Co-prescribing of topical and systemic beta-blockers in patients with glaucoma: a quality use of medicine issue in Australian practice.

PURPOSE: Prescribing topical beta-blockers for patients with glaucoma, who are also being treated with systemic beta-blockers, raises efficacy and safety concerns. This potentially inappropriate co-prescribing practice is a Quality Use of Medicine issue. This study aimed to quantify the extent of co-prescribing of topical and systemic beta-blockers in Australian clinical practice.
METHODS: This is a retrospective analysis of de-identified billing data for supply (surrogate marker for prescribing) of topical and systemic beta-blockers from the Pharmaceutical Benefits Scheme (1999-2004) to concessional patients supplied either topical or systemic beta-blockers. The primary outcome was the percentage of patients supplied systemic beta-blockers within the patient population supplied topical beta-blockers. This percentage was calculated for each financial year (July 1999-June 2004), age group (<65 years; 65-74 years; 75-84 years; > or =85 years) and sex.
RESULTS: Approximately 20% of patients supplied topical beta-blockers (representing Australian glaucoma patients) were also supplied systemic beta-blockers, equating to more than 20 000 patients per year. This percentage varied with age, but not with year or sex. The percentage of patients co-supplied topical and systemic beta-blockers was the lowest (13%) for patients <65 years and the highest (23%) for patients 75-84 years.
CONCLUSIONS: Pharmaceutical Benefits Scheme supply data shows that the potentially inappropriate practice of co-prescribing topical and systemic beta-blockers affects more than 20 000 concessional patients in Australia each year, particularly the elderly. This Quality Use of Medicine issue has now been quantified; doctors, pharmacists and patients must be made aware of the reduced efficacy and potential for more side-effects from this co-prescribing practice.