This is a prospective, multicenter, observational study designed to collect gastrointestinal related data in patients with Cystic Fibrosis (CF).

There are currently no large, multicenter prospective clinical trials examining management of constipation or other gastrointestinal (GI) symptoms in people with cystic fibrosis (CF). Current recommendations in the CF literature are largely based on expert consensus and opinions. Yet, constipation and other GI symptoms are crucial factors in quality of life (QOL) and maintenance of optimal nutritional state in people with CF. This study will use GI-symptomatology questionnaires to understand the multiple overlapping GI symptoms in people with CF.

Eligible subjects will be consented and enrolled in the study at the Enrollment Visit. At the visit, the subject or parent/guardian will complete the patient reported outcome surveys (PROs) using a mobile device (e.g., smartphone or tablet). The same questionnaires will be completed on a mobile device outside the clinic three additional times. The PROs will consist of four questionnaires: Patient Assessment of Constipation Symptoms (PAC-SYM), Patient Assessment of Gastrointestinal Symptoms (PAGI-SYM), Patient Assessment of Constipation Quality of Life (PAC-QOL) and a disease-specific questionnaire (Bristol Stool Scale and questions about fecal incontinence, and stool quality and frequency).

Inclusion Criteria:

1. All genders ≥ 2 years of age at time of consent

2. Documentation of a Cystic Fibrosis (CF) diagnosis as evidenced by one or more clinical features consistent with the CF phenotype and one or more of the following criteria:

   • Sweat chloride equal to or greater than 60 milliequivalent (mEq)/liter by quantitative pilocarpine iontophoresis test (QPIT)
   • Two well-characterized mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene
   • Abnormal nasal potential difference (NPD) (change in NPD in response to a low chloride solution and isoproterenol of less than -5 mV)

3. Enrolled in the Cystic Fibrosis Foundation Patient Registry (subjects may enroll in the Registry at Enrollment Visit if not previously enrolled)

4. Written informed consent (and assent when applicable) obtained from subject or subject's legal representative

5. Willing to complete questionnaires on mobile device

6. Able to use the Medidata Patient Cloud mobile application for completing the questionnaires

Exclusion Criteria:

1. Presence of a condition or abnormality that, in the opinion of the Investigator, would complicate interpretation of study outcome data or interfere with achieving the study objectives
2. Presence of a pulmonary exacerbation at the Enrollment Visit
3. Hospitalization for distal intestinal obstruction syndrome (DIOS) within the 28 days prior to the Enrollment Visit
4. Current gastrointestinal (GI) or abdominal/pelvic malignancy
5. Abdominal or pelvic surgery within the 28 days prior to the Enrollment Visit
6. At the time of the Enrollment Visit, planned abdominal or pelvic surgery or bowel cleanout in the 28 days after the Enrollment Visit
7. Initiation of new CFTR modulator therapy within the 4 weeks prior to the Enrollment Visit
8. Intent to initiate new CFTR modulator therapy within 28 days of the Enrollment Visit

Subjects with a diagnosis of Cystic Fibrosis (CF) who meet all the inclusion and none of the exclusion criteria will be eligible for participation in this study.