Peripheral arterial disease (PAD) is a strong risk factor for cardiovascular morbidity and mortality. Therefore, target low-density lipoprotein (LDL) cholesterol level in patients with PAD is ≤70 mg/dl, similar to patients with coronary artery disease (CAD). However, despite their high cardiovascular risk, patients with PAD less frequently achieve LDL cholesterol goals compared to patients with CAD. We aimed to compare LDL cholesterol control in patients after first coronary or peripheral vascular intervention. Included were patients ≥18 years of age without a history of cardiovascular disease who underwent first coronary or peripheral vascular intervention from 2004 through 2010. Primary end points were percentage of patients who achieved the LDL cholesterol goal of <100 and <70 mg/dl. Of 9,138 patients available for analysis, 7,512 (82.2%) underwent first coronary revascularization and 1,626 (17.8%) underwent first peripheral revascularization. Patients after first coronary revascularization were treated more frequently with any statin and with highly potent statins. Furthermore, they more frequently achieved the LDL cholesterol goals compared to patients after first peripheral intervention. This was true for the LDL cholesterol goal of <100 mg/dl (65% and 46.7%, p <0.0001) and for the lower LDL cholesterol goal of <70 mg/dl (23.3% and 13.3%, p <0.0001). Differences in LDL cholesterol control between the 2 groups remained statistically significant after multivariate adjustment. In conclusion, lipid control in patients with PAD is poor and significantly inferior to that of patients with CAD even after the first vascular intervention.
The population with peripheral artery disease (PAD) is heterogenous, with most patients being entirely asymptomatic and only a minority with serious disabilities requiring revascularization. Because most lipid studies have included patients with the entire clinical spectrum of PAD and many patients with concomitant coronary artery disease (CAD), there are insufficient data regarding lipid control in the specific group of patients with symptomatic PAD and without known CAD after vascular intervention. The aim of this study was to compare lipid-lowering treatment characteristics and low-density lipoprotein (LDL) cholesterol target achievement in patients after first coronary or peripheral vascular intervention.
Methods
The study population consisted of residents of the Sharon-Shomron district who are medically insured by the Clalit Health Services (CHS), the largest health maintenance organization in Israel. CHS insures most of the district population, which is mostly urban. The CHS computerized database was the source of data for our study. All medical information obtained at primary and secondary care clinics is recorded in the database and can be accessed at the level of the individual patient. Each primary care physician is responsible for routinely updating the computerized medical records during each patient visit and after any hospital admission. The database includes a list of all diagnoses, demographic data, laboratory values, medications, and medical procedures.
Included in our study were men and women ≥18 years of age without a history of CAD, cerebral artery disease, or PAD who underwent first coronary or peripheral vascular intervention from January 1, 2004 through December 31, 2010 and had ≥1 full lipid profile available ≥6 months after intervention. In patients with >1 complete lipid panel, the first after ≥6 months was used. Coronary intervention included percutaneous coronary interventions or coronary artery bypass grafting. Peripheral vascular interventions included carotid endarterectomy or stenting and lower limb surgical vascular reconstruction or percutaneous angioplasty. All vascular procedures were performed in regional hospitals and were automatically recorded in the computerized database. Age, gender, cigarette smoking status, diabetes mellitus, hypertension, body mass index (BMI), and current lipid-lowering medications were extracted from electronic medical records.
Primary end points were percentage of patients who achieved the LDL cholesterol goal of <100 mg/dl and percentage of those achieving a LDL cholesterol goal of <70 mg/dl in accord with updated National Cholesterol Education Program guidelines. We also examined the percentage of patients treated with more potent statins (atorvastatin and rosuvastatin), ezetimibe, or niacin. Adherence to medical treatment was assessed by examining the actual collection of medications from the pharmacy. All outcomes were compared in patients who underwent first peripheral versus coronary revascularization procedure.
Measurement of serum lipids was performed on fresh samples in a core laboratory facility. All measured biochemical markers were identified using a BM/Hitachi917 automated analyzer (Boehringer Mannheim, Mannheim, Germany).
The study was approved by the local institutional ethics committee in keeping with the principles of the Declaration of Helsinki. In accordance with ministry of health regulations, the institutional ethics committee did not require written informed consent because data were collected anonymously from computerized medical files, with no active participation of patients.
Study subjects were stratified into 2 groups. The first group included patients after first coronary intervention. The second group consisted of patients after first peripheral vascular intervention. Baseline clinical characteristics of the 2 groups and study outcomes were compared using analysis of variance for continuous variables and chi-square test for nonparametric variables. Multivariate logistic regression analysis methods were applied to control confounding effects using study outcomes as the dependent variable and predictors of age, gender, cigarette smoking, BMI, hypertension, triglycerides, diabetes, medication group, and adherence as independent variables. Statistical analysis was performed using SPSS 19.0 for Windows (SPSS, Inc., Chicago, Illinois).
Results
In total 11,867 patients with first coronary or peripheral revascularization procedure were available for analysis. Of them, 9,302 (78.4%) underwent first coronary revascularization and 2,565 (21.6%) underwent first peripheral vascular intervention. A full lipid profile within 6 months after vascular intervention was available for 7,512 patients (81%) in the CAD group and 1,626 patients (63%) in the PAD group (p <0.001), leaving 9,138 patients available for analysis. Baseline characteristics of the study population are presented in Table 1 . Patients after first coronary revascularization procedure were more frequently men and hypertensive and had higher BMI. Patients with PAD were more frequently current smokers.
| Variable | PAD (n = 1,626) | CAD (n = 7,512) | p Value |
|---|---|---|---|
| Age (years) | 60.1 ± 16.3 | 59.9 ± 13.5 | NS |
| Men | 58.4% | 74.0% | <0.0001 |
| Diabetes mellitus | 25.6% | 27.4% | NS |
| Hypertension | 32.0% | 35.4% | <0.01 |
| Current smokers | 21.8% | 16.8% | <0.01 |
| Body mass index (kg/m 2 ) | 27.2 ± 5.6 | 28.2 ± 4.9 | <0.0001 |
Table 2 presents a comparison of lipid levels of the 2 groups. Patients after first peripheral vascular intervention had a worse lipid profile including higher levels of total and LDL cholesterol and lower levels of high-density lipoprotein cholesterol compared to patients after first coronary intervention. Overall, 5,645 patients (61.8%) achieved the LDL cholesterol goal of <100 mg/dl, whereas only 1,970 (21.6%) achieved the lower LDL cholesterol goal of <70 mg/dl. Patients after first coronary revascularization procedure more frequently achieved LDL goals compared to patients after first peripheral intervention ( Figure 1 ). This was true for the LDL cholesterol goal of <100 mg/dl (65% and 46.7% in patients after first CAD or PAD intervention, respectively, p <0.0001) and for the lower LDL cholesterol goal of <70 mg/dl (23.3% and 13.3%, in patients after first coronary or peripheral intervention, respectively, p <0.0001). Differences in LDL cholesterol control between the 2 groups remained statistically significant even after multivariate adjustment for age, gender, smoking status, diabetes, hypertension, BMI, high-density lipoprotein cholesterol, and triglycerides (p <0.0001 for achieving LDL cholesterol goals <100 and <70 mg/dl).
| Variable | PAD (n = 1,626) | CAD (n = 7,512) | p Value |
|---|---|---|---|
| Total cholesterol (mg/dl) | 182.4 ± 44.0 | 166.6 ± 40.1 | <0.0001 |
| Low-density lipoprotein cholesterol (mg/dl) | 106.6 ± 38.3 | 93.7 ± 32.8 | <0.0001 |
| High-density lipoprotein cholesterol (mg/dl) | 43.7 ± 11.6 | 46.4 ± 13.4 | <0.0001 |
| Triglycerides (mg/dl) | 149.1 ± 96.5 | 144.8 ± 88.9 | 0.14 |
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