Abstract
Among 355 peripheral arterial disease (PAD) patients with low density lipoprotein cholesterol (LDL-C) levels ≥ 70 mg/dl, we assessed knowledge regarding optimal LDL levels and the importance of LDL-C-lowering therapy. We also assessed PAD participants’ behaviors and attitudes regarding their engagement with their physician in treatment decisions for LDL-C lowering. The average baseline LDL-C level of participants was 103.4 mg/dl ± 30.7 mg/dl. Seventy-six percent of participants were taking at least one cholesterol-lowering medication. Sixty-six percent were unable to define their optimal LDL-C. Only 47% strongly agreed that their own actions and decisions could reduce their LDL-C. Just 29.8% were aware that patients who request specific medications from their physician were more likely to receive them, and 16% had asked their physician whether they should be taking more cholesterol-lowering medication. These findings suggest that further study is needed to identify effective interventions to educate PAD patients and their physicians about the importance of cholesterol-lowering therapy and to encourage PAD patients to participate with their physician in decisions regarding cholesterol-lowering treatment.
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Keywords: atherosclerosis, cholesterol, intermittent claudication, peripheral vascular disease
Introduction
Men and women with lower extremity peripheral arterial disease (PAD) have a 1.5 to 2.0-fold increased risk of cardiovascular morbidity and mortality compared to individuals without PAD, even after adjusting for cardiovascular disease risk factors and history of cardiovascular disease.1,2 People with PAD have a comparable risk of future myocardial infarction compared to those with established coronary artery disease.3 Low-density lipoprotein-cholesterol (LDL-C)-lowering therapy significantly lowers cardiovascular morbidity and mortality rates in patients with PAD.4
Recent data from the Lipid Treatment Assessment Project-2 demonstrated that among 9955 patients from nine countries, only 30% of patients at very high risk for cardiovascular events achieved an LDL-C < 70 mg/dl.5 Individuals with PAD are less likely to have their LDL-C levels lowered to optimal levels than individuals with coronary artery disease.6,7 Recent data from the National Health and Nutrition Examination Survey demonstrated lower treatment rates for hypercholesterolemia among individuals with PAD compared to those with coronary disease.8
Both physician and patient factors may contribute to LDL-C undertreatment in PAD.9–11 A national survey demonstrated that primary care physicians and cardiologists believe that LDL-C lowering is less important for patients with PAD than for patients with coronary artery disease.7 A separate study demonstrated that patients with PAD are largely unaware of their increased risk of coronary events or the benefits of LDL-C lowering for patients with PAD.9 Thus, achieving ideal LDL-C levels in patients with PAD may require targeting both PAD patients and physicians caring for them.
Patients’ requests for treatment and attitudes about the importance of treatment are major determinants of physician behavior regarding the prescription of preventive interventions.10–12 However, to our knowledge, no prior studies have assessed PAD patients’ willingness to ask their physician questions about their cholesterol treatment, express their opinion about their cholesterol-lowering therapy, or request more intensive cholesterol-lowering medication. This paper describes the attitudes and knowledge of men and women with PAD about ideal LDL-C levels and the importance of treating LDL-C levels in patients with PAD. We describe PAD participants’ attitudes and behaviors regarding their participation with their physician in decisions regarding LDL-C-lowering therapy.
Methods
Study overview
The institutional review boards of participating sites approved the protocol. All participants gave written informed consent.
Participants were enrolled in a randomized controlled clinical trial conducted at Northwestern University and at the University of Massachusetts Medical School (UMMS). Findings reported here are cross-sectional results from baseline testing.
Recruitment
Recruitment and baseline measures were completed between 1 February 2006 and 30 September 2008. Each study institution pursued recruitment methods that were most fruitful in their respective cities. At Northwestern University, participants were identified from among patients with PAD evaluated in the non-invasive vascular laboratory or relevant clinics at Northwestern’s medical center and other Chicago-area hospitals. Other Chicago recruitment methods included newspaper and radio advertisements, posted signs, community outreach, bulk mailings to community dwelling men and women aged 60 years and older, and letters mailed to participants with PAD identified in the Life Line screening program. PAD participants who completed other research studies at Northwestern more than 3 months previously and indicated a willingness to participate in future research studies were also contacted.
Recruitment methods at UMMS consisted of mailed recruitment letters to patients with PAD identified at the University of Massachusetts Memorial Medical Center. Newspaper advertisements and posted flyers at senior centers in central Massachusetts were employed.
Inclusion and exclusion criteria
Inclusion criteria were the presence of PAD and an LDL-C ≥ 70 mg/dl.13 PAD was defined as one of the following: an ABI < 0.95 at the baseline study visit, a medical record documenting a history of lower extremity revascularization, a lower extremity angiogram demonstrating arterial obstruction ≥ 50% in one or more arteries, or a report from a certified non-invasive vascular laboratory indicating the presence of PAD.
Exclusion criteria (Table 1) consisted of factors that potentially prevented full participation in the intervention of the clinical trial in which participants were enrolled. The intervention phase of the study (not reported here) was designed to help patients with PAD achieve ideal LDL-C levels and increase their physical activity.
Table 1.
Exclusion criteria and the number of potential participants meeting each criterion among those completing a baseline visit (n = 345)
| Exclusion criteria |
|---|
| No peripheral arterial disease (n = 150) |
| Baseline LDL cholesterol < 70 mg/dl (n = 160) |
| Above or below knee amputation (n = 3) |
| Critical limb ischemia as defined by ABI = 0.20 or foot ulcers (n = 1) |
| Dementia as defined by MMSE score < 23 (n = 7) |
| No physician (not having seen a doctor in the previous 1 year) (n = 1) |
| Physician requests participant not participate (n = 1) |
| Life expectancy is thought to be < 1 year (n = 3) |
| Plans to move out of the area within 1 year (n = 1) Unable to have blood drawn (n = 7) |
| Current participation in other clinical trials (n = 2) |
| Any change in dose or type of cholesterol-lowering medication in the past 3 months, including starting a new cholesterol-lowering medication in the past 3 months (n = 7) |
| Cannot tolerate cholesterol-lowering drugs (n = 2) |
LDL, low-density lipoprotein; ABI, ankle–brachial index; MMSE, mini-mental state examination
Ankle–brachial index (ABI) measurement
A hand-held Doppler probe (Nicolet Vascular Pocket Dop II; Nicolet Biomedical Inc., Golden, CO, USA) was used to obtain systolic pressures in the right and left brachial, dorsalis pedis, and posterior tibial arteries. For each leg, the ABI was calculated by dividing the higher of the dorsalis pedis and posterior tibial pressures by the higher of the brachial pressures.
LDL cholesterol
LDL-C was measured using a homogenous direct method. A specific detergent was used to solubilize non-LDL lipoproteins. Another detergent solubilized LDL-C so that its cholesterol component could be measured enzymatically, generating a color reaction.
Measures of PAD participant knowledge, attitude, and behavior regarding cholesterol-lowering therapy
Study measures were health knowledge, self-efficacy regarding the participant’s ability to obtain the most from their physician office visits,14 the Patient Activation Measure (PAM) score,15 self-efficacy regarding participants’ ability to take their cholesterol-lowering medication regularly, and medication adherence behavior.16
Health knowledge questionnaire
A 27-item health knowledge questionnaire was developed to measure participant knowledge regarding the association of PAD with cardiovascular events, the importance of LDL-C lowering for patients with PAD, the ability of patients to influence physician behavior, the ideal LDL-C level, and characteristics of an LDL-C-lowering diet. The questionnaire was developed using cognitive interviewing in patients with PAD, feedback from national experts in PAD, and pilot testing in small groups of patients with PAD.
Self-efficacy questionnaire regarding patient–physician interactions
The Perceived Efficacy in Patient–Physician Interactions (PEPPI) questionnaire is a validated, reliable measure of self-efficacy in patient–physician interactions.14 The PEPPI measures patients’ self-efficacy in obtaining medical information and in focusing physician’s attention on the patient’s medical concerns.14 The questionnaire measures patients’ confidence in their ability to (a) know what questions to ask a doctor; (b) get a doctor to answer all of their questions; (c) make the most of their doctor visit; (d) get a doctor to take their chief health concern seriously; and (e) get a doctor to do something about their chief health concern. Each question is scored on a 0–10 scale, where 0 represents ‘not confident at all’ and 10 represents ‘very confident’.
Patient Activation Measure (PAM)
Patient activation refers to the degree to which patients take responsibility for and have the confidence and knowledge to influence their health care.15 We used the 13-item PAM questionnaire to assess patient activation.15 This questionnaire measures (a) the degree to which patients believe it is important for them to influence their health care; (b) patient confidence in their ability to influence their health care; (c) the degree to which patients take action to influence their healthcare; and (d) patient confidence that they can continue to affect their healthcare, even under stress. The PAM is scored on a 0–100 scale (100 = best).15 Participants were categorized into four stages based on their PAM score as follows: Stage 1 – patient may not yet believe that the patient role is important in influencing physician care; Stage 2 – patient believes the patient role is important but lacks confidence and knowledge to take action toward influencing their care; Stage 3 – patient is beginning to take action; Stage 4 – patient is taking action but has difficulty maintaining behaviors over time.
Ten additional questions were developed to assess participant behavior regarding the degree to which they had attempted to influence their physician’s treatment of their cholesterol during the previous 6 months and their beliefs regarding their role as an active partner in their physicians’ decisions regarding cholesterol-lowering medication (Table 3). These questions were developed using cognitive interviewing and pilot testing in patients with PAD. A 1–5 score was assigned for question responses that ranged from ‘strongly disagree’ to ‘strongly agree’. An average score was calculated for the 5-item questionnaire.
Table 3.
Peripheral arterial disease patients’ beliefs and behaviors regarding their role in discussing their cholesterol levels and treatment with their physician
| During your doctor appointments in the last 6 months did you do the following?: | % responding ‘yes’a |
|---|---|
| Told my doctor … what I think about my cholesterol treatment | 35.9 |
| … I was concerned that my cholesterol level might be too high | 19.1 |
| … that I was willing to increase the amount of cholesterol-lowering medication I was taking | 30.5 |
| or start a new cholesterol-lowering medication if needed | |
| Ask my doctor … questions about my cholesterol treatment | 47.0 |
| …whether I should be taking more cholesterol-lowering medication | 16.0 |
| To what extent do you agree or disagree with the following? | % responding ‘strongly agree’b |
| It is important for me to ask my doctor questions about my cholesterol level | 42.0 |
| It is important for me to express my opinion about my cholesterol treatment to my doctor | 35.3 |
| It is important that I monitor my cholesterol treatment to make sure I get the best care | 42.1 |
| It is my responsibility to bring up my cholesterol treatment with my doctor | 29.6 |
| My own actions and decisions can reduce my cholesterol level | 47.4 |
Other response options were No, Not sure, and Not applicable.
Other response options were Agree, Neutral, Disagree and Strongly disagree.
Adherence questionnaires
The Brief Medication Questionnaire (BMQ) measured adherence to cholesterol-lowering medication.16 The BMQ measures participant-report of the number of days during the previous week that they missed taking cholesterol-lowering medication. The BMQ also measures the degree to which participants perceive that their cholesterol-lowering medication is effective, costly, causes side effects, or is hard to take. To specifically measure a participant’s self-efficacy regarding his or her ability to adhere to cholesterol-lowering medication, six additional questions were developed. Participants were asked to assign a 1–5 score for each question, where ‘1’ indicated ‘not at all confident’ and ‘5’ indicated ‘completely confident’ (Table 5). An average score was calculated for each item.
Table 5.
Behavior of peripheral arterial disease participants regarding cholesterol-lowering medication adherence
| Brief Medication Questionnaire (n = 267)a | |
|---|---|
| Number (%) of participants who missed one or more cholesterol-lowering medications during the past week | 42 (15.7%) |
| Number (%) of participants who report that their cholesterol-lowering medication is very effectiveb | 119 (44.6%) |
| Number (%) of participants who report having side effects from their cholesterol-lowering medicationb | 31 (11.6%) |
| Self-efficacy questions regarding adherence to cholesterol-lowering medication | |
| During the next 6 months, how confident are you that you will … | % responding ‘completely confident’c |
| Take my cholesterol-lowering medication every day | 89.46 |
| … even when my routine is disrupted | 86.50 |
| … even when I am not feeling well | 86.90 |
| … even when I am experiencing muscle aches or joint pains | 85.26 |
| … even when I’m away from home | 89.84 |
| Fill my prescription for my cholesterol-lowering medication as needed, so that I never run out | 90.16 |
Questions limited to the 267 participants taking a cholesterol-lowering medication at baseline.
For participants taking more than one cholesterol medication, data refer to the first medication that the participant listed.
Responses on a 5-point scale were provided, with the lowest value (1) labeled ‘Not at all confident’ and the highest value (5) labeled ‘Completely confident’. Intermediate values were not labeled.
Other measures
Height and weight were measured and the body mass index (BMI) was calculated as weight (kg)/square of height (m2). Participant report was used to collect information on comorbidities, using established methods.17 Cigarette smoking history was measured by self-report.
Statistical analyses
Descriptive statistics were used to provide the mean characteristics of study participants and responses to study questionnaires. Cronbach’s alpha coefficient, a measure of score reliability, was calculated for questionnaire scores based on item sets developed by the investigators for the current study. An alpha coefficient is an estimate of the consistency or reproducibility of the score. Higher values indicate greater consistency. Lower values suggest more error in the measurement. Among participants taking cholesterol-lowering medication, analysis of variance was used to compare mean values for participants’ self-efficacy regarding their cholesterol-lowering medication among those who reported that their LDL-C-lowering medication was very effective versus those who reported that this medication was not very effective.
Results
A total of 893 potential participants scheduled a baseline visit. Of these, 193 did not attend their appointment and 345 were excluded (Table 1), leaving 355 participants. Of these, 209 were recruited in Chicago and 146 in Worcester.
Baseline characteristics of participants
Table 2 shows the characteristics of participants, according to recruitment site. Overall, the average age was 70.6 years ± 10.5, the average ABI was 0.68 ± 0.16, and the mean baseline LDL-C level was 103.4 mg/dl ± 30.7 (range: 70.3–293.4). Two hundred and sixty-seven participants were taking one or more cholesterol-lowering medications (Table 2). As compared to participants recruited in Worcester, those from Chicago were older and included higher prevalences of women and African-Americans. Participants recruited from Chicago were less likely to currently smoke cigarettes, had achieved higher education levels, and had lower prevalences of heart disease compared with those from Worcester. Participants from Chicago had higher levels of LDL-C and high-density lipoprotein-cholesterol (HDL-C), lower levels of triglycerides, and were less likely to be taking a statin medication than participants from Worcester.
Table 2.
Characteristics of participants with peripheral arterial disease (n = 355)
| Baseline characteristic | Overall n = 355 |
Recruited from Chicago, IL n = 209 |
Recruited from Worcester, MA n = 146 |
p-value |
|---|---|---|---|---|
| Age (years) | 70.6 ± 10.5 | 72.0 ± 10.5 | 68.6 ± 10.3 | 0.003 |
| Female | 144 (40.6%) | 96 (45.9%) | 48 (32.9%) | 0.014 |
| African-American ABI | 53 (14.9%) 0.68 ± 0.16 |
49 (23.4%) 0.67 ± 0.17 |
4 (2.7%) 0.70 ± 0.16 |
< 0.001 0.194 |
| Intermittent claudication | 54 (15.2%) | 24 (11.5%) | 30 (20.6%) | 0.019 |
| No exertional leg symptoms (asymptomatic) | 72 (20.3%) | 41 (19.6%) | 31 (21.2%) | 0.710 |
| Atypical exertional leg symptomsa | 193 (54.5%) | 122 (58.4%) | 71 (48.6%) | 0.081 |
| Body mass index (kg/m2) | 29.5 ± 6.2 | 29.8 ± 6.6 | 28.9 ± 5.6 | 0.193 |
| Cigarette smoking status | ||||
| Current smoker | 90 (25.4%) | 45 (21.5%) | 45 (30.8%) | 0.048 |
| Former smoker | 212 (59.7%) | 123 (58.9%) | 89 (61.0%) | 0.690 |
| Highest achieved educational degree | ||||
| Doctorate degree | 10 (2.8%) | 7 (3.4%) | 3 (2.1%) | 0.468 |
| Master’s degree | 32 (9.0%) | 27 (12.9%) | 5 (3.4%) | 0.002 |
| Graduated from college | 51 (14.4%) | 33 (15.8%) | 18 (12.3%) | 0.360 |
| Some college or technical school | 127 (35.8%) | 81 (38.8%) | 46 (31.5%) | 0.161 |
| Graduated from high school | 83 (23.4%) | 37 (17.7%) | 46 (31.5%) | 0.003 |
| Comorbidities Angina |
80 (22.6%) | 32 (15.3%) | 48 (33.1%)b | < 0.0001 |
| History of myocardial infarction | 86 (24.0%) | 38 (18.2%) | 48 (32.9%) | 0.002 |
| Heart failure | 38 (11.0%) | 20 (9.6%) | 18 (12.4%) | 0.404 |
| History of coronary revascularization | 129 (36.4%) | 65 (31.1%) | 64 (43.8%) | 0.014 |
| Hypertension | 283 (79.7%) | 166 (79.4%) | 117 (80.1%) | 0.870 |
| Diabetes mellitus | 91 (25.6%) | 50 (23.9%) | 41 (28.1%) | 0.377 |
| Stroke | 54 (15.2%) | 28 (13.4%) | 26 (17.8%) | 0.255 |
| Cholesterol measurements Total cholesterol (mg/dl) |
183.5 ± 39.8 | 186.1 ± 40.6 | 179.6 ± 38.5 | 0.128 |
| LDL cholesterol (mg/dl) | 103.4 ± 30.7 | 106.4 ± 32.1 | 99.2 ± 28.2 | 0.031 |
| HDL cholesterol (mg/dl) Triglycerides (mg/dl) Taking one or more cholesterol-lowering medication |
51.0 ± 14.1 151.4 ± 87.8 267 (76.0%)c |
52.0 ± 14.8 133.1 ± 68.6 136 (66.0%)c |
49.4 ± 13.0 177.5 ± 104.6 131 (89.7%) |
0.082 < 0.0001 < 0.0001 |
Data are means and standard deviations.
Atypical exertional leg symptoms’ refers to exertional leg symptoms that are not consistent with intermittent claudication. One participant had incomplete data on leg symptoms and could not be classified in any of the leg symptom categories.
Data were available for 145 Worcester participants.
Data were available for 352 participants (206 from Northwestern).
Baseline health knowledge
The mean percentage of items answered correctly on the health knowledge questionnaire was 57.9% ± 18.4. Cronbach’s alpha for the health knowledge questionnaire was 0.84. Twenty-one participants (6%) identified an LDL-C less than 70 mg/dl as an ideal LDL-C value. Thirty-five (10%) indicated that an ideal LDL-C was less than 100 mg/dl and 239 (67%) indicated they could not identify the optimal LDL-C level for patients with PAD. The remainder identified their optimal LDL-C level as between 100 and 300. Ninety-three percent reported that higher cholesterol levels are associated with an increased risk of heart disease and stroke in patients with PAD. Seventy-one percent indicated that high cholesterol is a significant problem for patients with PAD and 71% reported that cholesterol-lowering medication substantially lowers the risk of heart disease and stroke in patients with PAD. Thirty percent reported that patients who request specific medications from their physicians are more likely to receive the requested medication.
Self-efficacy and behavior regarding participation in therapeutic decisions about cholesterol-lowering medication
The mean baseline PEPPI score was 42.9 ± 10.11 out of a maximum score of 50, indicating that participants had relatively high self-efficacy regarding their perceived ability to make the most of their physician visits and obtain the necessary medical care from their physician interactions.
Table 3 shows the results of 10 questions measuring participants’ behaviors and beliefs about their engagement with their physician in decisions about cholesterol-lowering medication therapy. The Cronbach’s alpha was 0.84 for the five questionnaire items about participants’ beliefs in Table 3. Correlation coefficients between the PAM and PEPPI scores, with the mean score for these five questionnaire items, were 0.30 (p < 0.001) and 0.21 (p < 0.001), respectively.
Approximately 30% of participants strongly agreed that it was their responsibility to bring up their cholesterol-lowering therapy with their physician. Forty-seven percent strongly agreed that their own actions and decisions could reduce their cholesterol level. With regard to behavior, 19% of PAD participants indicated that in the last 6 months they had raised concerns about their cholesterol level to their physician and 16% reported asking their physician whether they should be taking more cholesterol-lowering medication (Table 3).
Patient activation measure
The mean PAM score was 60.99 ± 16.19 (maximum score = 100). Seventy-six percent of participants were unaware of the nature and causes of their health condition and 12.8% knew the different medical treatments available for their health condition (Table 4).
Table 4.
Participants’ self-reported activation regarding cholesterol-lowering therapy adherence and their beliefs regarding their role in influencing cholesterol-lowering therapy prescriptions (PAM)
| Activation statement | % responding ‘strongly agree’a |
|---|---|
| When all is said and done, I am the person who is responsible for managing my health condition | 63.3 |
| Taking an active role in my own health care is the most important factor in determining my health and ability to function | 60.6 |
| I am confident that I can take actions that will help prevent or minimize some symptoms or problems associated with my health condition | 43.8 |
| I know what each of my prescribed medications do I am confident that I can tell when I need to go and get medical care and when I can handle a health problem myself |
29.4 28.9 |
| I am confident I can tell my health care provider concerns I have even when he or she does not ask | 44.2 |
| I am confident that I can follow through on medical treatments I need to do at home | 46.3 |
| I understand the nature and causes of my health condition(s) | 24.3 |
| I know the different medical treatment options available for my health condition | 12.8 |
| I have been able to maintain the lifestyle changes for my health that I have made | 20.1 |
| I know how to prevent further problems with my health condition | 14.6 |
| I am confident I can figure out solutions when new situations or problems arise with my health condition | 13.1 |
| I am confident that I can maintain lifestyle changes like diet and exercise even during times of stress | 22.0 |
| PAM scoring by stages of activation | % of participants |
| STAGE 1: (PAM score < 47.0) | 18.9 |
| STAGE 2: (PAM score 47.1–55.1) | 21.4 |
| STAGE 3: (PAM score of 55.2–67.0) | 24.9 |
| STAGE 4: (PAM score > 67.1) | 34.9 |
Other response items were Agree, Disagree, and Strongly disagree.
Stage 1: May not yet believe that the patient role is important.
Stage 2: Lacks the confidence and knowledge to take action.
Stage 3: Beginning to take action.
Stage 4: Attempting to maintain patient activation behavior over time.
Adherence to cholesterol-lowering medication
Table 5 shows findings regarding cholesterol-lowering medication adherence. Among the 267 participants taking one or more cholesterol-lowering medications at baseline, 42 (15.7%) reported missing one or more cholesterol-lowering medications during the previous week (Table 5). Fewer than half believed their cholesterol-lowering medication was very effective.
Six questions developed to assess adherence to cholesterol-lowering medication were consistent with a high adherence rate (Table 5). Cronbach’s alpha for these six questions was 0.94. Correlation coefficients for the mean value of these six questions with the PAM and PEPPI scores were 0.22 (p < 0.001) and 0.28 (p < 0.001), respectively. The average values of these six questions were 4.90 ± 0.38 for participants who indicated that their cholesterol-lowering medication is very effective versus 4.75 ± 0.58 for those who indicated that their cholesterol-lowering medication is not very effective (p = 0.022).
When results in Tables 3–5 were compared between participants from Northwestern University and those from the UMMS, more participants from Northwestern were classified in Stage 3 in the PAM (28.9% vs 19.2%, p = 0.038), fewer participants from Northwestern reported that their cholesterol-lowering medication was very effective (38.2% vs 51.2%, p = 0.034), and more participants from Northwestern reported having side effects from their cholesterol-lowering medication (16.9% vs 6.2%, p = 0.006). No other significant differences between the two sites were identified.
Discussion
Previous studies have documented suboptimal rates of LDL-C-lowering therapy in patients with PAD,6,18 despite the fact that LDL-C-lowering therapy significantly reduces cardiovascular morbidity and mortality in patients with PAD.4 Previous work in other patient populations demonstrates that patients’ requests for therapies are significant determinants of physician prescribing behavior for preventive therapies.10–12 In this report, we document PAD patients’ beliefs and behaviors about influencing their physician’s prescribing practices for cholesterol-lowering medications. Among PAD participants with baseline LDL-C > 70 mg/ dl, 24% were not taking any cholesterol-lowering medications. Sixty-seven percent did not know the ideal LDL-C for patients with PAD. Only 6% of participants identified an ideal LDL-C as < 70 mg/dl, while 10% identified an ideal LDL-C level as < 100 mg/dl. Thus, important knowledge deficiencies exist among individuals with PAD. These knowledge deficiencies must be corrected in order for PAD patients to effectively engage with their physician about, therapies to achieve ideal LDL-C levels.
Data reported here indicate that most PAD patients are not engaging regularly in discussions with their physician regarding their cholesterol-lowering therapy. Few PAD patients strongly agreed that it was their responsibility to bring up their cholesterol treatment with their doctor. This finding suggests a potential target for interventions designed to help PAD patients take an active role with their physician in decision-making about their LDL-C lowering therapy. This type of intervention was employed in a multicenter randomized controlled clinical trial of 792 patients hospitalized for cardiac disease, in which Vale et al. demonstrated that a coaching intervention with telephone calls and mailings resulted in significantly greater reductions in total cholesterol as compared to the usual care group (21 mg/dl vs 7 mg/dl, p < 0.001).19
Most PAD patients reported a high degree of adherence to their cholesterol-lowering medication. Although patient-reported adherence has limitations,20 our findings suggest that poor adherence to LDL-C-lowering medication may not be a major contributor to suboptimal LDL-C levels among patients with PAD.
Physician behavior is difficult to change.21,22 However, a growing body of literature indicates that patients can influence their medical care by requesting specific tests or therapies.12,23,24 It is currently unclear whether interventions can successfully activate patients with cardiovascular disease to influence their own care. For example, in contrast to the work by Vale et al., a separate randomized controlled clinical trial of 756 hospitalized cardiac patients showed no difference in the percent of patients who achieved an optimal LDL-C level in a nurse-based educational program as compared to usual care.25
This study has limitations. First, a study inclusion criterion was an LDL-C level > 70 mg/dl. Thus, findings are generalizable to PAD participants with higher LDL-C levels. However, this population of PAD patients is most relevant to the current study questions, since their LDL-C levels are suboptimally controlled. Second, data collected were from patient report. Findings may over-estimate optimal patient behavior if patients reported behavior they thought they should be exhibiting rather than their actual behavior. Third, we did not collect data on physicians’ knowledge of optimal LDL-C levels in patients with PAD. It is conceivable that patient knowledge of optimal LDL-C levels may be influenced in part by their physician’s knowledge. Fourth, we did not collect comparable data in patients with coronary artery disease but without PAD. Thus, we could not compare findings between participants with PAD and coronary artery disease.
Although cholesterol-lowering therapy significantly improves cardiovascular morbidity and mortality in patients with PAD, PAD patients are significantly undertreated with cholesterol-lowering medication compared to patients with CAD.6–8 Helping PAD patients take a more active role in their physicians’ decisions regarding cholesterol-lowering medication may improve rates of successful LDL-C-lowering therapy in patients with PAD. Data reported here suggest an opportunity for intervention to help PAD patients take a more active role in their physicians’ decisions regarding cholesterol-lowering therapy. However, further study is needed to identify an effective intervention.
Acknowledgement and funding source
Supported by R01-HL073912 from the National Heart Lung and Blood Institute, National Institutes of Health (NIH).
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