A systematic review of mobility/immobility in thromboembolism risk assessment models for hospitalized patients

Hospitalized patients are at risk of venous thromboembolism (VTE) and prophylaxis is often suboptimal due to difficulty in identifying at-risk patients. Simple and validated risk-assessment models (RAMs) are available to assist clinicians in identifying patients who have a high risk for developing VTE. Despite the well-documented association of immobility with increased risk of thrombosis, immobility is not consistently defined in clinical studies. We conducted a systematic review of published VTE RAMs and used objective criteria to determine how the term immobility is defined in RAMs. We identified 17 RAMs with six being externally validated. The concept of immobility is vaguely described in different RAMs, impacting the validity of these models in clinical practice. The wide variability in defining mobility in RAMs precluded its accurate clinical application, further limiting generalization of published RAMs. Externally validated RAMs with clearly defined qualitative or quantitative terms of immobility are needed to assess VTE risk in real-time at the point-of-care.