Abstract: Failure to intensify medication and failure to adhere to medication have been shown to contribute to suboptimal low-density lipoprotein cholesterol goal attainment. To examine whether nonadherence to statins in 126,903 patients on stable statin therapy is associated with subsequent treatment intensification, we conducted a retrospective analysis using an integrated pharmacy and medical claims database. Pharmacy claims were analyzed to determine whether nonadherence, as measured by proportion of days covered on statins <80%, was associated with intensification of statin treatment over a 360-day follow-up. Of 11,361 patients who had treatment intensification, 44% were previously nonadherent to statins. Patients whose treatment was intensified had slightly lower adherence to statin therapy than those without intensification (76% vs 78%, p <0.0001) and were more likely to be nonadherent as defined by proportion of days covered <80% (44% vs 37%, p <0.0001). After controlling for confounding factors, patients nonadherent to statins were 30% more likely to have treatment intensification compared to adherent patients (odds ratio 1.30, 95% confidence interval 1.25 to 1.36). In addition, patients with statin intensification were more likely to be younger, women, and have coronary artery disease, diabetes, hypertension, dyslipidemia, stroke, peripheral arterial disease, heart failure, or depression. Primary care physicians were more likely to escalate therapy than cardiologists. In conclusion, nearly 1/2 of patients with therapy escalation were nonadherent to statins. Clinicians should inquire about adherence and consider adherence before escalating statin therapy.