Table 31.

—[Section 8.1] Summary of Findings: Fondaparinux vs Placebo for Acute SVT^a-c,382

Outcomes	No. of Participants (Studies), Follow-up	Quality of the Evidence (GRADE)	Relative Effect (95% CI)	Anticipated Absolute Effects
				Risk With No Fondaparinux	Risk Difference With Fondaparinux (95% CI)
Mortality	3,002 (1 study), 3 mo	Moderated-g due to imprecision	RR 1.99 (0.18-21.87)	4 per 1,000h	4 more per 1,000 (from 3 fewer to 83 more)
VTE	3,002 (1 study), 3 mo	Highd	RR 0.18 (0.06-0.53)	33 per 1,000h	27 fewer per 1,000 (from 16 fewer to 31 fewer)
SVT recurrence	3,002 (1 study), 3 mo	Highd	RR 0.31 (0.14-0.68)	19 per 1,000h	13 fewer per 1,000 (from 6 fewer to 16 fewer)
Major bleeding	2,987(1 study), 47 d	Moderated,e,i due to imprecision	RR 0.99 (0.06-15.86)e	1 per 1,000	0 fewer per 1,000 (from 1 fewer to 10 more)
QOL not measured	…	…	…	…	…

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 and 3 legends for expansion of abbreviations.

^aPatients with infusion-related SVT were excluded from CALISTO (Comparison of ARIXTRA in lower Limb Superficial Thrombophlebitis with Placebo).

^bFondaparinux 2.5 mg for 45 d.

^cPatients in the two treatment groups benefited from close clinical monitoring with adequate diagnostic procedures in the event of new or persistent symptoms.

^dAllocation concealed. Outcome adjudicators, steering committee, patients, providers, and data collectors blinded. Follow-up rate was 98%. Intention-to-treat analysis for efficacy outcomes. Not stopped early for benefit.

^eCI includes values suggesting large benefit and values suggesting large harm.

^fWe rated down by only one level because of the low event rate and large sample size.

^gSmall number of events.

^hBaseline risk derived from a large prospective cohort study.³⁷⁴

ⁱThe upper limit of the CI for absolute effect (10 more bleeds) is not low enough to suggest a clear balance of benefits vs harms.