Table 2.

Psychopathological dysfunctions.

Authors	Sample	Gender and Age	Instruments	Results
Brunner et al. [30]	n = 49	Men = 24 (49%) Women = 25 (51%) Average age = 47.08	NRS RMDQ SBT 4DSQ TSK	The sample with CPLBP showed the following correlations: -The scores of the SBT scale presented moderately positive correlations with the scores of the TSK scale (r = 0.59; p < 0.05). -The scores of the SBT scale presented moderately positive correlations with the scores of the 4DSQ scale, concretely in the dimensions of anxiety (r = 0.50; p < 0.05), depression (r = 0.43; p < 0.05), and distress (r = 0.63; p < 0.05). -The scores of the TSK scale presented regular positive correlations with the scores of the 4DSQ scale, concretely in the dimensions of anxiety (r = 0.13; p < 0.05), depression (r = 0.33; p < 0.05), and distress (r = 0.25; p < 0.05). Within the 4DSQ scale there existed moderately positive correlations between the scores of distress and depression (r = 0.56; p < 0.05), distress and anxiety (r = 0.66; p < 0.05), and depression and anxiety (r = 0.43; p < 0.05).
Clark et al. [31]	n = 165	Men = 39 (23.6%) Women = 126 (76.4%) Average age = 45	CSI AASP STAI MCSDS	The sample with CPLBP presented different sensory profiles as a result of combining the neurological thresholds to sensory stimuli with the adaptive behavioural response to sensory stimuli. The sensory profiles presented in the sample were one or more of the following: high trait sensory sensitivity (low threshold, passive response; 55%, n = 91), sensation avoidance (low threshold, active response; 44%, n = 72), low registration (high threshold, passive response; 36%, n = 60), and low trait sensation-seeking (high threshold, active response; 38%, n = 62). The proportions of the types of personality in the sample were defensive high anxious (45%; n = 75), high anxious (25%; n = 43), and repressor (25%; n = 41). The sample with CPLBP presented the following correlations: -The scores of the CSI presented moderate positive correlations with the sensory profiles, concretely with high trait sensory sensitivity (r = 0.63: p < 0.01), sensation avoidance (r = 0.48; p < 0.01), and a low trait sensation seeking (r = 0.54; p < 0.01). -The scores of the anxiety trait presented moderate positive correlations with the profile of high trait sensory sensitivity (r = 0.43; p < 0.01). As for the other profiles, the correlation was weak. -The scores of the anxiety trait also presented moderate positive correlations with the scores of the CSI (r = 0.46; p < 0.01). The linear regression model showed evidence that the increase in the scores of the CSI could be predicted through sensory hypersensitivity profiles with a low register, the scores of the anxiety trait, and the highly defensive and very anxious personality type.
Day et al. [33]	n = 69	Men = 33 (48%) Women = 36 (52%) Average age = 51	NRS PCS SOPA PROMIS SHS NRP–Avoidance scale CPAQ-8 BFI EEG	The sample with CPLBP showed the following correlations: -The intensity of the pain presented regular positive correlations with pain catastrophizing (r = 0.33; p < 0.01), depression (r = 0.24; p < 0.05), and anxiety (r = 0.23; NS), while it presented moderate negative correlations with the beliefs concerning pain control (r = −0.41; p < 0.01) and regular negative correlations with the acceptance of chronic pain (r = −0.33; p < 0.01). -Pain catastrophizing presented moderate positive correlations with depression (r = 0.44; p < 0.01), anxiety (r = 0.45; p < 0.01), avoidance behaviour (r = 0.63; p < 0.01), and neuroticism (r = 0.49; p < 0.01), while it presented moderate negative correlations with beliefs concerning pain control (r = −0.50; p < 0.01) and the acceptance of chronic pain (r = −0.49; p < 0.01) and regular negative correlations with happiness (r = −0.34; p < 0.01). -Depression presented moderate positive correlations with anxiety (r = 0.67; p < 0.01), avoidance behaviour (r = 0.40; p < 0.01), and neuroticism (r = 0.66; p < 0.01), while it presented moderate negative correlations with happiness (r = −0.63; p < 0.01) and the acceptance of chronic pain (r = −0.58; p < 0.01) and regular negative correlations with the beliefs concerning pain control (r = −0.34; p < 0.01) and extraversion (r = −0.30; p < 0.01). -Anxiety presented moderate positive correlations with avoidance behaviour (r = 0.41; p < 0.01) and neuroticism (r = 0.61; p < 0.01), while it presents moderate negative correlations with the acceptance of chronic pain (r = −0.48; p < 0.01) and regular negative correlations with beliefs concerning pain control (r = −0.23; NS) and happiness (r = −0.39; p < 0.01).
Fujii et al. [34]	n = 3100	Men = 1617 (52.2%) Women = 1483 (47.8%) Average age = 44.5	SSS-8 PHQ-2 EQ-5D	The sample with CPLBP showed the following correlations: -The total score of the SSS-8 scale presented moderately negative correlations with the scores of the EQ-5D scale (r = −0.55; p < 0.0001). As the score of the PHQ-2 scale increased, so did the proportion of the sample with very high scores of the SSS-8 scale; in addition, the score of the PHQ-2 scale was also associated with that obtained using the EQ-5D scale. In accordance with the regression model, a greater load of somatic symptoms in the sample with CPLBP was significantly associated with a lower quality of life with respect to health, independently of depression and the number of co-morbid illnesses (high score as opposed to very high score on SSS-8: β = 0.040; p < 0.0001/minimum score as opposed to very high score on SSS-8: β = 0.22; p < 0.0001).
Ho et al. [35]	n = 30,669 -CPLBP (6559). -Control (24,140).	Men = 14,006 (46%) Women = 16,663 (54%) Average age = 52.2	Clinical diagnoses from the HUNT Study 3 (2006–2008)	In the entire sample, 6.1% (n = 1871) of the participants presented insomnia and 2.4% insomnia and CPLBP (n = 719). The logistic regression model showed evidence that insomnia (OR = 2.46; p < 0.001), age (OR = 1.01; p < 0.001), physical activity (OR = 0.88; p < 0.001), depression (borderline: OR = 1.66; p < 0.001/possible: OR = 2.40; p < 0.001), and anxiety (borderline: OR = 1.73; p < 0.001/possible: OR = 2.48; p < 0.001) were all significantly associated with the presence of CPLBP. In the multiple logistic regression model, which included the said factors, those with insomnia presented almost double the probabilities of suffering from CPLBP as compared with those who did not suffer from insomnia (OR = 1.99; p < 0.0001).
Kasahara et al. [36]	n = 60	Men = 29 (48.3%) Women = 31 (51.7%) Average age = 54.9	CAARS CAARS-S CAARS–O NRS	Within the sample suffering from CPLBP, 48.3% (n = 29) obtained positive scores on CAARS-S and 60% (n = 36) obtained positive scores on CAARS-O. Overall, 76.6% (n = 46) obtained positive scores on CAARS-S or CAARS-O, and 31.1% (n = 19) obtained positive scores on both. The results obtained were compared with those obtained by the general population in another study in which the same instruments were administered. On both the CAARS-S and the CAARS-O scales, the group with CPLBP had significantly higher scores on the subscales of Inattention/Memory Problems (p < 0.05; p < 0.05), Hyperactivity/Restlessness (p < 0.001; p < 0.05), Problems with Self-Concept (p < 0.05; p < 0.001), DSM-IV Inattentive Symptoms (p < 0.005; p < 0.05), DSM-IV Hyperactive–Impulsive Symptoms (p < 0.005; NS), DSM-IV ADHD Symptoms Total (p < 0.001; NS), and the ADHD Index (p < 0.001; p < 0.005) with respect to the general population. Similarly, evidence of the following correlations was found: -The subscale of Hyperactivity/Restlessness on the CAARS-S presented a regular positive correlation with the maximum intensity of pain (r = 0.27; p < 0.05). -The subscale of Hyperactive–Impulsive Symptoms on the CAAR-S presented a regular positive correlation with the duration of the pain (r = 0.34; p < 0.01). -The subscale of Hyperactivity/Restlessness on the CAARS-O presented a moderate positive correlation with the maximum intensity of pain (r = 0.44; p < 0.001) and with the average intensity of pain (r = 0.44; p < 0.001). -The subscale of DSM-IV Hyperactive–Impulsive Symptoms of the DSM-IV on the CAARS-O presented a regular positive correlation with the average intensity of pain (r = 0.28; p < 0.05).
Moreira et al. [39]	n = 36 -CPLBP (18). -Control (18).	Men = 10 (26.6%) Women = 28 (77.7%) Average age = 24.2	CPM Protocol NRS SF-MPQ TSK BDI VAS PCS RMDQ	The group with CPLBP presented levels of intensity of pain (p < 0.01), symptoms of depression (p < 0.05), and symptoms of anxiety (p < 0.01) that were significantly higher than those of the control group. Furthermore, they present significantly higher levels of pain and mood symptoms (p < 0.01; p < 0.01), fear of movement and physical activity (p < 0.05), and pain catastrophizing (p < 0.05) with respect to the control group. The group with CPLBP showed a significantly lower pain pressure threshold (13.5%) with respect to the control group, as well as a considerable exacerbation of cognitive–behavioural changes.
Neumann and Hampel. [40]	n = 526	Men = 94 (17.9%) Women = 432 (82.1%) Average age = 53.2	MPSS CES-D HADS Mini-SCL SF-12 DSF	The sample with CPLBP was classified into three progressive states of pain depending on the pain’s level of chronification as follows: state of pain I (n = 126), state of pain II (n = 270), and state of pain III (n = 130). Among these three states there existed statistically significant differences in the duration of pain (p < 0.05), the location of pain (p < 0.01), and the average intensity of pain (p < 0.01); the differences were greater as the chronification of pain advanced. Similarly, there were statistically significant differences in the presence of depressive symptoms among the different groups (p < 0.01); the differences were greater as the chronification of pain advanced. As for the state of health, there were statistically significant differences for physical health (p < 0.01) but not for mental health.
Pakpour et al. [41]	n = 761	Men = 414 (55.4%) Women = 347 (44,6%) Average age = 41.15	VAS PSQI HADS	At the start of the study, 48% (n = 365) of the sample with CPLBP stated that they had problems sleeping in the previous month, increasing to a total of 67.6% (n = 514) after six months of monitoring. Regarding the intensity of pain, 38.3% of the sample presented severe levels of pain after six months of monitoring. The logistical regression model presented the following results: -Those with problems sleeping at the start of the study had a 50% possibility of having a deficient recuperation (OR = 1.50; p < 0.05) and more than double the possibility of having pain of greater intensity (OR = 2.48; p < 0.05) after six months of monitoring. -Those who did not manifest problems sleeping at the start of the study, but who developed this problem later, had almost double the possibility of having a deficient recuperation (OR = 2.17; p < 0.05) and almost triple the possibility of having a greater intensity of pain (OR = 2.88; p < 0.05) after six months of monitoring. -Those with persistent problems sleeping, both at the start of the study and during monitoring, had almost triple the possibility of having a deficient recuperation (OR = 2.95; p < 0.05) and more than triple the possibility of having a greater intensity of pain (OR = 3.45; p < 0.05) after six months of monitoring. Those with problems sleeping at the start of the study, but not during monitoring, had reduced probability of not recuperating (OR = 0.50; p < 0.05) and of having a greater intensity of pain (OR = 0.49; p < 0.05) after six months of monitoring.
Rogers et al. [43]	n = 294	Men = 92 (31.1%) Women = 202 (68.9%) Average age = 45.8	BPI ODSIS SSASI OPMM COMM	The sample with CPLBP declared having suffered, on average, for 4.30 years, with an average intensity of 6.54/10. Regarding the state of abusive consumption of opioids, 56.7% (n = 167) classified themselves as abusive consumers. In addition, the following correlations were found: -The intensity of pain presented regular positive correlations with depressive symptoms (r = 0.26; p < 0.01), the symptoms of anxiety sensitivity (r = 0.20; p < 0.01), coping motives (r = 0.13; p < 0.05), and pain management (r = 0.14; p < 0.05). -Depressive symptoms presented a moderate positive correlation with the symptoms of anxiety sensitivity (r = 0.55; p < 0.01) and the abusive use of opioids (r = 0.45; p < 0.01) and a regular positive correlation with coping motives (r = 0.37; p < 0.01) and pain management (r = 0.35; p < 0.01). -The symptoms of anxiety sensitivity presented a moderate positive correlation with coping motives (r = 0.47; p < 0.01), pain management (r = 0.48; p < 0.01), and the abusive use of opioids (r = 0.42; p < 0.01). -The coping motives presented a moderate positive correlation with pain management (r = 0.71; p < 0.01) and the abusive use of opioids (r = 0.51; p < 0.01); furthermore, pain management presented a moderate positive correlation with the abusive use of opioids (r = 0.51; p < 0.01). In accordance with the hierarchical regression model, anxiety sensitivity was significantly associated with coping motives (R2 = 0.29; p < 0.01) and coping with pain (R2 = 0.27; p < 0.01). In addition, anxiety sensitivity was indirectly associated with the state of the abusive use of opioids through both motives (OR = 1.03; p < 0.05/OR = 1.09; p < 0.05).
Rumble et al. [44]	n = 117 -CPLBP (82). -Control (35).	Men = 54 (46.2%) Women = 63 (53.8%) Average age = 43.4	GCPS CES-D The STOP-BANG Home sleep monitoring through the Actiwatch2 Sleep diaries	The group with CPLBP presented levels of pain intensity (p < 0.01), depressive symptoms (p < 0.01), wake after sleep onset (p < 0.01), and time spent in bed (p < 0.05) significantly higher than those of the control group. In addition, the group with CPLBP presented quality of sleep (p < 0.01) and of refreshed sleep (p < 0.01) significantly below that of the control group. -The intensity of pain presented regular positive correlations with sleep latency (r = 22; p < 0.05), while it presented regular negative correlations with sleep quality (r = −0.28; p < 0.05) and refreshed sleep (r = −0.31; p < 0.01). -Depressive symptoms presented regular positive correlations with the intensity of CPLBP (r = 36; p < 0.01) and with wake after sleep onset (r = 0.27; p < 0.01), while they presented moderate negative correlations with quality of sleep (r = −0.49; p < 0.01), refreshed sleep (r = −0.50; p < 0.01), and pain status (r = −0.54; p < 0.01). All the sleep variables were significantly correlated with each other (p < 0.05).
Skarpsno et al. [46]	n = 6200	Men = 2488 (40%) Women = 3712 (60%) Average age = 49.7	Information obtained from the HUNT Study 2 (1995–1997) and the HUNT Study 3 (2006–2008)	Within the sample suffering from CPLBP, the women (RR = 0.65) and men (RR = 0.81) who frequently/always experienced insomnia had lower probabilities of recuperating from CPLBP as compared with those who did not suffer from insomnia. The probability of recuperating from CPLBP was inversely associated with the number of symptoms of insomnia in women (one symptom: RR = 0.81; two: RR = 0.68; three: RR = 0.60) and, to a lesser extent, in men (one symptom: RR = 0.99; two: RR = 0.84; three: RR = 0.82). Both women and men with CPLBP had a lower probability of recuperation (RR = 0.46; 0.67) if they stated that they always/often suffered from insomnia in comparison with those who rarely/never suffered from insomnia (RR = 0.68; RR = 0.81)
Weiner et al. [48]	n = 47	Men = 41 (87.2%) Women = 6 (12.8%) Average age = 68	NRS RMDQ PHQ-9 GAD-7 The Insomnia Severity Index CSQ FABQ	Within the sample suffering from CPLBP, 83% (n = 39) presented factors that contribute to pain in the central nervous system. Concretely, 38.3% (n = 18) presented moderate levels of anxiety and depression, 63.8% (n = 30) moderate levels of insomnia, and 63.8% (n = 30) a catastrophizing cognition with respect to CPLBP and a maladaptive coping style with respect to physical activity. The presence of anxiety and depression (p < 0.05), insomnia (p < 0.01), and maladaptive coping strategies (p < 0.05) were significantly associated with more intense levels of pain.

Abbreviations: CPLBP = chronic primary low back pain; NS = not significant; NRS = the Numeric Rating Scale; RMDQ = the Roland–Morris Disability Questionnaire; SBT = STarT back screening tool; 4DSQ = the Four-Dimensional Symptom Questionnaire; TSK = the Tampa Scale of Kinesiophobia; CSI = the Central Sensitization Inventory; AASP = Adolescent/Adult Sensory Profile Questionnaire; STAI = the State–Trait Anxiety Inventory; MCSDS = the Marlowe Crowne Social Desirability Scale; PCS = the Pain Catastrophizing Scale; SOPA = the Survey of Pain Attitudes; PROMIS = the Patient-Reported Outcomes Measurement Information System; SHS = the Subjective Happiness Scale; NRP = the Negative Responsivity to Pain Avoidance scale; CPAQ-8 = the Chronic Pain Acceptance Questionnaire; BFI = the Big Five Inventory; EEG = continuous electroencephalogram; SSS-8 = the Japanese version of the Somatic Symptom Scale-8; PHQ-2 = Patient Health Questionnaire-2 Depression Scale; EQ-5D = The European Quality of Life-5; HUNT = The Nord–Trøndelag Health Study; CAARS = the Conners’ Adult ADHD Rating Scales; CAARS-S = the Conners’ Adult ADHD Rating Scales self-report; CAARS–O = the Conners’ Adult ADHD Rating Scales–Observer; CPM Protocol = Conditioned Pain Modulation Protocol; SF-MPQ = Short-form McGill Pain Questionnaire; BDI = Beck Depression Inventory; VAS = Visual Analogue Scale; MPSS = the Mainz Pain Staging System; CES-D = The Center for Epidemiological Studies—Depression; HADS = Hospital Anxiety and Depression Scale; Mini-SCL = the German short version of the Brief-Symptom-Checklist; SF-12 = 12-Item Short Form Health Survey; DSF = the German Questionnaire of Pain; PSQI = the Pittsburgh Sleep Quality Index; BPI = the Brief Pain Inventory; ODSIS = the Overall Depression Symptom and Impairment Scale; SSASI = the Short Scale Anxiety Sensitivity Index; OPMM = the Opioid prescription medication motives; COMM = the current opioid misuse measure; GCPS = the Graded Chronic Pain Scale; PHQ-9 = Patient Health Questionnaire Depression Scale; GAD-7 = Generalized Anxiety Disorder Scale; CSQ = the coping strategy questionnaire; FABQ = the Fear-Avoidance Beliefs Questionnaire.