Letter to the Editor
The Hong Kong Practitioner VOLUME 24 / December 2002

Antibiotic wastage costs in Hong Kong
K F Lam 林國輝，T P Lam 林大邦

Dear Editor,

Upper respiratory tract infections (URTIs) are the commonest condition for patients to attend their family doctors in Hong Kong.1 Despite ample evidence from the literature that antibiotics are of limited benefits for URTIs,2,3 they are still frequently prescribed.4,5

In our August - December 2001 survey of 1233 members of the Hong Kong College of Family Physicians on their use of antibiotics in URTI patients, 801 responded with a response rate of 65.0%.6 Twenty-two percents of the respondents felt that they might be prescribing antibiotics too often for URTIs. On average, they attended to 21.46 URTI patients per day, with a standard error of 1.11.

There are many disadvantages associated with inappropriate drug therapy for example antibiotic resistance, drug allergy and psychological dependency on pharmacological treatment for an otherwise self-limiting condition. Another concern is drug costs. We therefore attempt to estimate the drug costs due to inappropriate use of antibiotics on URTI patients in Hong Kong. In order to do that, we have to make several conservative assumptions:

(a)

there are 3500 primary care doctors who regularly attend to URTI patients,

(b)

only a quarter of the URTI patients were prescribed antibiotics inappropriately by those doctors who felt that they might prescribe too often for URTIs, and zero patients were prescribed inappropriately by the remaining 78% of the doctors,

(c)

only two days antibiotics were prescribed by the doctor on each visit (as this is still the most common practice),

(d) all the antibiotics were obtained at discounted prices such as those obtained by Hospital Authority.7

Since various antibiotics are prescribed for URTI, we therefore carried out the following calculations based on different costs:

(1)

Amoxycillin $0.3 per 250mg capsule If each patient is prescribed 3 capsules per day, the estimated wastage is 6 capsules per visit for a quarter of the URTI patients seen by 22% of 3500 doctors who see an average of 21.46 URTI patients per day.

$0.3 x 6 x 0.25 x 0.22 x 3500 x 21.46 x 365 = $2.714 Million per year with a standard error of $0.140 Million.

 

(2)

Cotrimoxazole (Septrin) $0.2 per 480mg tablet

Suppose each patient is prescribed 4 tablets per day, the estimated wastage would be $2.413 Million per year with a standard error of $0.125 Million.

 

(3)

Augmentin $3.8 per 375mg tablet

Suppose each patient is prescribed 3 tablets per day, the estimated wastage would be $34.379 Million per year with a standard error of $1.778 Million.

We admit these figures provide only a rough guide on the drug costs and may represent huge underestimates due to for example, higher drug costs, higher ratio of inappropriate use of antibiotics for URTI patients and higher percentage of doctors who may prescribe antibiotics inappropriately. They nevertheless provide some information on the scale of the problem.

K F Lam, PhD
Department of Statistics and Actuarial Science.

T P Lam, MFM, PhD, FHKAM(Family Medicine)
Family Medicine Unit,
Department of Medicine,
The University of Hong Kong.



References

1.

Lee A, Chan KKC, Wun YT, et al. A morbidity survey in Hong Kong 1994. HK Pract 1995;17(6):246-255.

2. Finkelstein JA, Metlay JP, Davis RL, et al. Antimicrobial use in defined populations of infants and young children. Arch Pediatr Adolesc Med 2000;154(4):395-400.
3. Gonzales R, Bartlett JG, Besser RE, et al. Principles of appropriate antibiotic use for treatment of non-specific upper respiratory tract infections in adults: background. Ann Intern Med 2001;134(6):490-494.
4. Arroll B, Goodyear-Smith F. General practitioner management of upper respiratory tract infections: when are antibiotics prescribed? N Z Med J 2000;113(1122):493-496.
5. Wang EE, Einarson TR, Kellner JD, et al. Antibiotics prescribing for Canadian preschool children: evidence of overprescribing for viral respiratory infections. Clin Infect Dis 1999;29(1):155-160.
6. Lam TP, Lam KF. Why do family doctors prescribe antibiotics for upper respiratory tract infection? Int J Clin Pract In press.
7. Queen Mary Hospital, Drug Formulary, 1999-2000.