Despite concerns about the benefit of low-dose CT (LDCT) lung cancer screening in older patients, a secondary analysis of data from the National Lung Screening Trial (NLST) has found the test’s positive predictive value is actually higher for those older than 65.

The findings, published online September 8 in Annals of Internal Medicine, come amid a debate over whether Medicare should pay for LDCT screening. Private insurers are required to cover the scans after the U.S. Preventive Services Task Force recommended yearly screening for people 55 and older with a 30-pack-year smoking history. Earlier this year, however, the Medicare Evidence Development and Coverage Advisory Committee panel voted against extending coverage to Medicare beneficiaries. The panel was concerned that the harms of screening seniors might outweigh the benefits, and it noted the limited evidence on this front—only a quarter of NLST participants were older than 65, for example.

To address the lack of evidence focused specifically on patients older than 65, Paul F. Pinsky, PhD, of the National Cancer Institute in Bethesda, Md., and colleagues conducted a secondary analysis of NLST data, separating the participants by age. The 19,612 participants aged 55-64 were compared against the 7,110 who were aged 65-74. Median follow-up was more than six years.

Results suggested that high-risk patients older than 65 benefit slightly more from LDCT lung cancer screening than younger patients. The positive predictive value was 4.9 percent in those older than 65 compared with 3 percent in those younger than 65. The number needed to screen to prevent one lung cancer death was 245 among older patients, and 364 in the younger group.

LDCT screening sensitivity was comparable between the two groups, though the older group had a significantly higher prevalence of lung cancer, which accounts for the higher positive predictive value.

Screening in older patients is not without its drawbacks, however. Pinsky and colleagues also found that the rate of false-positives was higher for those older than 65 compared with younger patients, at 28 percent versus 22 percent.

Regardless of the slightly higher rate of screening-related harms, the findings reflect similar trade-offs when screening older patients as when screening middle-aged patients, according to an accompanying editorial from Michael K. Gould, MD, MS, of Kaiser Permanente Southern California in Pasadena.

"Until there is new and direct evidence to the contrary, it does not seem reasonable to exclude persons aged 65 to 74 years from access to screening,” wrote Gould.

A coverage decision on LDCT lung cancer screening for Medicare beneficiaries is expected in early November.