Measurement of changes in antihypertensive drug utilisation following primary care educational interventions.

PURPOSE: To measure changes in drug utilisation following a national general practice education program aimed at improving prescribing for hypertension. METHODS: A series of nationally implemented, multifaceted educational interventions using social marketing principles focusing on prescribing for hypertension, was commenced in October 1999, and repeated in September 2001 and August 2003. The target group was all primary care prescribers in Australia and interventions were both active (voluntary) and passive. Newsletter and prescribing feedback was mailed in October 1999, September 2001 (newsletter only) and August 2003. Approximately a third of general practitioners (GPs) in Australia undertook at least one active educational activity (clinical audit, educational visit or case study) during the period October 1999-April 2004. National dispensing data from 1996 to 2004 were analysed using time series methodology with a decay term for intervention effect, to assess trends in prescribing of various classes of antihypertensives. In particular, the program aimed to increase the prescribing of thiazide diuretics and beta blockers. RESULTS: Consistent with key intervention messages, the program achieved an increase in low-dose thiazide and beta blocker prescribing. The rate of prescribing of low-dose thiazides doubled from 1.1 per 1000 consultations in October 1999 to 2.4 per 1000 in October 2003. Beta-blocker utilisation showed a more modest but significant increase over the time of the study, with the change in observed versus expected rate of prescribing increasing by 8% by April 2004. Therapeutic options for treating hypertension changed markedly in the time of the study with the advent of ACE inhibitor/Angiotensin II receptor antagonists and thiazide combination products. It is important, therefore, to interpret the results in light of these changes. CONCLUSION: A national education program aimed at GPs was successful in improving prescribing for hypertension. Lessons learned will be applied in evaluation of future NPS programs and are also applicable to analysis of other interventions aimed at influencing prescribing behaviour.

Measuring change in prescription drug utilization in Australia.

PURPOSE: The National Prescribing Service Ltd (NPS) aims to improve prescribing and use of medicines consistent with evidence-based best practice. This report compares two statistical methods used to determine whether multiple educational interventions influenced antibiotic prescription in Australia. METHODS: Monthly data (July 1996 to June 2003) were obtained from a national claims database. The outcome measures were the median number of antibiotic prescriptions per 1000 consultations for each general practitioner (GP) each month, and the mean proportion (across GPs) of each subgroup of antibiotics (e.g. roxithromycin) out of nine antibiotics having primary use for upper respiratory tract infection. Two approaches were used to investigate shifts in prescribing: augmented regression, which included seasonality, autocorrelation and one intervention; and seasonally adjusted piecewise linear dynamic regression, which removed seasonality prior to modelling, included several interventions, GP participation and autocorrelated errors. Both methods are variations of piecewise linear regression modelling. RESULTS: Both approaches described a similar decrease in rates, with a non-significant change after the first intervention. The inclusion of more interventions and GP participation made no difference. Using roxithromycin as an example of the analyses of proportions, both approaches implied that after the first intervention the proportion decreased significantly. The statistical significance of this intervention disappears when other interventions are included. CONCLUSIONS: The two analyses provide results which agree regarding the possible impact of the NPS interventions, but raise questions about what is the best way to model drug utilization, particularly regarding whether to include all intervention terms when they belong to an extended roll-out of related interventions.

Lessons from early large-scale adoption of celecoxib and rofecoxib by Australian general practitioners.

OBJECTIVE: To assess trends in the first two years of prescribing of COX-2-selective non-steroidal anti-inflammatory drugs (C2SNs) by Australian general practitioners. DESIGN: Retrospective analysis of deidentified electronic patient records from GPs enrolled in the General Practice Research Network (GPRN). SETTING AND PARTICIPANTS: Overall prescription rates for C2SNs and NSAIDs were assessed for all GPRN participants (437 GPs) between 1 September 1999 and 30 September 2002. Also, three cohorts of patients, with at least 12 months of prescription data, who received their first prescription for celecoxib between August and October 2000 (Cohort 1, 2366 patients), celecoxib between February and April 2001 (Cohort 2, 640 patients), and rofecoxib between February and April 2001 (Cohort 3, 608 patients) were selected for further analysis. MAIN OUTCOME MEASURES: Age and sex of patients; reason for prescription; previously prescribed pain medications and concomitant use of medications that could predispose to an adverse renal or bleeding event. RESULTS: Prescriptions for C2SNs increased dramatically after they were listed on the Pharmaceutical Benefits Scheme (PBS). C2SN prescriptions for patients aged less than 65 years accounted for 52.6%, 59.5% and 50.7% of those in Cohorts 1, 2 and 3, respectively; large numbers of patients in the study cohort had reasons recorded for prescription that did not comply with PBS restrictions, and between 36.7% and 61.3% of patients in the three cohorts had not received a prescription for any pain medication in the year before being prescribed a C2SN. Between 4.7% and 7.9% were coprescribed drugs that could cause renal complications. CONCLUSIONS: Rapid, early adoption of C2SNs by Australian GPs has resulted in prescribing and drug use patterns that were not in accord with quality use of medicine (QUM) principles.