LMWH compared to no prophylaxis for preventing VTE in adults undergoing KA

Patient or population: adults undergoing KA
Setting: hospital
Intervention: LMWH
Comparison: no prophylaxis

PE: assessed by CT arteriography (follow‐up: 30 days to 3 months)
 

⊕⊕⊕⊝
Moderate^a

LMWH probably leads to little or no difference in rates of PE.

3 per 1000

6 per 1000 (2 to 22)

Symptomatic DVT: assessed by presence of symptoms and confirmed by a positive compression ultrasound (follow‐up: 30 days to 3 months)
 

⊕⊕⊝⊝
Low^b

LMWH may lead to little or no difference in symptomatic DVT.

11 per 1000

7 per 1000 (2 to 22)

Asymptomatic DVT: assessed with compression ultrasound (follow‐up: 30 days to 8 weeks)

⊕⊝⊝⊝
Very low^c

It is uncertain if LMWH reduces the risk asymptomatic DVT.

81 per 1000

11 per 1000 (2 to 49)

All‐cause mortality (follow‐up: 30 days to 3 months)
 

Not estimable

No deaths occurred in any of the included studies.

All adverse effects, including allergies at injection site, minor and major bleeding, others (follow‐up: 30 days to 3 months)
 

⊕⊕⊕⊝

Moderate^a

LMWH probably leads to little or no difference in adverse effects.

13 per 1000

24 per 1000
(13 to 47)

Major bleeding (follow‐up: 30 days to 3 months)
 

⊕⊕⊕⊝
Moderate^a

LMWH probably leads to little or no difference in rates of major bleeding.

1 per 1000

1 per 1000

(0 to 22)

Minor bleeding (follow‐up: 30 days to 3 months)

⊕⊕⊕⊝
Moderate^a

LMWH probably leads to little or no difference in rates of minor bleeding.

11 per 1000

20 per 1000 (9 to 43)

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: confidence interval; CT: computed tomography; DVT: deep vein thrombosis;KA: knee arthroscopy; LMWH: low‐molecular‐weight heparin; PE: pulmonary embolism; RCT: randomized controlled trial; RR: risk ratio; VTE: venous thromboembolism.

GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect.
Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.
Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect.
Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.