Linking community pharmacy dispensing data to prescribing data of general practitioners

BACKGROUND: Databases are frequently used for pharmacoepidemiological research. However, most of these databases consist either of prescribing, dispensing or administrative data and therefore lack insight in the interaction between the several health professionals around the patient. METHODS: To determine the success rate of linking records from the dispensing database of the Foundation for Pharmaceutical Statistics to the prescribing database of the second Dutch national survey of general practice, conducted by NIVEL (Netherlands Institute for Health Services Research), a deterministic record linkage approach was used with patient and prescription characteristics as matching variables between the two databases. RESULTS: The catchment area included 123 community pharmacies, 90 GP practices and approximately 170,000 unique patients. Overall 110,102 (64.8%) unique patients were linked using the matching variables patient's gender, year of birth, the 4-digit part of the postal code, date of dispensing/prescribing and ATC-code. The final database contains of the 110,102 both prescribing data from 83 GP practices and dispensing data of 112 community pharmacies. CONCLUSION: This study shows that linkage of dispensing to prescribing data is feasible with a combination of patient characteristics, such as gender, year of birth and postal code, and prescription characteristics like prescription date and ATC-code. We obtained a linkage proportion of 64.8% resulting in complete prescribing and dispensing history of 110,102 patients. This offers an opportunity to gain insight in the mechanisms and factors influencing drug utilisation in general practice

Is new drug prescribing in primary care specialist induced?

<p>Abstract</p> <p>Background</p> <p>Medical specialists are often seen as the first prescribers of new drugs. However, the extent to which specialists influence new drug prescribing in primary care is largely unknown.</p> <p>Methods</p> <p>This study estimates the influence of medical specialists on new drug prescribing in primary care shortly after market introduction. The influence of medical specialists on prescribing of five new drugs was measured in a cohort of 103 GPs, working in 59 practices, over the period 1999 until 2003. The influence of medical specialists on new drug prescribing in primary care was assessed using three outcome measures. Firstly, the proportion of patients receiving their first prescription for a new or reference drug from a specialist. Secondly, the proportion of GPs prescribing new drugs before any specialist prescribes to their patients. Thirdly, we compared the time until the GP's first own prescribing between GPs who waited for prescriptions from specialists and those who did not.</p> <p>Results</p> <p>The influence of specialists showed considerable differences among the new drugs studied. The proportion of patients receiving their first prescription from a specialist was greatest for the combination salmeterol/fluticasone (60.2%), and lowest for rofecoxib (23.0%). The proportion of GPs prescribing new drugs before waiting for prescriptions from medical specialists ranged from 21.1% in the case of esomeprazole to 32.9% for rofecoxib. Prescribing new drugs by specialists did not shorten the GP's own time to prescribing.</p> <p>Conclusion</p> <p>This study shows that the influence of medical specialists is clearly visible for all new drugs and often greater than for the existing older drugs, but the rapid uptake of new drugs in primary care does not seem specialist induced in all cases. GPs are responsible for a substantial amount of all early prescriptions for new drugs and for a subpopulation specialist endorsement is not a requisite to initiate in new drug prescribing. This contradicts with the idea that the diffusion of newly marketed drugs always follows a two-step model, with medical specialists as the innovators and GPs as the followers.</p

The trade-off between cardiovascular and gastrointestinal effects of rofecoxib

BACKGROUND: The cyclooxygenase-2 (COX-2) inhibitor rofecoxib was registered in 1999. By 2000, the first reports were published indicating that the agent was possibly associated with an increased risk of myocardial infarction. Since then a surge of data supporting this association has become available. To interpret these data it is essential to ascertain the cardiovascular risk profile of users of rofecoxib relative to other non-steroidal anti-inflammatory drug (NSAID) recipients. OBJECTIVE: To assess differences in cardiovascular risk between starters of rofecoxib versus starters of any other NSAID. SETTING: Data sampled from a representative research network of Dutch general practitioners (GPs) in 2001. DESIGN: New users (starters) of rofecoxib were compared to starters of any other NSAID, unmatched and matched on age, gender, and indication nested in the cohort of the second Dutch National Survey of General Practice. RESULTS: A total of 40.4% of patients starting on rofecoxib had cardiovascular co-morbidity. Patients starting on rofecoxib were twice more likely to have a history of gastrointestinal (GI) morbidity, compared to patients starting on other NSAIDs (OR(adj) = 2.09; 95%CI = 1.65-2.66). These patients were also more likely to have cardiovascular co-morbidity (OR = 1.90; 95%CI = 1.60-2.24) compared to recipients of rofecoxib with no GI co-morbidity. Cardiovascular morbidity was present at the time of rofecoxib exposure in over 61% of carriers of a composite risk profile including age 60 years or older, GI co-morbidity and diagnosis of rheumatoid arthritis and osteoarthritis. CONCLUSIONS: In general, a typical recipient of an NSAID is aged and carrier of a serious cardiovascular risk profile. Selective prescribing of rofecoxib to provide claimed gastroprotection, indirectly and unintentionally resulted in prescribing rofecoxib in a population with high frequencies of cardiovascular morbidities