Rationale and background
Cystic fibrosis (CF) is a progressive genetic disorder associated with significant morbidity and premature mortality, primarily affecting the respiratory and gastrointestinal systems. It leads to chronic lung infections, pancreatic insufficiency, and other complications requiring comprehensive, lifelong management. This study aims to generate epidemiological evidence on the clinical haracteristics and monitoring of individuals diagnosed with CF across Europe between 2015 and 2024.
Research question and objectives
Research question:
What are the demographic and clinical characteristics of individuals diagnosed with cystic fibrosis (CF) in Europe between 2015 and 2024?
Study objectives:
1. To characterise individuals newly diagnosed with CF in terms of demographics, pre-specified comorbidities, Pseudomonas aeruginosa colonisation, CF screening, genotyping test and CFTR modulator treatment use, overall and stratified by paediatric and adult populations.
2. To characterise timing and availability of key clinical measurements including Forced Expiratory Volume (FEV), height, weight, Body Mass Index (BMI) measurements, sweat chloride levels and genotyping tests in
individuals who initiated any CFTR modulator treatment after CF diagnosis, overall and stratified by paediatric and adult populations.
3. To estimate the background incidence rates of pre-specified events of special interest: susceptibility for influenza virus infections, cataract, depression, anxiety and hepatotoxicity by treatment, in the CF population, overall and stratified by paediatric and adult populations and by calendar year.
4. To measure the incidence of pulmonary exacerbation among individuals newly diagnosed with CF overall and stratified by country/database, paediatric and adult populations, sex and time since diagnosis (one and two years post-diagnosis).
Methods
Study design
This retrospective cohort study aims to characterise individuals newly diagnosed with CF in terms of demographics, Pseudomonas aeruginosa colonisation, pre-specified comorbidities, CF screening test and genotyping test and CFTR modulator treatment use (objective 1), clinical characteristics including key clinical measurements (FEV, height, weight, BMI), sweat chloride levels and genotyping tests (objective 2) and to estimate the incidence of selected events of special interest and pulmonary exacerbation (objective 3 and 4).
Study period
1st January 2015 to 31st December 2024 (or latest available).
Study population
New CF diagnosis cohort (objective 1, 3 and 4): The study population will include all individuals with a first recorded diagnosis of CF in the period between 1st January 2015 and 31st December 2024 (or latest available). To ensure sufficient follow-up, only individuals diagnosed no later than 180 days prior to the end of data availability in each database will be included. Eligible individuals must have at least one year of data visibility prior to the date of CF diagnosis. The requirement of one year prior data availability will not hold or children below 1 year of age.
New CFTR modulator user cohort (objective 2): The study population will include individuals with a first diagnosis of CF in the period between 1st January 2015 and 31st December 2024 (or latest available) who initiated any CFTR modulator therapy after CF diagnosis. To ensure sufficient follow-up, only individuals diagnosed with CF at least 180 days before the end of data availability in each data source will be included.
Eligible individuals must have at least one year of prior data visibility prior to the date of CF diagnosis and no use of CFTR modulator therapy in one year preceding treatment initiation. This requirement will not hold for children < 1 year of age.
Condition of interest: cystic fibrosis
Variables
Medication of interest: CFTR modulator therapy CFTR modulator therapy WHO ATC classification code · Ivacaftor R07AX02
· Ivacaftor and lumacaftor R07AX30
· Ivacaftor and tezacaftor R07AX31
· Ivacaftor, tezacaftor and elexacaftor R07AX32
· Deutivacaftor, tezacaftor and vanzacaftor R07AX33
Pre-specified comorbidities: depression, anxiety, sleeping disorders, pregnancy, congenital adverse events,
diabetes, liver morbidity or mortality (if not feasible overall mortality), bone content (or measurements of
bone content), gastro-intestinal complaints including constipation, acid reflux and abdominal pain.
Events of special interest: susceptibility for influenza virus infections, cataract, depression, anxiety,
hepatotoxicity by treatment, pulmonary exacerbations.
Data sources
1. Assistance Publique – Hôpitaux de Marseille (APHM), France
2. Hospital Universitario 12 de Octubre (H12O), Spain
3. Norwegian Linked Health Registry data (NLHR), Norway
4. Research Repository @Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (POLIMI), Italy
5. The Information System for Research in Primary Care (SIDIAP), Spain
6. Semmelweis University Clinical Data (SUCD), Hungary
Statistical analysis
Descriptive characterisation will be performed at the patient level (objective 1). Age and sex at the time of the first recorded diagnosis of CF will be reported. The index date is defined as the date of the first recorded CF diagnosis for each individual. The number and percentage of individuals with a record of the prespecified condition of interest, colonisation with Pseudomonas aeruginosa, CF screening, genotyping test or CFTR modulator use will be assessed during pre-defined time windows. The statistical analysis will be conducted using “CohortCharacteristics” R package based on OMOP-CDM mapped data.
Clinical characterisation (objective 2) will include age and sex at the date of incident CFTR modulator initiation. Additionally, the number and proportion of individuals initiating CFTR modulator treatment with available record of clinical measurements (FEV, height, weight, BMI) at index date and during pre-defined time windows, will be reported overall and stratified age. If available, clinical measurements (FEV, height, weight, BMI) will be summarised using minimum, quartiles and maximum values at index date and during pre-defined time windows, overall and stratified age groups. Similarly, number and proportion of individuals initiating CFTR modulators with a record of sweat chloride and genotyping tests will be reported at the index date and during the pre-defined time windows, overall and stratified by age. Results of sweat chloride levels and genotyping tests (if available) will also be reported, overall and stratified by age. The statistical analysis will be conducted using “CohortCharacteristics” R package based on OMOP-CDM mapped data.
Incidence rates of pre-specified events of special interest (objective 3) will be estimated following CF diagnosis. The pre-specified events of interest are susceptibility for influenza virus infections, cataract, depression, anxiety and hepatotoxicity by treatment. These incidence rates will be expressed as the number of individuals with the event of interest following new CF diagnosis per 1,000 person-years of the individuals fulfilling the inclusion and exclusion criteria. Incidence rates will be reported overall and stratified by paediatric and adult populations and calendar year. The statistical analyses will be performed based on
OMOP-CDM mapped data using the “IncidencePrevalence” R package.
Incidence rates of newly diagnosed pulmonary exacerbation (objective 4) will be estimated following CF diagnosis. The results will be expressed as the number of individuals with the pulmonary exacerbation per 1,000 person-years of the individuals fulfilling the inclusion and exclusion criteria. Incidence rates will be calculated for consecutive yearly intervals since the CF diagnosis (index date), with a maximum follow-up period of 24 months. Incidence rates will be stratified by paediatric and adult populations and sex. These statistical analyses will be performed based on OMOP-CDM mapped data using the “IncidencePrevalence” R
package.
For all analyses a minimum cell counts of 5 will be used when reporting results, with any smaller counts obscured.