Risk factors for deep vein thrombosis in inpatients aged 65 and older: a case-control multicenter study

To identify independent risk factors of symptomatic deep vein thrombosis (DVT) in geriatric inpatients and to define high-risk patients likely to benefit from preventive treatment.

Hospital-based case-control multicenter study with prospective data collection.

Geriatric university hospitals with long-, intermediate-, and short-term care facilities.

All patients aged 65 and older in 19 geriatric departments were submitted to clinical surveillance over a 16-month period.

Twenty-three potential risk factors of phlebitis were screened for. Comparison using logistic regression of 310 consecutive patients with symptomatic DVT versus 310 randomly selected controls was performed. The risk for symptomatic DVT in geriatrics was then scored from the clinical risk factors identified using multivariate analysis. This score is defined by the sum of the odds ratio (OR) of each risk factor present.

Six factors were identified as independently related to the development of DVT: restriction of mobility (from OR=1.73, limited mobility without immobilization, to OR=5.64, bedridden during <15 days), aged 75 and older (OR=1.5/10 years), history of DVT or pulmonary embolism (OR=3.38), acute heart failure (OR=2.52), chronic edema of the lower limbs (OR=2.51), and paresis or paralysis of a lower limb (OR=2.06). The defined score of 8 or higher corresponded to an 88.7% probability of having symptomatic DVT.

Treatments to prevent symptomatic DVT in hospitalized elderly should be evaluated on patients with these factors.