Effects of age on the performance of common diagnostic tests for pulmonary embolism

PURPOSE: The diagnosis of pulmonary embolism in the elderly is often difficult because of comorbid medical conditions, and perhaps also because diagnostic tests have a lower yield. We analyzed the diagnostic performance of common diagnostic tests for pulmonary embolism in different age groups. METHODS: We analyzed data from two large studies that enrolled 1,029 consecutive patients presenting to the emergency department with clinically suspected pulmonary embolism. The clinical probability of pulmonary embolism (high [greater than or equal to 80%], intermediate, or low [less than or equal to 20%]) was estimated by the treating physician. AU patients underwent a sequential diagnostic protocol, including ventilation-perfusion lung scan, measurement of plasma D-dimer level, lower limb venous compression ultrasonography, and pulmonary angiography if the noninvasive work-up was inconclusive. RESULTS: The prevalence of pulmonary embolism increased progressively, from 12% in patients <40 years of age to 44% in those greater than or equal to 80 years of age. The positive predictive value of a high clinical probability of pulmonary embolism was greater in the elderly (71% to 78% in those greater than or equal to 60 years old versus 40% to 64% in those less than or equal to 59 years old). The sensitivity of D-dimer testing was 100% in all age groups, but its specificity decreased markedly with age, from 67% in those less than or equal to 40 years old to 10% in those greater than or equal to 80 years old. The diagnostic yield of lower limb compression ultrasonography was greater in the elderly. The proportion of lung scans that were diagnostic (normal, near-normal, or high probability) decreased from 68% to 42% with increasing age. CONCLUSIONS: Age affects the performance of common diagnostic tests for pulmonary embolism and should be kept in mind when evaluating patients suspected of having this condition. (C) 2000 by Excerpta Medica, Inc.