Table presents the study population of youth from the US, the Netherlands, and Germany by age group and gender. The total number of enrollees in 2000 was 127,157 (US), 110,994 (Netherlands) and 356,520 (Germany). Youth 0–4 years of age represented 51.7% of the US enrollees, 24.7% of the Dutch and 21.0% of the German enrollees. To address this disparity, prevalence data were adjusted to the distribution by age group of youths in the US 2000 census.
Age and gender characteristics for enrolled youth in 3 countries during 2000
Data in Table show the rank order of annual prevalence use of any psychotropic by country as 6.7% (US), 2.9% (Netherlands), and 2.0% (Germany). The prevalence differences are reflected in the prevalence ratio analyses which show that US usage was 2.27 (CI = 2.22, 2.32) and 3.33 (CI = 3.27, 3.40) times more likely than Dutch and German usage, respectively. Dutch usage was significantly greater than German usage [prevalence ratio of 1.47 (CI = 1.44, 1.51)]. The one year prevalence of receiving one or more of any psychotropic during 2000 was highest in all countries at ages 10–14 years for males and ages 15–19 for females. German youth led the 0–4 year-old rank order of prevalence of any psychotropic (1.63%), while Netherlands and US rates were equivalent (0.9%).
Prevalence per 100 and 95% CIs for the use of any psychotropic drug during the year 2000
Table illustrates that there was a limited but disparate use of lithium (< .01% in German, 0.01% in Dutch and 0.15% in US youth) and antiparkinsonian agents (0.01% in German and Dutch and 0.05% in US youth). Anxiolytic use was greater in Dutch youth than in German and US youth, respectively: 0.73% compared to 0.41% and 0.49%. Hypnotic use was twice as common in Dutch youth compared with US but scarcely used in German youth (0.09%). There was a wide disparity across countries in alpha-agonist use which was 9-fold and 120-fold more common in US youth than in Dutch and German youth, respectively.
Prevalence per 100 and 95% CIs for the use of six* selected psychotropic drugs during the year 2000
Antipsychotic prevalence in the countries assessed for year 2000 is presented on Table . In rank order, the prevalence of antipsychotics was 0.76% (US), 0.51% (Netherlands), and 0.34% (Germany). Though the total antipsychotic cross-national prevalence differences were relatively modest, Germany's prevalence was strikingly different in three respects. Atypical antipsychotics represented only 5% of the total in Germany, but 48% in the Netherlands and 66% in the US. The antipsychotic gender ratio (M:F) was distinctly lower in Germany (1.4:1) compared to the Netherlands (3.2:1) and the US (2.8:1). Furthermore, among 0–4 year olds, German youth had the highest antipsychotic prevalence (0.64%), followed by the Netherlands (0.10%), and the US (0.07%), a stark reversal of the leading usage trend observed in other drug classes, e.g. antidepressants and stimulants.
Prevalence per 100 and 95% CIs for the use of antipsychotics during the year 2000
As shown in Table , the prevalence of stimulants for youth was 4.3% in the US, 1.2% in the Netherlands, and 0.7% in Germany. Stimulant prevalence peaked in all three countries at ages 10–14 years. In 0–4 year-olds, the US stimulant prevalence was 0.5%, 10–25 times higher than that of the two Western European countries. The stimulant gender ratio (M:F) in the US was 3.4:1, whereas it was 5.3:1 to 4.8:1 in Germany and the Netherlands. In the US, methylphenidate and amphetamine compounds were prescribed equivalently, whereas in the two Western European countries, over 95% of prescribed stimulant use was for methylphenidate.
Prevalence per 100 and 95% CIs for the use of stimulants during the year 2000
Table presents the antidepressant prevalence for youth cross-nationally. In rank order, the prevalence for 2000 was 2.7% (US), 0.5% (Netherlands), and 0.2% (Germany).
Prevalence per 100 and 95% CIs for the use of antidepressants during the year 2000
In Germany and the Netherlands, 15–19 year olds were over 3 times more likely to utilize antidepressants than 10–14 year olds, whereas in the US the 15–19 year old group use was only 28% higher than in the younger aged group. In the US, only 14.8% of those on antidepressants were prescribed the TCA antidepressant subclass, whereas the proportion for TCAs was 48% in the Netherlands and 73% in Germany.
Concomitant psychotropic patterns
To assess concomitant therapy in 3 time frames, 1-month (April 2000), 3-month (April through June) and 12-month time periods were used to measure the one-month co-occurrence of psychotropic classes for youth in the US dataset. There was a linear increase in co-occurring use as the time period widened: 19.2%, 23.9% and 27.0%. For the present study, the most conservative approach, (monthly co-occurrence) was adopted to avoid exaggerated estimates. Combinations were assessed from the following classes: stimulants, antidepressants, anxiolytics/hypnotics, alpha-agonists, antipsychotics, anticonvulsant-mood stabilizers and lithium. Of the 1908 medicated youth in the US group, concomitant therapy (defined as monthly co-occurrence) applied to 19.2% and ranged from pairs (n = 279), triplets (n = 80), quadruplets (n = 7) to 6 drug classes (n = 1). The leading pairs were stimulants with antidepressants (33.7%) and stimulants with alpha-agonists (18.3%). Dutch concomitant use was substantially less common: 8.5% had combined therapy almost entirely as pairs (77/80), of which stimulants and antipsychotics were the leading combination. German concomitant use affected only 5.9% of medicated youth and the use was entirely pairs except for one triplet. Since the bulk (62%) of the German combinations involved anticonvulsant-mood stabilizer and an anxiolytic/hypnotic, it is not possible to determine the extent of seizure disorder treatment. The other German pairs were ranked as follows: stimulant and antipsychotic (8.9%), anticonvulsant-mood stabilizer and antipsychotic (7.6%) and stimulant and anticonvulsant-mood stabilizer (6.3%). Concomitant use with anticonvulsant-mood stabilizers affected 5.8% (110/1908) of US medicated youth, 1.9% (18/937) of medicated Dutch youth and 4.6% (62/1358) of medicated German youth.