Carpal tunnel syndrome among apprentice construction workers

BACKGROUND: In terms of lost-work time and restricted workdays, surgery, and rehabilitation, one of the most costly occupational musculoskeletal disorders is carpal tunnel syndrome (CTS). The purpose of this study was to determine the prevalence of CTS among apprentice construction workers. METHODS: This cross-sectional study included apprentices from four construction trades. Apprentices completed a self-administered questionnaire and received electrophysiologic studies assessing median nerve function across the carpal tunnel. A surveillance case definition for CTS was based on characteristic hand symptoms and the presence of median mononeuropathy across the carpal tunnel. RESULTS: Of the 1,325 eligible apprentices, 1,142 (86.2%) participated in the study. The prevalence of CTS among apprentices was 8.2%; sheet metal workers had the highest rate (9.2%). In operating engineers, the prevalence of CTS was significantly higher (OR = 6.9; 95% CI = 2.6-18.2) among the heavy equipment mechanics than the drivers of those vehicles. Body mass index, age, and self-reports of working overhead were associated with prevalent CTS. Less than 15% of the apprentices with CTS sought medical attention for their disorder. CONCLUSIONS: Many construction workers begin developing CTS before or during their apprenticeship. Few apprentices seek medical attention for hand symptoms characteristic of CTS. The results of this study indicate a public health need for the implementation of prevention strategies for CTS in the construction industry.     

Musculoskeletal problems among workers of an Iranian rubber factory

Musculoskeletal disorders (MSDs) are a common health problem throughout the world and a major cause of disability among the work force. Assessment of exposure level to MSD risk factors can be an appropriate base for planning and implementing interventional ergonomic programs in the workplace. This study was conducted among workers of an Iranian rubber factory with the objectives of (a) determination of the prevalence of MSDs among production line workers, and (b) assessment of the level of exposure to MSD risks. In this study, all 16 production units of the factory were studied. In each unit, 50% of the workers were randomly selected and included in the study. A total of 454 workers participated. The Nordic Musculoskeletal Questionnaire was used to study the prevalence of MSDs and the Quick Exposure Check (QEC) technique was applied to assess physical exposure to the risks. The videotaping technique was used to collect the required data for each worker. The vast majority of the workers (73.6%) had suffered from some kind of musculoskeletal symptoms during the last 12 months. The highest prevalence was reported in the lower back (50.2%), knees (48.5%) and upper back (38.1%). In 85.5% of the workers studied, the QEC score was high or very high. Statistical analysis showed a significant association between the QEC level of risk and MSDs symptoms (p<0.001). The most common ergonomics problems were found to be awkward postures and manual material handling. MSDs had occurred with a high rate among workers of this rubber factory. Corrective measures for reducing risk level seemed essential. Elimination of awkward postures and manual material handling in the workplace were recommended.     

Arbeitsmedizinische untersuchungen über ladearbeiten auf einem großflughafen

Summary In an epidemiologic cross-sectional study, 366 transport workers (age-range: 19–61 years) of a big German airport who are engaged in physical heavy work in unfavorable body positions in narrow freight spaces of airplanes, were investigated with regard to their subjective musculoskeletal complaints through a standardized anamnesis in an interview questionnaire. An additional clinical orthopedic examination was performed in 104 of the transport workers. Back pains were the most frequently reported complaints: at the time of examination 66% of the transport workers reported present back complaints. 57% had experienced previous back syndroms. Increasing age and stature were associated with a higher prevalence of these complaints. Years of exposure to transport work correlated positively with the prevalence of back complaints. After back complaints, knee complaints followed in the prevalence of locomotor complaints (41% of the interviewed workers). The prevalence increased with age and body weight significantly. Neck complaints were reported by 33% of the workers, arm complaints by 41%; again, age increased the prevalence of these complaints significantly. In the standardized clinical orthopedic examination, the prevalence of the functional findings were sometimes higher than in the interview. In contrast to the subjective complaints at the interview, individual factors (age, stature, weight, and work experience in the present occupation) had very little influence on the prevalence of objective findings.The clinical, epidemiologic screening methods employed have proved efficacious in detecting orthopedic disorders in an occupational collective. This study has shown that transport workers with wide discrepancies between body length and the space available in airplane cargo bellies, considerable overweight, or a history of former back syndromes should not be employed. Means to alter cargo belly dimensions in airplanes as well as the increased use of mechanical loading aids and additional training of the workers in proper lifting and carrying of cargo should be taken in to consideration.     

Suicide by occupational skill level in the Australian construction industry: data from 2001 to 2010

Objective: This study examines variation in suicide deaths by occupational skill level within the construction industry and changes in the rate of suicide over time. Methods: Suicide deaths were extracted from a national coronial database and occupations were coded. Adjusted suicide rates over the period 2001 to 2010 were calculated and incidence‐rate ratios (IRRs) used to compare the overall burden of suicide in the lowest skilled group (machine operators and labourers) against skilled tradespersons in the construction industry. Results: Those employed as labourers or machine operators had an adjusted rate of 18 per 100,000 persons (95%CI 14–22) and those employed in skilled trades had an adjusted rate of 13 per 100,000 (95%CI 11–15) over the period 2001 to 2010. Compared to skilled trades, the lower skilled group had significantly elevated suicide at several time points over the period 2001 to 2010. The most observable difference in IRRs were in the years 2002 and 2007. Conclusions: Low‐skilled workers in the construction industry had elevated rates of suicide compared to skilled trades workers. Implications: These workers should be targeted by prevention efforts.     

VIP in construction: systematic development and evaluation of a multifaceted health programme aiming to improve physical activity levels and dietary patterns among construction workers

Background  

The prevalence of both overweight and musculoskeletal disorders (MSD) in the construction industry is high. Many interventions in the occupational setting aim at the prevention and reduction of these health problems, but it is still unclear how these programmes should be designed. To determine the effectiveness of interventions on these health outcomes randomised controlled trials (RCTs) are needed. The aim of this study is to systematically develop a tailored intervention for prevention and reduction of overweight and MSD among construction workers and to describe the evaluation study regarding its (cost-)effectiveness.     

Chronic back pain among older construction workers in the United States: a longitudinal study

This study assessed chronic back pain among older construction workers in the United States by analyzing data from the 1992-2008 Health and Retirement Study (HRS), a large-scale longitudinal survey. Fixed-effects methods were applied in the multiple logistic regression model to explore the association between back pain and time-varying factors (e.g., employment, job characteristics, general health status) while controlling for stable variables (e.g., gender, race, ethnicity). Results showed that about 40% of older construction workers over the age of 50 suffered from persistent back pain or problems. Jobs involving a great deal of stress or physical effort significantly increased the risk of back disorders and longest-held jobs in construction increased the odds of back disorders by 32% (95% CI: 1·04-1·67). Furthermore, poor physical and mental health were strongly correlated with back problems. Enhanced interventions for construction workers are urgently needed given the aging workforce and high prevalence of back disorders in this industry.     

Physically demanding workloads and the risks of musculoskeletal disorders in homecare workers in the USA

Although musculoskeletal disorders (MSDs) are prevalent among homecare workers, little is known about the MSD risk factors. This study investigated whether physically demanding workloads among homecare workers are related to MSDs, especially in neck, shoulder and back pain. Data were taken from two waves of a random sample (June to December 2003 and December 2003 to February 2004). The sample included 1643 homecare workers at Wave 1 and 1198 homecare workers at Wave 2, respectively. A basic telephone interview and 30 minutes computer‐assisted interview were performed for homecare workers in Wave 1 and Wave 2. The prevalence of neck, shoulder and back MSDs was assessed at Wave 1 and Wave 2 using the Nordic questionnaire of musculoskeletal symptoms. The incidence of MSDs at 6 months was estimated at Wave 2 using only those who were in the asymptomatic reference group at Wave 1 as the denominator. At Wave 1, back MSDs were the most prevalent (10.2%), followed by neck (9.6%) and shoulder (7.1%) MSDs. After 6 months, the incidence of neck MSDs was the highest (7.0%), followed by back (6.4%) and shoulder (4.8%) MSDs. Physical demands of work were assessed using items developed from focus groups of workers. When compared with asymptomatic workers, those with MSDs showed a dose–response effect for physical job demands. After controlling for age, psychosocial demands and social support on‐the‐job, physical demands among homecare workers were significantly associated with an excessive odds of neck, shoulder and back MSDs incident at 6 months (odds ratios of 1.14–1.17 for each unit increase on a physical demand scale). Our study shows that the physical demands of work are a significant risk factor for MSDs among homecare workers. Considering the high physical demands among homecare workers, the finding in this study clearly indicates that practical intervention strategies should be implemented to protect homecare workers from exposure to MSD risk factors.     

Poor safety climate,long work hours,and musculoskeletal discomfort among Latino horse farm workers

This study investigated the prevalence of self-reported musculoskeletal discomfort (MSD) and work-related factors associated with elevated MSD among Latino thoroughbred farm workers. Participants (N = 225) were recruited using a community-based purposive sampling approach to participate in in-person interviews. Of these workers, 85% experienced MSD. MSD was divided into tertiles; the upper tertile was defined as elevated. Multivariable Poisson regression revealed associations between any elevated MSD and longer tenure on horse farms, longer work hours, and poor safety climate. Elevated neck/back MSD was associated with longer tenure, longer work hours, and poor safety climate. Elevated upper extremity MSD was associated with age and poor safety climate. Elevated lower extremity MSD was associated with longer tenure, longer work hours, and being female. Musculoskeletal discomfort is common among these workers. Improving safety climate and minimizing long work hours is recommended.     

The effectiveness of hearing protection among construction workers

Effective hearing conservation programs in the construction industry are rare. Where programs are present, they often rely on workers' use of hearing protection devices (HPDs) rather than on exposure controls to reduce noise exposure levels. Dependence on HPDs for protection from high noise is problematic, as the protection provided by the HPD depends on both the HPD's attenuation level and the time the HPD is used. This article presents an analysis of data on noise exposure and hearing protection among construction workers drawn from several large datasets covering nine construction trades. A unique combination of 1-min dosimetry noise exposure levels and simultaneous self-reported use of HPDs was evaluated, as were occupational and nonoccupational HPD use data collected by questionnaire as part of a longitudinal study of noise exposure and hearing loss among apprentices. Direct measurements of HPD attenuation were also made on workers at their work site. The workers assessed in this study were found to use hearing protection less than one-quarter of the time that they were exposed above 85 dBA. Workers who reported always using HPDs in high noise on questionnaires were found to wear them only one-third of the time their exposures exceeded 85 dBA. Workers' self-reported use of HPDs during most noisy nonoccupational activities was also found to be low. Direct attenuation measurements found that workers were able to achieve more than 50% of the rated attenuation of their HPD on average, but that the variability in achieved attenuation was large. When the measured HPD attenuation levels and use time data were combined, the effective protection afforded by HPDs was less than 3 dB, a negligible amount given the high exposure levels associated with construction work. However, there was substantial variation in effective protection among the different trades assessed. These results demonstrate the need for better hearing conservation programs and expanded noise control efforts in the construction industry.     

Hearing loss among older construction workers: Updated analyses

Background

A prior study of this construction worker population found significant noise‐associated hearing loss. This follow‐up study included a much larger study population and consideration of additional risk factors.

Methods

Data included audiometry, clinical chemistry, personal history, and work history. Qualitative exposure metrics for noise and solvents were developed. Analyses compared construction workers to an internal reference group with lower exposures and an external worker population with low noise exposure.

Results

Among participants (n = 19 127) an overall prevalence of hearing loss of 58% was observed, with significantly increased prevalence across all construction trades. Construction workers had significantly increased risk of hearing loss compared to reference populations, with increasing risk by work duration. Noise exposure, solvent exposure, hypertension, and smoking were significant risk factors in multivariate models.

Conclusions

Results support a causal relationship between construction trades work and hearing loss. Prevention should focus on reducing exposure to noise, solvents, and cigarette smoke.

     

Assessment of mortality in the construction industry in the United States, 1984–1986

Construction, one of the larger industries in the United States, employs 7.6 million workers, many in skilled trades occupations. Previously published data about potential worksite exposures and mortality of construction site workers are limited. We analyzed occupation and industry codes on death certificates from 19 U.S. states to evaluate mortality risks among men and women usually employed in construction occupations. Proportionate mortality ratios (PMRs) for cancer and several other chronic diseases were significantly elevated among 61,682 white male construction workers who died between 1984 and 1986. Men younger than age 65, who were probably still employed immediately prior to death, had significantly elevated PMRs for cancer, asbestos-related diseases, mental disorders, alcohol-related disease, digestive diseases, falls, poisonings, traumatic fatalities that are usually work-related, and homicides. Elevated PMRs for many of the same causes were observed to a lesser degree for black men and white women whose usual industry was construction. In addition, women experienced excess cancer of the connective tissue and suicide mortality. Various skilled construction trades had elevated PMRs for specific sites, such as bone cancer and melanoma in brickma-sons, stomach cancer in roofers and brickmasons, kidney and bone cancer in concrete/terrazzo finishers, nasal cancer in plumbers, pulmonary tuberculosis in laborers, scrotal cancer and aplastic anemia in electricians, acute myeloid leukemia in boilermakers, rectal cancer and multiple sclerosis in electrical power installers, and lung cancer in structural metal workers. Using a standard population of blue collar workers did not result in fewer elevated PMRs for construction workers. Despite lifestyle differences and other limitations of the study, the large numbers of excess deaths observed in this study indicate the need for preventive action for construction workers. © 1995 Wiley-Liss, Inc.     

How Work Impairments and Reduced Work Ability are Associated with Health Care Use in Workers with Musculoskeletal Disorders,Cardiovascular Disorders or Mental Disorders

Purpose the aim of this study was to explore how work impairments and work ability are associated with health care use by workers with musculoskeletal disorders (MSD), cardiovascular disorders (CVD), or mental disorders (MD). Methods in this cross-sectional study, subjects with MSD (n = 2,074), CVD (n = 714), and MD (n = 443) were selected among health care workers in 12 Dutch organizations. Using an online questionnaire, data were collected on individual characteristics, health behaviors, work impairments, work ability, and consultation of a general practitioner (GP), physiotherapist, specialist, or psychologist in the past year. Univariate and multivariate logistic regression analyses were performed to explore the associations of work impairments and work ability with health care use. Results lower work ability was associated with a higher likelihood of consulting any health care provider among workers with common disorders (OR 1.05–1.45). Among workers with MSD work impairments increased the likelihood of consulting a GP (OR 1.55), specialist (OR 2.05), and physical therapist (OR 1.98). Among workers with CVD work impairments increased the likelihood of consulting a specialist (OR 1.94) and physical therapist (OR 2.73). Among workers with MD work impairments increased the likelihood of consulting a specialist (OR 1.79) and psychologist (OR 1.82). Conclusion work impairments and reduced work ability were associated with health care use among workers with MSD, CVD, or MD. These findings suggest that addressing work-related problems in workers with common disorders may contribute in reducing health care needs.     

Epidemiologic study of occupational injuries among foreign and native workers in Taiwan

This study was designed to compare the risk of occupational injuries in foreign workers compared to native workers in Taiwan. The cohort of foreign workers under study was constructed by records of legally registered workers migrated from foreign countries to Taiwan from July 1, 1991 to December 31, 1993. The native Taiwanese workers for comparison were labor-insured workers working in the same industries as foreign workers in 1992. The number of occupational injuries in the first year of employment were obtained by matching the cohort of foreign workers with the labor insurance payment records by name, birth date and passport number. The 1-year incidence rate of occupational injuries in the first year of employment was calculated and a standardized morbidity ratio (SMR) was used for comparison with adjustment for age distribution and to accommodate the small sample size of foreign workers. The risk to occupational injuries among total (SMR = 0.86) and male (SMR = 0.58) foreign workers was not higher: indeed, it was even lower, than that among native workers in Taiwan. However, the risk to female migrant workers, especially in the construction industry, was significantly higher than that of female Taiwanese workers (SMR = 1.60). Stratified by industry, the incidence was high in the fabricated metal products manufacturing industry and in machinery and equipment manufacturing industry for male foreign workers, while a high incidence for the female foreign workers occurred in construction industry and rubber products manufacturing industry. The risk of occupational injuries was greater for foreign workers who had been in Taiwan for only a short time. Most fo the injuries occurred within the first 6 months of employment. Eighty-four out of the 394 occupational injuries among foreign workers resulted in disabilities. None of the accidents was fatal, but most of the disabilities were severe. The most common disabling injuries were cut or crushed fingers. The finding of a similar distribution of occupational injuries among foreign and native workers indicates that control measures are needed to reduce occupational injuries for all foreign and native workers in Taiwan. Am. J. Ind. Med. 31:623–630, 1997. © 1997 Wiley-Liss, Inc.     

Prevalence of upper limb work-related musculoskeletal disorders (UL-WMSDs) in workers of the upholstered furniture industry

BACKGROUND: The upholstered furniture industry, the so-called "triangle of the sofa industry", is a geographic area of national and strategic economic importance in southern Italy. The single tasks are carried out mostly manually, with the characteristics of a handicraft approach. OBJECTIVES: The aim of the survey was to assess the prevalence of upper limb work-related musculoskeletal disorders (UL-WMSDs) in 30 factories of the sofa industry located in a large geographic area of the Puglia and Basilicata Regions. METHODS: In the period 1 January-31 December 2003 a network of occupational physicians investigated a population of 5.477 subjects (exposed n=3481, controls n=1996, M=3865, F=1612) in 30 different factories of the area. More than 60 percent of the total workforce studied was employed in large-sized companies (>500 employees). The following work tasks were considered: filling preparation workers, leather-cutting operators, sewing and upholstery-assembly workers. Case-definition was assessed through standardized procedures: symptoms by questionnaire plus physical and laboratory/imaging findings. RESULTS: Cumulative prevalence rates of UL-WMSDs as at 31 December 2003 reached values of up to 30% in high risk groups. Prevalence rates showed good correlation with the concise OCRA index used for assessment of exposure to repetitive strain and movements of the upper limb. The most frequently occurring disorders were tendon-related cysts and wrist tendonitis. Shoulder disorders were more frequent in male and female leather-cutting operators. CONCLUSIONS: This survey showed a significantly high prevalence of UL-WMSDs in sofa industry workers. It did not seem to be confirmed in this study that there was a greater female susceptibility to UL-WMSDs with the exception of carpal tunnel syndrome: gender difference seems to be less relevant at increasing levels of occupational exposure to repetitive movements and exertion of the upper limbs.     

Musculoskeletal disorders among construction apprentices in Hungary.

The purpose of this study was to determine the prevalence of occupationally related musculoskeletal disorder (MSD) symptoms and carpal tunnel syndrome (CTS) among construction apprentices in Hungary. Symptoms of occupational MSDs and the job factors contributing to the symptoms were determined through an administered symptom and job factors survey. The prevalence of CTS was based on a case definition that included hand symptoms and nerve conduction studies of the median nerve across the carpal tunnel. The participation rate was 96% among the 201 eligible construction apprentices. More than 50% of the apprentices reported occupationally related musculoskeletal symptoms in the previous 12 months. Job tasks that required awkward postures and working in a static position were the two factors that contributed most to MSD symptoms. No cases of CTS were found in this sample of apprentices. Although disorders of the musculoskeletal system are more prevalent among experienced construction workers, this study indicated that symptoms of MSDs are present among young construction workers. Assessing the magnitude and nature of occupational related MSDs is the first step in promoting a healthier, safer, and more efficient workforce.     

Relationship between musculoskeletal disorders and work-related awkward postures among a group of health care workers in a hospital

BACKGROUND: There are few studies in the Italian literature on musculoskeletal disorders (MSD) among health care workers (HCW) keeping and holding awkward postures during their job. OBJECTIVES: The aims of this study were to determine the prevalence of low-back, neck and upper limb complaints and the association between risk factors and MSD in HCW working in 15 wards of the Hospital of Cuneo. METHODS: A questionnaire was submitted to 113 HCW. Information about demographic and occupational factors, and MSD characteristics were collected to be statistically elaborated. RESULTS: The prevalence of complaints regarding at least one of the 3 body regions was 71% in the whole sample (80 subjects). Low back, neck and upper limb were interested, respectively, in 58.4%, 50.4% and 25.7% of the cases. Logistic regression showed a significant association of MSD with score > 7 on the Borg scale (OR = 9.70; CI: 2.01-46.9; p < 0.01), positive musculoskeletal clinical history (OR = 3.67; CI: 1.24-10.88; p < 0.05), and visual defects (OR = 2.88; CI: 1.07-7.81; p < 0.05). Based on the answers from the questionnaire, the onset of MSD was attributed in 41 cases to organizational problems, and in 14 cases to the ergonomic characteristics of the job. CONCLUSIONS: The index of prevalence of MSD associated to work-related awkward postures (71%) is very high, greater than that observed among HCW exposed to manual lifting of weights (21%) in the hospital. Thereafter, assessment of exposure and containment of such occupational risk must be considered useful.     

Ache, pain, and discomfort: the reward for working with many cows and sows?

The main purpose of the study was to investigate the prevalence of perceived symptoms of musculoskeletal disorders (MSD) among workers on large-scale dairy and pig farms in Sweden (herd size more than 300 cows and 450 sows) and to identify potential risk factors in the development of MSD. A study based on questionnaires was carried out among 42 workers on 10 large dairy farms and among 37 workers on 10 large pig farms in Southern Sweden during the autumn of 2002. Most importantly, the study showed that 86% of the dairy workers and 78% of the pig workers reported some kind of MSD during a period of 12 months prior to the study. The most frequently reported MSD among both the dairy and the pig workers were in the "upper extremities" (52% and 62%, respectively) especially in the shoulders and in "the back" (60% and 57%, respectively) especially in the lower back. Furthermore, being of short stature, doing repetitive work, working in awkward positions and being exposed to dust were significant risk factors in having MSD among the workers in this study. Thus, working with many cows and sows on large-scale farms in Sweden can be considered as a high risk job with regard to MSD.     

Non-auditory effects of noise in industry

Summary A secondary analysis of data from a national survey was carried out in order to assess the number of industrial workers exposed to noise and other adverse working conditions. This permitted us to study correlations with parameters of health. More than half of the male blue collar workers in industry and building trades (sample n = 311) reported a great deal of noise. Dirty work and strenuous physical activity were also frequently mentioned. Noise exposure is often present together with exposure to stench and dirty and dangerous work. A weak correlation exists between reported noise exposure and experienced ill-being and diminished satisfaction with their own health. This observed relationship probably underestimates the true risks.     

Work-related disorders of the upper limb in female workers using orbital sanders

Objectives: To investigate the prevalence of vascular, neurological and musculoskeletal disorders of the upper limb in a group of female workers performing either mechanical or hand sanding in the furniture industry (n=100) and in a control group of female office workers (n=100). A further aim was to study the possible adverse effects of exposure to a combination of vibration and ergonomic risk factors in female workers. Methods: All female workers underwent a medical interview and a complete physical investigation. The clinical diagnoses of Raynauds phenomenon and carpal tunnel syndrome (CTS) were made according to international consensus criteria. Hand-transmitted vibration from orbital sanders was measured according to International Organization for Standardization (ISO) recommendations. Daily vibration exposure was assessed in terms of 8-h energy-equivalent frequency-weighted acceleration [A(8)] according to the European Directive on physical agents. Ergonomic load on the upper limbs was estimated by means of strain index methodology. Results: There was no significant difference in the prevalence of Raynauds phenomenon between the furniture workers (4%) and the controls (8%). The prevalence of CTS, peripheral sensorineural disturbances (after exclusion of CTS cases) and upper-limb musculoskeletal complaints was significantly greater in the furniture workers than in the controls. CTS was clinically diagnosed in 19% of the furniture workers and 8% of the controls. A log-binomial regression analysis showed that the occurrence of soft-tissue disorders of the upper limb increased significantly with the increase of both daily vibration exposure and the strain index score. It was estimated that the risk for CTS increased by a factor of 1.30 (95% CI 1.11–1.53) for each unit of increase in A(8) (ms^–2), and by 1.09 (95% CI 1.02–1.15) for each unit of increase in the strain index score. Conclusions: Even though the cross-sectional design of this epidemiological study does not allow aetiological considerations, our findings suggest a significant association between occupational use of vibratory tools and soft-tissue disorders in the upper limbs of female workers. Quantitative estimation of vibration exposure and ergonomic stress showed that these physical risk factors seem to contribute in a multiplicative way to the occurrence of chronic nerve and musculoskeletal disorders in female workers operating hand-held vibrating tools in the furniture industry.     

The influence of factors identified in adolescence and early adulthood on social class inequities of musculoskeletal disorders at age 30: a prospective population-based cohort study

BACKGROUND: Social class inequities have been observed for most measures of health. A greater understanding of the relative importance of different explanations is required. In this prospective population-based cohort study we explored the contribution of factors, ascertained at different stages between adolescence and early adulthood, to social class inequities in musculoskeletal disorders (MSD) at age 30. METHODS: We used data from 547 men and 497 women from a town in north Sweden who were baseline examined at age 16 and followed up to age 30. Using logistic regression models, we estimated the unadjusted odds ratios (OR) for MSD for blue-collar versus white-collar workers in men and women separately. We assessed the contribution of different factors identified between adolescence and early adulthood by comparing the unadjusted OR for social class differences with OR adjusted for these explanatory factors. RESULTS: We found significant class differences at age 30 with higher MSD among blue-collar workers (OR = 2.03 in men [95% CI: 1.42, 2.90] and 1.98 in women [95% CI: 1.29, 3.02]). After adjustment for explanatory factors, class differences decreased and were no longer significant, with OR of 1.20 in men (95% CI: 0.76, 1.95) and 1.18 in women (95% CI: 0.69, 2.03). School grades at age 16; being single and alcohol consumption at age 21; having children, restricted financial resources, physical activity, alcohol consumption, smoking, and working conditions at age 30 were important for men; parents' social class, school grade, smoking and physical activity at age 16; being single at age 21; and working conditions at age 30 were important for women. CONCLUSION: The accumulation of adverse behavioural and social circumstances from adolescence to early adulthood may be an explanation for the class differences in MSD at age 30. Interventions aimed at reducing health inequities need to consider exploratory factors identified at early and later stages in life, also including structural determinants of health.