Neck pain intensity does not predict pressure pain hyperalgesia: re-analysis of seven randomized controlled trials

To determine factors, including pain intensity, associated with pressure pain sensitivity in chronic non-specific neck pain and with changes after therapeutic interventions. This re-analysis used pooled data from 7 randomized controlled clinical trials. Pressure pain thresholds were assessed at the hand and at the site of maximal pain in the neck region before and after different non-pharmacological interventions. Age, gender, neck pain intensity and duration, mental health, expectancy and time interval between measurements were used to determine factors influencing pressure pain thresholds as well as pressure pain threshold changes. A total of 346 patients (77 males, 269 females, mean age 52.6 years (standard deviation 12.0 years)) were included in study, 306 of whom provided a complete data-set for analysis. Pressure pain thresholds at the neck area or the hand did not correlate with pain intensity. Changes in pressure pain thresholds correlated with time between measurements, indicating time-sensitive changes. No coherent correlations between pressure pain thresholds and pain intensity were found. Further research is needed to evaluate the relationship between pain intensity and pressure pain thresholds before its use as a valid substitute of pain rating can be supported. Until then, the results of trials with respect to using pressure pain thresholds as an outcome variable must be interpreted with care.