Additional Effect of Pain Neuroscience Education to Spinal Manipulative Therapy in Chronic Low Back Pain

The Numerical Pain Rating Scale (NPRS) used to assess pain intensity in this trial will consist in a sequence of numbers from 0 to 10, in which 0 represents "no pain" and 10 represents "worst pain imaginable".

The Brazilian Portuguese version of Oswestry Disability Index (ODI) will be used to assess low back pain related disability. This instrument consists of 10 items, each of which has six response options. The total score will be calculated by summing up all the points, with the largest possible sum being 50. This sum will be transformed into a percentage by multiplying it by two.

The global perceived effect (GPE) used for this trial is an 11-point scale that ranges from -5 ("vastly worse") through 0 ("no change") to +5 ("completely recovered") and participants are asked: "Compared to when this episode first started, how would you describe your back these days?". A higher score indicates higher perception of recovery from the condition.

The fear avoidance beliefs questionnaire (FABQ) adapted for Brazilian Portuguese consists of 16 self-response items, rated on a seven-point ordinal scale from 0 (completely disagree) to 6 (completely agree). The score is obtained for each separate subscale: one that addressed the fears and beliefs of individuals in relation to work and one that addressed their fears and beliefs about physical activities. As the content of PNE included topics about fear-avoidance, the construct will be assessed. A recent systematic review showed an association between baseline fear avoidance belief and worst levels of pain and disability as treatment outcome in chronic low back pain and showed that interventions that addressed FABs were more effective than others based on biomedical concepts.

The MMSE is a tool that can be used to systematically and thoroughly assess mental status. We used the Brazilian-Portuguese version of the tool. It is an 11-question measure that tests 5 areas of cognitive function: orientation, registration, attention and calculation, recall, and language. The maximum score is 30. A score of ≤22 is indicative of cognitive impairment. The Mini-Mental State Examination (MMSE) was used to exclude cognitive impairment.

The Pain Catastrophizing Scale (PCS) translated and validated to Brazilian Portuguese will be used. The scale is composed of 13 items staggered on 6-point ordinal scale (0-5). The total score is the sum of the items divided by the number of items answered, with the minimum score being 0 and the maximum being 5 for each item. Higher scores indicated a greater presence of catastrophic thoughts. The total score of the scale could vary between 0 and 52 points. A recent systematic review found that catastrophizing to be associated with pain and disability at follow-up in CLBP patients.

Study participants will be evaluated on self-efficacy related to chronic pain, which can be defined as an individual's confidence he/she can successfully produce desirable results related to living with chronic pain. The Pain Self-Efficacy Scale (PSES) has 10 items which are rated on a 7-point ordinal scale (ranging from 0: "not at all confident" to 6: "completely confident"). It was adapted and validated to Brazilian Portuguese. Previous research showed an effect on self-efficacy using a PNE intervention based on metaphors compared to an intervention using cognitive-behavioral concepts.

The HADS will be employed to identify anxiety disorders and depression. It was translated and validated into Portuguese. The HADS is divided into the anxiety subscale (HADS-A) and the depression subscale (HADS-D), both containing seven interspersed items. It is composed of seven items for depression and seven items for anxiety, each item including four response options ranging from 0 to 3. A cutoff of ≥8 was described with good sensitivity and specificity values (0.70-0.90) for anxiety and depression symptoms.

The SBST questionnaire was translated to Brazilian Portuguese and its psychometric measurements were checked. The questionnaire is comprised of 9 items. For the purposes of scoring and classification, respondents were given answer options of "I agree" and "I disagree" for the first 8 items, which were scored 1 and 0 points, respectively. For total scores greater than 3, classification was based on the psychosocial subscale score (items 5 to 9) as follows: scores ≤3 corresponded to medium risk and scores >3 corresponded to high risk.