Causal modelling of variation in clinical practice and long-term outcomes of ADHD using Norwegian registry data: the ADHD controversy project

Effect of ADHD medication on risk of injuries: a preference-based instrumental variable analysis

ADHD is associated with an increased risk of injury. Causal evidence for effects of pharmacological treatment on injuries is scarce. We estimated effects of ADHD medication on injuries using variation in provider preference as an instrumental variable (IV). Using Norwegian registry data, we followed 8051 patients who were diagnosed with ADHD aged 5 to 18 between 2009 and 2011 and recorded their ADHD medication and injuries treated in emergency rooms and emergency wards up to 4 years after diagnosis. Persons with ADHD had an increased risk of injuries compared to the general population (RR 1.35; 95% CI: 1.30-1.39), with higher risk in females (RR 1.47; 95% CI: 1.38-1.56) than males (RR 1.23; 95% CI: 1.18-1.28). The between-clinics variation in provider preference for ADHD medication was large and had a considerable impact on patients' treatment status. There was no causal evidence for protective effects of pharmacological treatment on injuries overall for young individuals with ADHD characterized by milder or atypical symptoms. However, there was an apparent effect of pharmacological treatment over time on the risk of injuries treated at emergency wards in this patient group.

Effect of Pharmacological Treatment of Attention-Deficit/Hyperactivity Disorder on Criminality

OBJECTIVE

Criminality rates are higher among persons with attention-deficit/hyperactivity disorder (ADHD), and evidence that medication reduces crime is limited. Medication rates between clinics vary widely even within universal health care systems, partly because of providers' treatment preferences. We used this variation to estimate causal effects of pharmacological treatment of ADHD on 4-year criminal outcomes.

METHOD

We used Norwegian population-level registry data to identify all unique patients aged 10 to 18 years diagnosed with ADHD between 2009 and 2011 (n = 5,624), their use of ADHD medication, and subsequent criminal charges. An instrumental variable design, exploiting variation in provider preference for ADHD medication between clinics, was used to identify causal effects of ADHD medication on crime among patients on the margin of treatment, that is, patients who receive treatment because of their provider's preference.

RESULTS

Criminality was higher in patients with ADHD relative to the general population. Medication preference varied between clinics and strongly affected patients' treatment. Instrumental variable analyses supported a protective effect of pharmacological treatment on violence-related and public-order-related charges with numbers needed to treat of 14 and 8, respectively. There was no evidence for effects on drug-, traffic-, sexual-, or property-related charges.

CONCLUSION

This is the first study to demonstrate causal effects of pharmacological treatment of ADHD on some types of crimes in a population-based natural experiment. Pharmacological treatment of ADHD reduced crime related to impulsive-reactive behavior in patients with ADHD on the margin of treatment. No effects were found on crimes requiring criminal intent, conspiracy, and planning.

STUDY PREREGISTRATION INFORMATION

The ADHD controversy project: Long-term effects of ADHD medication; https://www.isrctn.com/; 11891971.

Variation in attitudes toward diagnosis and medication of ADHD: a survey among clinicians in the Norwegian child and adolescent mental health services

Prevalence and medication rates of ADHD vary geographically, both between and within countries. No absolute cutoff exists between ADHD and normal behavior, making clinician attitudes (leading to local practice cultures) a potential explanation for the observed variation in diagnosis and medication rates. The objective of this study was to describe variation in attitudes toward diagnosis and medication of ADHD among clinicians working in child and adolescent mental health services (CAMHS). We hypothesized that attitudes would vary along a spectrum from "restrictive" to "liberal". We also explored whether differences in attitudes between clinicians were related to professional background and workplace (clinic). A survey in the form of a web-based questionnaire was developed. All CAMHS outpatient clinics in Norway were invited. Potential respondents were all clinicians involved in diagnosing and treating children and adolescents with ADHD. To investigate the existence of attitudes toward diagnosis and medication as latent constructs, we applied confirmatory factor analysis (CFA). We further examined how much of variance in attitudes could be ascribed to profession and clinics by estimating intraclass correlation coefficients. In total, 674 respondents representing 77 (88%) of the clinics participated. We confirmed variation in attitudes with average responses leaning toward the "restrictive" end of the spectrum. CFA supported "attitude toward diagnosis" and "attitude toward medication" as separate, and moderately correlated (r = 0.4) latent variables, representing a scale from restrictive to liberal. Professional background and workplace explained only a small part of variance in these attitudes.

A systematic meta-review of systematic reviews on attention deficit hyperactivity disorder

BACKGROUND

There are now hundreds of systematic reviews on attention deficit hyperactivity disorder (ADHD) of variable quality. To help navigate this literature, we have reviewed systematic reviews on any topic on ADHD.

METHODS

We searched MEDLINE, PubMed, PsycINFO, Cochrane Library, and Web of Science and performed quality assessment according to the Joanna Briggs Institute Manual for Evidence Synthesis. A total of 231 systematic reviews and meta-analyses met the eligibility criteria.

RESULTS

The prevalence of ADHD was 7.2% for children and adolescents and 2.5% for adults, though with major uncertainty due to methodological variation in the existing literature. There is evidence for both biological and social risk factors for ADHD, but this evidence is mostly correlational rather than causal due to confounding and reverse causality. There is strong evidence for the efficacy of pharmacological treatment on symptom reduction in the short-term, particularly for stimulants. However, there is limited evidence for the efficacy of pharmacotherapy in mitigating adverse life trajectories such as educational attainment, employment, substance abuse, injuries, suicides, crime, and comorbid mental and somatic conditions. Pharmacotherapy is linked with side effects like disturbed sleep, reduced appetite, and increased blood pressure, but less is known about potential adverse effects after long-term use. Evidence of the efficacy of nonpharmacological treatments is mixed.

CONCLUSIONS

Despite hundreds of systematic reviews on ADHD, key questions are still unanswered. Evidence gaps remain as to a more accurate prevalence of ADHD, whether documented risk factors are causal, the efficacy of nonpharmacological treatments on any outcomes, and pharmacotherapy in mitigating the adverse outcomes associated with ADHD.

Geographical variation in ADHD: do diagnoses reflect symptom levels?

Rates of ADHD diagnosis vary across regions in many countries. However, no prior study has investigated how much within-country geographic variation in ADHD diagnoses is explained by variation in ADHD symptom levels. We examine whether ADHD symptom levels explain variation in ADHD diagnoses among children and adolescents using nationwide survey and register data in Norway. Geographical variation in incidence of ADHD diagnosis was measured using Norwegian registry data from the child and adolescent mental health services for 2011-2016. Geographical variation in ADHD symptom levels in clinics' catchment areas was measured using data from the Norwegian mother, father and child cohort study for 2011-2016 (n = 39,850). Cross-sectional associations between ADHD symptom levels and the incidence of ADHD diagnoses were assessed with fractional response models. Geographical variation in ADHD diagnosis rates is much larger than what can be explained by geographical variation in ADHD symptoms levels. Treatment in the Norwegian child and adolescent mental health services is free, universally available upon referral, and practically without competition from the private sector. Factors beyond health care access and unequal symptom levels seem responsible for the geographical variation in ADHD diagnosis.

The Winding Road to Equal Care: Attitudes and Experiences of Prescribing ADHD Medication among Pediatric Psychiatrists: A Qualitative Study

Evidence is lacking on how to understand the reasons for variations, both in prevalence of ADHD and ADHD medication prescribing patterns in children and adolescents, within Region Skåne. These variations are not in line with current national clinical guidelines and seem to have increased over time. This qualitative interview study illuminates pediatric psychiatrists' attitudes toward ADHD and their experiences of prescribing ADHD medication. Eleven pediatric psychiatrists described the complex interplay of variables that they experienced while assessing a child, which had influence on their decision to prescribe medication. Being part of a local unit's culture influenced how ADHD medications were prescribed. They wished that the assessment of the child's symptoms was consistent with guidelines in every unit but noted that such alignment was not implemented. They pointed out that an ADHD diagnosis is dependent on the surrounding's motivation and capacity to adapt to the present state of the child. The participants described how they balanced clinical guidelines with demands from the family, as well as from society at large. Their personal attitudes and clinical experiences towards diagnosing and prescribing medications to children with ADHD influenced their decisions. The study adds information about how attitudes may lead to variation in diagnostics and therapy.

Improving Cohort-Hospital Matching Accuracy through Standardization and Validation of Participant Identifiable Information

Linking very large, consented birth cohorts to birthing hospitals clinical data could elucidate the lifecourse outcomes of health care and exposures during the pregnancy, birth and newborn periods. Unfortunately, cohort personally identifiable information (PII) often does not include unique identifier numbers, presenting matching challenges. To develop optimized cohort matching to birthing hospital clinical records, this pilot drew on a one-year (December 2020-December 2021) cohort for a single Australian birthing hospital participating in the whole-of-state Generation Victoria (GenV) study. For 1819 consented mother-baby pairs and 58 additional babies (whose mothers were not themselves participating), we tested the accuracy and effort of various approaches to matching. We selected demographic variables drawn from names, DOB, sex, telephone, address (and birth order for multiple births). After variable standardization and validation, accuracy rose from 10% to 99% using a deterministic-rule-based approach in 10 steps. Using cohort-specific modifications of the Australian Statistical Linkage Key (SLK-581), it took only 3 steps to reach 97% (SLK-5881) and 98% (SLK-5881.1) accuracy. We conclude that our SLK-5881 process could safely and efficiently achieve high accuracy at the population level for future birth cohort-birth hospital matching in the absence of unique identifier numbers.

Review: Adult Outcome as Seen Through Controlled Prospective Follow-up Studies of Children With Attention-Deficit/Hyperactivity Disorder Followed Into Adulthood

OBJECTIVE

To describe adult outcome of people with attention-deficit/hyperactivity disorder (ADHD) diagnosed in childhood and its several key predictors via a review of 7 North American controlled prospective follow-up studies: Montreal, New York, Milwaukee, Pittsburgh, Massachusetts General Hospital (MGH), Berkeley, and 7-site Multimodal Treatment Study of Children With ADHD (MTA).

METHOD

All studies were prospective and followed children with a diagnosis of ADHD and an age- and gender-matched control group at regular intervals from childhood (6-12 years of age) through adolescence into adulthood (20-40 years of age), evaluating symptom and syndrome persistence, functional outcomes, and predictors of these outcomes.

RESULTS

The rates of ADHD syndrome persistence ranged from 5.7% to 77%, likely owing to varying diagnostic criteria and the source of information (self-report vs informant report) across the studies. However, all studies observed high rates of symptomatic persistence ranging from 60% to 86%. The 7 studies were largely consistent in finding that relative to control groups, research participants with childhood-diagnosed ADHD had significant impairments in the areas of educational functioning, occupational functioning, mental health, and physical health as well as higher rates of substance misuse, antisocial behavior, and unsafe driving. The most consistently observed predictors of functional outcomes included ADHD persistence and comorbidity, especially with disruptive behavior disorders.

CONCLUSION

Childhood ADHD has high rates of symptomatic persistence, which is associated with negative functional outcomes. Characteristics that predict these negative outcomes, such as comorbid disruptive behavior disorders, may be important targets for intervention.