Risk factors associated with deep venous thrombosis in patients with different bed-rest durations: A multi-institutional case-control study.

Background: Deep vein thrombosis represents a threat to public health and a heavy economic burden to society, and often occurs as a complication or cause of death in bedridden patients. How to prevent deep vein thrombosis is a general concern in clinical practice. However, it remains uncertain whether the risk factors for deep vein thrombosis would be affected by different bed-rest durations. Solving this issue will be invaluable for the provision of more rational medical care to prevent deep vein thrombosis.

Objective: To explore whether risk factors for deep vein thrombosis are affected by bed-rest durations and to identify different risk factors in groups with different bed-rest durations.

Design: A retrospective multicenter case-control study.

Settings And Participants: This multicenter study was conducted in wards with high rates of bed rest in 25 general hospitals in China. Participants were bedridden patients from these wards.

Methods: Bedridden patients were identified from the research database of bedridden patients' major immobility complications. These data were collected from prospective descriptive studies by a standardized web-based online case report form. Cases were defined as bedridden patients who suffered deep vein thrombosis during hospitalization (n=186). Each case was matched with three controls, bedridden patients who did not suffer deep vein thrombosis in the same center with the same bed-rest duration (n=558). Descriptive statistics, univariate analysis, and multivariate conditional logistic regression models were employed.

Results: Among 23,985 patients, the overall incidence of deep vein thrombosis during hospitalization was 1.0%. Multivariate analysis showed that for patients with bed-rest duration of 4 weeks or less, older age (odds ratio [OR] =1.027, 95% confidence interval [CI] 1.013-1.041) and being in a surgical department (OR=2.527, 95% CI 1.541-4.144) were significantly associated with increased risk of deep vein thrombosis. Female sex (OR=4.270, 95% CI 1.227-14.862), smoking (OR=10.860, 95% CI 2.130-55.370), and special treatment (OR=3.455, 95% CI 1.006-11.869) were independent factors predicting deep vein thrombosis for patients with bed-rest durations from 5 to 8 weeks. For those with bed-rest durations from 9 to 13 weeks, Charlson Comorbidity Index (OR=1.612, 95% CI 1.090-2.385) was the only independent risk factor for deep vein thrombosis.

Conclusions: Risk factors for deep vein thrombosis varied among patients with different bed-rest durations. This finding is helpful for nurses to increase their awareness of prevention of deep vein thrombosis in patients with different bed-rest durations, and lays a more solid foundation for clinical decision making.