Introduction
Methods
Study design
Outcome measures
SF-12v2 (generic HRQL)
SIBDQ (disease-specific HRQL)
WPAI:SHP (WRO)
UC symptoms
Analysis plan
Patient baseline characteristics
Correspondence among PRO instruments
Responsiveness of PRO instruments to disease activity and sensitivity to treatment
Results
Patient baseline characteristics
Acute phase baseline (n = 132) | Maintenance phase baseline (n = 206) | Maintenance phase baseline for acute + maintenance phase subsample (n = 56) | Maintenance phase baseline for maintenance phase-only subsample (n = 150) | |
---|---|---|---|---|
Age [mean (SD)] | 43.4 (14.1) | 46.9 (13.7) | 42.9 (14.4) | 48.4 (13.2)a
|
Female [n (%)] | 74 (56.1 %) | 106 (51.5 %) | 27 (48.2 %) | 79 (52.7 %) |
Employed [n (%)] | 84 (63.6 %) | 150 (72.8 %) | 42 (75.0 %) | 108 (72.0 %) |
SF-12v2 [mean (SD)] | ||||
Physical functioning | 48.1 (10.1) | 53.5 (6.8) | 54.3 (4.4) | 53.2 (7.5) |
Role physical | 44.8 (10.5) | 52.8 (6.7) | 53.0 (6.1) | 52.7 (6.9) |
Bodily pain | 45.2 (11.3) | 53.6 (7.2) | 55.1 (6.1) | 53.1 (7.4) |
General health | 44.6 (10.7) | 51.8 (7.8) | 52.4 (5.9) | 51.5 (8.5) |
Vitality | 47.0 (10.3) | 53.6 (8.5) | 54.8 (8.8) | 53.2 (8.4) |
Social functioning | 44.7 (12.4) | 52.9 (7.3) | 53.3 (7.0) | 52.8 (7.4) |
Role emotional | 47.0 (10.7) | 51.7 (7.3) | 51.8 (7.5) | 51.6 (7.2) |
Mental health | 48.1 (10.8) | 53.1 (8.6) | 54.3 (8.9) | 52.7 (8.4) |
Physical summary (PCS) | 45.4 (9.8) | 53.2 (6.5) | 53.9 (4.4) | 53.0 (7.1) |
Mental summary (MCS) | 47.3 (10.1) | 52.3 (8.2) | 53.0 (8.6) | 52.1 (8.0) |
SIBDQ [mean (SD)] | ||||
Bowel symptoms | 12.8 (4.3) | 18.5 (2.6) | 18.6 (2.4) | 18.4 (2.7) |
Systemic symptoms | 8.9 (3.0) | 10.8 (2.5) | 11.2 (2.6) | 10.6 (2.6) |
Emotional function | 14.0 (4.3) | 17.3 (3.0) | 17.4 (3.3) | 17.2 (2.9) |
Social function | 10.1 (3.4) | 13.2 (1.5) | 13.2 (1.5) | 13.2 (1.5) |
Total score | 45.9 (12.9) | 59.8 (7.7) | 60.7 (7.5) | 59.4 (7.8) |
WPAI [mean (SD)] | ||||
Absenteeism | 8.8 (21.1) | 0.6 (3.5) | 1.4 (5.9) | 0.3 (1.7) |
Presenteeism | 27.5 (26.3) | 5.1 (9.7) | 5.2 (11.3) | 5.1 (9.1) |
Overall work impairment | 30.0 (29.2) | 5.5 (10.8) | 6.1 (13.7) | 5.3 (9.6) |
Activity impairment | 35.5 (31.2) | 7.6 (14.1) | 6.6 (14.4) | 8.0 (14.0) |
UC symptoms [mean (SD)] | ||||
Stool frequency | 0.73 (0.69) | 0.15 (0.33) | 0.15 (0.38) | 0.14 (0.31) |
Rectal bleeding severity | 0.88 (0.77) | 0.02 (0.12) | 0.02 (0.11) | 0.03 (0.12) |
Correspondence among changes in PRO domain scores during the acute phase

Responsiveness of PRO instruments to changes in disease activity
Stool frequency | Rectal bleeding severity | ||
---|---|---|---|
UC symptoms | Stool frequency | – | – |
Rectal bleeding severity |
0.52 (0.36, 0.65)
| – | |
SF-12v2 | Physical functioning |
−0.25 (−0.42, −0.05)
|
−0.30 (−0.47, −0.12)
|
Role physical |
−0.24 (−0.42, −0.05)
|
−0.30 (−0.47, −0.12)
| |
Bodily pain |
−0.33 (−0.49, −0.15)
|
−0.33 (−0.50, −0.15)
| |
General health |
−0.31 (−0.47, −0.12)
|
−0.28 (−0.45, −0.09)
| |
Vitality |
−0.29 (−0.46, −0.11)
|
−0.45 (−0.59, −0.28)
| |
Social functioning |
−0.34 (−0.50, −0.15)
|
−0.40 (−0.55, −0.23)
| |
Role emotional |
−0.24 (−0.41, −0.05)
|
−0.35 (−0.51, −0.16)
| |
Mental health | −0.15 (−0.33, 0.05) |
−0.26 (−0.44, −0.07)
| |
SIBDQ | Bowel symptoms |
−0.43 (−0.58, −0.26)
|
−0.52 (−0.65, −0.37)
|
Systemic symptoms |
−0.35 (−0.51, −0.17)
|
−0.40 (−0.55, −0.22)
| |
Emotional function |
−0.26 (−0.43, −0.07)
|
−0.41 (−0.56, −0.24)
| |
Social function |
−0.37 (−0.52, −0.18)
|
−0.50 (−0.63, −0.34)
| |
WPAI:SHP | Absenteeism |
0.25 (0.01, 0.46)
|
0.38 (0.15, 0.57)
|
Presenteeism |
0.38 (0.16, 0.57)
|
0.42 (0.20, 0.60)
| |
Overall work impairment |
0.36 (0.13, 0.55)
|
0.42 (0.20, 0.60)
| |
Activity impairment |
0.50 (0.33, 0.63)
|
0.51 (0.35, 0.64)
|
Estimated mean (SE) for non-recurrent patients (n = 117) | Estimated mean (SE) for recurrent patients (n = 29) |
P
a
| Effect size (d) | |
---|---|---|---|---|
SF-12v2 | ||||
Physical functioning | 53.8 (0.60) | 51.3 (1.23) | ns | 0.30 |
Role physical | 53.1 (0.66) | 49.3 (1.34) | <0.05 | 0.42 |
Bodily pain | 53.5 (0.76) | 47.4 (1.53) | <0.001 | 0.60 |
General health | 53.2 (0.71) | 48.8 (1.43) | <0.01 | 0.46 |
Vitality | 53.9 (0.75) | 48.6 (1.53) | <0.01 | 0.52 |
Social functioning | 52.8 (0.75) | 48.6 (1.51) | <0.05 | 0.41 |
Role emotional | 52.8 (0.73) | 49.0 (1.47) | <0.05 | 0.39 |
Mental health | 53.6 (0.70) | 49.0 (1.43) | <0.01 | 0.49 |
SIBDQ | ||||
Bowel symptoms | 18.3 (0.28) | 15.1 (0.58) | <0.001 | 0.86 |
Systemic symptoms | 10.9 (0.21) | 11.0 (0.43) | ns | 0.03 |
Emotional function | 17.6 (0.31) | 15.8 (0.62) | <0.01 | 0.46 |
Social function | 13.2 (0.18) | 11.8 (0.37) | <0.001 | 0.58 |
WPAI:SHP | ||||
Absenteeism | 2.4 (1.27) | 1.5 (2.62) | ns | −0.06 |
Presenteeism | 3.9 (1.70) | 16.6 (3.34) | <0.01 | 0.71 |
Overall work impairment | 6.1 (2.10) | 18.6 (4.35) | <0.05 | 0.55 |
Activity impairment | 7.5 (1.66) | 16.7 (3.29) | <0.05 | 0.43 |
Sensitivity of SF-12v2, SIBDQ, and WPAI:SHP to acute treatment
N
| Baseline [mean (SE)] | Week 8 [mean (SE)] | Mean difference |
P
a
| Effect size (d
z
) | |
---|---|---|---|---|---|---|
SF-12v2 | ||||||
Physical functioning | 107 | 49.1 (0.88) | 51.2 (0.76) | 2.1 | <0.01 | 0.27 |
Role physical | 107 | 45.8 (0.95) | 49.4 (0.85) | 3.6 | <0.001 | 0.40 |
Bodily pain | 107 | 46.5 (1.01) | 51.1 (0.95) | 4.6 | <0.001 | 0.45 |
General health | 107 | 45.3 (1.03) | 48.6 (0.91) | 3.3 | <0.01 | 0.32 |
Vitality | 107 | 47.7 (0.99) | 51.8 (0.90) | 4.1 | <0.001 | 0.38 |
Social functioning | 107 | 45.7 (1.13) | 49.4 (0.98) | 3.7 | <0.01 | 0.31 |
Role emotional | 107 | 48.3 (0.90) | 49.8 (0.93) | 1.5 | ns | 0.15 |
Mental health | 107 | 49.0 (0.97) | 52.5 (0.93) | 3.5 | <0.001 | 0.36 |
PCS | 107 | 46.4 (0.89) | 49.8 (0.81) | 3.4 | <0.001 | 0.45 |
MCS | 107 | 48.2 (0.91) | 51.1 (0.88) | 2.9 | <0.01 | 0.29 |
SIBDQ | ||||||
Bowel symptoms | 103 | 13.2 (0.43) | 17.2 (0.35) | 4.0 | <0.001 | 1.03 |
Systemic symptoms | 103 | 9.2 (0.3) | 10.6 (0.26) | 1.4 | <0.001 | 0.47 |
Emotional function | 103 | 14.6 (0.41) | 16.4 (0.37) | 1.8 | <0.001 | 0.44 |
Social function | 103 | 10.5 (0.32) | 12.1 (0.27) | 1.6 | <0.001 | 0.55 |
Total score | 103 | 47.5 (1.24) | 56.3 (1.05) | 8.8 | <0.001 | 0.79 |
WPAI:SHP | ||||||
Absenteeism | 70 | 6.8 (2.18) | 2.8 (1.54) | –4.0 | <0.05 | 0.26 |
Presenteeism | 69 | 25.2 (2.95) | 12.9 (2.59) | –12.3 | <0.001 | 0.46 |
Work productivity | 69 | 27.4 (3.25) | 13.6 (2.71) | –13.8 | <0.001 | 0.47 |
Activity impairment | 103 | 32.4 (2.97) | 18.2 (2.54) | –14.2 | <0.001 | 0.52 |
Discussion
Number | Statement of hypothesis | Reasoning underlying hypothesis | Hypothesis supported by findings? |
---|---|---|---|
1 | Most inter-domain correlations between PRO instruments will be moderately sized (i.e., falling within the range of 0.30–0.70) | Findings from prior research |
Yes; 65 of 80 (81 %) of inter-domain correlations were within this range |
2 | Correlations between SF-12v2 and SIBDQ domains will be larger than between SF-12v2 and WPAI:SHP domains | The SF-12v2 and SIBDQ measure the same underlying construct (HRQL), while the WPAI:SHP measures a different construct (WRO) |
Yes; the magnitude of the average inter-domain correlation between SF-12v2 and SIBDQ (0.44) was higher than between SF-12v2 and WPAI:SHP (−0.37) |
3 | Correlations between SIBDQ and WPAI:SHP domains will be larger than between SF-12v2 and WPAI:SHP domains | The SIBDQ and WPAI:SHP measure UC-specific health outcomes, while the SF-12v2 measures generic health outcomes |
Yes; the magnitude of the average inter-domain correlation between SIBDQ and WPAI:SHP (0.47) was higher than between SF-12v2 and WPAI:SHP (0.37) |
4 | Changes in UC symptoms from baseline to week 8 will correlate more highly with SIBDQ and WPAI:SHP domains than with SF-12v2 domains | Because the SIBDQ and WPAI:SHP measure UC-specific health outcomes, while the SF-12v2 measures generic health outcomes, the former two instruments should be more responsive to changes in UC-specific symptoms |
Yes; the magnitude of the average correlations of UC symptom scores with domains of the SIBDQ (0.41) and WPAI:SHP (0.40) was higher than between UC symptom scores and SF-12v2 domains (0.30) |
5 | Differences in change scores as a function of month 12 clinical recurrence status will be larger for SIBDQ and WPAI:SHP domains than for SF-12v2 domains | Because the SIBDQ and WPAI:SHP measure UC-specific health outcomes, while the SF-12v2 measures generic health outcomes, the former two instruments should be more responsive to changes in UC-specific symptoms |
No; the magnitude of average effect sizes for differences in domain scores between clinical recurrence status groups was similar across all PRO instruments (0.48 for SIBDQ, 0.45 for SF-12v2, and 0.44 for the WPAI:SHP) |
6 | SIBDQ and WPAI:SHP domains will show larger treatment effects during the acute treatment phase than will SF-12v2 domains | Because the SIBDQ and WPAI:SHP measure UC-specific health outcomes, while the SF-12v2 measures generic health outcomes, the former two instruments should be more sensitive to treatment that decreases UC-specific symptoms |
Yes; the magnitude of average effect size for changes in scores from Baseline to week 8 was larger for domains of the SIBDQ (average d = 0.62) and WPAI:SHP (0.43) than for SF-12v2 domains (0.33) |