Clinical remission is achieved when total crohn's disease activity index (CDAI) <150 or total of harvey-bradshaw index (HBI) score <5. CDAI assesses CD based on variables: extra-intestinal manifestations, abdominal mass, weight, hematocrit, total number of liquid stools, abdominal pain, use of antidiarrheal drug(s) and general well-being. CDAI score: asymptomatic remission: <150, mild: 150-220, moderate: 221-450, severe: >450. HBI parameters: general well-being (0-4, higher score means lower well-being), abdominal pain (0-3, higher score means more severe pain), number of liquid stools per day (score 1 per movement), abdominal mass (0=none, 1=dubious, 2=definite, 3=definite and tender) and complications (score 1 per item). Total score is sum of individual parameters. Score ranges from 0 to no pre-specified maximum score as it depends on number of complications and liquid stools per day. HBI score: <5 (remission), 5-7 (mild disease), 8-16 (moderate disease) and >16 (severe disease).

Clinical response is defined as decrease in total CDAI score from >=100 or a CDAI score <150 or decrease in total HBI score >=3 from baseline. CDAI assesses CD based on variables: extra-intestinal manifestations, abdominal mass, weight, hematocrit, total number of liquid stools, abdominal pain, use of antidiarrheal drug(s) and general well-being. CDAI score: asymptomatic remission: <150, mild: 150-220, moderate: 221-450, severe: >450. HBI parameters: general well-being (0-4, higher score means lower well-being), abdominal pain (0-3, higher score=more severe pain), number of liquid stools per day (score 1 per movement), abdominal mass (0=none, 1=dubious, 2=definite, 3=definite and tender) and complications (score 1 per item). Total score is sum of individual parameters. Score ranges from 0 to no pre-specified maximum score as it depends on number of complications and liquid stools per day. HBI score: <5 (remission), 5-7 (mild disease), 8-16 (moderate disease) and >16 (severe disease).

Steroid-free clinical remission is achieved when total CDAI score <150 or total HBI score <5, without use of any steroid preparations. CDAI assesses CD based on variables: extra-intestinal manifestations, abdominal mass, weight, hematocrit, total number of liquid stools, abdominal pain, use of antidiarrheal drug(s) and general well-being. CDAI score: asymptomatic remission: <150, mild: 150-220, moderate: 221-450, severe: >450. HBI parameters: general well-being (0-4, higher score=lower well-being), abdominal pain (0-3, higher score=more severe pain), number of liquid stools per day (score 1 per movement), abdominal mass (0=none, 1=dubious, 2=definite, 3=definite and tender) and complications (score 1 per item). Total score is sum of individual parameters. Score ranges from 0 to no pre-specified maximum score as it depends on the number of liquid stools per day and number of complications. HBI score: <5 (remission), 5-7 (mild disease), 8-16 (moderate disease) and >16 (severe disease).

Steroid-free clinical response: decrease in total CDAI score >=100 or total HBI score >=3 from baseline, without use of any steroid preparations. CDAI assesses CD based on variables: extra-intestinal manifestations, abdominal mass, weight, hematocrit, total number of liquid stools, abdominal pain, use of antidiarrheal drug(s) and general well-being. CDAI score: asymptomatic remission: <150, mild: 150-220, moderate: 221-450, severe: >450. HBI parameters: general well-being (0-4, higher score=lower well-being), abdominal pain (0-3, higher score=more severe pain), number of liquid stools per day (score 1 per movement), abdominal mass (0=none, 1=dubious, 2=definite, 3=definite and tender) and complications (score 1 per item). Total score is sum of individual parameters. Score ranges from 0 to no pre-specified maximum score as it depends on number of complications and liquid stools per day. HBI score: <5 (remission), 5-7 (mild disease), 8-16 (moderate disease) and >16 (severe disease).

Change from baseline in CRP at Week 24 will be reported.

Change from baseline in fecal calprotectin at Week 24 will be reported.

Disease progression is defined as the first occurrence of CD complications, or CD-related surgery and hospitalization from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time. CD-related surgery is defined as the first occurrence of any CD-related intestinal and perianal procedures. CD-related hospitalization is defined as the first occurrence of any CD-related admission, with causes including disease relapse, complication, and drug side effects, except for CD-related surgery.

Disease progression is defined as the first occurrence of CD complications, or CD-related surgery and hospitalization from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time. CD-related surgery is defined as the first occurrence of any CD-related intestinal and perianal procedures. CD-related hospitalization is defined as the first occurrence of any CD-related admission, with causes including disease relapse, complication, and drug side effects, except for CD-related surgery.

Percentage of participants who will switch to other therapy will be reported. Therapy switch is defined as switching to other biologic therapy from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with reasons for ustekinumab therapy switch to other therapy will be reported. Therapy switch is defined as switching to other biologic treatments from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with ustekinumab therapy discontinuation will be reported. Therapy discontinuation is defined as having a ustekinumab therapy gap of greater than or equal to (>=) 120 days without treatment switch or intravenous re-induction from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with reasons for ustekinumab therapy discontinuation will be reported. Therapy discontinuation is defined as having a ustekinumab therapy gap of >=120 days without treatment switch or intravenous re-induction from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Time to ustekinumab therapy switch or discontinuation will be reported. Therapy switch is defined as switching to other biologic therapy from index date to death or end of study. Therapy discontinuation is defined as having a ustekinumab therapy gap of >=120 days without treatment switch or intravenous re-induction from index date to death or end of study. The time to therapy switch or discontinuation is defined as follows: 1) For participants with an event date, it is calculated as the difference between the event date and index date, adding 1. 2) For participants without an event date, it is calculated as the difference between the end of the observation date (death/end of study) and the index date, adding 1; this time is a censoring time. The event date is the initiation date of therapy switch or discontinuation, whichever happens first. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with AEs and SAEs will be reported. An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product. SAE is an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with each AE will be reported. An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Duration of each AE will be reported. Duration of each AE's is defined as time from onset of AE to end date of each AE or till the end of the study. An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with each AE's outcome will be reported. Each AE's outcome includes recovered/resolved, recovered/resolved with sequelae, recovering/resolving, not recovered/not resolved, fatal, and unknown. An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product. Index date is defined as the date of initiating ustekinumab treatment for the first time.

Percentage of participants with ustekinumab therapy switch or discontinuation due to AEs will be reported. Therapy switch is defined as switching to other biologic therapy from index date to death or end of study. Therapy discontinuation is defined as having a ustekinumab therapy gap of >=120 days without treatment switch or intravenous re-induction from index date to death or end of study. Index date is defined as the date of initiating ustekinumab treatment for the first time. An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product.