ATLANTA—Annual rates of pulmonary thromboembolism (PTE) have declined by about 30% in the past 25 years.[1] Possible reasons for the reduction include a decreased incidence of PTE, a decreased case fatality rate (stemming from improved prevention, diagnosis, and treatment of both PTE and its risk factors), and more accurate reporting.

To address discrepancies in the reported rates of PTE mortality, a group of researchers from Emory University and the CDC reviewed the Multiple-Cause Mortality Files of persons who had died between 1979 and 1998 in the United States. These files are compiled by the National Center for Health Statistics and, beginning in 1979, included the ICD-9 codes for underlying cause of death and up to 20 comorbidities listed on the death certificate.

Of the 42,932,973 mortality files analyzed, 572,773 listed PTE as either the underlying or contributing cause of death. PTE was deemed the actual cause of death in 194,389 of the records (33.9% of the cases in which it was listed). These numbers, the researchers noted, are less than what is typically cited by other investigators but within the expected range.

The total number of deaths from PTE steadily decreased from 35,750 in 1979 to 24,947 in 1998. This corresponds to an age-adjusted drop in the PTE mortality rate from 191 per million to 94 per million.

The rate of PTE deaths that were associated with trauma or cancer remained relatively stable across the study period. For example, of the 572,773 death certificates that mentioned PTE, 11.8% listed both PTE and trauma in 1979, compared with 10.8% in 1998; for PTE and cancer, the comparative rates were 21.0% and 24.0%. A more striking difference was seen for cardiac disease. In 1979, 34.1% of the PTE deaths occurred in individuals with a cardiac comorbidity, compared with only 21.2% in 1998.

Although mortality from PTE declined for both sexes during the examined interval, the number of PTE deaths remained 20% to 30% higher for men than women. The age-adjusted rates were generally about 50% higher in blacks than in whites, and about 50% higher in whites than in the other racial/ethnic groups studied, including Asians and Native Americans.

Proportionate mortality ratios (PMRs) were calculated to evaluate the likelihood that certain risk factors were more (PMR > 1) or less (PMR < 1) likely to be associated with PTE deaths. Conditions or circumstances that were linked to an increased risk of PTE death included trauma, fractures, extended postoperative care, and obesity (adjusted PMRs, 1.89, 5.04, 1.85, 4.55, respectively.)

The most common and expected disorder to be associated with PTE on the death certificates was thrombophlebitis (adjusted PMR, 24.2); the most surprising was inflammatory bowel disease (mean PMR, 2.25). Serologic abnormalities are common in persons with Crohn’s disease and ulcerative colitis and may thus predispose them to PTE, the researchers said.

—Verna L. Schwartz, MS

Reference
1. Horlander KT, Mannino DM, Leeper KV. Pulmonary embolism mortality in the United States, 1979-1998. Arch Intern Med. 2003;163:1711-1717.

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