Prescriber adoption of newly approved selective COX-2 inhibitors

There is no consistent definition of prescribers who adopt new drug treatments early. This study examines if COX-2 inhibitors (coxibs) were prescribed by subsets of practitioners and describes GP adoption patterns of coxibs and existing NSAIDs over time.

A population-based drug utilisation study using a Dutch medication claims database. Prescribers of patients (18+yrs) prescribed an NSAID January 1999-December 2003 were identified. Four NSAID categories were chosen reflecting selectivity (coxibs, preferential COX-2 inhibitors and non-selective (ns) NSAIDs (sub-categorised as first or second line treatment)). The characteristics of prescribers issuing>10 prescriptions examined were: Type (GP, Specialist, Other); GP NSAID prescribing preference ratio (nsNSAIDs/coxib first prescription); coxib (ratio<3); prescriber proportion responsible for 100%, 80% and 50% of initiations. Odds Ratios (95%CI) were calculated (first-line nsNSAIDs as reference). Plots of prescribing proportions by quarter year were examined.

NSAID cohorts comprised: first-line ns (N=38783); second-line ns (N=1459); COX-2 preferential (N=3107); coxib (N=4202) patients. For all four cohorts, GPs were the most common prescriber type (>67%); the most frequent prescribing preference was for first-line nsNSAIDs; 50% percentile prescribing proportions were low (<9%). GPs were equally as likely to prescribe coxibs as first-line nsNSAIDs [OR 1.0 (0.9, 1.1)]. Plots of 100% prescriber proportion for first-line nsNSAIDs and coxibs showed convergence; 50th percentile prescriber proportions plots were constant.

Small subsets of prescribers accounted for the majority of initiations regardless of NSAID type. Further studies are needed on such prescribers to inform healthcare policies and encourage participation in post-marketing safety studies.