INDICATIONS FOR ANTIBIOTIC PRESCRIPTIONS

4. INDICATIONS FOR ANTIBIOTIC PRESCRIPTIONS

Available population-based studies which describe antibacterial use by indication use physician surveys or prescription databases as the data collec- tion mechanism. In most studies the most common indication for an antimi- crobial prescription is a respiratory tract infection (RTI) (60–70%) followed by urinary tract infections (UTI) (10–15%), and skin and soft tissue infections (10%). In children, more than 90% of infectious episodes are respiratory tract infections (including otitis media) and children also receive antimicrobial treatment more often than adults. In the elderly urinary tract infections becomes more prevalent as a diagnosis and increasing utilisation of antimicrobials are observed in the veteran population.

4.1. Europe

In the comparative studies from countries in Europe there are no national data on indications for prescribing, dose, or duration of treatment. However there are some studies on diagnosis for prescriptions in outpatient care.

In the West Midlands General Practice Research Database, United Kingdom, there was between 1993 and 1997 an overall decrease in prescribing from 963 to 807 prescriptions per 1,000 patients and year (Frischer et al.,

Antibiotic Use in the Community 575 2001). Non-specific lower respiratory tract infections and throat infections

accounted for the main decreases in antibiotic prescribing. In Norway, the most commonly recorded diagnosis was urinary tract infec- tions, followed by acute bronchitis, ear infections, and non-specific upper respiratory tract infections in 1989 (Straand, 1998). The most prescribed antibiotics were narrow-spectrum penicillins (29%), followed by tetracyclines (24%), trimethoprim-sulfamethoxazole (17%), and erythromycin (12%). Narrow- spectrum penicillin was used in a majority of ear infections, tonsillitis, non- specific upper respiratory tract infections and sinusitis. Tetracyclines were most often prescribed for acute bronchitis and pneumonia and trimethoprim- sulfamethoxazole for urinary tract infections.

In Sweden, a 1-week survey on 7,700 visits for infectious diseases in five counties was conducted in the year 2000 (Stalsby et al., 2002). Respiratory tract infections accounted for 70% of the diagnoses, of which 54% were pre- scribed an antibiotic, of which narrow-spectrum penicillin accounted for 62% of prescriptions, followed by tetracycline (14%). Most cases of acute otitis media and acute tonsillitis were prescribed narrow-spectrum penicillin. In acute bronchitis, 50% of cases were prescribed an antibiotic, of which tetracy- cline was the most common followed by narrow-spectrum penicillin and amoxicillin. In urinary tract infections, trimethoprim, pivmecillinam, and fluo- roquinolones accounted for one third each. About 50% of skin and soft tissue infections were treated with isoxazolylpenicillins whereas cefalosporins were used in 12%.

In Finland, indications for antibiotic prescribing has been studied in a point prevalence study conducted in 30 Health Centres (Rautakorpi et al., 2001). A total of 7,800 visits for infections were recorded. The most common cause for

a visit was a respriratory tract infection (74%), followed by skin/wound infec- tions and urinary tract infections (both 6%). Of the otitis media, 53% were treated with amoxicillin, 16% with a macrolide, and 16% with co-trimoxazole. Patients with acute bronchitis received antibiotic treatment in 70% of cases, mostly macrolides (39%) and doxycycline (36%).

4.2. United States

In a sample survey 2,500–5,000 office-based physicians reported data on office visits, including information on antimicrobial drug prescribing between 1980 and 1992 (McCaig and Hughes, 1995). During the years, an increasing trend in the visit rate to office-based physicians for otitis media was observed, while the visit rate for sinusitis among adults was found to be higher in 1992 than in each of the other study years. The five leading diagnoses for which oral antibiotics were prescribed were otitis media, upper respiratory tract infection, bronchitis, pharyngitis, and sinusitis.

576 Sigvard Mölstad and Otto Cars

A sample of community-based physicians in the National Ambulatory Medical Care Survey was used to collect data on 60,252 visits in 1991–2, 62,169 visits in 1994–5, and 37,467 visits in 1998–9 (Steinman et al., 2003). The estimated annual national number of prescriptions decreased from 230 million prescriptions in 1991–2 to 190 million prescriptions in 1998–9. Antibiotics were less frequently used in 1998–9 to treat acute respiratory tract infections, such as the common cold and pharyngitis. However, use of broad- spectrum agents increased from 24% to 40% of antibiotic prescriptions in adults and from 23% to 40% in children. For common cold and unspecified upper respiratory tract infection adult use of broad-spectrum antibiotics more than doubled. For adults, use of azithromycin and clarithromycin also increased from 1% to 16% of prescription. During the period, the use of fluoro- quinolones increased from 17% to 35% of antibiotics prescribed for urinary tract infections and from less than 1% to 13% of antibiotics to treat common cold and unspecified upper respiratory tract infection. Among children, use of broad-spectrum antibiotics increased for otitis media and more than doubled for common cold and unspecified upper respiratory tract infection. In 1998–9, nonpneumonic acute respiratory tract infections accounted for 54% of adult and 77% of paediatric prescriptions for broad-spectrum antibiotics. In addi- tion, nonpneumonic acute respiratory infection accounted for at least two thirds of prescriptions for azithromycin/clarithromycin, amoxicillin + clavu- lanate, and second and third generation cephalosporins. Also substantial regional differences in antibiotic use were noted.

In a sample survey, 2,500–3,500 office-based physicians reported data on 6,500–13,600 paediatric visits during 2-year periods from 1989 to 1990 through 1999 to 2000 (McCaig et al., 2002), population and visit-based antimicrobial prescribing rates were calculated for children and adolescents younger than

15 years. Respiratory tract infections (otitis media, pharyngitis, bronchitis, sinusitis, and upper respiratory tract infection) represented 75% of all antimicro- bial prescriptions. The average number of prescriptions per 1,000 children and adolescents younger than 15 years decreased from 838 in 1989–91 to 503 in 1999–2000. The visit-based rate decreased from 330 antimicrobial prescriptions per 1,000 office visits to 234. For the five major diagnoses of respiratory tract infections, the population-based prescribing rate decreased from 674 to 379 per 1,000 children and adolescents younger than 15 years, and the visit-based from 715 to 613 prescriptions per 1,000 office visits. Both population-based and visit- based prescribing rates decreased for pharyngitis and upper respiratory tract infection; however, for otitis media and bronchitis, declines were only observed in the population-based rate. This indicates that fewer visits were made because of bronchitis and otitis media, but those who consulted were prescribed antibi- otics as often as before. Prescribing rates for sinusitis remained stable.

Antibiotic Use in the Community 577 In the same report, similar trends were found for children ⬍5 years old,

as for those ⬍15 years old (McCaig et al. 2002). The overall prescribing decreased by 40%, from 1,422 antimicrobial prescriptions per 1,000 children younger than five years in 1989–90 to 851 in 1999–2000. A similar decreasing trend was also found for the five respiratory tract infections combined (otitis media, pharyngitis, bronchitis, sinusitis, and upper respiratory tract infection) between 1989–90 and 1999–2000, representing a decrease of 43%, from 1,184 to 678 antimicrobial prescriptions per 1,000 children. Antibiotic prescribing decreased between 1989–90 and 1999–2000 for all five included respiratory tract infections; for otitis media (42% decrease, from 722 to 418), pharyngitis (51% decrease from 224 to 109), bronchitis (71% decrease from 112 to 32), and upper respiratory tract infections (40% decrease from 120 to 72). In this study, it was not possible to link diagnosis to a particular drug.

4.3. Canada

Information on indications was retrieved from The Drug Information Network, a prescription database, which reflects drug use for the Manitoba population. For new cases of upper respiratory tract infection or pharyngitis, an antibiotic was recorded for 57% of urban patient encounters and for 73% of rural patient encounters (Carrie et al., 2000). For sinusitis the most prescribed antibiotics was doxycycline (21%), amoxicillin–clavulanate (18%), and cefa- clor (15%). For bronchitis, the most prescribed antibiotics was amoxicillin (18%), followed closely by roxithromycin (16.5%) and cefaclor. In urinary tract infections TMP-SMZ (28.5%) was most commonly prescribed, followed by cephalexin (18.9%), and amoxicillin–clavulanate (17.2%).

4.4. Australia

Diagnoses for which patients were prescribed antibiotics were obtained from a survey, based on a sample of 420 general practitioners, stratified in line with the total population by age, location, and practice size (McManus et al., 1997). In 1995, for sinusitis, the most prescribed antibiotics were tetracycline (21%), amoxicillin–clavulanate (18%), and cefaclor (15%). For otitis media, the most prescribed antibiotics were cefaclor (36%), amoxicillin (21%), and amoxicillin–clavulanate (21%) and for bronchitis, amoxicillin (18%) was followed by roxithromycin (17%) and cefaclor (15%). In urinary tract infec- tions, trimethoprim-sulfamethoxazole (29%) was most commonly prescribed followed by cephalexin (19%), and amoxicillin–clavulanate (17%).

578 Sigvard Mölstad and Otto Cars