Introduction
The effect of treatment
Measuring the effect
Statistical significance vs. clinical significance
Effect size
Calculation of the effect size
The regional effect of spinal manipulation on experimentally induced pain in asymptomatic subjects
Spinal manipulation
Pressure pain threshold
Spinal manipulation and its regional effect on the pressure pain threshold
The research objectives
Method
Design
Search strategy and extraction of data
First author Year | Quality score as reported in previous review (Honoré and al, 2018) | - Area of spinal manipulation - Regional testing site/s | Number of follow-ups and time of follow-ups | -Is there a reported effect size? (Yes/No) - Which type of “effect size” was reported (between or within-group comparison)? |
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Ruiz Saez 2007 | 8/9 | - Cervical - Upper trapezius | 3 follow-ups: 1) Immediately after 2) 5 min after 3) 10 min after | -Yes -Within-group comparison |
Srbely2013 | 7.5/9 | -Cervical (bilateral) - Infraspinatus muscle | 4 follow-ups: 1) 1 min after 2) 5 min after 3)10 min after 4) 15 min after | -No - NA |
Fernandez de la Penas 2008 | 7/9 | - Cervical - C5-C6 level | 1 follow-up: 1) 5 min after | -Yes - Within-group comparison |
Fernandez de la Penas 2007 | 7/9 | - Cervical - Ipsilateral and contralateral epicondyle | 1 follow up: 1) 5 min after | - Yes - Within-group comparison |
Hamilton 2007 | 7/9 | - Cervical - Between C0 and C2 | 2 follow-ups: 1) 5 min after 2) 30 min after | - Yes - Within-group comparison |
Yu 2012 | 8/9 | - Lumbar - L5-S1 over apophyseal joints - L5 dermatome | 1 follow-up: 1) Immediately after | - No - NA |
Thomson 2009 | 6/9 | - Lumbar -Spinous process of L3 | 1 follow-up: 1) Immediately after | - Yes -Within-group comparison |
Fryer 2004 | 5/9 | -Thoracic -Thoracic spinous process between T1 and T4 | 1 follow-up: 1) Immediately after | - Yes - Within-group comparison |
First author Year | Did the authors report the between-group effect size? (Yes/No) | 1) Did the authors report the ‘exact’ formula they used? (Yes/No/NA) 2) Or, at least: - Did they provide a reference? (Yes/No/NA) If so, - Was this an “exact” reference? | Did they report: 1) Number of study participants in each group 2) Exact mean values 3) Exact standard deviations | Did they report the 95% CI of their effect size, or of their within group ‘effect’ size? (Yes/No) | Was it possible to calculate between-group effect size based on data provided in the articles? |
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Ruiz Saez 2007 | No, only the within-group comparison | 1) No 2) -Yes -Yes | 1) Yes 2) Yes 3) Yes | No | Yes |
Srbely 2013 | No, not even the within-group comparison | 1) NA | 1) Yes 2) Yes 3) Yes | NA | Yes |
Fernandez de la Penas 2008 | No, only the within-group comparison | 1) No 2) -Yes - No | 1) Yes 2) Yes 3) Yes | No | Yes |
Fernandez de la Penas 2007 | No, only the within-group comparison | 1) No 2) -Yes -No | 1) Yes 2) Yes 3) Yes | No | Yes |
Hamilton 2007 | No, only the within-group comparison | 1) No 2) - Yes - No | 1) Yes 2) Yes 3) Yes | No | Yes |
Yu 2012 | No, not even the within-group comparison | 1) NA | 1) Yes 2) Yes 3) Yes | NA | Yes |
Thomson 2009 | No, only the within-group comparison | 1) No 2) - No - No | 1) Yes 2) Shown in figures, so lack of precision. −3) Yes | No | Yes |
Fryer 2004 | No, only the within-group comparison | 1) No 2) - No - No | 1) Yes 2) Yes 3) Yes | No | Yes |
First author Year | 1) What is the number of participants of the experimental group (NE) and the control group (NC) and are they equal? - NE = NC − NE ≠ NC 2) Are the standard deviations of the experimental group (SDE) and the control group (SDC) equal? - SDE = SDC - SDE ≠ SDC 3) Which type of effect size coefficient should be used? - Cohen’s d coefficient (if NE = NC and SDE = SDC or SDE ≠ SDC) - Hedges’ g coefficient (if NE ≠ NC and SDE ≠ SDC) 4) Give the equations that would be used: - Effect size (d/g) - Standard deviation of PPT values used to calculate the effect size (SD* or SD pooled) - Standard deviation of the effect size (SD(d)) - Confidence interval of the effect size (95% CI) | What are the reported mean PPT values for the experimental group (ME) and for the control group (MC) with their standard deviation (+/− SD), at each follow-up time (units)? | At each follow-up time, what are the: - Effect size (d/g), - Its standard deviation (SD(d)) - Its confidence interval (95% CI) - p value between groups | Effect sizes of clinical significant findings at each follow-up: 0.2 to 0.49 (small) - 0.5 to 0.79 (medium) - 0.8 to 1.00 (large) |
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Ruiz Saez 2007 | 1) NE = NC = 36 2) SDE ≠ SDC 3) Cohen’s d coefficient 4) -\( d=\frac{M_E-{M}_C}{SD^{\ast }} \) - \( \mathrm{SD}\ast =\sqrt{\frac{{SD_E}^2+{SD_C}^2}{2}} \) - \( \mathrm{SD}(d)=\sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | -T0: ME = + 1.35 +/− 0.5 Kg/cm2 MC = + 1.27 +/− 0.4 Kg/cm2 -T + 5: ME = + 1.38 +/− 0.5 Kg/cm2 MC = + 1.15 +/− 0.4 Kg/cm2 -T + 10: ME = + 1.39 +/− 0.5 Kg/cm2 MC = + 1.1 +/− 0.5 Kg/cm2 | -T0: -d = 0.17 -SD(d) = 0.24 - 95% CI: [− 0.29; + 0.63] - p value: NS -T + 5: -d = 0.51 -SD(d) = 0.24 - 95% CI: [+ 0.04; + 0.98] - p < 0.01 -T + 10: -d = 0.58 -SD(d) = 0.24 - 95% CI: [+ 0.11; + 1.05] -p < 0.01 | T0: small T + 5: medium T + 10: medium |
Srbely 2013 | 1) NE = NC = 18 2) SDE ≠ SDC 3) Cohen’s d coefficient 4) -\( d=\frac{M_E-{M}_C}{SD^{\ast }} \) -\( \mathrm{SD}\ast =\sqrt{\frac{{SD_E}^2+{SD_C}^2}{2}} \) -\( \mathrm{SD}(d)=\sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | -T + 1: ME = + 34.4 +/− 9.6 N MC = + 30.7 +/− 7.5 N -T + 5: ME = + 37.5 +/− 11.9 N MC = + 28.7 +/− 6.0 N -T + 10: ME = + 37.9 +/− 14.4 N MC = + 28.9 +/− 6.3 N -T + 15: ME = + 34.3 +/− 11.5 N MC = + 28.6 +/− 7.0 N |
-T + 1:
-d = 0.42 -SD(d) = 0.34 - 95% CI: [− 0.24; + 1.08] -p < 0.01 -T + 5: -d = 0.93 -SD(d) = 0.35 − 95% CI: [+ 0.24; + 1.62] -p < 0.01 -T + 10: -d = 0.80 -SD(d) = 0.35 - 95% CI: [+ 0.12; + 1.48] -p < 0.01
-T + 15:
-d = 0.59 -SD(d) = 0.34 - 95% CI: [− 0.08; + 1.26] -p < 0.01 | T + 1: small T + 5: large T + 10: large T + 15: medium |
Fernandez de la Penas 2008 | 1) NE = NC = 10 2) SDE ≠ SDC 3) Cohen’s d coefficient 4) - \( d=\frac{M_E-{M}_C}{SD^{\ast }} \) - \( \mathrm{SD}\ast =\sqrt{\frac{{SD_E}^2+{SD_C}^2}{2}} \) - \( \mathrm{SD}(d)=\sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | -T + 5: (dominant side/dominant side) ME = + 387.6 +/− 70.9 kPa/s MC = + 312.3 +/− 47.7 kPa/s | -T + 5: -d = 1.24 -SD(d) = 0.49 - 95% CI: [+ 0.28; + 2.20] -p < 0.05 | T + 5: large |
Fernandez de la Penas 2007 | 1)NE = NC = 15 2) SDE ≠ SDC 3) Cohen’s d coefficient 4) - d = \( \frac{M_E-{M}_C}{SD^{\ast }} \) - SD*= \( \sqrt{\frac{{SD_E}^2+{SD_C}^2}{2}} \) - SD(d)=\( \sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | -T + 5: ME = + 2.9+/− 0.6 Kg/cm2 MC = + 2.3+/− 0.5 Kg/cm2 | -T + 5: -d = 1.08 -SD(d) = 0.48 − 95% CI: [+ 0.14; + 2.02] -p < 0.01 | T + 5: large |
Hamilton 2007 | 1) NE ≠ NC - NE = 35 - NC = 25 2) SDE ≠ SDC 3) Hedge’ g coefficient 4)
\( {\mathrm{SD}}_{\mathrm{pooled}}=\sqrt{\frac{\left({\mathrm{N}}_{\mathrm{E}}\hbox{-} 1\right){\mathrm{SD}}_{{\mathrm{E}}^2}+\left({\mathrm{N}}_{\mathrm{C}}\hbox{-} 1\right){\mathrm{SD}}_{{\mathrm{C}}^2}}{{\mathrm{N}}_{\mathrm{E}}+{\mathrm{N}}_{\mathrm{C}}\hbox{-} 2}} \)
- \( \boldsymbol{g}=\frac{{\boldsymbol{M}}_{\boldsymbol{E}}-{\boldsymbol{M}}_{\boldsymbol{C}}}{{\boldsymbol{SD}}_{\boldsymbol{Pooled}}} \) -\( \mathrm{SD}\left(\mathrm{g}\right)=\sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | -T + 5: ME = + 398.06 +/− 133.51 kPa/s MC = + 368.44 +/− 208.16 kPa/s -T + 30: ME = + 374.58 +/− 127.50 kPa/s MC = + 368.68 +/− 192.62 kPa/s | -T + 5: -g = 0.17 -SD(g) = 0.26 − 95% CI: [− 0.34; + 0.68] -p < 0.01 -T + 30: -g = 0.03 -SD(g) = 0.26 − 95% CI: [− 0.48; + 0.54] -p value: NS | T + 5: small T + 30: small |
Yu 2012 | 1) NE = NC = 30 2) SDE ≠ SDC 3) Cohen’s d coefficient 4) - d = \( \frac{M_E-{M}_C}{SD^{\ast }} \) - SD*= \( \sqrt{\frac{{SD_E}^2+{SD_C}^2}{2}} \) - SD(d)=\( \sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] |
-L5-S1 PD side
T0: ME = + 5.64+/− 1.13 Kg/cm2 MC = + 4.85+/− 1.12 Kg/cm2 -L5-S1 OPD side T0: ME = + 5.56+/− 1.17 Kg/cm2 MC = + 4.91+/− 1.13 Kg/cm2 -L5 dermatome PD side T0: ME = + 4.77+/− 0.96 Kg/cm2 MC = + 4.14+/− 1.13 Kg/cm2 -L5 dermatome OPD side T0: ME = + 4.63+/− 0.95 Kg/cm2 MC = + 4.09+/− 0.82 Kg/cm2 |
-L5-S1 PD side
T0 -d = 0.70 -SD(d) = 0.27 − 95% CI: [+ 0.18; + 1.22] -p < 0.05 -L5-S1 OPD side T0 -d = 0.56 -SD(d) = 0.26 − 95% CI: [+ 0.04; + 1.08] -p < 0.05 - L5 dermatome PD side T0 -d = 0.60 -SD(d) = 0.26 − 95% CI: [+ 0.08; + 1.12] -p < 0.05 - L5dermatome OPD side T0 -d = 0.60 -SD(d) = 0.26 − 95% CI: [+ 0.08; + 1.12] -p < 0.05 |
-L5-S1 PD side
T0: medium -L5-S1 OPD side T0: medium - L5 dermatome PD side T0: medium - L5dermatome OPD side T0: medium |
Thomson 2009 | 1) NE ≠ NC - NE = 19 - NC = 13 2) SDE ≠ SDC 3) Hedge’g coefficient 4) - g = \( \frac{M_E-{M}_C}{SD_{Pooled}} \)
\( {\mathrm{SD}}_{\mathrm{pooled}}=\sqrt{\frac{\left({\mathrm{N}}_{\mathrm{E}}\hbox{-} 1\right){\mathrm{SD}}_{{\mathrm{E}}^2}+\left({\mathrm{N}}_{\mathrm{C}}\hbox{-} 1\right){\mathrm{SD}}_{{\mathrm{C}}^2}}{{\mathrm{N}}_{\mathrm{E}}+{\mathrm{N}}_{\mathrm{C}}\hbox{-} 2}} \)
-\( \mathrm{SD}\left(\mathrm{g}\right)=\sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | (Approximate data) -T0: ME = + 2.2 +/− 1.1 Kg/cm2 MC = + 2.1 +/− 0.8 Kg/cm2 | -T0: -g = 0.10 -SD(g) = 0.36 − 95% CI: [− 0.61; + 0.81] -p value: NS | T0: small |
Fryer 2004 | 1) NE = NC = 32 2) SDE ≠ SDC 3) Cohen’s d coefficient 4) -\( d=\frac{M_E-{M}_C}{SD^{\ast }} \) -\( \mathrm{SD}\ast =\sqrt{\frac{{SD_E}^2+{SD_C}^2}{2}} \) -\( \mathrm{SD}\left(\mathrm{g}\right)=\sqrt{\frac{N_E+{N}_C}{N_E\times {N}_C}+\frac{d^2}{2\left({N}_E+{N}_C\right)}} \) - 95% CI: [d − 1.96 × SD (d); d + 1.96 × SD(d)] | -T0: ME = + 216.51 +/− 90.50 kPa MC = + 244.64 +/− 91.59 kPa | -T0: -d = 0.30 -SD(d) = 0.25 − 95% CI: [− 0.19; + 0.79] -p value: NS | T0: medium |