Variations in the Management of Canadian Patients With CFTR Related Metabolic Syndrome/Cystic Fibrosis Screen Positive, Inconclusive Diagnosis (CRMS/CFSPID).

Background: With routine newborn screening for cystic fibrosis (CF) now considered standard of care, the designation of CFTR Related Metabolic Syndrome (CRMS) or CF screen positive, indeterminate diagnosis (CFSPID) has been established. The majority of CRMS/CFSPID patients remain asymptomatic; however, 3.8%-44% of these patients may progress to a diagnosis of CF. This raises the question of how to optimally manage CRMS/CFSPID patients. We set out to gain a better understanding of the past practices employed at CF centers across Canada in the care of patients with a diagnosis of CRMS/CFSPID.

Methods: An invitation to participate in an online survey was disseminated to CF centers in Canada through the REDCap database. The survey was completed in 2018. It included questions addressing patient population, timing of follow-up of CRMS/CFSPID patients, and details around specific investigations ordered.

Results: Twelve out of 20 qualifying clinics completed the survey. The total patient population compiled included 1412 patients, of which 171 (12%) were classified as CRMS/CFSPID. There was wide variability in the timing of follow-up with a median (IQR) of 6 (5.25-12) months and a range of 3-12 months. There was also wide variability in the timing of repeat investigations such as sweat chloride, respiratory cultures, chest x-rays and spirometry.

Conclusions: With current evidence showing that a considerable number of CRMS/CFSPID patients may progress to CF, ensuring these patients are identified as early as possible and followed in a consistent manner is essential. The Cystic Fibrosis Foundation and European Cystic Fibrosis Society have recently developed guidelines regarding the care of these patients. This survey describes historical practices for follow up of CRMS/CFSPID patients to help inform the development of Canadian consensus guidelines.