Attention deficit hyperactivity disorder late birthdate effect common in both high and low prescribing international jurisdictions: a systematic review.

BACKGROUND: Multiple studies have found that the youngest children in a classroom are at elevated risk of being diagnosed with, or medicated for, ADHD. This systematic review was conducted to investigate whether this late birthdate effect is the norm and whether the strength of effect is related to the absolute risk of being diagnosed/medicated. METHODS: A literature search of the PubMed and ERIC databases and snowball and grey literature searching were conducted. RESULTS: A total of 19 studies in 13 countries covering over 15.4 million children investigating this relationship were identified. Three other studies exploring related topics were identified. The diversity of methodologies prevented a meta-analysis. Instead a systematic review of the 22 studies was conducted. A total of 17 of the 19 studies found that the youngest children in a school year were considerably more likely to be diagnosed and/or medicated than their older classmates. Two Danish studies found either a weak or no late birth date effect. There was no consistent relationship between per-capita diagnosis or medication rates and the strength of the relative age effect, with strong effects reported in most jurisdictions with comparatively low rates. CONCLUSIONS: It is the norm internationally for the youngest children in a classroom to be at increased risk of being medicated for ADHD, even in jurisdictions with relatively low prescribing rates. A lack of a strong effect in Denmark may be accounted for by the common practice of academic 'redshirting', where children judged by parents as immature have a delayed school start. Redshirting may prevent and/or disguise late birthdate effects and further research is warranted. The evidence of strong late birthdate effects in jurisdictions with comparatively low diagnosis/medication rates challenges the notion that low rates indicate sound diagnostic practices.

Trends in Australian government health expenditure by age: a fiscal incidence analysis.

OBJECTIVE: Australian government health expenditure per capita has grown steadily across the past few decades, but little is known about trends in the age distribution of health expenditure. METHODS: In this paper, the Australian Bureau of Statistics (ABS) fiscal incidence studies, which track expenditure at the household level between 1984 and 2010, are used to shed light on this topic. RESULTS: The main finding was that spending has shifted focus from the younger half to the older half of the population. This shift is evident in three areas: (1) acute care (hospitals); (2) community health services (doctors); and (3) pharmaceuticals. Together, these areas account for approximately 88% of expenditure. The trend is independent of demographic aging. It is unlikely to reflect changes in population health. Its explanation is open to debate. CONCLUSIONS: Growth in expenditure per household has been more than threefold faster for elderly than young households. Across this period, expenditure per household per week has increased by 51% for the young, by 79% for the middle aged and by 179% for the elderly. This age-related growth is most prominent in expenditure on acute care, community health services and pharmaceuticals. WHAT IS KNOWN ABOUT THE TOPIC?: The Productivity Commission has published figures that relate age and Australian heath expenditure. However, there has been no published study of age-related trends in Australian health expenditure. WHAT DOES THIS PAPER ADD?: In addition to tracking age-related trends across 26 years, this paper adds a breakdown of those trends into four categories of expenditure, namely acute care, community health services, pharmaceutical benefits, and other. This breakdown shows that the trends vary by expenditure type. WHAT ARE THE IMPLICATIONS FOR PRACTITIONERS?: The paper shows that forward projections in health expenditure need to take into account age-related trends as well as demographic trends.