Table 24.

—[Section 4.1] Summary of Findings: Elastic Compression Stockings vs No Elastic Compression Stockings to Prevent PTS of the Leg^a,b,451

Outcomes	No. of Participants (Studies), Follow-up	Quality of the Evidence (GRADE)	Relative Effect (95% CI)	Anticipated Absolute Effects
				Risk With No Elastic Compression Stockings	Risk Difference With Elastic Compression Stockings (95% CI)
PTS	421 (2 studies), 2 y	Moderatec due to risk of bias	RR 0.46 (0.34-0.63)d	479 per 1,000e,f	259 fewer per 1,000 (from 177 fewer to 316 fewer)g
Recurrent VTE	374 (2 studies), 5 y	Moderateh,i due to imprecision	RR 1.01 (0.61-1.67)d	210 per 1,000j	2 more per 1,000 (from 82 fewer to 141 more)
QOL not reported		…	…	k	…

The basis for the assumed risk (eg, the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). Working group grades of evidence are as follow: High quality, further research is very unlikely to change our confidence in the estimate of effect; moderate quality, further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate; low quality, further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate; very-low quality, we are very uncertain about the estimate. See Table 1,3 and 10 legends for expansion of abbreviations.

^aPrandoni et al²⁰² excluded patients with recurrent ipsilateral DVT, preexisting leg ulcers, or signs of chronic venous insufficiency, bilateral thrombosis, a short life expectancy or a contraindication for use of stockings (eg, advanced-stage peripheral arterial insufficiency). Brandjes et al²⁰¹ excluded patients with short life expectancy, paralysis of the leg, bilateral thrombosis, leg ulcers, or extensive varicosis.

^bBrandjes²⁰¹ used graded elastic compression stockings (40 mm Hg of pressure at the ankle, 36 mm Hg at the lower calf, and 21 mm Hg at the upper calf); stockings were applied 2 to 3 wk after the first episode of proximal DVT. Prandoni et al²⁰² used flat-knitted stockings (30 to 40 mm Hg of pressure at the ankle); stockings were started at hospital discharge, an average of 1 wk after admission. In both studies, stockings were used for 2 y.

^cPatients were not blinded to the treatment assignment, and outcomes were partly based on subjective report of symptoms.

^dThe effect estimate shown here results from a meta-analysis (Mantel-Haenszel fixed-effects model) of the two relevant trials. A fixed-effects model was chosen because of the small number of studies available.

^eThis estimate is based on the findings of the VETO study.⁷⁰ This probably underestimates PTS baseline risk given that overall, 52% of patients reported the current use of compression stockings during study follow-up.

^fIn Prandoni et al,²⁰² most events occurred during the first 6 mo. The cumulative incidence of the PTS in the control group was 40% after 6 mo, 47% after 1 y, and 49% after 2 y.

^gSevere PTS: assuming the same RR of 0.46 and a baseline risk of 8.1% over 2 y, the absolute reduction is 44 fewer severe PTS per 1,000 (from 30 fewer to 53 fewer) over 2 y.

^hWe did not rate down the quality of evidence for recurrent VTE for the lack of blinding because this a more objective outcome than PTS.

ⁱCI includes both negligible effect and appreciable benefit or appreciable harm.

^jThis estimate is the mean of two estimates derived from two studies: 12.4% probable/definite VTE (Heit et al¹⁶⁵) and 29.1% confirmed VTE (Prandoni et al²⁰⁸).

^kThis is an important outcome that should be considered in future studies.