Clinical consequences of generic substitution of lamotrigine for patients with epilepsy
Bibliographic record
Abstract
OBJECTIVES: To measure the proportions of patients switching from generic to branded drugs among users of antiepileptic drugs (AED) compared to other therapeutic areas and to investigate medical services utilization associated with generic switching of lamotrigine. METHODS: Medical and pharmacy claims data from Régie de l'Assurance Maladie du Québec database from April 1998 to July 2006 were used. Patients with an epilepsy diagnosis (International Classification of Diseases-9 345) and treated with lamotrigine for >60 of the 90 days before the entry date of generic lamotrigine in Quebec (February 1, 2003) were selected. The proportion of patients switching back to brand were calculated for lamotrigine, for other AEDs (clobazam, carbamazepine CR, gabapentin) and for non-AED chronic medications (carvedilol, fosinopril, simvastatin). Medical resource utilization was compared between periods of branded vs generic use of lamotrigine. RESULTS: Of 671 patients treated with branded lamotrigine, 187 patients (27.9%) switched to a generic, and 51 of these patients (27.5%) switched back to the branded medication. Rates of switchback were from 20.8% to 44.1% for various AEDs and from 7.7% to 9.1% for non-AEDs. Relative to the branded lamotrigine use period, generic lamotrigine use period was associated with a 5.1% increase in mean daily dose of lamotrigine (239.1 vs 251.4 mg; p = 0.0149), a higher number of dispensations for other AEDs (20.4 vs 23.9 dispensations per person-year; p < 0.001) as well as non-AED drugs (26.4 vs 32.8 dispensations per person-year; p < 0.0001), a higher utilization rate of medical services (8.7 vs 9.8 visits per person-year; p < 0.0001), and a longer hospital length of stay (3.29 days vs 4.86 days per person-year; p < 0.0001). CONCLUSION: A higher propensity to switch back to branded medications was observed among antiepileptic drug users compared to users of antihypertensives and antihyperlipidemics, similar to findings from Andermann et al. Switch to generic lamotrigine was significantly associated with increased physician visits and hospitalizations.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".