An Open-Label, Long-term Study to Assess the Immunogenicity of LINZESS® (Linaclotide) Administered Orally to Adult Participants With Irritable Bowel Syndrome With Constipation or Chronic Idiopathic Constipation

Number of Participants With Positive Treatment-Related Anti-Drug Antibodies (ADA) in Serum

Time frame · Baseline (Day 1) up to 52 weeks or 8 months post last dose if ADA positive at Week 52 (approximately 84 weeks)

Participants who met either of the following criteria: 1) treatment-induced ADA-positive (≥ 1 postbaseline ADA-positive sample) for baseline ADA negative or ADA-undetermined participants or 2) treatment-boosted ADA-positive (≥ 1 postbaseline ADA-positive sample with titer values ≥ 4-fold the baseline titer value) for baseline ADA-positive participants were reported as a ADA positive responder.

Change From Baseline in Participant's Assessment of Constipation Severity

Time frame · Baseline (Day 1) to Weeks 2, 4, 12, 26, 40 and 52 (Open Label Treatment Period)

Participants rated constipation severity during the previous 7 days on a 5-point ordinal scale where, 1=None, 2=Mild, 3=Moderate, 4=Severe and 5=Very Severe. Higher scores indicate greater severity. A negative change from Baseline indicates improvement.

Change From Baseline in Participant Assessment of Irritable Bowel Syndrome (IBS) Symptom Severity for Participants With Irritable Bowel Syndrome With Constipation (IBS-C)

Time frame · Baseline (Day 1) to Week 2, 4, 12, 26, 40 and 52 (Open Label Treatment Period)

Participants rated IBS symptoms severity during the previous 7 days on a 5-point ordinal scale where, 1=None, 2=Mild, 3=Moderate, 4=Severe and 5=Very severe. Higher scores indicate greater severity. A negative change from Baseline indicates improvement.

Change From Baseline in Degree of Relief of IBS Symptoms for Participants With IBS-C

Time frame · Baseline (Day 1) to Weeks 2, 4, 12, 26, 40 and 52 (Open Label Treatment Period)

Participants rated degree of relief of IBS symptoms during previous 7 days on a 7-point balanced ordinal scale where, 1=completely relieved, 2=considerably relieved, 3=somewhat relieved, 4=unchanged, 5=somewhat worse, 6=considerably worse and 7=as bad as I can imagine. Lower scores indicate greater relief. A negative change from Baseline indicates improvement.

IBS Treatment Satisfaction Assessment Postbaseline for Participants With IBS-C

Time frame · Weeks 2, 4, 12, 26, 40 and 52 (Open Label Treatment Period)

Participants rated degree of satisfaction with the LINZESS®'s ability to relieve IBS symptoms on a 5-point ordinal scale where, 1=Not at all satisfied, 2=A little satisfied, 3=Moderately satisfied, 4=Quite satisfied and 5=Very satisfied. Higher scores indicate greater satisfaction.

Constipation Treatment Satisfaction Assessment Postbaseline for Participants With Chronic Idiopathic Constipation (CIC)

Time frame · Weeks 2, 4, 12, 26, 40 and 52 (Open Label Treatment Period)

Participants rated degree of satisfaction with LINZESS®'s ability to relieve constipation symptoms on a 5-point ordinal scale where 1=Not at all satisfied, 2=A little satisfied, 3=Moderately satisfied, 4=Quite satisfied and 5=Very satisfied. Higher scores indicate greater satisfaction.

Number of Participants With Recurrence of Diarrhea

Time frame · From first dose in the Double-blind Treatment Period to Week 52

Participant reporting any instance of diarrhea during the Double-blind Treatment Period.

Number of Participants With Recurrence of Intolerable Diarrhea

Time frame · From first dose in the Double-blind Treatment Period to Week 52

Participants reporting any instance of intolerable diarrhea during the Double-blind Treatment Period (Non-responder otherwise). Only includes participants reporting intolerable diarrhea during the Open-label Treatment Period.

Percentage of Participants With Treatment Emergent Adverse Events (TEAE)

Time frame · From first dose of study treatment up to Week 52

An adverse event is any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An adverse event can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product. A TEAE is an AE that occurred after receiving the first dose of investigational product or an AE present prior to first dose but increased in severity during the Treatment Period.

Time to First Recurrence of Diarrhea

Time frame · From first dose in the Double-blind Treatment Period to Week 52

Time to first recurrence of diarrhea was defined as event/censored date - double-blind start date + 1, where event date (responders) = first recurrence of diarrhea date during the double-blind treatment period; censoring date (non-responders) = double-blind end date. Only includes participants reporting intolerable diarrhea during the open-label treatment period.

Time to First Recurrence of Intolerable Diarrhea

Time frame · From first dose in the Double-blind Treatment Period to Week 52

Time to first recurrence of intolerable diarrhea was defined as event/censored date - double-blind start date + 1, where event date (responders) = first recurrence of intolerable diarrhea date during the double-blind treatment period; censoring date (non-responders) = double-blind end date. Only includes participants reporting intolerable diarrhea during the open-label treatment period.