Lung cancer is the deadliest form of the disease, though radiologists can help catch this concern with proper screening using low-dose CT. Only 46% of patients actually stick to their annual exam schedule, however, with a few factors proving predictive, experts detailed on Tuesday.

In particular, being between the ages of 55-64 or 75-79, living in a rural area, and using Medicaid or fee-for-service Medicare were all associated with lower adherence. University of Colorado Anschutz Medical Campus researchers analyzed data from more than 9,000 patient encounters for the analysis and believe the findings could help practices boost compliance.

“Quantifying population-based adherence rates and understanding factors associated with annual adherence is a critical first step in improving screening adherence and ultimately reducing lung cancer death,” corresponding author Stephen Malkoski, MD, PhD, with the Division of Pulmonary Sciences and Critical Care Medicine at CU Anschutz, and co-authors wrote March 30 in JACR.

For the study, scientists looked to the Colorado All Payer Claims Dataset, targeting those who received a low-dose CT lung cancer screening between 2012-2018. They defined adherence as cases where there was a second claim for such imaging 10-18 months after the initial exam. Those parameters produced a set of more than 9,000 records, including nearly 3,100 patients who stuck to their screening schedule and 3,600 who did not. Another 2,400 were “unclassifiable,” since an insufficient amount of time had passed from the baseline exam.

Malkoski and colleagues found that about 46% of patients returned for another LDCT screening within 18 months. The adherence rate leapt to 53% if any return for screening was considered compliant (even if it was within less than 10 months), they noted. Higher healthcare usage and increased comorbidity burden were both associated with greater adherence, though the two factors were interdependent.

The authors speculated several reasons why certain groups might miss their next LCS appointment. Reduced adherence among individuals 75-79 is likely explained by recommendations to stop LCS as they reach their mid-70s. And younger individuals (55-64) are less likely to receive preventive services than individuals 65 and up, while also grappling with time priorities and misperceptions about screening costs. Rural populations, meanwhile, have higher smoking rates, lower socioeconomic status and use less preventive care than urban counterparts, among other factors, the authors noted.

You can read more about the study results in the Journal of the American College of Radiology here.