Factors influencing candidate blood donors' deferral, retention and blood safety in Tanzania: A prospective cross-sectional study.

Pulmonary embolism (PE) remains one of the most common causes of hospitalization and is the third leading cause of cardiovascular death. Mortality is higher among patients with more severe presentations. Management strategies and treatment modalities vary depending on patient risk stratification, which is an evolving science. Clinical presentation is highly variable, ranging from asymptomatic cases to severe hemodynamic compromise. Several factors influence disease severity including functional status, presence of cardiopulmonary comorbidities, and characteristics of the embolism itself. These factors also guide management decisions and are important for assessing the risk of recurrence and the need for long term anticoagulation. Prior even to the diagnosis of PE, pre-test probability scores can be clinically useful. In hemodynamically stable patients, the primary tools for assessing pulmonary embolism pretest probability are the Wells clinical prediction rule () and the revised Geneva score (). The Wells score is calculated by assigning points to select clinical characteristics: 1.5 points each for prior history of DVT/PE, tachycardia (>100 beats per minute), and recent surgery or immobilization within 4 weeks; 1 point each for hemoptysis and active malignancy (treatment within 6 months); and 3 points each for clinical signs and symptoms of DVT and for a subjective assessment that PE is the most likely diagnosis. The calculated Wells score can then be used to predict the probability of PE, <2 points indicate low probability (<3.6%), 2–6 points indicates moderate probability (<20.5%), >7 points indicate high probability (66.6%). The Geneva score was originally published in 2001 and subsequently revised and simplified in 2006. The Geneva score is more standardized than the Wells score because it does include a subjective component in its scoring. Like the Wells rule, points are assigned to clinical characteristics: 5 points for a heart rate ≥95 beats per minute; 4 points for unilateral lower-limb edema or pain on palpation; 3 points for prior history of DVT/PE, unilateral limb pain, or heart rate 75–94 beats per minute; and 2 points for surgery or fracture within the previous month, active malignancy, or hemoptysis. The calculated Geneva score can then be used to estimate pretest probability of PE, 0–3 points indicate low probability (8%), 4–10 points indicate intermediate probability (28%), and 11 points or more indicate high probability. Studies comparing the Wells score and Geneva score have demonstrated similar predictive accuracy for PE diagnosis in the emergency department setting.