Prevalence and treatment of chronic musculoskeletal pain focused on service gaps: a comparative analysis by age group and body part

Introduction

Occupational health, grounded in occupational medicine, aims to enhance the well-being and labor productivity of the working population. Within this realm, there has been growing concern over the increasing instances of labor loss due to diminished physical capacity and the rise in chronic diseases (Takano, 2015). Labor losses can be categorized into absenteeism and presenteeism. While absenteeism generally pertains to sickness absences or medical leave, presenteeism refers to the reduced performance of employees attending work despite health issues (Yamashita & Arakida, 2006). The productivity loss from presenteeism has been reported to be approximately three times the cost of absenteeism (Nagata et al., 2018). Furthermore, presenteeism has been identified as a subsequent risk factor for absenteeism (Janssens et al., 2013; Taloyan et al., 2012), emphasizing the necessity to address the underlying health issues causing presenteeism so as to enhance organizational productivity. When examining the loss per individual due to presenteeism among Japanese workers based on specific symptoms, the most common health complaints (arranged in descending order) were mental disorders, neck pain/shoulder stiffness, and lower back pain (Yoshimoto et al., 2020). These findings suggest that psychological factors and musculoskeletal disorders significantly influence presenteeism in the Japanese workplace. Therefore, implementation of preventive measures and interventions to address the mental and physical health of the workers is of paramount importance.

Chronic pain is also associated with musculoskeletal disorders. As defined by the International Association for the Study of Pain, chronic pain is described as “pain that persists beyond the normal time frame expected for healing, or pain based on progressive non-malignant pain.” Typically, pain lasting for more than 3 months is classified as chronic. In the revised International Classification of Diseases (ICD-11) from 2018, chronic pain is divided into two primary categories: chronic primary pain and chronic secondary pain (Treede et al., 2019). Among these categories, chronic musculoskeletal pain, whether primary or secondary, can influence the previously mentioned presenteeism. By addressing prevention and improvement measures for both types of chronic musculoskeletal pain, enhanced labor productivity can be anticipated.

Understanding trends based on age and affected regions of the body is indispensable for developing strategies to address chronic musculoskeletal pain in workers. Previous epidemiological studies in Japan have indicated a higher prevalence of chronic pain in the elderly (Hattori, 2006). However, when focusing solely on the musculoskeletal system, research has shown a higher incidence among individuals in their 30 to 50 s, who are commonly referred to as middle-aged adults (Nakamura et al., 2011). While these studies offer age-based comparisons, they target individuals who experience chronic pain in “any region of the body”; to our knowledge, no study has specifically elucidated the trends for distinct body regions by age. Moreover, considering the severity and physical burden of pain, elucidating the number of pain sites according to age could provide critical insights for future research and pain management strategies. However, no research currently exists that offers a comparison of the number of pain sites by age.

Another pressing issue related to chronic musculoskeletal pain was made evident in the 2022 Comprehensive Survey of Living Conditions. Symptoms, such as lower back pain, shoulder stiffness, and joint pain, consistently rank high in prevalence. Comparing these data with results from a decade ago, there was no notable change in the reported prevalence rate or symptoms, indicating that the percentage of individuals experiencing pain had not decreased (Japan Hawsi, 2022). One potential reason for this stagnant situation is the general tendency to downplay chronic musculoskeletal pain as it does not pose a direct threat to life, leading to inadequate treatment. This phenomenon, where needed assistance services are underutilized, is referred to as a “service gap” (Kushner & Sher, 1991). In psychology, it is reported that only about 20% of individuals with conditions such as depression or eating disorders seek medical interventions (Cachelin & Striegel-Moore, 2006). A 2019 survey showed that only 3% utilized psychological counseling, with only 6% expressing a proactive intention to do so (Innovation of SMEaR, 2019). Therefore, we hypothesized that there may be a similar service gap in the treatment of chronic musculoskeletal pain. Existing studies have primarily discussed treatment for chronic pain with moderate to severe intensity (VAS 5 or higher). However, considering the service gap where even mild pain persists for more than three months without improvement, it is essential to include investigations that also consider mild pain. It is also imperative to investigate whether the service gap manifests differently across age groups.

The primary objectives of this study were to elucidate age-related trends in the prevalence of chronic musculoskeletal pain by body region and number of pain sites, as well as to uncover the age- and region-specific tendencies in treatment when experiencing chronic musculoskeletal pain.

Survey methodology

Results

In the current study, of the 1,946 participants, 627 (32.2%) reported experiencing chronic pain in at least one body part within the past year. Of the 973 male participants, 276 (28.4%) reported chronic pain, whereas among the 973 female participants, 361 (36.1%) reported the same, demonstrating a higher prevalence in women (χ2 = 13.260, p < 0.001).

Table 1 shows the number of participants by age group who had chronic pain in one or more areas, including those in their 20 s (27.4%), 30 s (33.5%), 40 s (33.7%), 50 s (33.7%), 60 s (33.7%), and 70 s (34.3%). The results of the chi-square test showed no significant differences (χ2 = 4.558, p = 0.472). Next, we compared the age groups with chronic pain at one, two, and three or more sites using the chi-square test. The results were significant for one site and three or more sites (χ2 = 28.359, p = 0.019), and the residuals were significantly higher for those in their 70 s for one site, significantly higher for those in their 30 s for three or more sites, and significantly lower for those in their 70 s.

Table 2 presents the proportion of individuals with chronic pain by body site, categorized by age group. An initial comparison among the age groups for each body site using a chi-square test and residual analysis revealed that the neck, shoulder, and lower back showed significantly higher values from the 20 to 60 s age groups than at other sites. In the 70 s age group, the shoulder and lower back pain scores were significantly higher. Further comparison by body site among the age groups showed significant results for the neck (χ2 = 12.677, p = 0.027), hands/wrists (χ2 = 11.897, p = 0.036), and knees (χ2 = 16.845, p = 0.005). The 70 s age group reported a significantly lower value (8.6%) for the neck, the 30 s age group reported a significantly higher value (9.5%) for the hands/wrists, the 20 s age group reported a significantly lower value (4.9%) for the knees, and the 60 s age group reported a significantly higher value (12.0%) for the knees.

Table 3 presents the proportion of individuals who underwent treatment for chronic pain, categorized by body site and age. The proportion of individuals who engaged in treatment was lowest for the wrists (47.4%) and highest for the lower back (60.8%). Comparisons between body sites and age groups revealed no significant differences.

Table 4 displays the proportion of treatment by age group for those body sites (neck, shoulder, lower back, and knee) that had higher rates of chronic pain.

Regarding hospital consultations, a comparison of age groups by body part revealed significant differences for the neck, shoulder, and lower back (Neck: χ2 = 12.635, p = 0.027; Shoulder: χ2 = 16.991, p = 0.005; Lower Back: χ2 = 35.832, p < 0.001). Examination of the residuals revealed that individuals in their 70 s (32.1%) had a significantly higher rate of consultations for neck pain. Individuals in their 30 s (17.2%) had significantly lower rates of shoulder pain, whereas those in their 70 s (27.0%) had significantly higher rates for it. Individuals in their 20 s (28.8%) and 30 s (17.1%) had significantly lower rates of lower back pain, whereas those in their 60 s (45.5%) and 70 s (45.1%) had significantly higher rates for it. Notably, the hospital consultation rates for individuals in their 30 s were below 30% in all cases.

No significant differences were observed between the body parts and age groups for rehabilitation. Similarly, no significant disparities were noted across the different body parts and age groups regarding the utilization of acupuncture clinics, orthopedic clinics, and chiropractic care.

Regarding massage usage, significant differences among age groups were observed for both the shoulder and lower back (Shoulder: χ2 = 14.546, p = 0.012; Lower Back: χ2 = 18.927, p = 0.002). Specifically, individuals in their 30 s had notably higher rates of shoulder (37.5%) and lower back pain (35.7%).

Table 5 shows the proportion of individuals who underwent rehabilitation among those who visited a hospital, broken down by body part: the knee showed the highest (44.2%) while the wrist displayed the lowest (20.0%) proportion. Upon comparison between body parts, no significant difference was found (χ2 = 12.003, p = 0.10).

Discussion

This study examined intergenerational differences among individuals with chronic pain and found no age-related differences in those with pain in one or more sites of the body. Previous research has reported a higher prevalence of pain among the elderly (Hattori, 2006; Matsudaira, 2011), while other studies have indicated its greater occurrence in middle-aged individuals in their 30 to 50 s (Nakamura et al., 2011). This survey focused on the musculoskeletal system and anticipated that a higher number of younger individuals would experience pain at one or more sites in the body. However, the actual results contradicted this expectation. This discrepancy may have arisen due to a recent amendment in the guidelines of the International Association for the Study of Pain that now defines chronic pain as pain lasting 3 months or longer. At the time of publication of a study by Nakamura et al. (2011) chronic pain was identified as that persisting for 6 months or more. Adhering to the new guidelines, the present study classified pain lasting 3 months or more as chronic pain. This adjustment potentially broadened the scope of individuals identified as having chronic pain compared to prior studies. Indeed, compared to the 10% to 20% prevalence reported in the Nakamura et al. (2011) survey, the current study indicates a higher prevalence, ranging from 25% to 35%. This suggests that our study categorizes individuals with milder symptoms as having chronic pain.

Next, a comparison was made regarding the number of pain sites among different age groups with chronic pain. The results revealed that individuals in their 30 s reported pain in three or more areas more frequently, whereas fewer instances were noted in those in their 70 s. The presence of pain in three or more areas suggests a significant burden on the body, indicating a condition that is difficult to heal. Individuals with pain in three or more areas were interpreted as having severe chronic pain. From this perspective, the prevalence of severe chronic pain in middle-aged patients was consistent with the findings of previous studies. Despite amendments to the guidelines related to chronic pain, the results of this study do not contradict those of previous research. Therefore, the results of this study can be interpreted based on the findings of previous studies.

When analyzing the prevalence of chronic musculoskeletal pain across different body regions, significantly higher rates were noted in the lower back, shoulders, and neck, and this is consistent with previous studies. Bipedalism, unique to human beings, is posited as a potential cause of this pain distribution (Plomp et al., 2015). Specifically, the postural demands of a bipedal stance and the spinal curvature during ambulation can exert significant stress on the torso and cervical areas, potentially predisposing the lower back and neck to chronic pain. Moreover, bipedalism has granted human beings greater upper-limb mobility, expanding the range of motion in the shoulders. This increased mobility could lead to augmented stress on the shoulders, thereby increasing their susceptibility to pain. Thus, as the level of human activity intensifies, the propensity for chronic pain in the shoulders, lower back, and knees may increase. Notably, middle-aged individuals with higher activity levels exhibit a pronounced prevalence of pain in the shoulders, lower back, and neck. This underscores the possibility that heightened activity could be a salient factor underlying the elevated incidence of pain in these regions in the younger population.

Conversely, the incidence of chronic knee pain tends to increase with age. One plausible cause of this increase is the cumulative strain on the lower limbs due to weight bearing. The knee, with its limited joint flexibility, is presumed to be significantly affected by this strain. Furthermore, the knee is significantly influenced by bipedalism. Therefore, the effects of bipedalism should be considered when identifying the causes of knee pain. Strain in the musculoskeletal system due to daily human activities can be regarded as a contributing factor to chronic pain. In light of the above, understanding and taking appropriate measures to prevent the onset of musculoskeletal chronic pain, and to address it when it occurs, are essential for maintaining and improving health.

Focusing on the healthcare service gap issue and examining the presence or absence of treatment for chronic pain, it was revealed that about 50% of the participants did not undertake specific treatment. Furthermore, the presence or absence of treatment did not demonstrate any differences based on location in the body or age. From these survey results, it can be inferred that a service gap in chronic musculoskeletal pain consistently exists, irrespective of body location and age group, affecting approximately half of the participants.

When examining treatment actions by age, the hospital consultation rate was found to be lower among younger individuals, particularly those in their 30 s, and increased with age. Specifically, only approximately 20% of individuals in their 30 s who were experiencing back, shoulder, and neck pain consulted a hospital. This consultation rate is nearly equivalent to the reported consultation rates for depression and eating disorders in psychology (Cachelin & Striegel-Moore, 2006). Meanwhile, the use of massage therapy was higher in individuals in their 30 s than in other age groups. This could reflect the elevated levels of daily chores and increased time management challenges faced by the working-age population. Previous studies on back pain have clarified the effectiveness of early intervention (O’Connell et al., 2016), emphasizing the importance of early treatment for chronic musculoskeletal pain. While massage may provide temporary relief, cases requiring specialized treatment through hospital consultation are anticipated. Despite this, the trend of the working-age population in their 30 s to avoid hospital consultation and opt only for massage may lead to labor loss, particularly presenteeism. Considering this background, the medical consultation behavior of the working-age population in their 30 s with chronic musculoskeletal pain is likely to have a significant socioeconomic impact.

Among the patients with chronic pain who consulted a hospital, only approximately 30% underwent rehabilitation, with no observed differences related to the location of pain. According to a recent systematic review, rehabilitation centered on exercise therapy is recommended as a nonpharmacological treatment for chronic pain (Ambrose & Golightly, 2015; Geneen et al., 2017). Therefore, encouraging early rehabilitation in patients with chronic musculoskeletal pain should be considered as an initiative aimed at improving pain. However, despite the demonstrated effectiveness of evidence-based rehabilitation, there is concern that approximately 70% of patients with chronic pain who have consulted a hospital have not undergone rehabilitation. This situation is not believed to stem from issues of patient knowledge or awareness, but rather from problems on the side of healthcare providers. Specifically, the lack of awareness on the part of physicians that chronic pain can be alleviated through rehabilitation and the existence of therapists lacking adequate rehabilitation techniques for chronic pain treatment are notable issues. Furthermore, the lack of sharing of the latest knowledge and techniques related to chronic pain among healthcare professionals has been cited as a major factor. Thus, it is essential for healthcare providers to acquire specialized knowledge and skills related to chronic musculoskeletal pain and to enhance communication among staff.

Conclusions

This study revealed that approximately 50% of patients with chronic musculoskeletal pain did not undergo treatment. Furthermore, the presence or absence of these treatments showed no significant differences based on the affected body site or age group. These findings suggest the possibility of a consistent healthcare service gap in the management of chronic musculoskeletal pain for patients in Japan, irrespective of the affected site or age group.

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