Summary of findings 5. Low‐molecular‐weight heparin versus active control (3).
| LMWH compared with VKA for primary thromboprophylaxis in ambulatory cancer patients receiving chemotherapy | |||||||
|
Patient or population: ambulatory cancer patients receiving chemotherapy Settings: outpatient clinics Intervention: LMWH Comparison: VKA | |||||||
| Outcomes | Relative effect (95% CI) | Illustrative comparative risks* (95% CI) | Differenceb (95% CI) | No of participants (studies) | Certainty of the evidence (GRADE) | What it means | |
| Assumed riska | Corresponding risk | ||||||
|
With VKA Number of events per 1000 participants |
With LMWH
(any dosage) Number of events per 1000 participants |
||||||
|
Symptomatic VTE Follow‐up: median 25 months |
RR 0.33 (0.14 to 0.83) | High‐risk populationc | 55 per 1000 fewer events (14 fewer to 70 fewer) | 439 (1) | ⊕⊕⊕⊕ Highd | LMWH reduces the incidence of symptomatic VTE when compared to VKA in multiple myeloma. | |
| 82 per 1000 | 27 per 1000 (11 to 68) | ||||||
|
Major bleeding Follow‐up: median 25 months |
Not estimablee | High‐risk populationc | NA | NA | NA | We do not know how LMWH affects major bleeding when compared to VKA across different cancer types. | |
| NA | NA | ||||||
|
Symptomatic PE Follow‐up: median 25 months |
RR 0.11 (0.01 to 2.06) | High‐risk populationc | 16 per 1000 fewer events (18 fewer to 19 more) | 439 (1) | ⊕⊕⊝⊝ Lowf | LMWH may reduce the incidence of symptomatic PE when compared to VKA in multiple myeloma. | |
| 18 per 1000 | 2 per 1000 (0 to 37) | ||||||
|
Symptomatic DVT Follow‐up: median 25 months |
RR 0.43 (0.17 to 1.10) | High‐risk populationc | 36 per 1000 fewer events (53 fewer to 6 more) | 439 (1) | ⊕⊕⊕⊝ Moderateg | LMWH probably reduces the incidence of symptomatic DVT when compared to VKA in multiple myeloma. | |
| 64 per 1000 | 27 per 1000 (11 to 70) | ||||||
|
Any VTE Follow‐up: NA |
NAh | High‐risk populationc | NA | NA | NA | We do not know how LMWH affects any VTE when compared to VKA across different cancer types. | |
| NA | NA | ||||||
|
1‐year overall mortality Follow‐up: NA |
NAh | High‐risk populationc | NA | NA | NA | We do not know how LMWH affects 1‐year overall mortality when compared to VKA across different cancer types. | |
| NA | NA | ||||||
|
Clinically relevant bleeding Follow‐up: NA |
NAh | High‐risk populationc | NA | NA | NA | We do not know how LMWH affects clinically relevant bleeding when compared to VKA across different cancer types. | |
| NA | NA | ||||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (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; DVT: deep vein thrombosis; LMWH: low‐molecular‐weight heparin; NA: not applicable; PE: pulmonary embolism; RR: risk ratio; VKA: vitamin K antagonist; VTE: venous thromboembolism. | |||||||
|
GRADE Working Group grades of evidence High certainty: further research is very unlikely to change our confidence in the estimate of effect. Moderate certainty: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low certainty: 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 certainty: we are very uncertain about the estimate. | |||||||
aThe assumed risk was calculated from the observed control group risk in Palumbo 2011. bDifference calculated as the absolute risk difference between the assumed risk and corresponding risk, expressed per 1000. cHigh‐risk population refers to the median observed risk to experience symptomatic VTE in the trials contributing to the analyses (82 per 1000). Rates from 7% and higher are considered high risk (Khorana 2008). dAlthough there was some risk of attrition bias, imputation of the missing data in various ways showed that estimates would not change in a clinically relevant manner (data not shown). eNot estimable due to zero event count in both trial arms. fDowngraded two levels because of imprecision. gDowngraded one level because of imprecision. hNo trials contributed to this outcome.