Summary of findings for the main comparison. Does compression treatment prevent post‐thrombotic syndrome?

Compression therapy for prevention of post‐thrombotic syndrome Participants or patients: adults with objectively diagnosed DVT Setting: outpatient or clinical Intervention: compression (elastic stockings, Unna boots, bandages) Comparison: no compression or placebo
Outcomes	Anticipated absolute effects (95% CI)		Relative effect (95% CI)	No. of Participants (studies)	Quality of the evidence (GRADE)	Comments
	Risk with no compression or with placebo compression	Risk with compression
Cumulative incidence of any PTS (follow‐up 2 to 6.3 years)	Study population		RR 0.62 (0.38 to 1.01)	1393 (5 RCTs)a	⊕⊕⊝⊝ lowb,c
	400 per 1000	248 per 1000 (152 to 404)
Cumulative incidence of severe PTS (follow‐up 2 to 6.3 years)	Study population		RR 0.78 (0.53 to 1.15)	1224 (4 RCTs)d	⊕⊕⊝⊝ lowb,c
	86 per 1000	67 per 1000 (46 to 99)
VTE: recurrence of DVT occurring in the first 2 weeks after initiation of treatment (follow‐up 2 to 6.3 years)	Study population		RR 0.94 (0.69 to 1.28)	1212 (4 RCTs)e	⊕⊕⊝⊝ lowb,c
	118 per 1000	111 per 1000 (81 to 151)
VTE: incidence of PE occurring in the first 2 weeks after initiation of treatment (follow‐up 2 to 5 years)	PE occurrence was low and exactly when the PE occurred was unclear. Partsch reported no difference in PE occurrence between groups (Unna boot group: 2, stocking group: 1, bed rest group: 1) (Partsch 2004). Kahn reported 9 occurrences in the active stockings group and 12 in the placebo group (Kahn 2014). Prandoni reported recurrent VTE in 12 patients in the stockings group and in 13 controls; 7/25 were PE, but it was unclear when these occurred, and if they were from the control or stockings group (Prandoni 2004). In a later study, Prandoni reported no PE (Prandoni 2012)			1296 (4 RCTs)f	⊕⊕⊝⊝ lowb,c,g
Adverse effects (follow‐up 2 to 5 years)	No serious adverse events occurred. Side effects (i.e. itching, erythema, or other forms of allergic reaction) were poorly reported in 4 studies. The largest study found that 2% in either group reported itching (Kahn 2014). Another study reported itching in about 6% of the elastic stockings group (Prandoni 2004). Two studies found more frequent occurrence of side effects (Partsch 2004; Prandoni 2012). Of participants allocated to the thigh‐length group, 40.7% developed side effects, as did 27.3% of those randomised to the below‐knee group (P = 0.017) (Prandoni 2012). Combining the bandaging and elastic stockings group revealed that 25% had minor skin changes or itching, which did not lead to discontinuation (Partsch 2004).			1296 (4 RCTs)h	⊕⊕⊝⊝ lowb,c,g,i	We present data from all studies and all comparisons in the review reporting on adverse effects.
Patient satisfaction or QOL (follow‐up 2 years)	Kahn 2014 (active stockings vs placebo): no significant difference in SF‐36 physical score (P = 0.12) and mental score (P = 0.79). No significant difference in VEINES‐QOL score (P = 0.81) Mol 2016 (1 year vs 2 years of compression stockings): no significant difference in median quality of life at end of follow‐up (P = 0.99) or mean intraindividual change in VEINES‐QOL (P = 0.21) and VEINES‐Sym (P = 0.12) Partsch 2004: significantly faster and more pronounced improvement in well‐being and DVT‐related quality of life with compression than with bed rest (P < 0.05) in the first 9 days after DVT. Psychological and somatic quality of life did not differ between groups.			1377 (3 RCTs)j	⊕⊕⊕⊝ moderateb,k	We present data from all studies and all comparisons in the review reporting on patient satisfaction or QOL.
Compliance (percentage compliance with treatment during 2‐year study periodl)	Aschwanden 2008: 92% stockings Brandjes 1997: 76% stockings Jayaraj 2015: 60% stockings Kahn 2014: 56% in active stockings group and 55% in placebo group (56% for both) Mol 2016: 85% stockings Partsch 2004: 73% in bed rest group and 50% in active group, with both receiving the same compression stockings for 2 years Prandoni 2004: 80% stockings Prandoni 2012: 67% in thigh‐length stockings group and 83% in knee‐length stockings group			1639 (8 RCTs)m	⊕⊕⊝⊝ lowb,c,n	We present data from all studies and all comparisons in the review reporting on compliance.
CI: confidence interval; DVT: deep vein thrombosis; PE: pulmonary embolism; PTS: post‐thrombotic syndrome; QOL: quality of life; RCT: randomised controlled trial; RR: risk ratio; VTE: venous thromboembolism.
GRADE Working Group grades of evidence. 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.

^aAschwanden 2008; Brandjes 1997; Ginsberg 2001; Kahn 2014; Prandoni 2004.
 ^bDowngraded owing to high heterogeneity between studies.
 ^cDowngraded owing to lack of or unclear risk of blinding due to assessment scores and reasons for loss to follow‐up not clearly described.
 ^dBrandjes 1997; Ginsberg 2001; Kahn 2014; Prandoni 2004.
 ^eAschwanden 2008; Brandjes 1997; Kahn 2014; Prandoni 2004.
 ^fKahn 2014; Partsch 2004; Prandoni 2004; Prandoni 2012.
 ^gScarcely and not always clearly reported. Therefore not pooled.
 ^hKahn 2014; Partsch 2004; Prandoni 2004; Prandoni 2012.
 ⁱDowngraded owing to risk of bias concerns over selective reporting.
 ^jKahn 2014; Mol 2016; Partsch 2004.
 ^kDifferent measurements were used by studies reporting on this outcome.
 ^lPercentage compliant with allocated treatment (compression stockings, placebo stockings, bandages).
 ^mAschwanden 2008; Brandjes 1997; Jayaraj 2015; Kahn 2014; Mol 2016; Partsch 2004; Prandoni 2004; Prandoni 2012.
 ⁿProportions were described narratively because of heterogeneity between studies and differences in control groups, with only one study placebo controlled and most having no treatment as control. Therefore, results were not pooled.