Participants with factors affecting the participant's decision to accept or continue with the proposed treatment using the physician's treatment decision questionnaire (EORTC Quality of Life Questionnaire) will be reported.

ORR is defined as the percentage of participants achieving the best response of complete or partial response (including CR, CRi, PR or PR-L).

DoR is defined as time (in months ) from the first date of achieving complete or partial response (including CR, CRi, PR, or PR-L) to the date of first documented evidence of progressive disease (PD) or death.

PFS is measured from the start of I+V treatment to documented disease progression, relapse, or death due to any cause.

OS is measured from the start of I+V treatment to date of death due to any cause.

TOT is defined as time from the start of I+V treatment to the time of the end of treatment.

TTD is defined as the time from the start of I+V treatment to the premature discontinuation of ibrutinib or venetoclax (whichever is earlier).

TTNT is measured from the start of I+V treatment to the start of subsequent chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) treatment where applicable.

The EORTC QLQ-CLL17, comprising 17 questions, was developed to supplement the core questionnaire and to specifically assess the health status of participants with CLL. It comprises 17 items grouped into 3 multi-item scales: 1) symptom burden, 2) physical condition/fatigue, and 3) worries/fears about health and functioning. Each question is rated using a 4-point response scale ("not at all," "a little," "quite a bit," and "very much"). The scores of each subscale are calculated and then transformed to a 0 to 100 scale. Higher scores represent higher levels of symptom burden, physical condition/fatigue, or worries/fears about health and functioning.

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. An SAE is any AE that results in: death, persistent or significant disability/incapacity, requires inpatient hospitalization or prolongation of existing hospitalization, is life-threatening experience, is a congenital anomaly/birth defect and may jeopardize participant and/or may require medical or surgical intervention to prevent one of the outcomes listed above. Number of participants with AEs, all serious AEs, and all special situations (for example, medication error, overdosing, abuse, lack of effect, unexpected benefits following exposure to ibrutinib etc.) will be reported.

Number of participants with tumor lysis risk (absolute lymphocyte count [ALC] and lymph node diameter) will be reported. Tumor lysis will be categorized as: 1) high: any lymph node with largest diameter greater than or equal to (>=) 10 centimeter (cm) or any lymph node with largest diameter >=5 cm and ALC >=25 gram/liter (G/L); 2) intermediate: any lymph node >=5 cm to less than (<) 10 cm or ALC >=25 G/L; and 3) low: all lymph nodes <5 cm and ALC <25 G/L.

Participants with hospitalization for venetoclax ramp-up for The I+V treatment will be reported.

Duration of hospitalization is defined as number of days from the day of admission to discharge.

Emergency room visits, other than due to a serious adverse event following exposure to ibrutinib will be reported.