Intensive statin therapy (IST) has been shown to decrease cardiovascular events in patients with acute coronary syndrome (ACS). Numerous studies have described statin use for secondary prevention; however, few data have highlighted IST use after ACS. The objective of the present study was to describe IST use in an ACS population before hospitalization, on discharge, and during early follow-up after discharge. A retrospective chart review was conducted of randomly selected patients admitted to a tertiary care center from November 1, 2007 to October 31, 2008. Eligible patients included adults admitted to cardiology with a most responsible diagnosis of ACS ( International Classification of Diseases code 20-25). The exclusion criteria included transfer to another hospital or cardiovascular surgery ward and in-hospital death. Phase 1 included an inpatient chart review. Phase 2 was a follow-up cardiologist clinic letter review that included only patients who started IST in-hospital. Of 234 charts reviewed, 111 (47%) patients met the inclusion criteria (mean age 65 ± 11.7 years, 76% men). Most patients (93%) were discharged with a statin. However, although 72% of the study population were eligible for IST, only 52% had IST during hospitalization. Of the patients who started IST with clinic letters available (n = 31), 68% continued IST (mean interval to follow-up 85 days, range 33 to 208). In conclusion, although statin use is good, IST use after ACS is suboptimal. Additionally, newly initiated IST demonstrates poor persistence after discharge.
Statins are a well-established treatment modality in the secondary prevention of cardiovascular disease. More recently, intensive statin therapy (IST) or high-dose therapy has been shown to improve the outcomes in patients with acute coronary syndromes (ACS). IST after ACS, compared to either placebo or low-dose statin therapy, has been shown to decrease cardiovascular events, myocardial infarction, and all-cause mortality by 11% to 16%, 17%, and 25% respectively. However, an increase in adverse effects and discontinuation rates has also been reported. Data has shown that chronic statin therapy is often underused in patients with ACS. Only 50% to 86% of patients with ACS are discharged with statin therapy. Limited reports have described the use and tolerability of IST in patients after ACS in a “real world” setting; therefore, the objective of the present study was to describe the practice patterns of IST use in an ACS population.
Methods
The present study was a retrospective chart review of randomly selected patients with ACS admitted to the University of Alberta Hospital (Edmonton, Alberta, Canada) from November 1, 2007 to October 31, 2008. Patient charts were identified by medical records according to the International Classification of Disease codes and numbered sequentially. Charts were selected using a random sequence generator and assessed for eligibility by 1 study investigator. Eligible patients were ≥18 years old and were admitted to any cardiology ward with a most responsible diagnosis of ACS ( International Classification of Disease code 20–25). The exclusion criteria included transfer to another hospital or cardiovascular surgery ward and in-hospital death. There were 2 study phases. Phase 1 included all eligible patients with ACS and characterized statin use before and at discharge from the hospital. Phase 2 included only patients in whom IST had been started in the hospital, continued at discharge, and then was able to be assessed after discharge. One investigator, using standardized data collection forms and definitions, performed data abstraction from the inpatient medical record (phase 1) and cardiology follow-up clinic letters (phase 2).
In the present study, IST was defined as atorvastatin 80 mg/day or simvastatin 80 mg/day according to the Myocardial Ischemia Reduction with Aggressive Cholesterol Lowering (MIRACL), Pravastatin or Atorvastatin Evaluation and Infection Therapy–Thrombolysis in Myocardial Infarction 22 (PROVE–IT–TIMI 22), and A to Z studies. Rosuvastatin 20 or 40 mg/day was not included in the definition of IST because of a lack of published data for the use of rosuvastatin in this clinical ACS setting. IST eligibility was determined by comparing the patients with ACS to selected exclusion criteria used in the MIRACL, PROVE–IT–TIMI 22, and A to Z studies. The selected criteria reflected the potential safety concerns with IST. Patients were deemed not eligible for IST initiation on admission if 1 of the following was present: concomitant therapy with agents increasing the risk of myopathy (fibrates, cyclosporine, clarithromycin, erythromycin, ketoconazole, itraconazole, fluconazole, amiodarone, verapamil, diltiazem), creatinine >177 μmol/L (2.0 mg/dl), alanine aminotransferase >2 times the upper limit of normal, a documented statin adverse reaction before admission, or current use of other lipid-lowering agents (i.e., niacin or fibrate).
The present study was a descriptive study of statin practice patterns and tolerability. Univariate logistic regression analysis was performed to determine whether there were independent predictors of IST initiation. The independent predictors selected included gender, age, secondary prevention, high risk, previous statin use, concomitant therapy increasing myopathy risk, and low-density lipoprotein (LDL) level. Statistical analysis was performed using Microsoft Excel 2003 (Microsoft, Redmond, Washington) and the Statistical Package for Social Sciences (SPSS, Chicago, Illinois). The primary end point was the percentage of IST study criteria-eligible post-ACS patients discharged with newly initiated IST. The secondary end points included the percentage of patients not receiving statin therapy or IST after ACS at cardiology admission and discharge, the percentage of patients with ACS newly prescribed IST continuing with IST at follow-up, and the percentage of patients with follow-up laboratory test results (liver function tests [LFTs], creatinine kinase, fasting lipid panel) after discharge.
Results
Of 1,112 charts identified by medical record review in the selected study period, 234 were randomly selected, representing a 20% convenience sample. Of the 234 charts screened, 111 patients (47%) met the phase 1 inclusion criteria. The most common reason for exclusion was that ACS was not the most responsible diagnosis (n = 39; Figure 1 ) . Of those patients discharged with newly initiated IST (n = 46), 31 patients (67%) had cardiologist clinic letters available and were eligible for phase 2 ( Figure 1 ).
The baseline patient characteristics as documented in the admission history are listed in Table 1 . The mean age was 65 ± 11.7 years, and 69% of the study population were men. The most common discharge diagnosis was non–ST-segment elevation myocardial infarction (38.7%), and the 2 most common cardiovascular risk factors on admission were dyslipidemia (70.3%) and hypertension (68.5%). Before the current ACS admission, 50% of the patients were considered in secondary prevention. At baseline 47% of patients were already receiving statin therapy. The statin use patterns at admission and discharge are listed in Table 2 . Most patients were not receiving a statin on admission but were discharged with statin therapy. Atorvastatin 80 mg was the only IST used in the present study sample.
| Characteristic | Value |
|---|---|
| Men | 76 (69%) |
| Mean ± SD age (years) | 64.8 ± 11.7 |
| Non–ST-segment elevation myocardial infarction | 43 (39%) |
| ST-segment elevation myocardial infarction | 35 (32%) |
| Unstable angina pectoris | 20 (18%) |
| Undifferentiated acute coronary syndrome | 13 (12%) |
| Dyslipidemia ⁎ | 78 (70%) |
| Hypertension ⁎ | 76 (69%) |
| Current or past smoker | 63 (57%) |
| No risk factors | 1 (1%) |
| Coronary artery disease | 53 (48%) |
| Diabetes mellitus | 33 (30%) |
| Chronic kidney disease | 15 (14%) |
| Stroke/transient ischemic attack | 8 (7%) |
| Peripheral artery disease | 4 (4%) |
| No cardiovascular condition | 39 (35%) |
| High risk † | 72 (69%) |
| Secondary prevention ‡ | 56 (50%) |
| Cardiovascular medication | |
| Antiplatelet and/or warfarin | 71 (64%) |
| Angiotensin converting enzyme inhibitor/angiotensin receptor blocker | 61 (55%) |
| Previous statin | 52 (47%) |
| Atorvastatin 10 mg | 6 (5%) |
| Atorvastatin 20 mg | 8 (7%) |
| Atorvastatin 40 mg | 9 (8%) |
| Atorvastatin 80 mg | 7 (6%) |
| Atorvastatin (no dose recorded) | 2 (2%) |
| Simvastatin 10 mg | 1 (1%) |
| Simvastatin 20 mg | 2 (2%) |
| Simvastatin 40 mg | 5 (5%) |
| Simvastatin (no dose recorded) | 1 (1%) |
| Rosuvastatin 5 mg | 5 (5%) |
| Rosuvastatin 10 mg | 3 (3%) |
| Rosuvastatin 40 mg | 1 (1%) |
| Pravastatin 20 mg | 1 (1%) |
| Pravastatin 40 mg | 1 (1%) |
| β Blocker | 51 (46%) |
| Calcium channel blocker | 28 (25%) |
| None | 28 (25%) |
⁎ Defined per chart documentation of condition.
† Chronic kidney disease and/or diabetes mellitus, coronary artery disease, stroke or transient ischemic attack, or peripheral vascular disease.
‡ Coronary artery disease and/or stroke/transient ischemic attack, or peripheral vascular disease.
| Statin Use | IST | No IST | No Statin |
|---|---|---|---|
| Before admission ⁎ | 7 (6%) | 45 (41%) | 59 (53%) |
| Mean atorvastatin equivalent dose (mg) | 80 | 25 | NA |
| At discharge | 53 (48%) | 50 (45%) | 8 (7%) |
| Mean atorvastatin equivalent dose (mg) | 80 | 33 | NA |
⁎ Assumed that 3 patients without doses documented before admission were in no IST group.
A total of 104 patients were assessed for IST eligibility on admission. Of the study population, 74 (72%) were eligible for IST when admitted; however, only 54 (52%) were discharged with newly initiated IST during hospitalization. Of those not eligible for IST at admission, 7 (24%) were started with IST during hospitalization. The most common reasons for ineligibility included therapy with agents increasing the risk of myopathy (n = 14), documented statin adverse drug reaction before admission (n = 11), and concomitant use of niacin or fibrates (n = 9). The only significant predictor of IST initiation was age <63 years (odds ratio 2.7, 95% confidence interval 1.2 to 5.8; Table 3 ).
| Independent Predictors of Intensive Statin Therapy Initiation | Odds Ratio (95% CI) |
|---|---|
| Age <63 years | 2.7 (1.2–5.8) |
| Men | 1.9 (0.8–4.3) |
| Secondary prevention | 0.6 (0.3–1.2) |
| High risk | 0.5 (0.2–1.1) |
| Previous statin | 0.7 (0.3–1.6) |
| Concomitant therapy increasing myopathy risk | 2.5 (0.6–10.6) |
| Low-density lipoprotein | |
| 2.1–3.4 mmol/L (81–132 mg/dl) | 1.1 (0.4–3.0) |
| ≥3.5 mmol/L (135 mg/dl) | 1.9 (0.6–3.0) |
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