Suboptimal choices and dosing of statins at start of therapy.
OBJECTIVE
To assess dosing and determinants of the choice of statins among starters of statins.


METHODS
Data were obtained from the PHARMO database comprising pharmacy and linked hospital discharge records of approximately 300 000 subjects in the Netherlands. All new users of statins in 1998 were selected. Patient characteristics and drug regimens were compared between starters of different statins. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using polytomous logistic regression modelling, using the start of simvastatin therapy as reference category.


RESULTS
In 1998, 1738 patients started using simvastatin (41.1%), pravastatin (23.1%), fluvastatin (11.9%), atorvastatin (22.8%) or cerivastatin (1.0%). Compared with starters with simvastatin [mean dose 1.02 +/- 0.39 defined daily doses (DDDs)], starters with pravastatin (1.27 +/- 0.56 DDDs) and atorvastatin (1.43 +/- 0.59 DDDs) received higher doses (P < 0.001), whereas users of fluvastatin (0.78 +/- 0.37 DDDs) and cerivastatin (0.81 +/- 0.30 DDDs) received lower doses (P < 0.001). Patients already using CYP3A4 inhibitors more frequently received fluvastatin (OR = 1.80; 95% CI 1.11, 2.94), metabolized by non-CYP3A4 pathways, and atorvastatin (OR = 1.62; 95% CI 1.06, 2.47), which is metabolized by CYP3A4, than simvastatin. Statin doses were not adjusted when prescribed to patients using CYP3A4 inhibitors.


CONCLUSIONS
Many patients starting statin therapy did not receive a statin of first choice. The coadministration of potentially interacting drugs may have led to a change in statin choice, but not in dosage lowering. These findings suggest that the quality of statin therapy could be improved.
Mantel-Teeuwisse
Aukje K
AK
Department of Pharmacoepidemiology & Pharmacotherapy, Utrecht Institute for Pharmaceutical sciences (UIPS), Utrecht University, Utrecht, the Netherlands. a.k.mantel-teeuwisse@pharm.uu.nl
Klungel
Olaf H
OH
Schalekamp
Tom
T
Verschuren
W M Monique
WM
Porsius
Arijan J
AJ
de Boer
Anthonius
A
D002755:Choice Behavior; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005194:Family Practice; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D017060:Patient Satisfaction; D010818:Practice Patterns, Physicians'; D011787:Quality of Health Care
D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human