Twenty-six RCTs (n=7,639) were included.
Twelve studies reported double-blinding. Two additional studies reported a blinded outcome assessment.
Based on 24 studies (n=5,933) using FUT, venography or ultrasound DVT detection methods, the overall DVT rate was lowest among patients who received heparin prophylaxis (LDUH or LMWH high or low dose) plus mechanical prophylaxis, compared with patients who received heparin prophylaxis alone (LDUH or LMWH) or no prophylaxis: 5% versus 12.7% and 35.2%, respectively.
DVT rates using different methods of DVT detection.
For studies using FUT detection, the DVT rate was significantly lower among patients who received heparin prophylaxis (LDUH or LMWH) plus mechanical prophylaxis or heparin prophylaxis (LDUH or LMWH) alone compared with no prophylaxis: 5% and 11.1% versus 36.7% (p<0.05 for all heparin versus control), based on 17 studies (n=4,005). For studies using ultrasound detection, the rate of DVT detection among patients receiving heparin prophylaxis (LDUH or LMWH) was significantly lower than the control group: 1.8% versus 6.3% (p<0.05), based on 2 studies (n=107). Rates of DVT detection among patients receiving any type of heparin were greatest for venography (16.4%), followed by FUT (11.1%) and ultrasound (1.8%), and were lowest for clinical examination (0.2%, based on 2 studies). The difference between all different methods of DVT detection was statistically significant (p<0.05).
Type of heparin (17 studies using FUT).
There was no significant difference in DVT rates between groups receiving LDUH compared with LMWH (p>0.05). Rates of DVT were significantly lower for patients receiving high-dose LMWH compared with low-dose LMWH (7.9% versus 14.5%, p<0.0001) and for patients receiving high-dose LDUH compared with low-dose LDUH (8% versus 13.4%, p=0.0132).
DVT location (9 studies, n=284).
Proximal DVTs were significantly less common among patients receiving LDUH or LMWH compared with no prophylaxis (12.7% versus 41.4%, p=0.0001).
There were no significant differences (p>0.05) between LDUH and LMWH groups in terms of minor complications (7 studies, n=2,114), major complications (7 studies, n=2,083) or discontinuation rates in high-dose regimens (4 studies, n=1,668).