Effects of age on the performance of common diagnostic tests for pulmonaryembolism

PURPOSE: The diagnosis of pulmonary embolism in the elderly is often diffic ult because of comorbid medical conditions, and perhaps also because diagno stic tests have a lower yield. We analyzed the diagnostic performance of co mmon diagnostic tests for pulmonary embolism in different age groups. METHODS: We analyzed data from two large studies that enrolled 1,029 consec utive patients presenting to the emergency department with clinically suspe cted pulmonary embolism. The clinical probability of pulmonary embolism (hi gh [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 ultrason ography, and pulmonary angiography if the noninvasive work-up was inconclus ive. 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 probabili ty of pulmonary embolism was greater in the elderly (71% to 78% in those gr eater 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 t hose less than or equal to 40 years old to 10% in those greater than or equ al to 80 years old. The diagnostic yield of lower limb compression ultrason ography 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 pul monary embolism and should be kept in mind when evaluating patients suspect ed of having this condition. (C) 2000 by Excerpta Medica, Inc.