A 12-lead ECG was conducted at screening, week 24, and week 52 or at the last postbaseline observation. For rollover participants, the ECG performed at the final visit of study 3079 served as the 1st ECG in study 3080. A qualified physician was responsible for interpreting the ECG. Any ECG finding that was judged by the investigator as a clinically meaningful change (worsening) compared with baseline was considered an adverse event.

For overall results, the worst postbaseline finding for the participant was summarized.

Results below are formatted as Baseline ECG result - Overall ECG result.

Pure tone audiometry was performed by trained personnel. During the test, the patient wore headphones and was seated in a quiet room; trained personnel manipulated the audiometry equipment to test the patient's hearing. For serial audiograms, the criteria for a clinically significant (CS) hearing change were based on the guidance from the American Speech-Language Hearing Association (ASHA) 1994 (Konrad-Martin et al 2005). These criteria included the following: greater than 20 decibels (dB) pure tone threshold shift at 1 frequency; greater than 10 dB shift at 2 consecutive test frequencies; or threshold response shifting to "no response" at 3 consecutive test frequencies.

SOAPP-R is a clinician-rated scale used to assess each patient's risk of developing aberrant drug use behaviors while on long term opioid therapy. SOAPP-R consists of 24 questions that address 8 concepts: substance abuse history, medication related behaviors, antisocial behaviors/history, psychosocial problems, psychiatric history, physician patient relationship factors, emotional attachment to pain medications, and personal care and lifestyle issues (Butler et al 2008). Each question is answered using a 5 point Likert-like scale, with 0=never, 1=seldom, 2=sometimes, 3=often, and 4=very often for a total range of 0-96. The higher the overall score, the greater the probability the patient is at risk for displaying aberrant behaviors consistent with drug use.

An overall score of 18 or higher is considered positive for predicting aberrant drug related behavior, therefore the reported risk categories are

• <18 and
• <=18. Results indicate timeframe followed by risk cat

The ABC was a clinician rated scale that consisted of a brief (21 item) questionnaire designed to track behaviors characteristic of addiction related to prescription opioid medications in chronic pain populations. Items were focused on observable behaviors noted both during and between clinic visits. Each affirmative response was counted as 1 point, and points were added to calculate the total score. All but 1 of the 21 items (the provider's impression) was used in calculating the total score, consequently resulting in scores ranging from 0 to 20 (0=no addiction-related behaviors seen and higher scores indicating an increasing number of addition-related behaviors seen). Participants with a total score of 3 or greater were classified as exhibiting inappropriate opioid use during the study.

The COMM was a clinician-rated scale developed as a brief self-report measure of current aberrant drug-related behavior for patients with chronic pain who were already on long-term opioid therapy. A total score was calculated as the sum of the 17 questions. The total score ranged from 0 to 68. A score of 0 indicates no aberrant drug-related behaviors were seen. Patients with a total score of 9 or greater were classified as exhibiting aberrant drug-related behavior.

The subpopulation of participants who completed study C33237/3079 (NCT01240863) and 'rolled over' to participate in this study.

Participants were titrated (or re-titrated for roll-over participants) at escalating dosages of hydrocodone ER tablets at dosages of 15, 30, 45, 60, or 90 mg every 12 hours until deemed successful for managing their pain during the open-label titration period. Once a successful dose was identified, participants entered the 52 week open-label treatment period in which hydrocodone ER was administered at a successful dose (15, 30, 45, 60, or 90 mg) every 12 hours.

The subpopulation of participants who completed study C33237/3079 (NCT01240863) and 'rolled over' to participate in this study.

Participants were titrated (or re-titrated for roll-over participants) at escalating dosages of hydrocodone ER tablets at dosages of 15, 30, 45, 60, or 90 mg every 12 hours until deemed successful for managing their pain during the open-label titration period. Once a successful dose was identified, participants entered the 52 week open-label treatment period in which hydrocodone ER was administered at a successful dose (15, 30, 45, 60, or 90 mg) every 12 hours.

The subpopulation of participants who completed study C33237/3079 (NCT01240863) and 'rolled over' to participate in this study.

Participants were titrated (or re-titrated for roll-over participants) at escalating dosages of hydrocodone ER tablets at dosages of 15, 30, 45, 60, or 90 mg every 12 hours until deemed successful for managing their pain during the open-label titration period. Once a successful dose was identified, participants entered the 52 week open-label treatment period in which hydrocodone ER was administered at a successful dose (15, 30, 45, 60, or 90 mg) every 12 hours.

The subpopulation of participants who completed study C33237/3079 (NCT01240863) and 'rolled over' to participate in this study.

Participants were titrated (or re-titrated for roll-over participants) at escalating dosages of hydrocodone ER tablets at dosages of 15, 30, 45, 60, or 90 mg every 12 hours until deemed successful for managing their pain during the open-label titration period. Once a successful dose was identified, participants entered the 52 week open-label treatment period in which hydrocodone ER was administered at a successful dose (15, 30, 45, 60, or 90 mg) every 12 hours.

The subpopulation of participants who completed study C33237/3079 (NCT01240863) and 'rolled over' to participate in this study.

Participants were titrated (or re-titrated for roll-over participants) at escalating dosages of hydrocodone ER tablets at dosages of 15, 30, 45, 60, or 90 mg every 12 hours until deemed successful for managing their pain during the open-label titration period. Once a successful dose was identified, participants entered the 52 week open-label treatment period in which hydrocodone ER was administered at a successful dose (15, 30, 45, 60, or 90 mg) every 12 hours.

The subpopulation of participants who completed study C33237/3079 (NCT01240863) and 'rolled over' to participate in this study.

Participants were titrated (or re-titrated for roll-over participants) at escalating dosages of hydrocodone ER tablets at dosages of 15, 30, 45, 60, or 90 mg every 12 hours until deemed successful for managing their pain during the open-label titration period. Once a successful dose was identified, participants entered the 52 week open-label treatment period in which hydrocodone ER was administered at a successful dose (15, 30, 45, 60, or 90 mg) every 12 hours.