Table 3.
Responsiveness of Brief Pain Inventory and PEG Pain Scales in 6 Trials
| Variable* | SCAMP (n=427) | INCPAD (n=274) | SCOPE (n=244)¶ | CAMEO (n=261) | SPACE (n=240) | SSM (n=258) |
|---|---|---|---|---|---|---|
| Population | Primary care | Oncology | Primary care | Primary care | Primary care | Post-Stroke |
| Anchor-Based Responsiveness | ||||||
| SRM for Improvement, retrospective* | ||||||
| • BPI Severity | 1.00 | 1.13 | 0.71 | 0.72 | 1.18 | 0.17 |
| • BPI Interference | 0.86 | 0.91 | 0.94 | 0.76 | 1.20 | 0.17 |
| • BPI Total | 1.02 | 1.10 | 0.93 | 0.83 | 1.29 | 0.17 |
| • PEG | 0.99 | 1.08 | 0.86 | 0.77 | 1.43 | 0.18 |
| SRM for Improvement, prospective* | ||||||
| • BPI Severity | -- | -- | -- | 0.67 | 1.35 | 0.72 |
| • BPI Interference | -- | -- | -- | 0.65 | 1.21 | 0.75 |
| • BPI Total | -- | -- | -- | 0.73 | 1.31 | 0.76 |
| • PEG | -- | -- | -- | 0.85 | 1.45 | 0.77 |
| AUC for any improvement† | ||||||
| • BPI Severity | .82 | .78 | .73 | .72 | .76 | .55 |
| • BPI Interference | .74 | .73 | .68 | .73 | .77 | .53 |
| • BPI Total | .80 | .79 | .73 | .75 | .79 | .54 |
| • PEG | .76 | .74 | .71 | .72 | .79 | .54 |
| AUC for moderate improvement† | ||||||
| • BPI Severity | .83 | .81 | .74 | .74 | .78 | .60 |
| • BPI Interference | .72 | .73 | .69 | .69 | .76 | .59 |
| • BPI Total | .79 | .80 | .74 | .73 | .80 | .60 |
| • PEG | .75 | .75 | .72 | .73 | .75 | .59 |
| Responsiveness to Treatment | ||||||
| Between-group Treatment Effect Size‡ | ||||||
| • BPI Severity | .56 | .58 | .38 | -- | -- | -- |
| • BPI Interference | .59 | .46 | .37 | -- | -- | -- |
| • BPI Total | .64 | .58 | .42 | -- | -- | -- |
| • PEG | .58 | .52 | .37 | -- | -- | -- |
SRM = standardized response mean, which is the within-group change effect size between two time points calculated as (T1 mean score – T2 mean score) / SD of change score). For each trial, SRM was calculated for three global change groups (improved, unchanged, worse). All trials used a retrospective global anchor question to estimate SRM, and three trials also used a prospective global anchor. The SRM is a type of effect size and therefore, SRMs of 0.2, 0.5, and 0.8 represent small, moderate, and large effect sizes respectively. In this table, the SRM is reported for the improved group only.
AUC = area under the curve as determined by ROC analysis. The discriminatory strength of the scale for determining any improvement and moderate improvement using the retrospective global anchor was estimated by the AUC. Whereas good AUCs for diagnostic tests are often > 0.80, AUCs for scales in determining improvement are typically lower, and what is more important is determining whether scales have comparable AUCs (i.e., similar responsiveness).
The between-group treatment effect size is calculated as: (intervention group mean change – control group mean change) / pooled change score SD. Treatment effect sizes of 0.2, 0.5, and 0.8 represent small, moderate, and large intervention effects, respectively. End-of-trial treatment effect size data was available for 3 of the 4 trials that had a usual care (rather than active comparator) control group.
Data in this column is from the 244 SCOPE participants who completed both baseline and 3-month assessments.