Low myopathy rates associated with statins as monotherapy or combination therapy with interacting drugs in a group model health maintenance organization.
OBJECTIVE
Because the risk for myopathy increases when 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) are used with other agents known to inhibit cytochrome P450 3A4 in patients with dyslipidemia, we sought to quantify this risk in a diverse, real-world sample of patients receiving statin therapy.


METHODS
Retrospective chart review.


METHODS
Kaiser Permanente Colorado (KPCO), a group model health maintenance organization with approximately 360,000 members.


METHODS
Four hundred sixty-eight patients who were identified as having a diagnosis of myopathy over a 4-year period using KPCO computerized data systems.


RESULTS
Medical records were reviewed to confirm myopathy cases associated with statin therapy. Of the 468 patients, 61 had received statin therapy before their diagnosis, and 41 (67%) of these patients had confirmed myopathy (documented creatine kinase level>or=1000 IU/L). The prevalence of myopathy was 0.12% with statin monotherapy and 0.22% with statins in combination with interacting drugs. Only 17 of the 41 (41%) patients had confirmed myopathy with no other plausible clinical explanation, such as a muscle injury. Increased risk of myopathy associated with statin therapy in combination with interacting drugs approached statistical significance (p=0.052) but was of minimal clinical significance.


CONCLUSIONS
The prevalence of confirmed myopathy in patients receiving statin therapy is low (<1%). Combining statin therapy with interacting drugs (e.g., fibrates) was not associated with a clinically important increase in the prevalence of myopathy. The risk of developing myopathy during statin therapy is outweighed by the benefits derived from the therapeutic effects of the therapy.
Shanahan
Roberta L
RL
Anticoagulation and Cardiac Risk Service, Westminster Primary Care, Longmont, Colorado 80305, USA. roberta.shanahan@kp.org
Kerzee
Jane A
JA
Sandhoff
Brian G
BG
Carroll
Nikki M
NM
Merenich
John A
JA
D000328:Adult; D000368:Aged; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D004357:Drug Synergism; D005260:Female; D006279:Health Maintenance Organizations / Q000706:statistics & numerical data*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D006949:Hyperlipidemias / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000139:chemically induced / Q000453:epidemiology*; D019338:Polypharmacy; D012189:Retrospective Studies
D065607:Cytochrome P-450 Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A