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Single-patient trials viable option to assess statin myopathy
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Single-patient “n-of-1” trials may be a feasible approach to assessing statin tolerability in patients with a history of statin-related myalgia whose symptoms are not easily diagnosed, according to recent findings.
In a proof-of-concept study, researchers recruited eight adult participants (mean age, 66 years) via advertisements and referrals from a tertiary care center. Patients included for analysis had a history of hypercholesterolemia for which statin therapy was indicated, statin-related myalgia and no clinically significant creatine kinase elevations within 3 weeks of initiation of open-label statin treatment. Study participants also had a history of prior statin therapy that had been discontinued due to myalgia.
Patients underwent n-of-1 trials of up to 33 weeks, consisting of as many as three double blind statin and placebo treatment pairs, with a 3-week washout period between each consecutive rechallenge pair. Each participant received the statin and dose that had previously been associated with myalgia development in their n-of-1 trial.
The researchers conducted a physical exam and medical history at baseline, and administered questionnaires regarding potential myalgia symptoms. Participants were assessed for myalgia symptoms on a weekly basis via myalgia and symptom-specific visual analog scales, as well as the Brief Pain Inventory Short Form, which includes separate scores for both pain severity and degree of pain interference in daily life. Fasting LDL also was measured and recorded at baseline. Treatment adherence, creatine, creatine kinase, aspartate aminotransferase, alanine aminotransferase and adverse events were assessed at follow-up visits during the course of each trial.
Of the eight patients enrolled, seven completed three treatment pairs and one finished two treatment pairs. Treatment adherence was 92% across all participants. For each single-patient trial, there was no statistically significant difference in myalgia symptoms during statin and placebo treatment. Similar results also were observed regardless of treatment for the symptom-specific or pain interference scores. Patients indicated significantly more pain severity while receiving statin therapy compared with placebo, but the difference was not considered clinically significant.
Five of the participants continued to receive an open-label statin regimen after completing the study, with a median post-trial follow-up of 10 months. Researchers noted an association between statin resumption and improved mean LDL levels (P=.018).
“Our findings show that not all patients developing myalgia during open-label statin treatment have true statin-related myopathy, and that n-of-1 trials may be an effective way to assess statin myopathy in some patients in whom evaluation for the cause of myalgia may be difficult,” the researchers concluded. “… Given the importance of statin-related myalgia, larger studies of n-of-1 trials for this condition that include longer follow-up and comparison with concurrent control groups should be considered.”
Disclosure: See the full study for a list of relevant financial disclosures.
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