More CFRD Screening Can Improve Outcome of People with CF, Study Suggests

Clinical centers with high screening rates for cystic fibrosis-related diabetes (CFRD) were more likely to achieve early CFRD diagnosis and prevent lung function decline, a study has found.

This was reported in a study, “The association of pediatric cystic fibrosis-related diabetes screening on clinical outcomes by center: A CF patient registry study,“ published in the Journal of Cystic Fibrosis.

CFRD is a complication that affects approximately 40–50% of adults and 20% of adolescents with cystic fibrosis (CF). For many of them, there are no obvious symptoms of this secondary disorder, and many subtle symptoms are often overlooked as typical signs of CF progression. Thanks to advances in CF clinical care, people are living longer, which highlights the importance of early CFRD detection.

In 2010, CFRD Clinical Care Guidelines were updated to recommend that CF patients begin annual CFRD screening at 10 years old, the age at which the prevalence of CFRD increases significantly. Despite these recommendations, in 2017, only 43% of patients 10 and older had undergone an oral glucose tolerance test (a standard test to diagnose diabetes) at CF centers in the United States. 

To better understand the impact of screening practices, researchers used patient data from the CF Foundation Patient Registry to assess the association between screening practices at CF centers with the eventual diagnosis of CFRD. They also examined trends in lung function, as determined by the percent predicted forced expiratory volume in one second (ppFEV1) and body mass index (BMI), both before and after CFRD diagnosis. 

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They analyzed the records of 3,553 patients followed at 104 centers between 2008 and 2015. At these centers, CFRD screening involved either a positive fasting blood glucose level (125 mg/dl) or a negative fasting blood glucose level followed by an oral glucose test. Of all patients, 445 were diagnosed with CFRD at a mean age of 13.1 years old. 

After analyzing the screening rates of each CF center, the team found that those with higher screening rates diagnosed more patients with CFRD. Centers with the highest screening rates also had the shortest time until CFRD diagnosis. 

Around age 12, the percentage of CFRD diagnosis did not vary among centers, but by age 16, 30% of adolescents were diagnosed at the centers with the highest screening rates (80–100%), while only 9% were diagnosed at the centers with the lowest screening rates (0–19%). 

In general, the average ppFEV1 remained consistent two years before CFRD diagnosis (89%) and declined at an overall rate of 2.5% per year until diagnosis and 1.9% per year after diagnosis.  However, at centers with low screening rates, steeper rates of FEV1 decline were identified two years prior to diagnosis.

Patients who were followed at centers with the lowest screening rates (0–19%) experienced an annual rate of FEV1 decline twice that of patients followed at centers with 60–79% screening rates, and seven times that of patients in the highest screening centers (80–100%), the researchers reported.

These results suggest that CF centers with higher screening rates detected and diagnosed CFRD earlier, even before a decline in lung function. 

General trends in BMI were not identified before or after CFRD diagnosis. But trends varied according to CFRD screening levels, with the highest and lowest rates of screening trending upward. 

“This study supports the notion that adherence to CF Foundation guidelines can significantly improve patient outcomes,” the researchers stated. “With more therapeutic options available each year, CF care teams are tasked with the goal of identifying and prioritizing the most effective and affordable options for their patients.”