JAMA : the journal of the American Medical Association
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Comparative Study
Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED).
To determine the sensitivities and specificities of ventilation/perfusion lung scans for acute pulmonary embolism, a random sample of 933 of 1493 patients was studied prospectively. Nine hundred thirty-one underwent scintigraphy and 755 underwent pulmonary angiography; 251 (33%) of 755 demonstrated pulmonary embolism. Almost all patients with pulmonary embolism had abnormal scans of high, intermediate, or low probability, but so did most without pulmonary embolism (sensitivity, 98%; specificity, 10%). ⋯ Of 322 with intermediate-probability scans and definitive angiograms, 105 (33%) had pulmonary embolism. Follow-up and angiography together suggest pulmonary embolism occurred among 12% of patients with low-probability scans. Clinical assessment combined with the ventilation/perfusion scan established the diagnosis or exclusion of pulmonary embolism only for a minority of patients--those with clear and concordant clinical and ventilation/perfusion scan findings.
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It is estimated that more than 3 million American children under 18 years of age consume 947 million packs of cigarettes and 26 million containers of smokeless tobacco yearly. These tobacco products account for annual sales of $1.26 billion. ⋯ Tax revenues to the federal ($152 million) and state ($173 million) governments from cigarette sales to children dwarf governmental expenditures on smoking and health. We describe how dozens of communities have effectively enforced laws that prohibit the distribution of tobacco to children and offer some suggestions for increasing efforts to prevent nicotine addiction.