Duloxetine Versus Placebo in Chronic Low Back Pain

A self-reported scale that measures the severity of pain based on the average pain over the past 24-hours. The severity scores range from 0 (no pain) to 10 (pain as severe as you can imagine).

A scale that measures the patient's perception of improvement at the time of assessment. The score ranges from 1 (very much better) to 7 (very much worse).

Roland-Morris questionnaire will be completed by the patient and measures the degree of disability due to back pain. The questionnaire consists of 24 statements and the patient is instructed to put a mark next to each appropriate statement. The number of statements marked will be added up by the clinician and a total score is given. The total score ranges from 0 (no disability) to 24 (severe disability).

24-hour average pain severity scores recorded daily on an 11-point Likert scale, an ordinal scale ranging from 0 (no pain) to 10 (worst possible pain). Patients should complete the electronic diary at bedtime. The 11-point Likert scale will also be used for assessment of night pain and worst pain each day, and evaluated as weekly means. Average interference was calculated as the average of non-missing scores of individual interference items.

BPI-S and BPI-I are self-reported scales measuring severity of pain and interference on function. Severity scores: 0 (no pain) to 10 (severe pain) on each question assessing worst pain, least pain, and average pain in past 24 hours, and pain right now. Interference scores: 0 (does not interfere) to 10 (completely interferes) on each question assessing interference of pain in past 24 hours for general activity, mood, walking ability, normal work, relations with other people, sleep, and enjoyment of life. Average interference = average of non-missing scores of individual interference items.

Measures severity of illness at the time of assessment. Scores range from 1 (normal, not at all ill) to 7 (among the most extremely ill patients).

Response to treatment was defined as at least a 30% reduction of weekly mean score in in Brief Pain Inventory (BPI) Average Pain severity ratings from baseline to endpoint. The number of participants who met this criteria are presented.

Response to treatment was defined as at least a 50% reduction of weekly mean score in in Brief Pain Inventory (BPI) Average Pain severity ratings from baseline to endpoint. The number of participants who met this criteria are presented.

Estimates sleep difficulty. Consists of 8 items rated on a 4-point scale of 0 (no problem at all) to 3 (very serious problem). Total score of the 8-item version ranges from 0-24.

The SF-36 Health Status Survey is a generic, health-related scale assessing subjects' quality of life on 8 domains: physical functioning, social functioning, bodily pain, vitality, mental health, role-physical, role-emotional and general health and 2 summary scores (mental component summary [MCS] and physical component summary [PCS]). MCS and PCS scores=0-100 (higher scores indicate better health status). Domain scores: general health=5-25; physical functioning=10-30; role-physical=4-8; role-emotional=3-6; social functioning=2-10; bodily pain=2-11; vitality=4-24; mental health=5-30.

The EuroQoL Questionnaire - 5 Dimension (EQ-5D) is a generic, multidimensional, health-related, quality-of-life instrument. The profile allows patients to rate their health state in 5 health domains: mobility, self-care, usual activities, pain/discomfort, and mood. A single score between 1 and 3 is generated for each domain. For each patient, the outcome rating on the 5 domains will be mapped to a single index through an algorithm. The index ranges between 0 and 1, with the higher score indicating a better health state perceived by the patient. Scores presented used the UK Based Index Score.

WPAI: self-administered instrument used to measure effect of general health and symptom severity on work productivity and regular activities and yields 4 types of scores: Absenteeism (work time missed); Presenteeism (impairment at work/reduced on-the-job effectiveness); Work Productivity Loss (overall work impairment/absenteeism plus presenteeism); and Activity Impairment. Higher scores are indicative of greater impairment.

• Absenteeism=(Q2/(Q2+Q4))*100
• Presenteeism=(Q5/10)*100
• Work productivity loss=(Q2/(Q2+Q4)+[(1-Q2/(Q2+Q4))x(Q5/10)])*100
• Activity Impairment=(Q6/10)*100

A 21-item, patient-completed questionnaire to assess characteristics of depression. Each of the 21 items corresponding to a symptom of depression is summed to give a single score. There is a four-point scale for each item ranging from 0 to 3. Total score of 0-13 is considered minimal range, 14-19 is mild, 20-28 is moderate, and 29-63 is severe.

A 14-item questionnaire with 2 subscales: anxiety and depression. Each item is rated on a 4-point scale, giving maximum scores of 21 for anxiety and depression. Scores of 11 or more on either subscale are considered to be a significant 'case' of psychological morbidity, while scores of 8-10 represent 'borderline' and 0-7, 'normal.'

Serious adverse events during the extension phase reported based on the original treatment group to which the patient was randomized. Dictionary used was MedDRA 11.0.

Treatment-emergent adverse events during the extension phase reported based on the original treatment group to which the patient was randomized. Dictionary used was MedDRA 11.0.