The repeatability of pressure algometry in asymptomatic individuals over consecutive days

BackgroundTo determine if electronic pressure algometry is a statistically stable measure of spinal pressure pain threshold (PPT) in asymptomatic individuals, in particular, to determine if repeated measurements at the same site changes the PPT, and to determine if repeatability differs in each of the spinal regions tested.DesignRepeated measures design.SettingUniversity teaching clinic.ParticipantsThirty-three asymptomatic participants.InterventionsThe PPT of three spinal segments (C6, T6 and L4) was measured three times in consecutive measures (10 s apart), then repeated one day and two days post-initial measurement. Measurements were taken using an electronic pressure algometer.Main outcome measuresPPT, intra-class correlation coefficient and test of significant equality.ResultsResults demonstrated that the PPT measurement is statistically stable both between days (p < 0.001) and within day (p < 0.001). The intra-class correlation coefficient (ICC) values between the mean scores of daily trials demonstrated excellent concordance for each spinal segment (ICC = 0.860–0.953), with the exception of the correlation between day 1 and day 3 at T6, demonstrating good concordance (ICC = 0.676). All trial-to-trial correlations demonstrated excellent concordance both within trials of the same day (ICC = 0.833–0.988) and subsequent days (ICC = 0.823–0.940).ConclusionElectronic pressure algometry is a repeatable and statistically stable measure of the spinal PPT, both between days and within-day. The results provide evidence that the use of this device may be of value as an outcome measure for primary spinal complaints such as low back or thoracic spine pain.