Results Summary
What was the research about?
About 8.5 million Americans ages 40 or older live with peripheral arterial disease, or PAD. This health problem partially or completely blocks blood vessels, usually those that deliver needed oxygen to the legs. PAD often causes calf pain during walking.
Treatment for PAD aims to improve blood flow. The American Heart Association recommends noninvasive treatments, including exercise therapy, aids to help patients quit smoking, and certain medicines. Antiplatelet medicines prevent blood clots. Statin medicines lower cholesterol levels. Invasive procedures, such as stents or surgery to open or bypass blocked vessels, can also treat PAD.
Over a year, the research team carried out three separate comparisons of treatment approaches:
- Patients receiving invasive treatment after their first clinic visit versus patients receiving only noninvasive treatment
- Patients receiving both antiplatelet and statin medicines versus patients receiving only one or none of these medicines
- Patients receiving all four American Heart Association recommended treatments—antiplatelet and statin medicines, exercise therapy, and aids to stop smoking—versus patients not receiving all four treatments
The research team asked patients with new or worsening PAD-related leg problems questions about their health status, including PAD symptoms, ability to function, quality of life, and satisfaction with care.
What were the results?
Invasive treatment. At the beginning of the study, health status was worse in patients who received invasive treatment than in patients who received noninvasive treatment. But health status in both groups of patients ended up being similar 3, 6, and 12 months after the first visit.
Antiplatelet and statin medicines. At the first visit and at three and six months, health status was better in patients taking both medicines compared with patients who weren’t taking both. At 12 months, health status was similar in the two groups.
Antiplatelet and statin medicines, exercise therapy, and aids to stop smoking. At the first visit, health status was similar in patients who received all four treatments and those who didn’t. At three months, health status was better in people receiving all four treatments. Then at 6 and 12 months, health status in the two groups was similar.
Patient characteristics. At all visits, men had better health status than women. White patients had better health status than patients who were races other than white.
Who was in the study?
The study included 797 adults with PAD of the legs. Of these patients, 42 percent were women, and 28 percent were races other than white. All patients had new or worsening symptoms. The patients received care at 10 clinics focused on PAD. The clinics were in big cities in seven states.
What did the research team do?
The research team selected patients at their first visit to a PAD clinic. The patients completed a survey about their health status related to PAD at the first visit and again after 3, 6, and 12 months. The research team also collected information about the patients, such as their sex and race, and about treatments received during the study.
What were the limits of the study?
The study included only patients with PAD severe enough to be referred to a specialized clinic. These patients received care in only 10 clinics in seven cities. The results may be different for people who have less severe symptoms or who live in other places.
Only about 5 percent of patients received all four recommended treatments. Patients who received all four treatments may differ from patients who didn’t. Results may be different if more patients had received all four treatments. Future research could examine why not many patients received all four recommended treatments.
How can people use the results?
Health status improved in patients, no matter which treatment patients received. Patients and doctors may use these results to inform discussions about treatments for PAD.
Professional Abstract
Objective
To quantify health status outcomes related to treatment and patient characteristics during a one-year period in patients with peripheral arterial disease (PAD)
Study Design
| Design Elements | Description |
|---|---|
| Design | Observational: cohort study |
| Population | 797 adults with PAD and new onset or recent exacerbations of exertional leg symptoms |
| Interventions/ Comparators |
|
| Outcomes |
PAD-specific health status, reflecting the affected leg, physical function, symptoms, symptom stability, social limitation, treatment satisfaction, and quality of life related to functioning impacted by PAD |
| Timeframe | 1-year follow-up for study outcomes |
This prospective, multi-center, observational study evaluated PAD-specific health status outcomes in patients undergoing routine care. The study included 797 adults at 10 clinics that specialized in PAD care in large cities within seven states. The median patient age was 69. Of the patients, 42% were female, 72% were white, and 28% were other races.
Patients enrolled in the study during their first clinic visit. Researchers used the Peripheral Artery Questionnaire (PAQ) summary score to assess patients’ PAD-specific health status during this visit. Patients also completed the PAQ again 3, 6, and 12 months later. Clinic physicians directed treatment.
Researchers compared PAQ summary scores for three treatment approaches:
- Early invasive treatment, defined as endovascular or surgical revascularization, within the first three months of follow-up versus noninvasive treatment
- Prescription of both statin and antiplatelet medicines versus only one or none of these medicines
- Treatment following all four PAD strategies recommended by the American Heart Association: antiplatelet and statin medicines, exercise therapy, and smoking cessation interventions versus not following all four treatment strategies
Researchers obtained input on study design and implementation from panels of patients and physicians experienced in PAD.
Results
Overall health and patient characteristics. PAQ summary scores were significantly lower in women than in men and in patients of other races than in white patients at baseline and at all three follow-up visits (p<0.05 for each comparison). Lower scores indicate worse health status.
Early invasive treatment. Approximately 20% of patients received early invasive treatment. The mean baseline PAQ summary score was lower in patients who underwent invasive treatment than in those who received noninvasive treatment (p=0.003). PAQ summary scores improved more in the invasive treatment group than in the noninvasive treatment group (p<0.001). Given that the invasive treatment group scores were lower at baseline, the greater improvement after treatment resulted in no significant differences in PAQ summary scores between groups at 3, 6, and 12 months.
Medicines. Approximately 78% of patients received both antiplatelet and statin medicines during follow-up. Mean PAQ summary scores were significantly higher at baseline and at three and six months in patients receiving both medicines than in those not receiving both medicines (p<0.05). The scores were similar for both groups at 12 months (p=0.142).
All PAD strategies. Mean PAQ summary scores at baseline and 6 and 12 months were similar in patients receiving all four PAD strategies and in patients not receiving all four strategies (p>0.05). At three months, the scores were higher in patients receiving all four PAD strategies (p=0.034) than in the other patients.
Limitations
This study examined only patients with referrals to 10 PAD clinics in seven states. Findings may not apply to patients in other areas or in patients with less severe symptoms who were not referred to a specialty clinic.
As an observational study, a potential for bias exists because of the nonrandomized treatment assignment. Only 4.6% of patients received all four American Heart Association strategies. Results may have been different if more patients had been treated using all four American Heart Association strategies.
Conclusions and Relevance
Patients with new onset or recent exacerbations of PAD leg symptoms experienced improvements in health status following each of the treatment approaches. At one-year follow-up, no differences in health status were observed as a function of treatment. Being female and a race other than white were associated with worse health status at baseline and during follow-up.
Future Research Needs
Future research could examine PAD-related health status in a nationwide sample of patients with PAD or in patients with less severe PAD. This study’s observational design prohibits definitive conclusions regarding treatment effectiveness. Future research could use randomized controlled trials to compare the effects of specific PAD treatments on health status.
Final Research Report
View this project's final research report.
Journal Citations
Related Journal Citations
Peer-Review Summary
Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also confirms that the research has followed PCORI’s Methodology Standards. During peer review, experts who were not members of the research team read a draft report of the research. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. Reviewers do not have conflicts of interest with the study.
The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve how the research team analyzed its results or reported its conclusions. Learn more about PCORI’s peer-review process here.
In response to peer review, the PI made changes including
- Completing multivariate analyses to account for repeated measures. These analyses were initially planned by the researchers, but did not appear to have been carried out before peer review, and reviewers were concerned that univariate analyses could be misinterpreted given the relationships among the outcome variables. The researchers also completed multivariate analyses focusing on one-year health status outcomes that help understand the importance of variables that predict patients' one-year health status outcomes.
- Addressing reviewer concerns about the handling of missing data by providing a more extensive description of actions that the researchers took to reduce the frequency of missing data, and using a multiple-imputation approach to account for missing data. The PI indicated that this approach was appropriate because missing data were infrequent in the analyses.
- Providing details on the sites that were included in the study, and why they were included. The researchers stressed their intentions of focusing on sites with sicker patients who they believed would benefit most from treatment.