This study clarifies the level of involvement for HRQoL in people with cMSS, compared to those with aMSS and those with woMSS. This study found that the following are risk factors for low HRQoL in its physical dimension: the female sex, age over 44 years and rural area of residence. On the other hand, high educational level was found to be a protective factor for low HRQoL in its physical and mental dimensions.
In relation to chronic pain, cMSS worldwide prevalence demonstrate wide ranges (12 to 41%) (14), which would be explained by the different definitions for chronic pain, types of studies, data collection methodology and measurement instruments. The present study reports a higher prevalence than the upper limit of the previously reported range. The foregoing could be explained as similar prevalence is presented in studies with the same cut-off points of chronic pain (3 months duration) and similar methodologies of data collection (population surveys type face-to-face interviews) (15). In Colombia, a cross-sectional descriptive population study in urban areas reported a chronic pain prevalence of 33.9% (7) and in Brazil, a cross-sectional population study in São Luís exhibited a 42.3% prevalence (8). The present study results resemble similar outcomes across Latin America. A study conducted in Ireland obtained a 62.6% cMSS prevalence, which is greater than that found in the present study. This could be explained because the population from which the data were obtained, which was a sample drawn from current pain patients (16). Subjects who were interviewed through a national telephone survey generated a low response rate (16.6%) (16).
Another factor that could create disparity in reported chronic pain prevalence centers on the high heterogeneity in chronic pain definitions and the different methodologies used for evaluating population studies worldwide. These disparities make difficult the ability to relate global epidemiological chronic pain findings with consistency in healthcare policy across countries (17, 18).
Regardless of the differences with other countries, for Chile the prevalence of cMSS is greater than the national prevalence of dyslipidemia for dyslipidemia (38.5%), hypertension (26.9%), respiratory symptoms (24.5%), depressive symptoms (17.2%) and type 2 diabetes (9.4%) (12)
The low HRQoL scores found both in mental (47.7 + 10.6) and physical (43.8 + 10.1) dimensions in cMSS Chilean population are consistent with research assessing HRQoL measured through SF-12, which suggests that quality of life is reduced in chronic pain sufferers, even when cMSS intensity is low (15). A cross-sectional survey study developed in Japan, showed that when using SF-12 to measure HRQoL in cMSS patients and comparing those data with asymptomatic individuals, both physical (PCS 44.23 vs 47.48; p <0.05) and mental (MCS 44.26 vs 51.14, p<0.05) scores demonstrated differences that exceeded the established clinically relevant cut-off points, emphasizing the dramatic effect of chronic pain in the patient's health experience (16).
In a study carried out in Brazil, people with chronic pain presented with significantly lower (P<0.001) health-related quality of life scores (measured through EuroQol), (19). In Ireland, chronic pain patients reported lower physical and mental HRQoL scores compared to the normal population (20). The mental composite scores (MCS) were lower versus physical composite scores, which confirms that the HRQoL should be treated as a multidimensional construct (2).
The multiple logistic regression analysis shows that the cMSS variable is independent of the control variables (sex, age, educational level and residence area) in its ability to explain the presence of "low HRQoL", both in PCS as in MCS. However, this study’s findings show that the female sex is a risk factor and that the high educational level is protective factor of presenting "low HRQoL". Increasing age seems to be a risk factor only for low HRQoL in the physical dimension. These considerations should be incorporated into national health program planning, especially in the following groups: women, elderly and people with medium and low educational level.
In relation to the approach in groups of medium and low educational levels, it is necessary to establish dissemination strategies to health professionals in primary health care, especially in vulnerable sectors. The aim of investigating subjects that, considering their educational level, could be considered more chronic in MSS added to a social context of minimum health priorities in many unsolved cases. This could be due to greater physical labor demand, ignorance of the need for early management and consultation in case of musculoskeletal diseases.
The research results illustrate the evolution of HRQoL results in MSS between the National Health Surveys 2009-2010 and NHS 2016-2017, whose data will soon be available. In Chile, the best approach to MSS management has not been determined (18). Before concluding the best approach, biomedical and biopsychosocial factors must be further considered. The biopsychosocial approach emphasizes the patient's self-management and their HRQoL. This explains the existing training gap that health professionals face within this epidemiological problem. This study’s findings support the need to establish standardized management policies and practices for treating chronic MSS(18).
This study was strengthened by performing the analysis on population data, which allows a generalized application and reflects Chile’s state of health. The limitations of the study center on the study methodology. Since the study used a cross-sectional analytical approach, the methodology implies some biases, such as the response bias that the subjects might have during the survey process reporting history of musculoskeletal symptoms or HRQoL. Another limitation related to the cross-sectional design of the study is that it does not imply a cause-effect relationship.