Mart\uednez Calder\uf3n, Javier

Abstract: The current doctoral thesis, entitled "Psychological factors, pain and function in individuals with chronic shoulder pain" has been conducted under the co-supervision regime between the University of Malaga, Spain and the University of Antwerp, Belgium. Therefore, a summary in English is exposed on the content of this. During the first chapter, this doctoral thesis shows us a deep vision about the importance of pain in our society. Pain is a major public health priority. It is considered one of the most frequent causes to seek health care. Traditionally, the International Association for the Study of Pain has defined pain as \u201can unpleasant sensory and emotional experience associated with actual/potential tissue damage or described in terms of such damage\u201d. Everyone will experience pain at some point in their lifetime. Annually, estimations suggest that one in five adults have acute or subacute pain, whereas one in ten adults endure chronic pain. The pain experience of every individual is extremely complex. Pain is undeniably subjective. Indeed, people who have similar diagnostic criteria often perceive pain in a different manner. As a consequence of pain subjectivity, the term \u201cpain\u201d has acquired a broad range of dimensions in order to cover all the sensations that an individual feel when is in pain. In this sense, intensity, severity, affect and sensitivity are probably the most studied dimensions of pain. Pain intensity describes how intense we perceive pain on a specific moment. Pain intensity is the most noteworthy dimension of pain, which is often assessed through unidimensional self-reported scales. The numerical pain rating scale and the visual analogue scale are the most common tools used to measure pain intensity. However, certain factors such as the context or culture influences how intense an individual perceives its pain. Pain contains multidimensional attributes and subtle connotations such as aching or burning among others. Thereby, pain intensity should not be considered a linear phenomenon and exclusively quantified through unidimensional tools. In this context, pain severity and pain affect have emerged as multidimensional dimensions of pain which include the term \u201cpain intensity\u201d. Both are commonly assessed through multidimensional self-reported scales. Pain severity involves pain intensity and pain interference with daily activities. Pain affect refers to pain intensity and the emotional changes that an individual feel when he/she is in pain. Pain sensitivity is a relevant dimension of pain. It describes the tendency to react to standardized experimental or pathological stimuli. When repeated or intense noxious stimuli (actual or potential tissue damaging events) occur, pain hypersensitivity emerges. Pain hypersensitivity is characterized by allodynia (increased sensitivity for normally non-painful stimuli) and hyperalgesia (noxious stimuli produce an exaggerated and prolonged response to pain). Pain hypersensitivity is initially an adaptive process that arouse our alert systems in situations where there is a potential risk of damage. When tissues heal, pain hypersensitivity returns to normal baseline values. However, some individuals report pain hypersensitivity after the tissues heal, even in asymptomatic areas where the primary pain input did not occur. This phenomenon represents the sensitization of the central nervous system which is probably a key driver in syndromes such as fibromyalgia or chronic fatigue syndrome. Acute pain (pain present for less than three months) is very common worldwide. Unfortunately, certain individuals show an inadequate control of its acute pain, developing chronic pain and pain-related symptoms. Many factors are involved in how an individual perceives, processes, interprets and copes with its pain experience. Thus, not only sensory and emotional factors, but also cognitive, behavioural and social factors are considered important in the distressful experience of pain. Some of these factors may favour maladaptive responses to pain, which may suppose a bridge in the transition and perpetuation to chronicity. But first, what is chronic pain? Chronic pain refers to pain that persists or recurs more than three months, once the normal healing process has occurred. Chronic pain is a global issue which affects up to 34% of population. The socioeconomic burden occasioned by chronic pain is enormous. Biopsychosocial consequences are critical. Certain individuals reject their chronic situation. These individuals are often socially excluded which may lead to unpleasant results in terms of insomnia, depression, opioid overuse, suicidal ideation and premature mortality. In this sense, numerous surgical and conservative interventions have been proposed in order to improve the poor prognosis of chronic pain. However, chronicity continues to increase. Chronic musculoskeletal pain is the most prevalent chronic pain sondition and it is also a huge concern in clinical practice. Indeed, more than 20% of individuals with this condition annually consult a health professional. Additionally, chronic musculoskeletal pain is viewed as the fourth global burden on health in terms of economic costs and psychosocial consequences. In this sense, a large number of conservative and surgical interventions have been proposed to improve chronic musculoskeletal pain and its pain-related outcomes. However, its recurrence and persistence are frequent. Certain chronic musculoskeletal symptoms, such as widespread pain, are not associated with a tissue damage or a pathophysiological reason. This causes that the course of chronic musculoskeletal pain is unpredictable which entails an immense challenge for clinicians and researchers. The present doctoral thesis focused on a specific type of musculoskeletal pain, shoulder pain. Shoulder pain is the third most common musculoskeletal pain condition after low back and neck pain. Interestingly, a large percentage of individuals with shoulder pain disorders consult a health professional. However, roughly 50% of them develop chronic shoulder pain. A great deal of factors influences the delay of recovery in individuals with shoulder pain which cause a negative circle of more pain, frustration, disability and emotional distress. In this sense, there is a large amount of research focused on how biological, psychological and social factors that surround an individual with chronic pain are fundamental in the prognosis of this. Within these factors, psychological factors seem to be key in how an individual perceives, interprets and responds to their chronic pain. Given these considerations, the acquisition of in-depth knowledge about the impact that psychological factors play in the perpetuation of chronic shoulder pain is essential in order to design targeted interventions that promote the increase of protective factors such as pain selfefficacy and resilience. With this, people with chronic shoulder pain can establish active coping strategies that facilitate the control of their pain and adherence to rehabilitation programs such as exercise programmes. For this reason, the current doctoral thesis aimed to evaluate the role that psychological factors play in pain and disability in individuals with chronic shoulder pain. This first chapter serves as background and justification for the development of the present doctoral thesis. The second chapter lists the general and specific objectives of this doctoral thesis. The first general aim was to explore the current state of knowledge about the role that psychological factors (especially cognitive and emotional factors) play in individuals with shoulder pain. The second general aim was to determine the potential associations between a set of psychological factors (specifically pain catastrophizing, pain selfefficacy, kinesiophobia or fear of movement and emotional distress) and chronic shoulder pain intensity and pain-related variables such as disability. The third chapter aimed to respond the first general objective of this doctoral thesis. In this context, a systematic review was performed in order to analyse the role that psychological factors play in the perpetuation of chronic shoulder pain intensity and disability in operative and non-operative samples. A systematic search was conducted in PubMed, AMED, CINAHL, PubPsych and EMBASE from the incception of these databases until July 2017. Longitudinal studies which evaluated the role that psychological factors play in the perpetuation of chronic shoulder pain intensity and disability were included. The risk of bias across the included studies was assessed through the Newcastle Ottawa scale. The overall quality and strength of the evidence per outcome (pain intensity and disability) was examined through the GRADE approach. A total of 27 longitudinal studies satisfied our inclusion criteria, and thus, were included in this systematic review. The total sample was of 11,176 individuals with chronic shoulder pain. The risk or bias was variable across the included studies. The quality and the strength of the evidence was very low. Higher levels of self-efficacy, resilience and expectations of recovery were significantly associated with lower levels of pain intensity and disability. Conversely, higher levels of emotional distress, depressive symptoms, anxiety, preoperative concerns, fear-avoidance beliefs, somatization and pain catastrophizing were significantly associated with higher levels of pain intensity and disability. Our results suggest that psychological factors may influence the perpetuation of pain intensity and disability in individuals with chronic shoulder pain. Nevertheless, the overall quality and strength of the evidence in terms of inconsistency, risk of bias and imprecision of results was very low, and hence, further research in this field is required. This article was published in the year 2018 in the journal BMJ Open. The fourth chapter also aimed to satisfy the first general objective of this doctoral thesis. Therefore, another systematic review focused specifically on pain beliefs was conducted, since inside of psychological factors, cognitive and emotional factors has been shown as key factors and modulables through a long battery of conservative interventions such as physiotherapy. The objective of this systematic review was to evaluate the association between pain beliefs, pain intensity and disability in individuals with acute, subacute and chronic shoulder pain. A systematic search was established in PubMed, EBSCOhost, AMED, CINAHL, EMBASE and PubPsych from the inception of these databases until July 2017. Grey literature was also searched. The selection of studies was based on crosssectional and longitudinal observational studies that explored the association and the predictive value that pain beliefs play in shoulder pain intensity and disability. A total of thirty-three articles were included with a total sample of 10,293 individuals with shoulder pain. In the cross-sectional analysis, higher levels of catastrophic thoughts in response to pain and kinesiophobia were significantly associated with higher levels of pain intensity and disability. On the other hand, in this same analysis, higher levels of expectations of recovery and self-efficacy beliefs were significantly associated with lower levels of pain intensity and disability. In the longitudinal analysis, higher baseline levels of catastrophic thoughts in response to pain, fear-avoidance beliefs and kinesiophobia predicted the perpetuation of pain intensity and disability over time. Conversely, greater baseline levels of expectations of recovery and self-efficacy beliefs predicted the reduction in the progression of pain intensity and disability over time. Evidence suggests that pain beliefs are associated with and predict to the course of pain intensity and disability in shoulder pain. However, the overall quality and strength of the evidence in terms of inconsistency, risk of bias and imprecision of the results was very low through the included studies. Further research using higher quality longitudinal designs and procedures are needed in order to draw firm conclusions in this regard. This article was published in the year 2018 in the journal Musculoskeletal Science & Practice. The fifth chapter is a proposal to address the second general objective of the current doctoral thesis. In this sense, a study protocol was developed to determine the role that psychological factors play in the prognosis of chronic shoulder pain through a prospective cohort study. The study was designed to have a longitudinal perspective, with a followup of 12 months. This study will be carried out in four primary care centres as well as a hospital. It will include a total of 307 participants older that 18 years old with chronic shoulder pain. The following variables will be assessed: pain intensity, disability, pain self-efficacy, kinesiophobia, fear of pain, catastrophic thoughts in response to pain and expectations of recovery among others. A total of four measurement points will be taken: at baseline; 3 months; 6 months and 12 months follow-up. This article was published in the year 2017 in the journal BMJ Open. The sixth chapter was addressed to satisfy the second general objective of the present doctoral thesis. In this context, a cross-sectional observational study was developed which showed two aims. The first objective was to explore the potential associations between a set of psychological factors (catastrophic thoughts in response to pain, pain self-efficacy and emotional distress) and experimental pain measures (local and generalized pain hypersensitivity). The second objective was to evaluate the potential associations between the aforementioned psychological factors and pain intensity and disability in individuals with chronic shoulder pain. A total of 90 participants with chronic shoulder pain meet our inclusion criteria and therefore, they were included in this study. Pain hypersensitivity was assessed through the pressure pain threshold, a measure which was obtained using a pressure algometry. Pain intensity and disability were evaluated with the "The Shoulder and Disability Index" questionnaire. Pain self-efficacy was explored through the questionnaire "The Pain Self-Efficacy Questionnaire". Pain catastrophizing was evaluated using the "The Pain Catastrophizing Scale" questionnaire. Emotional distress was assessed through the questionnaire "The Hospital Anxiety and Depression Scale". Multivariate regression analyses were performed to determine the potential associations between psychological factors and both pain measurements (clinical and experimental), as well as the level of disability. All analyses were adjusted by gender. In the regression analysis, higher levels of pain self-efficacy were associated with lower levels of local pain hypersensitivity (p = 0.046), lower levels of pain intensit

Psychological factors, pain and function in individuals with chronic shoulder pain

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