Table 3.
Quantitative sensory testing measures in high-pain and low-pain chronic low back pain subsamples.
| High-pain CLBP subsample Clinical pain intensity ≥ NRS 4/10 (n = 32) |
Low-pain CLBP subsample Clinical pain intensity < NRS 4/10 (n = 27) |
|||||||
|---|---|---|---|---|---|---|---|---|
| Raw values* | Z-scores | Z statistic | P † | Raw values* | Z-scores | Z statistic | P † | |
| MP‡ | ||||||||
| CDT [°C] | 2.9 (2.25) | −0.6 (1.35) | −3.5 | <0.001 | 3.0 (2.04) | −0.5 (1.26) | −2.4 | 0.016 |
| WDT [°C] | 3.4 (1.73) | −0.2 (1.71) | −1.3 | 0.190 | 3.1 (1.15) | 0.0 (1.88) | 0.1 | 0.898 |
| TSL [°C] | 6.9 (3.39) | −0.2 (1.19) | −0.9 | 0.345 | 6.6 (2.56) | 0.1 (1.08) | 0.3 | 0.754 |
| CPT [°C] | 11.6 (10.73) | −0.6 (1.32) | −3.4 | 0.002§ | 12.2 (10.1) | −0.4 (1.19) | −2.1 | 0.099§ |
| HPT [°C] | 43.2 (4.10) | −0.2 (1.23) | −1.1 | 0.428§ | 42.9 (3.11) | −0.1 (0.94) | −0.4 | 0.708§ |
| PPT [kg/cm2] | 5.3 (2.77) | 0.3 (1.18) | 1.8 | 0.226§ | 5.3 (2.57) | 0.4 (1.24) | 1.9 | 0.081§ |
| MPT [mN] | 31.0 (34.12) | −0.0 (1.08) | −0.1 | 0.917§ | 36.3 (40.22) | −0.3 (1.35) | −1.3 | 0.278§ |
| MPS [NRS] | 4.9 (4.59) | 0.3 (1.02) | 1.7 | 0.097§ | 4.6 (6.43) | 0.1 (1.15) | 0.6 | 0.563§ |
| WUR [NRS ratio] | 3.0 (2.00) | −0.3 (0.91) | −1.9 | 0.186§ | 3.1 (1.98) | −0.2 (0.96) | −1.0 | 0.452§ |
| MDT [mN] | 20.3 (37.18) | −0.5 (1.48) | −3.0 | 0.002 | 12.9 (23.66) | −0.2 (1.39) | −0.9 | 0.361 |
| VDT [V.U.] | 5.7 (2.33) | −0.6 (1.39) | −3.3 | <0.001 | 5.2 (2.95) | −0.7 (1.75) | −3.5 | <0.001 |
| PHS [count] | 0 | 0.381 | 2 | 1¶ | ||||
| DMA [count] | 9 | 0.033 § | 4 | 1§¶ | ||||
| AD‡ | ||||||||
| CPT [°C] | 11.7 (10.56) | 0.0 (0.96) | 0.1 | 0.906§ | 8.9 (10.80) | −0.2 (0.93) | −1.0 | 0.373§ |
| HPT [°C] | 43.7 (3.98) | −0.1 (1.32) | −0.4 | 0.726§ | 42.7 (3.54) | 0.2 (1.10) | 1.3 | 0.634§ |
| PPT [kg/cm2] | 5.6 (2.41) | 0.1 (0.91) | 0.5 | 0.647§ | 5.9 (2.43) | 0.0 (0.86) | 0.1 | 0.942§ |
| MPT [mN] | 38.9 (41.8) | 0.3 (1.02) | 1.9 | 0.163§ | 52.6 (90.06) | 0.0 (1.42) | 0.1 | 0.938§ |
| MPS [NRS] | 4.2 (4.12) | 1.0 (1.34) | 5.5 | <0.001 § | 3.7 (3.83) | 0.6 (1.74) | 2.9 | 0.011§ |
| WUR [NRS ratio]‖ | 3.0 (1.66) | −0.2 (1.01) | −1.2 | 0.252§ | 3.2 (2.44) | −0.1 (1.15) | −0.8 | 0.452§ |
| DMA [count] | 8 | 0.381§ | 5 | 0.333§¶ | ||||
| CON | ||||||||
| CPT [°C] | 9.0 (9.94) | −0.2 (1.22) | −1.0 | 0.450§ | 8.8 (8.72) | −0.2 (1.09) | −0.9 | 0.373§ |
| HPT [°C] | 45.5 (3.80) | −0.4 (1.16) | −2.0 | 0.135§ | 44.7 (3.46) | −0.1 (1.00) | −0.6 | 0.708§ |
| PPT [kg/cm2] | 4.5 (2.15) | −0.1 (1.14) | −0.8 | 0.647§ | 4.0 (1.94) | 0.4 (1.52) | 2.0 | 0.081§ |
| MPT [mN] | 52.7 (69.39) | 0.1 (1.48) | 0.4 | 0.917§ | 56.6 (69.97) | −0.3 (1.33) | −1.3 | 0.278§ |
| MPS [NRS] | 4.9 (5.01) | 0.5 (1.04) | 2.7 | 0.009§ | 4.5 (6.41) | 0.2 (1.09) | 1.3 | 0.293§ |
| WUR [NRS ratio] | 4.2 (11.33) | −0.2 (1.14) | −1.1 | 0.252§ | 2.4 (1.36) | −0.2 (0.95) | −0.9 | 0.452§ |
| DMA [count] | 7 | 0.125§ | 3 | 0.667§¶ | ||||
All QST measures except for CPT, HPT, and VDT were log-transformed before Z-score conversion. Values are presented as mean (SD). Minimum and maximum Z-score value for each QST measure was set to ±4 to reduce influences of single extreme outliers. Effect sizes are not reported because for Z-tests against mean = 0 and SD = 1, Cohen's d is identical to the mean of the Z-scores.
Raw values might not reflect Z-scores because (1) most QST measures were log-transformed before Z-score conversion, (2) outlier influences are larger for raw values than for Z-scores, and (3) raw values are not age and sex matched.
Statistical comparison to an ideal Z-value distribution (mean = 0, SD = 1) for Z-tests and to control participants for Fisher's exact tests.
N = 35 for control participants because 10 control participants had been matched to another chronic pain cohort of the Clinical Research Priority Program “Pain.”
FDR-corrected for three tests.
N = 31 for high-pain CLBP subsample because 1 patient rated the highest possible single stimulus intensity as not painful.
Fisher's exact test.
AD, pain-free area adjacent to most painful area; CDT, cold detection threshold; CLBP, chronic low back pain; CON, remote, pain-free control area; CPT, cold pain threshold; DMA, dynamic mechanical allodynia; FDR, false discovery rate; HPT, heat pain threshold; MDT, mechanical detection threshold; MPS, mechanical pain sensitivity; MPT, mechanical pain threshold; NRS, numeric rating scale; PHS, paradoxical heat sensation; PPT, pressure pain threshold; QST, quantitative sensory testing; TSL, thermal sensory limen; VDT, vibration detection thresholds; V.U., vibration units in X/8; WUR, wind-up ratio. Bold entries: P < 0.05 for PHS and DMA and P < 0.001 for other QST measures.