Systemic antibiotic prescribing to paediatric outpatients in 5 European countries: a population-based cohort study

Antibiotics are among the most widely prescribed medications in Europe [1]. Resistance to common antibiotic agents has grown among a majority of bacterial pathogens and is widely acknowledged to be an increasing threat to global public health [2, 3]. Population exposure to antibiotics is recognised as an important cause for the emergence of resistant bacterial strains [4–6]. Due to a high burden of respiratory infections in paediatric populations, antibiotic prescribing is particularly common in the treatment of childhood diseases. However, frequent childhood respiratory conditions such as sore throat, acute otitis media, acute cough, sinusitis, common cold, and acute bronchitis are predominantly caused by viruses and mostly do not benefit from antibiotic therapy [7–10]. Thus, high prescribing of antibiotic agents to the paediatric population is a recognised indicator for inappropriate prescribing patterns in primary care [11].

Several studies have been published in the last decade either assessing antibiotic use in paediatric populations of single European countries [11–15] or conducting comparisons of paediatric antibiotic use between up to three countries [16, 17]. Findings showed wide variations across Europe in the prescribing of systemic antibiotics to children and adolescents [12]. Comparability of these studies was, however, limited due to differences in drug utilisation measures, inclusion criteria of the study populations, age group categorizations and classifications of antibiotic subgroups [11–18]. In addition, comparison of the age-group-specific distributions of antibiotic subgroups between countries is lacking so far.

The aim of the present study was to compare outpatient prescribing of systemic antibiotics to children and adolescents in the age group 0-18 years between Denmark, Italy, Germany, the Netherlands and the UK for the years 2005-2008, based on a standardised protocol for data extraction and analysis for each database in these countries. Special attention was paid to differences of age-group-specific use of different antibiotic subgroups across countries. Seasonal variations of prescribing rates were described to assess impact of antibiotic treatment of mostly viral respiratory infections during winter months on total use.

The average annual total population comprised 334,991 children from Denmark, 773,492 children from the Italian region Emilia Romagna, 1,340,163 children from Germany, 622,450 children from the Netherlands and 798,253 children from the UK.

In all five countries and all years, the highest prescription rates were found in the age group ≤4 years and the lowest rates were observed in the age group 10-14 years (Table 1).

Prescription rates in children and adolescents in the Netherlands and the UK fluctuated slightly between the years 2005 and 2008, overall and in different age groups (Table 1). Similarly, the number of prescriptions per 1,000 person years in Danish children changed marginally throughout the course of the study. Nevertheless, an increase by 22.7% could be observed in the age group ≤4 years between 2005 and 2008 (Table 1). In Germany, a progressive decline of the annual prescription rates could be observed over all four age groups during the study period (Table 1).Monthly prescription rates were lowest in July and August and rose continuously until reaching their peak between December and March of the following year. Seasonal increases in the winter months were most pronounced in Italy followed by Germany (Figure 1).

Cephalosporins were hardly prescribed to Danish and Dutch children, whereas second and third generation cephalosporins were the most prescribed cephalosporins in Germany and Italy, respectively. Relative use of second and third generation cephalosporins was highest in the age group ≤4 years and gradually decreased with age (Table 2).

Use of macrolides increased with age and accounted for 20.7% of total use in Italy, 20.3% in Germany, 16.0% in the Netherlands, 12.5% in the UK and 13.5% in Denmark. Proportions of macrolide use increased with age (Table 2).

Overall, tetracyclines covered varying proportions, from 0.4% in Denmark to 7.8% in the UK. In line with age restrictions, relevant relative use of tetracyclines was only found above ten years of age in all five countries (Table 2).

Our study provides comprehensive information on the utilisation of systemic antibiotics among children and adolescents in the age group ≤18 years in Denmark, Italy, Germany, the Netherlands and the UK during the years 2005 to 2008. Our findings illustrate striking variations of total systemic antibiotic use in paediatric outpatient care between these countries. Substantial differences of outpatient antibiotic use among children across Europe have been described before, but these previous studies only provided comparable data of drug use for up to three countries and suffered from different definitions of drug utilisation measures. Furthermore, comprehensive data about age-group-specific distributions of antibiotic subgroups was lacking for most countries of this study and a comparison has not been conducted so far. In 2001, the European Surveillance of Antimicrobial Consumption Project was established to gather reliable and comparable information on the utilisation of antibiotics in Europe, however, without distinguishing between adults and children [1]. The current study captured outpatient systemic paediatric antibiotic use of five countries in different European regions ensuring high inter-country comparability, due to consistent definition of drug utilisation measures, age groups and classification of antibiotic subgroups.

Overall, the annual antibiotic prescription rates in the Italian region Emilia Romagna were more than three times higher than those in the Netherlands, the country with the lowest prescription rates, and still substantially higher than those in Germany, the country with the second highest use. When compared to other studies, magnitude of paediatric antibiotic use in Italy exceeded use reported for Canada (608 prescriptions per 1000 children <15 years of age in 2003) [19] and Sweden (764 prescriptions per 1000 children 0-6 years of age in 2002) [15] as well, but appears to be comparable to the U.S. (910 prescriptions per 1000 person years in children <18 years of age in 2001) [22].

High antibiotic prescribing in the Italian outpatient setting compared to the other countries in our study might be related to differences with regard to historical backgrounds, cultural and social factors, awareness about antibiotic resistance in the community and among healthcare providers [23] as well as the ability of physicians to adequately diagnose common infectious diseases [16]. So far, reasons for strong variations of antibiotic use across European countries have not yet been fully investigated. Nevertheless, previous studies suggest that awareness about antibiotic resistance [24] and inadequacy of antibiotics to treat viral infections [25] is poor among Italian patients and perception of parent expectations by Italian physicians is a major determinant of antibiotic prescribing to children [26].

In contrast, several previous studies showed antibiotic utilisation in the Netherlands to be lowest in Europe, overall and in the paediatric setting [6, 13]. The Netherlands are a country with a strict prescribing policy for antiinfectives, and there are intensive efforts into promoting guideline-appropriate prescribing habits to combat antibiotic resistance [27].

Although antibiotic use was by far the highest among Italian children and adolescents, antibiotic prescription rates in Denmark, Germany and UK still exceeded those in the Netherlands to a great extent. These observed strong variations of total paediatric antibiotic use among the countries of study are unlikely to reflect an actual therapeutic need which would have to be based on marked differences in the burden of infectious diseases between these countries. This assumption is also supported by the observed pronounced increases of prescription rates during winter months which were expectedly highest in Italy, and smallest in the Netherlands. Increases of antibiotic use are most likely related to seasonal rise of predominantly viral respiratory infections and hence should be limited [1].

Since our findings could not provide information beyond the 4-year study period, we compared our prescription rates with those of other studies which included other study years or longer time periods. In this respect, our data for the years 2005-2008 in the Netherlands agreed well with the findings by de Jong et al. who reported a variation of the total annual number of antibiotic prescriptions between 282 and 307 per 1,000 Dutch children in the years 1999-2005 [13]. This suggests an overall stable total antibiotic use among Dutch children for almost ten years. Gagliotti et al. observed annual prescription rates per 1,000 person years among children 0-14 years of age from Emilia Romagna, varying between 1,158 and 1,358 during 2000-2002 [13]. This is in line with our findings in children below 15 years of age of 1,123 (2007) and 1,034 prescriptions per 1,000 person years (2008), indicating marginal changes over time of total paediatric use in Emilia Romagna. Prescription rates among British children did not show any apparent trend towards lower or higher prescribing in our study over the study years. Gradual annual increases of prescription rates between 2000 and 2007 were reported in the UK based on data from the General Practice Research Database (GPRD) [11]. However, differences to our findings for the years 2005 to 2007 were small and might have resulted from variations in the regional distribution of general practices contributing data to THIN and/or the GPRD. We observed a steady decrease in prescription rates in Germany during 2005-2008. Another German study also based on GePaRD data found slightly higher prescription rates among German children without an obvious downward trend for the years 2004-2006 [18]. This former study, however, included data from four rather than three health insurances, resulting in a study population of about twice as many children as in this study which may explain the difference.

We also detected remarkable differences in the choice of antibiotic subgroups between the countries of our study. Narrow spectrum penicillins formed the majority of systemic antibiotics in Denmark, whereas prescriptions of broad spectrum penicillins were most frequent in the four other countries. In line with that, the highest agent-specific prescription rates were reported for phenoxymethylpenicillin in Denmark, amoxicillin in Germany, the Netherlands and the UK and amoxicillin plus enzyme inhibitor in Italy. Relatively high use of narrow spectrum penicillins in Denmark in comparison to other European countries has also been reported previously [6]. However, it is noteworthy that even though proportions for narrow spectrum penicillins were highest in Denmark, broad spectrum penicillins formed the antibiotic subgroup most frequently prescribed to children in the age group ≤4 years in all 5 countries. This might be due to frequent use of amoxicillin or amoxicillin and enzyme inhibitor in the treatment of acute otitis media, which shows the highest incidence in the first two years of life [28].

Macrolides were commonly prescribed in all five countries with the highest use in the age groups 10-14 and 15-18 years. Relative proportions of macrolide use were lowest in Denmark. This finding is in agreement with a Danish practice guideline which recommends restricting the use of macrolides to patients with penicillin allergies in the treatment of common childhood infections [21]. Several studies from the U.S. and Europe show a strong association of high macrolide use and the emergence of resistant strains of pneumococci and other common pathogens [23–25]. Hence high prescription rates of macrolides are questionable and likely to unnecessarily increase selective pressure on bacterial pathogens. In particular high use of clarithromycin and azithromycin in the Emilia Romagna region appears unjustified, since international guidelines do not recommended these agents as first-line treatment of common childhood infections [29–32]. Furthermore, longer plasma half-life of azithromycin and clarithromycin in contrast to erythromycin might even accelerate the emergence of antibiotic resistance [33, 34].

Our findings regarding paediatric cephalosporin use are in line with previous studies which reported strong variations of cephalosporin prescribing across Europe, with the lowest prescription rates in the Netherlands and Denmark [13, 18–20, 35]. Overall, the prescription rate of cefaclor (a second generation cephalosporin) in German children was the second highest after amoxicillin, and use of second generation cephalosporins was particularly common in very young children. Only in Italy, the parenterally administered third generation agent ceftriaxone was prescribed frequently. Considerably higher prescribing of parenteral antibiotics in Italian outpatient care in contrast to Northern European countries has been reported previously [36]. The high relative use of cephalosprines in Germany and Italy as observed here, suggests frequent prescribing of these antibiotics as a first–line treatment of common paediatric respiratory infections. This is in conflict with international practice guidelines [29, 30] recommending that cephalosporins should be preserved for second-line treatment in cases such as treatment failure of first-line agents, non-type 1 allergy to penicillins or unusually severe symptoms.

Comparison of paediatric antibiotic consumption between different European countries revealed a wide variability of antibiotic prescribing patterns. Strong variations of overall and age-group-specific distributions of antibiotic subgroups across countries, suggests that antibiotics are inappropriately used to a large extent. Considerably higher prescription rates along with higher seasonal increases, particularly in Italy, in contrast to the Netherlands suggest frequent utilisation of antibiotics in the treatment of mostly viral respiratory infections. This study showed the benefit of using a common methodological approach to provide comparable and detailed data on paediatric antibiotic prescribing across Europe. Study results allow health care practitioners and policy makers to audit country and age-group-specific patterns of paediatric antibiotic use with regard to both total level of prescribing and the distribution of antibiotic subgroups/substances.