Evidence-Based Summary of Guidelines From the Society for Vascular Surgery and the American Venous Forum

The Evidence Pyramid

The best evidence is usually provided by systematic reviews and meta-analyses of prospective randomized trials. Guidelines that adhere to accepted reporting standards and lack conflict of interest bring us the highest quality evidence on effectiveness of a therapy. Single prospective randomized trials, registry data, retrospective cohort studies, and case control studies are additional sources of evidence, although retrospective studies have limitations, and they provide a lower level of evidence. Case reports, editorials, and expert opinions as well as animal and in vitro research studies are at the bottom of the evidence pyramid, but even with very low level of evidence, they can support a treatment modality ( Fig. 27.2 ). For high-quality evidence, the effects of therapy are precise, and further research is unlikely to change our confidence in the effect. In contrast, the estimated benefit provided by low-quality evidence may be unclear and subject to change as better-quality evidence becomes available.

Grading Recommendations and Evidence

Current approaches to the evaluation of clinical evidence are based largely on an assessment of the estimate of effect, beneficial or ill, associated with a treatment. The approach developed by the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) working group has been adopted by the Society for Vascular Surgery (SVS) and the American Venous Forum in developing practice guidelines. According to this system, there are two components to any treatment recommendation: the first a designation of the strength of the recommendation (1 = strong; 2 = weak) based upon the degree of confidence that the recommendation will do more good than harm; the second an evaluation of the strength of the evidence (A to D) based upon the confidence that the estimate of effect is correct ( Table 27.1 ).

TABLE 27.1

GRADE Approach to Treatment Recommendations

Adapted from Guyatt G, Schunemann HJ, Cook D, et al. Applying the grades of recommendation for antithrombotic and thrombolytic therapy. Chest. 2004;126:179S–187S.

Recommendation	Benefit Versus Risk	Quality of Evidence	Comment
1A	Clear	High: consistent results from RCTs or observational studies with large effects	Strong recommendation, generalizable
1B	Clear	Moderate: RCTs with limitations and very strong observational studies	Strong recommendation; may change with further research
1C	Clear	Low: observational studies Very low: case series, descriptive reports, expert opinion	Intermediate recommendation; likely to change with further research
2A	Balanced or unclear	High: consistent results from RCTs or observational studies with large effects	Intermediate recommendation: may vary with patient values
2B	Balanced or unclear	Moderate: RCTs with limitations and very strong observational studies	Weak recommendation; may vary with patient values
2C	Balanced or unclear	Low: observational studies Very low: case series, descriptive reports, expert opinion	Weak recommendation; alternative treatments may be equally valid

GRADE, Grading of recommendations, assessment, development, and evaluation; RCTs, randomized control trials.

The strength of a recommendation (1 or 2) reflects the balance of benefits and risks, as well as cost to the health care system. Grade 1 recommendations are those in which the benefits of intervention clearly outweigh its risk and burdens. All well-informed patients would choose such a treatment, and the physician, often without a detailed knowledge of the underlying data, can securely recommend it. Grade 2 recommendations are weaker and reflect therapies in which the benefits and risks are either uncertain or more closely balanced. For such interventions, patients may choose different options based upon their underlying values. The SVS and the American Venous Forum have adopted the language of recommending the use of strong grade 1 guidelines and suggesting the use of weaker grade 2 guidelines.

The grade system is based on four levels (A to D) of methodologic quality (see Table 27.1 ), defined by the location of the evidence in the pyramid (see Fig. 27.2 ). As mentioned earlier, studies on the top have high-quality, or grade A, evidence that usually comes from data of well-executed, randomized trials yielding consistent results and occasionally from large observational studies with significant effects. Moderate-quality evidence (grade B) frequently comes from randomized clinical trials with important limitations, registry data, and strong retrospective observational cohort studies. Low-quality to very low-quality evidence (grade C) includes most observational studies, cross-sectional or longitudinal, and experimental studies, located at the bottom of the pyramid (see Fig. 27.2 ). The term best practice has been adopted by expert panels to support treatments and procedures that have been used with success for years, but scientific evaluation has been sparse or not satisfactory to confirm significant benefit.

Clinical Practice Guidelines on Venous Disease

Evidence-based clinical practice guidelines of the SVS and the American Venous Forum (AVF) have been published in recent years on the care of patients with varicose veins and associated chronic venous diseases, on the management of venous leg ulcers, and on early thrombus removal strategies for the treatment of acute deep venous thrombosis (DVT). Additional, major, national and international practice guidelines and reviews have also been published on prevention and treatment of acute venous thromboembolism and chronic venous diseases, and they all have been helpful to make decisions on how to evaluate and appropriately treat patients with venous diseases. These guidelines should be viewed as a summary of the best available clinical evidence to guide management of patients with chronic venous disease. However, consistent with the goals of evidence-based medicine, they are subject to the physician's clinical judgment, resources, and expertise and the patient's individual values and preferences. They should not be interpreted as a rigid standard of care.

This chapter summarizes the most important current guidelines on evaluation and management of patients with chronic venous disease adopted by our two major vascular societies, SVS and AVF. Details on evaluation and treatment are included in previous chapters of this book. For a list of the full venous guidelines of the SVS and the AVF, the readers should consult the original documents and the recently published fourth edition of the Handbook of Venous and Lymphatic Disorders, which includes 300 of the latest evidence and consensus-based guidelines for the management of acute and chronic venous and lymphatic disorders.

Evaluation and Classification

Evaluation of the patient with venous disease should include a thorough history, focusing on the underlying etiology (congenital, primary, or secondary), symptoms, and risk factors for venous disease. The degree of disability and effect on the patient's quality of life should also be assessed. Physical examination should focus on specific features of venous disease and exclusion of other etiologies of the patient's signs and symptoms. In clinical practice, every patient should be characterized using both the basic clinical, etiologic, anatomic pathophysiologic (CEAP) classification ( Table 27.2 ) and the Venous Clinical Severity Score (VCSS).

TABLE 27.2

Evaluation and Classification of Chronic Venous Disease

Guideline Number	Guideline	Grade of Recommendation (1: Strong; 2: Weak)	Grade of Evidence (A: High Quality; B: Moderate Quality; C: Low or Very Low Quality)
Classification
1	We recommend using the CEAP (clinical, etiologic, anatomic, pathophysiologic) classification to describe chronic venous disorders	1	B
Evaluation with duplex ultrasound
2	A cutoff value of 1 second is recommended to define reflux in the femoral and popliteal veins and of 500 ms for the great saphenous vein, the small saphenous vein, the tibial, deep femoral, and the perforating veins	1	B
3	We recommend that pathologic perforating veins include those with an outward flow of duration of ≥500 ms, with a diameter of ≥3.5 mm and a location beneath healed or open venous ulcers (CEAP class C5–C6).	1	B

Duplex ultrasonography, including an evaluation of reflux in the upright position, should be the initial diagnostic test in patients with suspected venous disease. Threshold values of greater than 500 ms are recommended for reflux in the saphenous, deep femoral, tibial, and perforating veins and greater than 1 second in the femoral and popliteal veins (see Table 27.2 ). Pathologic perforating veins should be differentiated from incompetent perforating veins. Pathologic perforating veins are those 3.5 mm or greater in diameter with outward flow of 500 ms or greater, located beneath an open or a healed venous ulcer defined by ultrasound (grade 1B).

Evaluation of patients with more advanced chronic venous insufficiency frequently includes additional physiologic and imaging studies, including computed tomography, magnetic resonance, or conventional contrast venography to delineate the underlying venous anatomy, pathology and plan therapy. For details of evaluation of these patients please consult Chapter 4 .