We evaluated psychological and social factors in a total of 170 participants, including 51 subjects (28 men, 23 women, mean age 23.3 ± 6.5 years) with unclear origin low back pain (unclear origin pain group), 34 subjects (27 men, 7 women, mean age 21.4 ± 2.4 years) with low back pain possibly due to extension-related (extension-related pain group), and 85 subjects (58 men, 27 women, mean age 20.6 ± 2.3 years) in the non-low back pain (control group). The evaluation scales used were the GHQ-12, BS-POP for patients, and STAI. The mean total score of the GHQ-12 was 28.5 ± 4.5 points in the group with pain of unclear origin, 26.2 ± 6.5 points in the extension-related pain group, and 23.8 ± 5.8 points in the control group. The highest scores were observed in the group with pain of unclear origin, followed by the extension-related pain group and the control group (p<0.001). The mean total score of the BS-POP for patients was 17.5 ± 2.9 points in the unclear origin pain group, 16.7 ±3.0 points in the extension-related pain group, and 15.7 ± 2.6 points in the control group, with the scores increasing in the order of the unclear origin group, the extension-related pain group, and the control group (p<0.001). The mean total score of STAI (A-state) was 46.8 ± 7.9 points in the unclear origin pain group, 45.0 ± 10.4 points in the extension-related pain group, and 44.0 ± 9.8 points in the control group, with the scores increasing in the order of the unclear origin group, the extension-related pain group, and the control group, but no statistically significant difference was observed. The mean total score of STAI (A-trait) was 51.5 ± 7.9 points in the unclear origin pain group, 48.0 ± 10.1 points in the extension-related pain group, and 47.0 ± 8.9 points in the control group. The highest scores were observed in the group with pain of unclear origin, followed by the extension-related pain group and the control group (p<0.001). In the unclear origin group, psychological and social factors were suggested to be involved based on three assessment tools—GHQ-12, BS-POP for patients, and STAI (A-trait); in contrast, STAI (A-state) indicated no such involvement.
近年，非特異的腰痛においては心理・社会的要因が関与している可能性があるといわれている．そこで今回，原因不明の腰痛を有する者（原因不明腰痛群）51名（男性28名，女性23名，平均年齢23.3 ± 6.5歳；19歳～48歳），後部障害型腰痛の可能性が考えられる腰痛を有するもの（後部障害型腰痛群）34名（男性27名，女性7名，平均年齢21.4 ± 2.4歳；19歳～30歳），および対照群（非腰痛群）85名（男性58名，女性27名，平均年齢20.6 ± 2.3歳；19歳～38歳）の計170名を対象として，心理・社会的要因の評価を行った．評価尺度として，GHQ-12：精神的ストレスによる身体的症状，不安と不眠，社会的活動障害，うつ傾向の存在，患者用BS-POP：整形外科患者における精神医学的問題，STAI（A-state：検査を実施したときの主観的な不安，A-trait：普段においてどの程度不安になりやすいかという傾向）を用いた．GHQ-12の合計得点の平均は原因不明腰痛群が28.5 ± 4.5点，後部障害型腰痛群が26.2 ± 6.5点，非腰痛群が23.8 ± 5.8点であり，原因不明腰痛群，後部障害型腰痛群，非腰痛群の順で高値を示した（p<0.001）．患者用BS-POPの合計得点の平均は原因不明腰痛群が17.5 ± 2.9点，後部障害型腰痛群が16.7 ± 3.0点，非腰痛群が15.7 ± 2.6点であり，原因不明腰痛群，後部障害型腰痛群，非腰痛群の順で高値を示した（p<0.001）．STAI（A-state）の合計得点の平均は原因不明腰痛群が46.8 ± 7.9点，後部障害型腰痛群が45.0 ± 10.4点，非腰痛群が44.0 ± 9.8点であり，原因不明腰痛群群，後部障害型腰痛群，非腰痛群の順で高値を示したが，統計学的有意差がみられなかった．STAI（A-trait）合計得点の平均は原因不明腰痛群が51.5 ± 7.9点，後部障害型腰痛群が48.0 ± 10.1点，非腰痛群が47.0 ± 8.9点であり，原因不明腰痛群，後部障害型腰痛群，非腰痛群の順で高値を示した（p<0.001）．これらの結果より，GHQ-12，患者用BS-POP，STAI（A-trait）の3つの評価法では，原因不明腰痛群における心理・社会的要因の大いなる関与が示唆されたが，逆にSTAI（A-state）の評価法ではこれらの関与が証明できなかった．
Most cases of low back pain are not associated with severe underlying diseases, and the specific cause of the pain cannot be identified. Such cases are classified as nonspecific low back pain (NSLBP), which is characterised by the absence of lower limb neurological symptoms and difficulty in identifying an anatomical cause [1]. Even with X-rays or MRI examinations, no abnormalities are observed [2]. This condition accounts for 85% [3] of low back pain cases.
Recently, psychological and social factors have been suggested to contribute to NSLBP, adding complexity to its mechanism of onset. Pain that would typically not be perceived as severe might be amplified by psychological and social factors. This pain is defined as one for which no clear organic lesions or pathophysiological mechanisms can be identified. Among NSLBP cases, 25–75% of those with chronic pain are also said to experience depression, which is influenced by underlying psychological factors [4].
Modern individuals are exposed to a variety of psychological and social stressors, and psychogenic low back pain can arise as a result of these diverse forms of mental stress in an increasingly complex society. For instance, there have been reports suggesting a relationship between perceived stress and low back pain [5, 6]. In addition, significant correlations have been found between occupational low back pain among female workers primarily engaged in seated tasks and the scale measuring everyday irritations [7]. Furthermore, analyses of daily life events and their associations with low back pain have reported that family environments—such as lack of understanding or conflict between family members—as well as school environments—such as changes in academic paths or bullying—are related to the occurrence of low back pain [8, 9]. Moreover, individuals suffering from low back pain have been reported to harbor anxiety stemming from various psychological issues, such as future financial concerns and interpersonal relationship difficulties, and their inability to cope with these problems [10]. Nevertheless, a comprehensive and systematic evaluation of the influence of psychological and social factors on NSLBP remains lacking. This study investigated the psychological and social factors in individuals reporting NSLBP using evaluation scales designed to assess these aspects.
The study included 85 individuals (55 males, 30 females; mean age: 22.4 ± 5.3 years: 19–48 years) who had low back pain and voluntarily agreed to participate following randomized recruitment. None of them exhibited neurological symptoms in the lower extremities, such as pain, sensory disturbances, or muscle weakness. Additionally, there were no individuals previously diagnosed with lumbar disc herniation, spondylolysis, or other lumbar spine disorders. On the other hand, the control group consisted of 85 individuals without lower back pain (55 males and 30 females, with an average age of 20.6 ± 2.3 years).
Left: flexible curve ruler
Center: place a ruler (Th12-S2)
Right: inverse trigonometric functions
Using a flexible curve ruler (Fig. 1; left), the straight line connecting Th12 and S2 (L) and the perpendicular line passing through the apex of the curve (H) were measured [11] (Fig. 1; middle). The lumbar lordosis angle was calculated using the following formula: 4 × [arc tangent (2H/L)] (Fig. 1; Right). Lumbar lordosis was defined as an angle of 36° or greater based on previous measurements in healthy individuals by Muramoto et al. [11]. According to prior reports, extension-related low back pain, especially lumbar facet joint syndrome is often associated with pain arising in the buttocks or posterolateral thighs during lumbar extension [12]. When the lumbar spine extends, the lower edge of the inferior articular process contacts the lower vertebral arch, and the lower portion of the joint capsule may become impinged between them [13]. Based on this, the presence or absence of pain aggravation upon lumbar extension was also evaluated. It has been reported that excessive muscle contraction of the lumbar and back muscles during movement may increase muscle stiffness, potentially leading to the development of myofascial low back pain [14], and that this condition is exacerbated by trunk flexion and extension movements [15].
Individuals who did not exhibit increased lumbar lordosis or worsening of low back pain during trunk extension were categorized as the “group with unclear causes of low back pain (unclear origin pain group)”. In contrast, those who experienced pain and increased lumbar lordosis during trunk extension were classified as the “group with possible extension-related low back pain (extension-related pain group)”.
The unclear origin group consisted of 51 individuals (28 males, 23 females; mean age: 23.3 ± 6.5 years; age range: 19–48 years). The extension-related pain group included 34 individuals (27 males, 7 females; mean age: 21.4 ± 2.4 years; age range: 19–30 years). The non-low back pain group (control group) consisted of 85 individuals (58 males and 27 females; mean age: 20.6 ± 2.3 years; age range: 19–38 years).
2. Assessment toolsPsychological and social factors were evaluated for all 170 participants using the following assessment tools: General Health Questionnaire-12 [16, 17] (GHQ-12); The presence of physical symptoms caused by psychological stress, alongside anxiety, insomnia, impaired social functioning, and depressive tendencies, Brief Scale for Evaluation of Psychiatric Problems in Orthopaedic Patients [18, 19] (BS-POP for patients); Psychiatric problems in orthopedic patients and State-Trait Anxiety inventory: A-state; Subjective anxiety during medical examinations and A-trait; Tendency to experience anxiety in daily life [20] (STAI).
3. Statistical AnalysisThe total scores of the GHQ-12, BS-POP for patients, STAI (A-state), and STAI (A-trait) were compared among the unclear origin pain group, the extension-related pain group, and the control groups using the Kruskal-Wallis test [21]. Multiple comparisons were performed using Dunn’s test [22]. Statistical analysis were performed using the Stat Flex Ver. 6.0 software (Artec Co., Ltd.).
4. Ethical ConsiderationsThis study was conducted in accordance with the Declaration of Helsinki. Detailed explanations regarding the methods and potential risks were provided to all participants, who provided written informed consent. The collected information was managed to ensure confidentiality (Approval No. 37 by the Ethics Committee of Kagoshima Medical Welfare College).
The mean total scores were 28.5 ± 4.5 in the unclear origin pain group, 26.2 ± 6.5 in the extension-related pain group, and 23.8 ± 5.8 in the control group.
The scores were highest in the order of the unclear origin pain group, the extension-related pain group, and the control group (p<0.001). Multiple comparisons showed statistically significant differences between the control group and the unclear origin pain group (p<0.01) as well as between the extension-related pain group and the unclear origin pain group (p<0.05) (Table 1).
The average total scores of GHQ-12, BS-POP for patients, and STAI (state and trait)
| unclear origin pain group | extension-related pain group | control group | |
|---|---|---|---|
| Number of people | 51 | 34 | 85 |
| Gender ratio (male/female) | 28/23 | 27/7 | 58/27 |
| Mean age (years old) | 23.3 ± 6.5 (19–48) | 21.4 ± 2.4 (19–30) | 20.6 ± 2.3 (19–38) |
| ***The mean total score of the GHQ-12 | **28.5 ± 4.5 | *26.2 ± 6.5 | 23.8 ± 5.8 |
| ***The mean total score of the BS-POP for patients | **17.5 ± 2.9 | *16.7 ± 3.0 | 15.7 ± 2.6 |
| The mean total score of STAI (A-state) | 46.8 ± 7.9 | 45.0 ± 10.4 | 44.0 ± 9.8 |
| ***The mean total score of STAI (A-trait) | **51.5 ± 7.9 | *48.0 ± 10.1 | 47.0 ± 8.9 |
***p<0.001 **p<0.01 *p<0.05
The mean total scores were 17.5 ± 2.9 in the unclear origin pain group, 16.7 ± 3.0 in the extension-related pain group, and 15.7 ± 2.6 in the control group.
The scores were highest in the order of the unclear origin pain group, the extension-related pain group, and the control group (p<0.001). Multiple comparisons revealed statistically significant differences between the control group and the unclear origin pain group (p<0.01) as well as between the extension-related pain group and the unclear origin pain group (p<0.05) (Table 1).
3. STAI (A-state)The mean total scores were 46.8 ± 7.9 in the unclear origin pain group, 45.0 ± 10.4 in the extension-related pain group, and 44.0 ± 9.8 in the control group.
Although the scores were highest in the order of the unclear origin pain group, the extension-related pain group, and the control group, no statistically significant differences were observed (Table 1).
4. STAI (A-trait)The mean total scores were 51.5 ± 7.9 in the unclear origin pain group, 48.0 ± 10.1 in the extension-related pain group, and 47.0 ± 8.9 in the control group.
The scores were highest in the order of the unclear origin pain group, the extension-related pain group, and the control group (p<0.001). Statistically significant differences were found between the control group and the unclear origin pain group (p<0.01) as well as between the extension-related pain group and the unclear origin pain group (p<0.05) (Table 1).
This study assessed psychosocial factors in the unclear origin pain group, the extension-related pain group, and the control group using four evaluation scales: GHQ-12, BS-POP for patients, STAI (A-state), and STAI (A-trait). Results showed that the average total scores for all scales were generally higher in the unclear origin pain group than in the other two groups, with statistically significant differences in the GHQ-12, BS-POP for patients, and STAI (A-trait) scores.
In contrast, the lack of significant differences in STAI (A-state) scores might be due to its focus on measuring temporary anxiety, which might not adequately reflect the psychological effects specific to different pain mechanisms.
Koyama et al. [23] investigated the psychological and social factors in workplace environments and reported higher GHQ-30 scores in the low back pain group than in the non-low back pain group. Notably, GHQ-12, with its fewer items, offers advantages such as fewer missing values while maintaining reliability and validity [24]. However, there are no prior reports on GHQ-12 evaluations specific to low back pain patients.
Among patients with chronic low back pain, over 80% reportedly had high BS-POP scores [25]. Yoshida et al. [26] found the average BS-POP score in chronic low back pain patients to be 16.7 ± 3.7 points, comparable to the 16.7 ± 3.0 points observed in the unclear origin pain group of this study. However, the extension-related pain group showed a slightly higher score of 17.5 ± 2.9 points. Self-assessments using BS-POP may include subjective or intentional responses, such as attempts to present oneself in a more favourable or unfavourable light, indicating limitations in using self-assessments for evaluate psychiatric issues [18].
Kasuya et al. [27] reported an average STAI (A-trait) score of 36.3 ± 7.5 in patients with chronic low back pain, whereas this study found much higher scores in the extension-related pain group (48.0 ± 10.1) and unclear origin pain group (51.5 ± 7.9). Endo et al. [28] reported significant differences in both state and trait anxiety based on the severity of low back pain, suggesting a relationship between anxiety tendencies and the degree of pain.
Hasegawa [29] reported that stress, anxiety, and suppressed anger had a significant impact on the autonomic nervous system, causing ischaemia due to vasoconstriction in muscles, nerves, tendons, and ligaments. This results in the production of reactive oxygen species, leading to cellular damage and pain. Matsudaira [30] defined NSLBP as a condition where dysfunction of both the musculoskeletal system, particularly the spine, and the brain coexists. Mechanical stress from poor posture leads to musculoskeletal dysfunction, while dissatisfaction with work, lack of social support, or psychological factors, including fear-avoidance behaviour induce mental stress, potentially causing brain dysfunction such as abnormalities in the dopamine-opioid system of the midbrain-limbic system [31].
The response to brain dysfunction can result in hypersensitivity to pain (central sensitisation) accompanied by depression and autonomic dysregulation, manifesting in diverse somatic symptoms and dysfunction of the descending pain inhibitory system [32, 33].
As an unexplained type of lower back pain, psychogenic back pain had been previously highlighted, but its mechanisms remained largely unknown. Recently, the International Association for the Study of Pain defined “nociplastic pain” as a third type of pain, alongside nociceptive pain and neuropathic pain [34].
Nociplastic pain is defined as “pain arising from altered nociception, despite no clear evidence of actual or threatened tissue damage activating peripheral nociceptors, or evidence of disease or injury affecting the somatosensory system [35]”. This type of pain corresponds to what has previously been referred to as psychogenic pain or non-organic pain [33].
The higher scores in the nociplastic pain group can be attributed to central sensitization [36], a major mechanism of nociplastic pain, which increases pain sensitivity. Psychological stress and anxiety may exacerbate pain, and comorbidities such as depression and anxiety likely contribute to higher GHQ-12 and STAI (A-trait) scores. Social factors, such as loneliness and isolation may amplify physical pain, while excessive focus on pain and maladaptive cognitive-behavioral responses may prolong or worsen it [35, 37].
In today’s complex and stress-laden society, the existence of psychogenic low back pain [38], a form of nociplastic pain, has garnered significant attention. Future studies should focus on psychogenic low back pain for a deeper understanding accordingly.
The classification of the unclear origin pain group and the extension-related pain group was based solely on physical findings—specifically, lumbar lordosis angle and trunk extension tests—without the use of X-ray or MRI examinations. This decision was made due to the large number of study participants, which would have incurred significant costs, and the inclusion of female participants, for whom the possibility of pregnancy could not be ruled out. As a result, definitive clinical diagnoses were not established. Therefore, in this paper, these groups were treated as the “suspected unclear origin pain group” and the “suspected extension-related pain group”.
Since the primary focus of this study was the analysis of psychosocial factors, no objective assessment of pain severity was conducted. Consequently, it was not possible to demonstrate the relationship between pain intensity and psychosocial factors.
There are many other scales available for examining psychosocial factors, and this study adopted four of them. Among these, statistically significant differences were observed in three scales. Although further investigation using other scales may be necessary, this was not conducted due to the large number of items in each scale, which require considerable time to complete, and the possibility of not obtaining consent from research participants.
Analyzing the relationships among individual items within each scale could provide a more detailed understanding of psychosocial factors; however, this aspect was not examined in the present study.
These represent the limitations of the present study.
This study, which used the GHQ-12, BS-POP for patients, and (A-trait) as indicators, suggested that psychological and social factors were more involved in individuals with the unclear origin pain group than in those with the extension-related pain group and the control group. However, STAI (A-State) could not provide evidence of this involvement.
The author would like to thank the many individuals who participated in the present study and Professor Ken’ichiro Tanaka (Professor, Graduate School of Social Informatics, Nihon University) who provided valuable advice.
