactivity disorder: results from a population-based study

The purpose of this study was to offer detailed information about stimulant medication treatment provided throughout childhood to 379 children with research-identified attention-deficit hyperactivity disorder (ADHD) in the 1976-1982 Rochester, MN, birth cohort. Subjects were retrospectively followed from birth until a mean of 17.2 years of age. The complete medical record of each subject was reviewed. The history and results of each episode of stimulant treatment were compared by gender, DSM-IV subtype of ADHD, and type of stimulant medication. Overall, 77.8% of subjects were treated with stimulants. Boys were 1.8 times more likely than girls to be treated. The median age at initiation (9.8 years), median duration of treatment (33.8 months), and likelihood of developing at least one side effect (22.3%) were not significantly different by gender. Overall, 73.1% of episodes of stimulant treatment were associated with a favorable response. The likelihood of a favorable response was comparable for boys and girls. Treatment was initiated earlier for children with either ADHD combined type or ADHD hyperactive-impulsive type than for children with ADHD predominantly inattentive type and duration of treatment was longer for ADHD combined type. There was no association between DSM-IV subtype and likelihood of a favorable response or of side effects. Dextroamphetamine and methylphenidate were equally likely to be associated with a favorable response, but dextroamphetamine was more likely to be associated with side effects. These results demonstrate that the effectiveness of stimulant medication treatment of ADHD provided throughout childhood is comparable to the efficacy of stimulant treatment demonstrated in clinical trials.

Math learning disorder: incidence in a population-based birth cohort, 1976-82, Rochester, Minn

OBJECTIVE

To report the incidence of math learning disorder (Math LD) among school-aged children, overall and by gender. To compare incidence estimates obtained by using three different methods to identify Math LD cases. To assess the extent to which children manifest Math LD alone, versus Math LD with comorbid reading disorder.

METHODS

This is a population-based, retrospective, birth cohort study. Subjects included all children born 1976-82 who remained in Rochester, Minn after age 5 (N = 5718). Using records from all public and private schools, medical facilities, and private tutorial services, all individually administered intelligence quotient and achievement tests and extensive medical, educational, and socioeconomic information were abstracted. Math LD was established using research criteria based on 3 formulas (regression-based discrepancy, nonregression-based discrepancy, low achievement).

RESULTS

Cumulative incidence rates of Math LD by age 19 years varied from 5.9% to 13.8% according to the formula used. Boys were more likely to be affected than girls, with relative risk ratios from 1.6 to 2.2 depending on the formula applied. Many children with Math LD (35% to 56.7%, depending on the formula used to define Math LD) did not have a comorbid reading disorder.

CONCLUSIONS

These results, from a community-based birth cohort, suggest that Math LD is common among schoolchildren, and is significantly more frequent among boys than girls, regardless of definition. Many children with Math LD do not have an associated reading disorder.

Case definition in epidemiologic studies of AD/HD

PURPOSE

Propose a five-step multigating, multimodal procedure for research case definition and identification of attention-deficit/hyperactivity disorder (AD/HD) in population-based epidemiologic studies.

METHODS

Subjects included a birth cohort of all children born between 1976 and 1982 who remained in Rochester after age 5. Screening for AD/HD required 4 steps, using these sources: school/medical records, computerized diagnostic index, and private psychiatry records. In step 5, research criteria were applied to potential cases. The model for defining cases used combinations of three categories of information (DSM-IV, questionnaire, clinical diagnosis). Validity was tested by comparing medication treatment, substance abuse, school outcomes, and comorbidities between cases who did or did not meet DSM-IV criteria.

RESULTS

Among 5718 subjects, 1344 potential cases were identified; 379 met research criteria. No difference in gender, treatment, school outcome, or professional making clinical diagnoses was found between cases who did (N=228) and did not (N=151) meet DSM-IV criteria. However, cases not meeting DSM-IV criteria were more inattentive (33.8% vs. 17.1%; p < 0.001), older (age 12.8 vs. 10.5 years; p=0.01), with less substance abuse (15.2% vs. 26.3%; p < 0.001) and psychiatric comorbidities (43.1% vs. 54.4%; p=0.031).

CONCLUSIONS

If only DSM-IV criteria were applied, 151 cases would not have been identified. This study underscores the importance of using multiple sources and combinations of documented information for case definition and identification.

Psychostimulant treatment and risk for substance abuse among young adults with a history of attention-deficit/hyperactivity disorder: a population-based, birth cohort study

OBJECTIVE

The aim of this study was to evaluate the association between stimulant treatment and the risk for substance abuse among young adults with a childhood diagnosis of attention- deficit/hyperactivity disorder (ADHD).

METHODS

Subjects included 295 research-identified ADHD incidence cases treated with psychostimulant medication and 84 ADHD cases not treated with psychostimulants. These subjects are from a 1976-1982 population-based birth cohort, retrospectively, followed from birth until emigration, death, or last follow-up (mean = 17.2 years of follow-up). Medical and school records were reviewed for documented substance abuse and psychostimulant treatment. The association was evaluated using logistic regression models.

RESULTS

Socioeconomic characteristics at birth, and comorbidities, were similar between treated and untreated ADHD cases. Sixty (20.3%) of treated ADHD cases had documented substance abuse compared to 23 (27.4%) of cases not treated (OR = 0.7; 95% CI = 0.4-1.2). Among treated ADHD boys, 21.8% had substance abuse compared to 36.4% not-treated ADHD boys (OR = 0.5; 95% CI = 0.3-0.9). Among treated ADHD girls, 15.2% had substance abuse compared to 10.3% not-treated ADHD girls (OR = 1.5; 95% CI = 0.4-6.1).

CONCLUSION

While these results cannot demonstrate cause and effect, our findings indicate that psychostimulant treatment of childhood ADHD is associated with reduced risk for later substance abuse among boys with ADHD.

The incidence of autism in Olmsted County, Minnesota, 1976-1997: results from a population-based study

OBJECTIVE

To determine the incidence of autism among children in Olmsted County, Minnesota.

DESIGN

Through the Rochester Epidemiology Project, all inpatient and outpatient diagnoses are indexed for computerized retrieval. This computerized diagnostic index was used to identify children with any developmental disorder. A glossary of symptoms of autism was used to review medical and school records of these children for symptoms consistent with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for autistic disorder.

SETTING

Olmsted County, Minnesota. Subjects All residents of Olmsted County 21 years or younger between 1976 and 1997. Main Outcome Measure The incidence of research-identified autism based on DSM-IV criteria for autistic disorder.

RESULTS

The age-adjusted incidence of research-identified autism was 5.5 (95% confidence interval, 1.4-9.5) per 100 000 children from 1980 to 1983 and 44.9 (95% confidence interval, 32.9-56.9) from 1995 to 1997 (8.2-fold increase). This increase was confined to children younger than 10 years who were born after 1987.

CONCLUSIONS

The incidence of research-identified autism increased in Olmsted County from 1976 to 1997, with the increase occurring among young children after the introduction of broader, more precise diagnostic criteria, increased availability of services, and increased awareness of autism. Although it is possible that unidentified environmental factors have contributed to an increase in autism, the timing of the increase suggests that it may be due to improved awareness, changes in diagnostic criteria, and availability of services, leading to identification of previously unrecognized young children with autism.