Therapy Nadroparin in the Prevention of Deep Vein Thrombosis in Acute Decompensated COPD
This review may be edited
Summary
Posted By:	A Delaney
E-Mail:	apdelane@doh.health.nsw.gov.au
Posted Date:	3/10/2002
Title:	Nadroparin in the Prevention of Deep Vein Thrombosis in Acute Decompensated COPD
Authors:	FRANÇOIS FRAISSE, LAURENT HOLZAPFEL, JEAN-MICHEL COULAND, GERALD SIMONNEAU, BERNARD BEDOCK, MARC FEISSEL, PATRICK HERBECQ, REGINALD PORDES, JEAN-FRANÇOIS POUSSEL, LOUIS ROUX, and The Association of Non-University Affiliated Intensive Care Specialist Physicians of France
Reference:	Am. J. Respir. Crit. Care Med., Volume 161, Number 4, April 2000, 1109-1114
Link:	Click here for a direct link to the paper. A password may be required for access to fulltext.
Abstract:	Low molecular weight heparins are as effective as unfractionated heparin in deep-vein thrombosis (DVT) prophylaxis for major surgery. However, there is no evidence nor consensus for prophylaxis in medical patients. We compared the efficacy and safety of nadroparin calcium (nadroparin) with placebo in medical patients at high risk of DVT. A total of 223 patients mechanically ventilated for acute, decompensated chronic obstructive pulmonary disease, were randomized to treatment with subcutaneous nadroparin adjusted for body weight (0.4 ml, i.e., 3,800 AXa IU, or 0.6 ml, i.e., 5,700 AXa IU) or placebo. The average duration of treatment was 11 d. The incidence of DVT in patients receiving nadroparin was significantly lower than that in patients receiving placebo (15.5 versus 28.2%; p = 0.045). Although the incidence of adverse events was high in both groups, there were no significant differences between nadroparin and placebo for total adverse events (46.3 versus 39.8%; p = 0.33), serious adverse events (25.0 versus 19.5%; p = 0.32), or those resulting in early permanent discontinuation of treatment (12.0 versus 8.8%; p = 0.44). The most common adverse event was hemorrhage. There was the same number of deaths in both treatment groups. Subcutaneous nadroparin resulted in 45% decrease in incidence of DVT compared with placebo.
Are the Results Valid?
1. Was the assignment of patients to treatments randomized? ( Was allocation concealment maintained?)
	The authors state that the patients were randomised but give no details as to the method used.
2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?
2a. Was followup complete?
	Venography was only performed in 76% of randomised patients. All patients were followed for 21 days to look for morbidity and mortality.
2b. Were patients analyzed in the groups to which they were randomized?
	Yes, the analysis was performed on an intention to treat basis.
3. Were patients, health workers, and study personnel blind to treatment?
	Yes, patients, health care workers and study personnel were blinded to the treatment allocation.
4. Were the groups similar at the start of the trial?
	Patients in the treatment group were significantly older than those in the placebo group. There was no significant differences between the two groups at the start of the trial.
5. Aside from the experimental intervention, were the groups treated equally?
	It appears so. There is no mention made of the use of mechanical means to prevent DVT (compression stockings or intermittant pneumatic compression devices).
What are the Results?
1. How large was the treatment effect?
	There was an absolute risk reduction of 12.7%, a relative risk reduction of 45%. 8 patients would need to be treated to prevent 1 DVT at 21 days.
2. How precise was the estimate of the treatment effect?
	The 95% confidence intervals for the absolute risk reduction range from 0.4% to 25% which means that the NNT could be from 4 to 250 patients.
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care?
	Patients with COPD who require mechanical ventilation are common in most ICU's. Preventing DVT is an important part of the management of these patients. The question that could be raised here is whether this effect would be found with all low molecular weight heparins (LMWH), as nadroparin is not universally available.
2. Were all clinically important outcomes considered?
	The incidence of DVT is probably a clinically important outcome given that it can have both acute (pulmonary embolism, death, pain..) consequences and long term consequences (propensity for further DVT, chronic venous insufficiency). However, there was no comparison between groups regarding the incidence of pulmonary embolism. There was no difference between the two groups with regards to mortality within the time frame of the study. The trend towards increased bleeding (5.6% in the treatment group compared to 2.7% in the placebo group) is a concern, and would limit the generalisability of these results to all mechanically ventilated patients, especially those with an increased risk of bleeding.
3. Are the likely treatment benefits worth the potential harms and costs?
	Prevention of DVT in Intensive care patients is an important issue. There are some issues with this study which leave open the question regarding the overall efficacy of nadroparin in particular and low molecular weight heparin in general for the prevention of DVT in mechanically ventilated patients. One interesting aspect of the trial was the use of a placebo group for comparison . Previous studies have shown a similar redcution in the rate of DVT with the use of standard low dose heparin (5000 units sci bd) which could be seen as a cheaper, safer alternative. Mechanical means of DVT prevention have also been shown to be effective in some populations of patients and in this trial no mention was made of their use. Whether nadroparin or other LMWH's are more effective, cost effective or safer than the standard means of preventing DVT's in Intensive Care patients remains to be seen. The fact that this is a small trial with some methodological flaws means that it is unable to give a definitive answer.
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