“Older Workers with Musculoskeletal Injuries: Characteristics and Prognostic Factors” – F. Algarni - PhD Thesis, Faculty of Rehabilitation Medicine, University of Alberta, Canada, September 11th 2015

FS, Algarni . 2015
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Background: Older workers often require more recovery time than younger workers due to various considerations such as comorbidities, which may result in prolonged work disability. Work disability and its negative consequences may be reduced by identifying injured workers who are at increased risk of developing work disability. The question of whether older injured workers have the same characteristics and prognostic factors as younger injured workers, however, requires more investigation. Objectives: This thesis aimed to determine the characteristics and prognostic factors for occupational disability following musculoskeletal (MSK) injuries among older workers, and to determine whether these characteristics and prognostic factors are significantly different than those for younger injured workers. Methods: The present investigation comprises three studies: one cross-sectional study and two cohort studies. All studies utilized a dataset containing administrative and clinical data for claims from the Workers’ Compensation Board of Alberta. This database provides information about injured workers who had incurred work-related MSK injuries in Alberta and underwent a comprehensive return to work (RTW) assessment, and includes many variables (i.e. demographic and social, occupational, health/injury, and health care utilization). The dataset also includes information on whether the claimant continued to receive compensation payments 3 months following the RTW assessment or after discharge from subsequent rehabilitation programs (i.e. Functional Restoration). The study’s participants consisted of three age groups: younger and middle-aged working adults (25-54 years), adults nearing retirement (55-64 years), and adults past retirement age (65 years and older). Variables were compared between the age groups. In the two cohort studies, logistic regression analysis examined the relevant variables as prognostic factors for work disability, as indicated by the receipt of wage replacement benefits. In addition to identifying prognostic factors, regression analysis determined whether these factors were the same in the younger and older age groups by considering the interaction between each predictor variable and a dichotomous variable indicating age group. Results: All three studies revealed differences in the characteristics of injured employees among the age groups. Injured workers aged 65 years or older had a greater likelihood of lower educational attainment, working in trades and labour occupations, and not having rehabilitation recommended despite incurring more severe injuries. Furthermore, six factors – SF-36 Role Physical, modified work availability, number of health care visits, time period between accident and comprehensive RTW assessment, sex, and age – appear to be important in predicting work disability. In the second study, interactions between health care factors and the categorized age variable were statistically significant, with more physician and physical therapy visits predictive of delayed recovery only in younger workers. In the third study of workers discharged from rehabilitation programs, no significant interactions were observed between age group and any of the prognostic factors. However, age was a predictor of work disability, with older workers more likely to receive wage replacement. Conclusions: The study results indicate the need for researchers, healthcare workers, and employers to distinguish younger and older employees with respect to RTW considerations. As a group, workers aged 65 or older with MSK injuries appear to experience disadvantages from a vocational rehabilitation perspective. The research also revealed significant differences in prognostic factors for wage replacement across different age groups, especially related to the number of physician and physical therapy visits. More primary health care visits were associated with increased risk of prolonged occupational disability in younger, but not older age groups, implying that different treatment and prevention approaches should be considered for the younger group, such as early referral to multidisciplinary health services and rehabilitation. Finally, despite significant disparities between the traits of younger and older workers, these two groups did not display major differences in prognostic factors for wage replacement after undergoing occupational rehabilitation. However, the negative prognostic factor of age indicates that older employees had a greater likelihood of experiencing prolonged occupational disability; this result emphasizes the need to examine other as yet unmeasured prognostic factors.