The Impact of Venous Thromboembolism In Critically Ill Patients: A Meta-Analysis of Major Clinical outcomes

Critically ill patients are at high risk of developing venous thromboembolism (VTE) during their stay in the intensive care unit (ICU) because of premorbid medical and surgical conditions. The clinical consequences of Deep Vein Thrombosis (DVT) have the potential to be serious yet are frequently unrecognized in the Intensive Care Unit (ICU). In contrast to the extensive documentation on the short and long–term outcomes of patients with DVT evaluated in other clinical settings, little is known about the clinical course of this disease in the ICU setting.

We hypothesized that both undetected and clinically evident VTE would affect the prognosis of critically ill patients.

To systematically review whether a diagnosis of DVT in critically ill patients affects clinically important outcomes including length of stay, duration of mechanical ventilation and mortality.

MEDLINE and EMBASE databases were searched up to June 2010. Two reviewers performed study selection independently. Studies were selected if evaluate one or more of the following outcomes: hospital and ICU mortality, duration of patient stay in hospital and in ICU, and duration of mechanical ventilation. Two investigators independently extracted and reviewed data from each study; including study and patient characteristics and outcomes.

Association between DVT and hospital and ICU mortality, and the mean difference of duration of patient stay in hospital and in ICU, and duration of mechanical ventilation in patients with and without DVT were calculated using a random-effects model (DerSimionan and Laird method). Pooled results are reported as relative risk (RR) and mean difference and are presented with 95% confidence interval (CI) and with 2-sided P values. A P value of .05 or less was considered statistically significant. Statistical heterogeneity was evaluated using the I2 statistic, which assesses the appropriateness of pooling the individual study results [22]. The I2 value provides an estimate of the amount of variance across studies due to heterogeneity rather than chance.

Cohen's Kappa for inter-rater agreement was used to assess inter-rater reliability.

Six studies for a total of 1518 patients were included in the systematic review. Patients diagnosed with DVT compared to those without DVT had increased ICU and hospital stay (7.3 days (95% CI 1.4 to 13.2; P= 0.02) and 16.5 days (95% CI 1.51 to 30.59; P= 0.03), respectively. Duration of mechanical ventilation appeared to be increased in patients with DVT although this difference was not statistically significant (weighted mean difference: 3.41 days 95 % CI –1.12 to 7.94; P=0.14).

Patients diagnosed with DVT also had a marginally significant increase in the RR of hospital mortality (RR 1.31 95%CI,0.99 to 1.74,P=0.06), and a non statistically significant increase in the RR of ICU mortality (RR 1.96; 95% CI 0.74 to 5.19; P = 0.17).

A diagnosis of DVT upon ICU admission appears to affect clinically important outcomes including length of ICU and hospital stay and hospital mortality. Further research involving larger prospective study designs are warranted.

No relevant conflicts of interest to declare.