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Original research
Association between educational level and self-reported musculoskeletal pain and physical functioning in Danes 60–70 years old from 2010 to 2017: a longitudinal analysis of trends over time on data from the Danish Health and Morbidity Survey
  1. Jeanette Hansen1,
  2. Henrik Hansen2,
  3. Charlotte Nilsson3,4,
  4. Ola Ekholm5,
  5. Stig Molsted6
  1. 1Department of Midwifery, Physiotherapy, Occupational Therapy and Psychomotor Therapy, University College Copenhagen, Copenhagen, Denmark
  2. 2Respiratory Research Unit, Department of Respiratory Medicine, Hvidovre Hospital, Hvidovre, Denmark
  3. 3Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
  4. 4National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
  5. 5Department of Clinical Research, Nordsjællands Hospital, Copenhagen, Denmark
  6. 6Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
  1. Correspondence to Dr Stig Molsted; stig.moelsted{at}regionh.dk

Abstract

Objectives The aims of this study were to investigate the association between educational level and musculoskeletal pain and physical function, respectively, in persons 60–70 years old, and to investigate if the association changed from 2010 to 2017.

Design and participants This is a sex-stratified, cross-sectional study based on data from the Danish Health and Morbidity Survey in 2010 (n=15 165) and in 2017 (n=14 022).

Self-reported data from respondents who were 60–70 years old and reported data for pain or physical function, sociodemographic, education and behavioural factors were included.

Primary outcome measures Prevalence of pain and physical limitations.

Results Among men, a high educational level was associated with reduced odds of pain compared with low educational level (OR 0.56 (95% CI 0.41; 0.74)). Medium and high educational levels were associated with reduced odds of pain in women (0.74 (0.59; 0.92) and 0.64 (0.41; 1.00), respectively). High educational level was associated with reduced odds of physical limitations in men (0.35 (0.19; 0.65)) and women (0.33 (0.14; 0.78)). The interaction terms between time and education were not associated with pain and physical function, respectively.

Conclusion High education was associated with reduced musculoskeletal pain and reduced limitations of physical function. The association between education and musculoskeletal pain and physical function did not change significantly over time. Musculoskeletal pain during the past 14 days and chronic pain among old men and women 60–70 years and their level of physical function contribute to important knowledge of a group near the retirement age. The future perspectives illustrate trends and importance of focusing on adapting job accommodations for senior workers.

  • Chronic Pain
  • EPIDEMIOLOGY
  • Aging

Data availability statement

Data are available upon reasonable request.

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STRENGTHS AND LIMITATIONS OF THIS STUDY

  • The study is based on a large nationwide sample of the general Danish population with a fairly high response.

  • The use of calibration weighting reduced the impact of non-response bias.

  • While the highest level of education was used as a proxy for socioeconomic status (SES), data from household income would have improved the SES assessments.

Introduction

It is a well-described phenomenon that functional ability declines with increasing age. Physical functional ability encompasses basic mobility activities including walking, stair climbing, kneeling, stooping, and using arms and core strength to lift and carry, and other activities related to household and work. Apart from ageing-related changes in muscle mass and strength and flexibility, pain is a significant predictor of physical functional decline. Pain is closely related to diseases such as arthritis and other musculoskeletal disorders but may also be reported more unspecifically because of wear and tear and increasing age per se.1 2

Health and morbidity are systematically unevenly distributed in the Danish society according to socioeconomic status (SES).3–5 Low level of SES, for example, low educational level, is associated with an elevated disease burden and may lead to impaired physical function, a reduced ability to work and an increased mortality risk.3 6 7 Several concomitant determinants of morbidity increase the likelihood of accumulated pain and functional impairment.5 The latter is described in a conceptual model by Diderichsen and Evans describing the impact of SES on health. From a model perspective, differential exposure to risk factors according to educational level will increase the likelihood of, for example, musculoskeletal disorders,8 meaning that individuals with low education may be more exposed to risk factors including low level of physical activity, nutritional deficits, life course exposures to physical work and the like. The clustering of risk factors among individuals with low education may cause a higher level of vulnerability towards the development of musculoskeletal disorders, pain and physical functional decline. Further, people with pain or physical disabilities may face challenges during treatment and rehabilitation and in finding and sustaining productive employment compared with their counterparts without disabilities when entering the retirement age.9–11 According to the Diderichsen and Evans model,8 these consequences of pain and physical disabilities are also differing according to educational level or other markers of SES.

As the Danish government has increased the retirement age and it is expected to increase from 66.5 (mean) years in 2021 to 69 years in 2036, it is recommended adapting the physical work requirements to the capacity of workers in different age groups and reducing any skewed withdrawal from the labour market due to, for example, pain and functional limitations.12 13 Within this context, it is important to understand not only the physical function level of the population nearing their retirement age, but also the level of pain which may have a large impact on the ability and readiness to stay active in the labour market as well as to live independently. A recent Danish study identified differences according to the type of work and thus educational backgrounds in the level of self-reported poor physical health and self-reported disbelief in being able to deal with work among men and women aged 50+ years,14 and differences seemed constant between 2018 and 2020. The mentioned study and others15 have described that in recent years, the prevalence of physical functional limitations in individuals around the retirement age has not declined, despite increased focus on early diagnoses of diseases, disease management programmes and particularly rehabilitation after severe diseases. In parallel, it has been described that social inequalities in health and function in Denmark have not decreased in recent years but tend to increase in many parameters in terms of clustering of risk factors.16 Therefore, socioeconomic differences, exemplified by differences in educational level, in pain and physical disability, and how these associations vary over time, are important to consider when evaluating healthcare needs and planning for an ageing workforce.

The aims of this study were to investigate the association between educational level and musculoskeletal pain and physical function, respectively, in persons 60–70 years old, and to investigate if the association changed from 2010 to 2017. The investigation started by studying the interaction term between time and education level as an overall proxy for SES.

Our hypothesis was that the prevalence of musculoskeletal pain and self-reported physical functional limitations increased more among individuals with low education than in those with high education from 2010 to 2017.

Materials and methods

Data were derived from the nationwide Danish Health and Morbidity Survey in 2010 and 2017.17 The survey regularly assesses trends in physical and mental health and morbidity in the Danish population and investigates factors that are associated with physical and mental health status and health behaviour. The two surveys were based on random samples of 25 000 adults (16 years or older). In 2010, 15 165 individuals (response rate 60.7%) completed a self-administered questionnaire vs 14 022 individuals (56.1%) in 2017.17

The present study was restricted to respondents 60–70 years of age, who had indicated their self-reported pain prevalence, pain localisation, pain intensity and physical function. The response rate for the respondents 60–70 years of age in the present study consisted in 2010 of 3119 persons out of 4269 who were invited (73.1%) and in 2017 of 2852 persons out of 4123 invited (69.2%). A random subsample of the individuals invited to the survey in 2010 was also invited to the survey in 2017 (n=3125), and 2306 completed the questionnaire in both waves. In all, 219 of these were between 60 and 70 years of age in both waves.

Data were stratified by sex as it may be associated with different types of pain sensitivity and tolerance, which may be results of multifaceted factors including neuroanatomical, hormonal, neuroimmunological, psychological, social and cultural factors.18

All data were self-reported, except for sex and age that were obtained from the Danish Civil Registration System. Cohabitation status was classified by combining self-reported information and data from the Danish Civil Registration System.19

Main exposures

The highest level of education was assessed and reported as years of attended schooling and categorised into four levels: low (<10 years’ education), medium (10–12 years’ education), high (13 years’ education) and other forms of education (mainly foreign education).

The divisions in this classification represent a classification based on the Danish Education Nomenclature and are considered equivalent to the International Standard Classification of Education.

Survey year (2010 and 2017) was another exposure.

Outcome variables

Musculoskeletal pain was assessed using three questions regarding pain during the past 14 days: pain or discomfort in the shoulder/neck; in the back/lower back; or in the arms/hands/legs/knees/hips/joints (the limbs).17 The questions had three response categories: yes, very bothered; yes, slightly bothered; or no. The reported answers regarding pain were recoded into ‘yes’/‘no’.

We created a composite score of musculoskeletal pain from the accumulated number of pain locations (0–3). The composite score was defined similar to other studies20–22 and dichotomised into the following groups: ‘none/one painful location’ or ‘two/three painful locations’.

Chronic pain intensity during the past week was assessed using the Numerical Rating Scale from 0 to 10 (0 indicated no pain at all, 10 indicated worst possible pain).23 24 The question on pain intensity was only asked to respondents who answered positively to the question: do you have chronic/long-lasting pain lasting 6 months or more (‘yes’ or ‘no’)?

Physical function was assessed using three questions: (1) Can you walk 400 m?; (2) Can you climb a flight of stairs without resting? and (3) Can you carry 5 kilos? The questions had the response categories: yes, without difficulty; yes, with little difficulty; yes, with much difficulty; or no, not at all,17 which in the present study was recoded into ‘limited’ or ‘not’.

We created a composite score of physical function from the accumulated number of limitations (0–3). The composite score was defined similar to other studies20–22 and the categories were dichotomised into ‘none/one physical limitation’ or ‘two/three physical limitations’.

Covariates

The variables age, body mass index (BMI), marital status and level of morbidity were included as confounders of the association between education and the outcomes. BMI was calculated using self-reported body weight (kilograms) divided by the squared height (metres). Marital status was categorised as being married/living with a partner or living alone/not married.

The cohort was described with data on leisure time physical activity level (PAL), alcohol consumption and smoking. The PAL was assessed using the Saltin-Grimby Physical Activity Level Scale with four levels: inactive, moderate activity, medium activity and high activity.25 26 To stratify the respondents into physically ‘inactive’ or ‘active’, the highest levels of leisure time PAL (moderate, medium and high active) were combined into one level. Alcohol consumption was assessed using the reported number of standard drinks, defined as 12 g of alcohol (~a beer, a glass of wine or four cL of spirits). High alcohol intake was defined as exceeding the low-risk limits recommended by the Danish Health Authority (7 standard drinks/week for females and 14 for males),27 which were current Danish standards in this study period.

Smoking status was categorised into smoking or not.

Multimorbidity was defined as two or more of the following reported diseases28: asthma, allergy, diabetes, hypertension, ischaemic heart disease, chronic obstructive pulmonary disease, osteoarthritis, rheumatoid arthritis, osteoporosis, cancer, migraine, depression or anxiety, other psychiatric diseases, back disorder, cataracts and tinnitus.

The estimates of the covariates are presented to explore their potential impact on the outcomes.

Patient and public involvement

The respondents were not involved in the design, conduct, reporting or dissemination plans of this research. The purpose and the content of the survey were described in the letter of introduction and it was emphasised that participation was voluntary. Completing the questionnaire was considered as consent for participation.

Statistical analysis

Descriptive demographic data are presented as numbers and percentages or mean±SD. Differences by sex and survey year in the outcomes were analysed using an unpaired t-test for continuous data and a Χ2 test for categorical data. The distributions of continuous variables were analysed with visual inspections using Q-Q plots and histograms.

The associations between education and survey year in relation to the outcomes (musculoskeletal pain and physical function, respectively) were tested in multiple logistic regression models. Since the initially included interaction terms between education and survey year were not associated with the outcomes (p>0.05), the interaction terms were removed from the model. The models were stratified by sex and adjusted for age, BMI (as a continuous variable), marital status, physical activity and multimorbidity to control for confounding. The regression analysis of physical function was in addition adjusted for musculoskeletal pain. The confounders were selected a priori based on previous analyses.

The results are presented as OR with 95% CI. Results were considered statistically significant (two-tailed) when p<0.05. Data were analysed using IBM SPSS V.26, and the analyses were performed with supervision from an associate professor statistician.

Calibration weighting was applied to reduce the potential impact of non-response bias on the estimates since unit non-response was not missing at random.19 All individuals with a permanent residence in Denmark have a unique personal identification number. Thus, it was possible to link the personal identification numbers of both respondents and non-respondents on an individual level to relevant administrative registers. Individuals less likely to respond were given a higher weight in the analyses to represent the larger number of non-respondents with similar characteristics. Accordingly, individuals more likely to respond were given a lower weight. The weights were computed by Statistics Denmark based on register-based variables, among them sex, age, marital status, highest level of completed education, income, employment status, country of origin and healthcare utilisation. The weighting procedure is described in detail elsewhere.17

Results

Characteristics of the study population are presented in table 1. The mean age of respondents was similar in the two survey years. The percentages of women and men, respectively, with a low education level were higher in 2010 than in 2017. In women, the percentage with multimorbidity was higher in 2017 compared with 2010. A higher percentage of men and women was physically inactive in 2017 compared with 2010.

Table 1

Characteristics of the respondents in 2010 and 2017

The prevalence of musculoskeletal pain and physical limitation is presented in table 2. In women and men, the primary pain location was in the limbs. A slightly higher proportion of women than men reported pain in two or three locations in 2010. The pain intensity in chronic pain was elevated in women compared with men.

Table 2

Prevalence of musculoskeletal pain and physical limitation

Table 3 presents the associations of the interactions between education and survey year with musculoskeletal pain and physical limitations. Missing data in the analyses were: musculoskeletal pain during the past 14 days, women n=498 and men n=411; and physical limitations, women n=523 and men n=428. None of the omnibus tests of the interactions were significant; thus, the multiple regression analyses were performed again without the interactions.

Table 3

The impact of the interaction between education and test year on musculoskeletal pain and physical limitations after adjustments of covariates

Table 4 presents the associations of education, survey year and covariates with musculoskeletal pain.

Table 4

The associations of the independent variables: education, survey year and covariates on musculoskeletal pain in multiple logistic regression analyses

Medium and high education levels were associated with reduced odds of musculoskeletal pain compared with low education in women (medium education 0.74 (0.59; 0.92), p=0.006). A high level of education was associated with reduced odds of musculoskeletal pain compared with low education in men (0.56 (0.41; 0.74), p<0.001). Multimorbidity was associated with ORs of 3.97 (3.28; 4.81, p<0.001) and 2.82 (2.33; 3.41, p<0.001) for musculoskeletal pain in women and men, respectively.

In table 5, associations of education, survey year and covariates with physical limitations are presented. Medium and high education levels were associated with reduced odds of physical limitations compared with low education in men (0.53 (0.34; 0.83), p=0.005, and 0.35 (0.19; 0.65), p=0.001, respectively). In women, a high level of education was associated with reduced odds of physical limitations compared with a low level of education (0.33 (0.14; 0.78), p=0.012). Being physically active was associated with ORs of 0.22 (0.16; 0.30, p<0.001) and 0.20 (0.14; 0.28, p<0.001) for physical limitations compared with physical inactivity in women and men, respectively.

Table 5

The impact of the independent variables: education, survey year and covariates on physical limitations in multiple logistic regression analyses

Discussion

The main findings of this study were that education level did not interact with survey year in relation to musculoskeletal pain and physical function in Danes 60–70 years old from 2010 to 2017. Thus, the prevalence of self-reported musculoskeletal pain and physical limitations did not increase more among individuals with a low level of education than those with a high level of education in the study period.

A higher level of education was associated with reduced odds of physical function limitations compared with a low level of education in women and men, and our findings are supported by other studies, where those with a higher level of education were more likely to age with less comorbidity, pain and disabilities.5 29 In addition, the study also found that having an elevated BMI, more pain localisation and multimorbidity were associated with physical limitations. Multimorbidity was strongly associated with musculoskeletal pain, and this indicates that multimorbidity may have a pronounced impact on musculoskeletal pain and thus likely also the ability to work as a person 60–70 years old. These results highlight the importance of considering multiple factors that are associated with physical function across the life course. The complexity emphasises that priorities of recent decades for the working environment, and personal and healthy worker strategies remain crucial to address the challenges that may affect sustainable employment.30

A greater proportion of women reported pain in more locations compared with men, and the pain intensity reported for those with chronic pain was more elevated in women. These findings are consistent with results from other studies, and the sex difference may be due to different perceptions and adaptations to pain, as well as different hormonal, social, cultural, psychological and neuroanatomical aspects.18

Overall, the identified sex and educational differences in reported pain and physical limitations, combined with the higher prevalence of pain and physical limitations in 2017 compared with 2010, call for continuous attention towards inequalities in these self-reported functional outcomes. The lack of a statistically significant interaction between time and education may be due to a lack of statistical power. Further, a synergistic effect between a low level of education and other risk factors for pain and physical limitations causing increased vulnerability to disability and social consequences cannot be precluded, particularly if social inequalities in physical health in Denmark continue to be stable.

The study has strengths and limitations. The data in this study were provided by a national survey with a large sample size, and this is a strength in the external validity. The representativeness is ensured by a random extract from the Danish Civil Registration System and increases the likelihood of involving respondents from different social classes with different degrees of pain and physical limitations. The use of calibration weighting has with all certainty reduced the impact of non-response bias, as indicated in a recent study using data from the 2017 wave.31

The study has several limitations. First, the design does not allow for conclusion about causality. Second, it might be a too low study period to observe changes related to the tested interaction. Furthermore, it may be anticipated that there was a certain selection of resourceful respondents in this study due to the interest in contributing to public data, and a potential effect of healthy workers’ data may have occurred with an underestimation of adverse physical health effects.

The short reference periods of the measurements of the pain status may have reduced the risk of recall bias. Physical limitations and pain discomfort were relatively roughly divided. Moreover, the outcome variables and the covariate physical activity were dichotomised; thus, details in those variables were reduced. Overestimation may have occurred as a result of dichotomisation of outcomes in the regression models. Yet, the collapse of categories was in accordance with and comparable with previously published paper.

While educational level is a strong determinant of overall SES,32 other aspects of SES such as income, occupation and financial assets could have been relevant to include, but were not available in the data. Data regarding household income or financial assets could have improved the SES assessments, as previous literature indicate that for many individuals entering old age, the level of education is less representative of the socioeconomic circumstances throughout the life course.33 34

The study has perspectives for the future and illustrates trends and importance of focusing on adapting job accommodations for senior workers. The consequences of muscular disorders and pain include increased risk of sick absences and early forced retirement.4 35 36 Workplace support, including health benefits and work modifications, plays a potential role in addressing the limitations to employment participation. More research focusing on limiting the physical health problems among the ageing workforce is needed to ensure the individual worker a long and sustainable working life.

In conclusion, self-report of musculoskeletal pain and physical function among Danish men and women around retirement age differed by educational level, but this association did not change over time between 2010 and 2017. Thus, this study showed a physical health inequality related to education.

Data availability statement

Data are available upon reasonable request.

Ethics statements

Patient consent for publication

Ethics approval

This study involves human participants and was performed with the approval of the National Ethical Committee and the Danish Data Protection Agency (P-2020-1153). The data access and processing agreement was approved by the legal section at the National Institute of Public Health, University of Southern Denmark, Denmark. Participants gave informed consent to participate in the study before taking part.

References

Footnotes

  • Contributors Concept and design of the study—all authors. Acquisition of data—JH, HH, OE and SM. Analysis of data—SM, HH, JH and CN. Drafting of the manuscript—JH. Revision of the manuscript critically for important intellectual content—all authors. Approval of the final manuscript—all authors. SM is responsible for the overall content as the guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.