Summary of results
Only eleven studies were identified of poor epidemiological quality and, therefore, results need to be interpreted with caution. The findings of this review suggest that chronic pain is more prevalent, more widespread, and more severe in immigrants than natives, and that chronic pain potentially deteriorates with length of stay in the destination country. Immigrant women were identified as a particularly vulnerable group for developing chronic pain and comorbid mental health disorders. Apart from gender, older age, lower education, financial hardship, being underweight or obese, time in transit, experience of trauma, and immigration status were also associated with chronic pain in immigrants. Anxiety, depression, and PTSD diagnoses were also shown to be more prevalent in immigrants and were significantly associated with chronic pain.
- Why chronic musculoskeletal pain more prevalent in immigrants than natives?
The high prevalence of chronic pain in immigrants is in line with evidence showing that immigrants report poorer physical health in general (19, 28). There are various reasons that potentially explain the poorer physical health and worse chronic musculoskeletal pain, including occupational factors, barriers to healthcare, vitamin D deficiency, and mental health comorbidities.
Immigrants face discrimination in the labour market and are exposed to occupational risk factors that may contribute to the development of chronic musculoskeletal pain. Immigrants are overrepresented in less desirable, low-skilled, physically demanding jobs due to poor language skills and difficulties in validating education and technical training (29). A systematic review showed that immigrants report higher exposure to physical and mechanical factors, and are therefore more susceptible to develop musculoskeletal symptoms (29). Higher quality epidemiological evidence on immigrant occupational health is needed to improve the working conditions of immigrants.
Immigrants face multiple barriers to accessing health services and are at risk of remaining untreated which may lead to chronicity (30). Language difficulties, unfamiliarity with the healthcare system, cultural differences, lack of confidence in the healthcare system, legal issues, inadequate knowledge of healthcare professionals, and structural racism are some of the barriers that lead to poor and fragmented usage of healthcare services by immigrants (31). Qualitative research shows that immigrants often feel ignored, disregarded, and not taken seriously during their medical encounters, leading to a sense of isolation, discrimination and stress that further exacerbates pain symptoms (32-34). At the same time, health professionals feel ill-equipped to deal with ethnic minorities and chronic pain patients (35). It is therefore essential to develop strategies that inform and educate immigrants and healthcare professionals to eliminate these barriers.
Severe vitamin D deficiency has been observed in immigrants from the Middle East, Africa and Asia in Europe because of lower ultraviolet exposure than in the country of origin, more pigmented skin, skin-covering clothes due to cultural and religious habits, and dietary habits (36). Vitamin D deficiency has been associated with chronic musculoskeletal pain and studies confirm the association in immigrant populations in Europe (37, 38). Randomised control trials are needed to confirm causality and inform healthcare for appropriate prevention, diagnosis, and treatment.
Another contributing factor is the high prevalence of depression, anxiety and PTSD in immigrant communities. According to World Health Organisation, 25% of the European population suffers from depression and anxiety, while present data showed higher rates in immigrants (33%, 35% and 55%)[7]. These findings are in accordance with previous research that showed that anxiety and depression were more prevalent in immigrants (39-41). The prevalence of PTSD was higher in immigrants at 7% to 21% than the European population, which was estimated to be between 1% and 3% (42). The comorbidity and bidirectionality between mental health disorders and chronic pain is well-established (43). Present data suggest that this bidirectionality also holds for immigrant populations. Depression and anxiety had a significant increased effect on chronic pain (21) and 88% of PTSD patients suffered from chronic pain at clinical levels (not significant) (24). Several migration factors, such as history of trauma, insecurity, and isolation, may explain the high prevalence of mental disorders in immigrants. Mental disorders and chronic pain maintain and exacerbate each other via various mechanisms, and it is therefore essential to develop culturally sensitive multidisciplinary interventions (24, 43).
Chronic pain is not unique to immigrants but is a result of a complex interplay of socio-economic, mental and lifestyle factors that may be associated with immigration. Chronic pain in immigrants was shown to be associated with lower socio-economic status, lower education, high and low body mass index (BMI), and poorer mental health. The prevalence of chronic pain may potentially be better explained by the lower socio-economic and education status, which hinder health behaviours such as exercising, better diet, getting regular treatments, and socialising (44, 45). In fact, Waxenegger et al. (19), showed that differences in physical and psychological quality of life, subjective health and musculoskeletal pain between individuals with migration background and without one get smaller when adjusting for age, socio-economic status and health related behaviours. However, significant differences in physical quality of life, subjective health and musculoskeletal pain between native women and immigrant women from countries with low HDI remain after adjustment, which suggests that gender and pre-immigration factors are important determinants of physical health.
- Does chronic pain depend on immigration status?
The present data shows that there is no change in the prevalence of chronic pain from the transit to the early post-migration phase. However, the prevalence of chronic pain is higher in the general immigrant population than in early immigrants, suggesting that chronic pain is higher in the late post-migration phase. This is in line with the view that migrant health deteriorates with length of stay, known as ‘migrant exhausted effect’ theory (17, 46, 47). Qualitative research on immigrants with chronic pain provides important insights into how unfulfilled expectations and mental exhaustion may be linked to the development of chronic pain (33). Several factors such as unemployment and insecurity, loss of socio-economic status, collision of norms, and comparison to life at home lead to feelings of hopelessness, loneliness, and loss of self that both impact and cause pain (33, 48). Mixed-method research with long follow-up would allow the investigation of migration status and chronic pain.
Previous research reports higher prevalence of chronic pain and of depression comorbid with chronic pain in women, which is in line with present data on immigrant women compared to immigrant men (3, 49, 50). Biological differences, gender roles, and cognitive factors have been proposed to explain the observed differences in the prevalence of chronic pain, but the issue remains inconclusive (50). Various studies are reporting cultural and gender differences in the perception, expression, and tolerance of pain, while negative medical encounters are found in both immigrant and female patients (34, 50). To the author’s knowledge, there are no studies comparing pain thresholds, coping mechanisms and medical encounters between immigrant and native women, nor between immigrant women and immigrant men. Nevertheless, immigrant women in pain find themselves in the intersecting structure of ethnicity, class and gender that leads to multiple forms of isolation: at home, at work, socially and in clinical settings (32, 51). This may explain why immigrant women with chronic pain are more likely to be on longer sick leave than native women, to have depression, to use more painkillers, to experience more severe pain, and to have more pain sites than immigrant men (52).