Table 1

Initial measurement of predictor variables

PredictorHow will be measuredHow will be coded
Duration of current episode (days)How many days ago did your back pain start?*7–10; 11–14; 15–23; 24–49
Number of previous episodesHow many previous episodes of low back pain have you had?270; 1–2; 3–8s; >9
DepressionHow much have you been bothered by feeling depressed in the past week? Measured on a 0–10 scale where 0=not at all and 10=extremely280 depression score; 1–3 depression score; 4–6 depression score; 7–10 depression score
Pain intensityUsing Numeric Pain Rating
Scale (NPRS)29: I would like you to rate your pain on a scale from 0 to 10 where 0 is no pain and 10 is the worst possible pain. Please give a number to describe your average pain over the last
24 hours.30
Mild: 2–4; moderate: 5–7; severe: 8–10
Pain intensity change from first visit to 1-week review as an absolute valueCalculated by subtracting the
NPRS at day 1 from NPRS at ‘1-week review’
Worse: ≤−2; not much change: −1,
0, 1; small change: 2, 3; moderate and large change: ≥4
  • All predictor variables will be measured at initial presentation for care except for the pain intensity (collected at the first weekly follow-up) and pain intensity change variables.

  • *Seven days will be added to duration of current episode collected at initial presentation to reflect the duration of episode at 1-week review.