Cognitive Ability in Midlife and Labor Market Participation Among Older Workers: Prospective Cohort Study With Register Follow-up.

BACKGROUND: The study aimed to determine the association of individual cognitive ability in late midlife with labor market participation among older workers. METHODS: This prospective cohort study estimates the risk of long-term sickness absence, disability pension, early retirement, and unemployment from scores on the Intelligenz-Struktur-Test 2000R by combining data from 5076 workers from the Copenhagen Aging and Midlife Biobank with a register on social transfer payments. Analyses were stepwise adjusted for age, gender, physical and psychosocial work environment, health behaviors, occupational social class, education, and chronic diseases. RESULTS: In the fully adjusted model, low cognitive ability (≥1 standard deviation below the mean for each gender) and high cognitive ability (≥1 standard deviation above the mean for each gender) were not associated with risk of any of the four labor market outcomes. CONCLUSION: Individual cognitive ability in late midlife was not associated with risk of long-term sickness absence, disability pension, early retirement, and unemployment in the fully adjusted model. Thus, no direct effect of individual cognitive ability in late midlife was observed on the risk of permanently or temporarily leaving the labor market.

The Danish Psychosocial Work Environment Questionnaire (DPQ): Development, content, reliability and validity.

Objectives The aim of this study was to describe the development and the content of the Danish Psychosocial Work Environment Questionnaire (DPQ) and to test its reliability and validity. Methods We describe the identification of dimensions, the development of items, and the qualitative and quantitative tests of the reliability and validity of the DPQ. Reliability and validity of a 150 item version of the DPQ was evaluated in a stratified sample of 8958 employees in 14 job groups of which 4340 responded. Reliability was investigated using internal consistency and test-retest reliability. The factorial validity was investigated using confirmatory factor analysis (CFA). For each multi-item scale, we undertook CFA within each job group and multi-group CFA to investigate factorial invariance across job groups. Finally, using multi-group multi-factor CFA, we investigated whether scales were empirically distinct. Results Internal consistency reliabilities and test-retest reliabilities were satisfactory. Factorial validity of the multi-item scales was satisfactory within each of the 14 job groups. Factorial invariance was demonstrated for 10 of the 28 multi-item scales. The hypothesis that the scales of the DPQ were empirically distinct was supported. The final DPQ version consisted of 119 items covering 38 different psychosocial work environment dimensions. Conclusions Overall, the DPQ is a reliable and valid instrument for assessing psychosocial working conditions in a variety of job groups. The results indicate, however, that questions about psychosocial working conditions may be understood differently across job groups, which may have implications for the comparability of questionnaire-based measures of psychosocial working conditions across job groups.

Implementation of the Danish return-to-work program: process evaluation of a trial in 21 Danish municipalities.

OBJECTIVES: The aim of this study was to evaluate the implementation of the Danish national return-to-work (RTW) program in 21 Danish municipalities. METHODS: We conducted a structured process evaluation on (i) reach and recruitment, (ii) fidelity, (iii) dose-delivered, (iv) dose-received, and (v) context by formulating 29 implementation criteria and analyzing qualitative and quantitative data from administrative records, interviews, field notes, and questionnaires. RESULTS: All municipalities integrated the basic features of the RTW program into the existing framework of the sickness benefit management system to an acceptable degree, ie, establishment of RTW teams, participation of RTW team members in the training courses, and following the general procedures of the program. However, the level of implementation varied considerably between the municipalities, particularly with respect to fidelity (defined as implementation consistent with the principles of the interdisciplinary RTW process). Five municipalities had high and eight had low fidelity scores. Similar large differences were found with regard to dose-delivered, particularly in the quality of cooperation with beneficiaries, employers, and general practitioners. Only 50% of the first consultations with the RTW coordinator were conducted in time. Among participants who were employed when their sickness absence period started, only 9% had at least one meeting with their workplace. CONCLUSION: It was feasible to implement the basic features of the Danish RTW program, however, large variations existed between municipalities. Establishment of well-functioning interdisciplinary RTW teams might require more time and resources, while ensuring early assessment and more frequent cooperation with employers might need more general adjustments in the Danish sickness benefit system.

Effect of physical exercise on workplace social capital: Cluster randomized controlled trial.

AIMS: While workplace health promotion with group-based physical exercise can improve workers' physical health, less is known about potential carry-over effects to psychosocial factors. This study investigates the effect of physical exercise on social capital at work. METHODS: Altogether, 200 female healthcare workers (nurses and nurse's aides) from 18 departments at three hospitals were randomly allocated at the department level to 10 weeks of (1) group-based physical exercise at work during working hours or (2) physical exercise at home during leisure time. At baseline and follow-up, participants replied to a questionnaire concerning workplace social capital: (1) within teams (bonding); (2) between teams (bridging); (3) between teams and nearest leaders (linking A); (4) between teams and distant leaders (linking B). RESULTS: At baseline, bonding, bridging, linking A and linking B social capital were 74 (SD 17), 61 (SD 19), 72 (SD 22) and 70 (SD 18), respectively, on a scale of 0-100 (where 100 is best). A group by time interaction was found for bonding social capital (P=0.02), where physical exercise at work compared with physical exercise during leisure time increased 5.3 (95% confidence interval 2.3- 8.2)(effect size, Cohen's d = 0.31) from baseline to follow-up. For physical exercise at home during leisure time and exercise at work combined, a time effect (P=0.001) was found for linking A social capital, with a decrease of 4.8 (95% confidence interval 1.9-7.6). CONCLUSIONS: Group-based physical exercise at work contributed to building social capital within teams at the workplace. However, the general decrease of social capital between teams and nearest leaders during the intervention period warrants further research.

Effect of the Danish return-to-work program on long-term sickness absence: results from a randomized controlled trial in three municipalities.

OBJECTIVES: The aim of this study was to evaluate the effect of the Danish return-to-work (RTW) program on long-term sickness absence in a randomized controlled trial in three municipalities. METHODS: The intervention group comprised 1948 participants while the control group comprised 1157 participant receiving ordinary sickness benefit management (OSM). Study participants were working-age adults receiving long-term (≥8 weeks or more) benefits, included regardless of reason for sickness absence or employment status. Each beneficiary was followed-up for a maximum period of 52 weeks. Cox proportional hazards model was used to estimate hazard ratios (HR) for return to work (RTW) with 95% confidence intervals (95% CI). RESULTS: The intervention effect differed significantly between the municipalities (P=0.00005). In one municipality (M2) the intervention resulted in a statistically significant increased rate of recovery from long-term sickness absence (HR 1.51, 95% CI 1.31-1.74). In the other two municipalities, the intervention did not show a statistically significant effect (HR M11.12, 95% CI 0.97-1.29, and HR M30.80, 95% CI 0.63-1.03, respectively). Adjustment for a series of possible confounders only marginally altered the estimated HR. CONCLUSION: The effect of the intervention differed substantially between the three municipalities, indicating that that contextual factors are of major importance for success or failure of this complex intervention.

Enterprise size and return to work after stroke.

INTRODUCTION: It has been hypothesised that return to work rates among sick-listed workers increases with enterprise size. The aim of the present study was to estimate the effect of enterprise size on the odds of returning to work among previously employed stroke patients in Denmark, 2000-2006. METHODS: We used a prospective design with a 2 year follow-up period. The study population consisted of 13,178 stroke patients divided into four enterprise sizes categories, according to the place of their employment prior to the stroke: micro (1-9 employees), small (10-49 employees), medium (50-249 employees) and large (>250 employees). The analysis was based on nationwide data on enterprise size from Statistics Denmark merged with data from the Danish occupational hospitalisation register. RESULTS: We found a statistically significant association (p = 0.034); each increase in enterprise size category was followed by an increase in the estimated odds of returning to work. CONCLUSIONS: The chances of returning to work after stroke increases as the size of enterprise increases. Preventive efforts and research aimed at finding ways of mitigating the effect are warranted.

Time trend analysis of return to work after stroke in Denmark 1996-2006.

BACKGROUND: In the period 1997-2005, the Danish government initiated a series of legislative changes aimed at facilitating RTW (return to work) in the Danish population. In the present study, we investigated the odds of being gainfully occupied ca. two years after stroke as a function of onset calendar year, 1996-2006. METHODS: All previously employed 20-57 year-old stroke patients in Denmark 1996-2006 (N = 19985) were followed prospectively through national registers. The analysis was controlled for the type of stroke and a series of demographic, structural and occupational variables. RESULTS: The odds for RTW increased significantly during the study period (P < 0.0001). The odds at the end of the period were more than twice as high as they were at the beginning, even after post hoc control for improved survival and decreased unemployment rates. The most conspicuous increase coincided with a change in the sickness benefit act that took place in 2005. CONCLUSION: The study provides quite strong circumstantial evidence that the legislative changes had an effect on the odds of return to work after stroke. More direct evidence is desirable, but such can only be obtained through a randomized controlled study.

The Danish national return-to-work program--aims, content, and design of the process and effect evaluation.

The Danish national return-to-work (RTW) program aims to improve the management of municipal sickness benefit in Denmark. A study is currently ongoing to evaluate the RTW program. The purpose of this article is to describe the study protocol. The program includes 21 municipalities encompassing approximately 19 500 working-age adults on long-term sickness absence, regardless of reason for sickness absence or employment status. It consists of three core elements: (i) establishment of multidisciplinary RTW teams, (ii) introduction of standardized workability assessments and sickness absence management procedures, and (iii) a comprehensive training course for the RTW teams. The effect evaluation is based on a parallel group randomized trial and a stratified cluster controlled trial and focuses on register-based primary outcomes - duration of sickness absence and RTW - and questionnaire-based secondary outcomes such as health and workability. The process evaluation utilizes questionnaires, interviews, and municipal data. The effect evaluation tests whether participants in the intervention have a (i) shorter duration of full-time sickness absence, (ii) longer time until recurrent long-term sickness absence, (iii) faster full RTW, (iv) more positive development in health, workability, pain, and sleep; it also tests whether the program is cost-effective. The process evaluation investigates: (i) whether the expected target population is reached; (ii) if the program is implemented as intended; (iii) how the beneficiaries, the RTW teams, and the external stakeholders experience the program; and (iv) whether contextual factors influenced the implementation. The program has the potential to contribute markedly to lowering human and economic costs and increasing labor force supply. First results will be available in 2013. The trial registrations are ISRCTN43004323, and ISRCTN51445682.

A nationwide prospective cohort study on return to gainful occupation after stroke in Denmark 1996-2006.

BACKGROUND: Return to work is an important outcome factor for working-age patients poststroke. Previous epidemiological studies on this topic have been small (on average 125 patients per study). Their estimated effects are therefore associated with a tremendous statistical uncertainty. The present study estimates the effect of various predictors on the odds of returning to work after stroke in the total population of 20-57-year-old previously employed hospital treated patients with stroke in Denmark 1996-2006 (N=19,985). METHODS AND RESULTS: The patients were followed through national registers; 62% were gainfully occupied 2 years after stroke. The odds of returning to work were higher among people with intracerebral infarction, OR 1.0 (the reference group), than they were among people with subarachnoid haemorrhage, OR 0.79 (95% CI 0.71 to 0.88), and intracerebral haemorrhage, OR 0.39 (0.35 to 0.43). The odds of returning to work were lower among workers in elementary occupations OR 1.0 (reference group) than they were among workers in occupations that require skills at a basic level, OR 1.50 (1.38 to 1.64), technicians and associate professionals, OR 2.33 (2.05 to 2.65) and professionals, OR 3.04 (2.70 to 3.43). Patients in municipalities with a brain-injury rehabilitation centre did not have a better prognosis than patients in other municipalities, OR 0.91 (0.78 to 1.06). Being a woman, OR 0.79 (0.74 to 0.84), self-employed, OR 0.87 (0.78 to 0.96), or ≥ 50 years, OR 0.61 (0.57 to 0.65), was associated with an adverse prognosis. CONCLUSION: Further research is needed to explain the gender inequality, which suggests either a potential to improve return-to-work rates among the females or a tendency among the males to return too early.

Effect of brief daily exercise on headache among adults--secondary analysis of a randomized controlled trial.

OBJECTIVE: This paper investigates secondary outcomes (headache) in a randomized controlled trial with physical exercise among office workers with neck/shoulder pain. METHODS: A total of 198 office workers with frequent neck/shoulder pain were randomly allocated to either one of two intervention groups (10 weeks of resistance training with elastic tubing for 2 or 12 minutes per day, 5 times a week) or the control group, which received weekly health information. Secondary outcomes included changes in frequency, intensity, and duration of headache after ten weeks. RESULTS: Compared with the control group, headache frequency decreased in the 2- and 12-minute intervention groups [0.64 days/week (95% confidence interval [95% CI]) 0.23-1.0) and 0.79 days/week (95% CI 0.37-1.2), corresponding to a 43% and 56% decrease from baseline, respectively]. Intensity and duration of the remaining headaches were unaffected. CONCLUSIONS: Two minutes of daily resistance training for ten weeks reduces headache frequency among office workers with neck/shoulder pain. The vast number of adult workers suffering from one or two days of weekly headaches and who could potentially comply with and benefit from brief exercise programs stresses the applicability of our findings.

Effectiveness of small daily amounts of progressive resistance training for frequent neck/shoulder pain: randomised controlled trial.

UNLABELLED: Regular physical exercise is a cornerstone in rehabilitation programs, but adherence to comprehensive exercise remains low. This study determined the effectiveness of small daily amounts of progressive resistance training for relieving neck/shoulder pain in healthy adults with frequent symptoms; 174 women and 24 men working at least 30 h per week and with frequent neck/shoulder pain were randomly assigned to resistance training with elastic tubing for 2 or 12 minutes per day 5 times per week, or weekly information on general health (control group). Primary outcomes were changes in intensity of neck/shoulder pain (scale 0 to 10), examiner-verified tenderness of the neck/shoulder muscles (total tenderness score of 0 to 32), and isometric muscle strength at 10 weeks. Compared with the control group, neck/shoulder pain and tenderness, respectively, decreased 1.4 points (95% confidence interval -2.0 to -0.7, p<0.0001) and 4.2 points (95% confidence interval -5.7 to -2.7, p<0.0001) in the 2-minute group and 1.9 points (95% confidence interval -2.5 to -1.2, p<0.0001) and 4.4 points (95% confidence interval -5.9 to -2.9, p<0.0001) in the 12-minute group. Compared with the control group, muscle strength increased 2.0 Nm (95% confidence interval 0.5 to 3.5Nm, p=0.01) in the 2-minute group and 1.7Nm (95% confidence interval 0.2 to 3.3 Nm, p=0.02) in the 12-minute group. In conclusion, as little as 2 minutes of daily progressive resistance training for 10 weeks results in clinically relevant reductions of pain and tenderness in healthy adults with frequent neck/shoulder symptoms. TRIAL REGISTRATION: www.isrctn.org/ISRCTN60264809. In generally healthy adults with frequent neck/shoulder muscle pain, as little as 2 minutes of daily progressive resistance training reduces pain and tenderness.

Study protocol to a nationwide prospective cohort study on return to gainful occupation after stroke in Denmark 1996 - 2006.

BACKGROUND: Successful return to work is regarded as one of the most important outcome factors for working-age post stroke patients. The present study will estimate the effect of various predictors on the odds of returning to work after stroke. Nearly twenty thousand 20-57 year-old stroke patients in Denmark who were gainfully occupied prior to the stroke will be included in the study. METHODS/DESIGN: Stroke patients will be followed prospectively through national registers. Multi-level logistic regression will be used to model the odds of being gainfully occupied ca. two years after the stroke as a function of the following predictors: Age (20-49 years, 50-57 years) gender, occupational class, self-employment (yes; no), onset calendar year (1996, 1997, ..., 2006), diagnosis (subarachnoid haemorrhage; intracerebral haemorrhage; cerebral infarction; stroke, not specified as haemorrhage or infarction) and 'type of municipality' (the variable is set to 1 if the person lived in a municipality which had a brain injury rehabilitation centre at the time of the stroke. Otherwise it is set to 0). Municipalities will be treated as the subjects while individual observations within municipalities are treated as correlated repeated measurements. DISCUSSION: Since our follow-up is done through registers and all people in the target population are included, the study is free from sampling bias, recall bias and non-response bias. The study is also strengthened by its size. The major weakness of the study is that it does not contain any stroke severity measures. Thus, it cannot accurately predict whether a particular stroke patient will in fact return to work. The study is, however, quite useful from a public health perspective. It can be used to estimate the proportion of patients in a certain group that is expected to return to work, and thereby provide a comparison material, which e.g. municipalities can use to evaluate their success in returning their stroke patients to work.

Muscle activation and perceived loading during rehabilitation exercises: comparison of dumbbells and elastic resistance.

BACKGROUND: High-intensity resistance training plays an essential role in the prevention and rehabilitation of musculoskeletal injuries and disorders. Although resistance exercises with heavy weights yield high levels of muscle activation, the efficacy of more user-friendly forms of exercise needs to be examined. OBJECTIVE: The aim of this study was to investigate muscle activation and perceived loading during upper-extremity resistance exercises with dumbbells compared with elastic tubing. DESIGN: A single-group, repeated-measures study design was used. SETTING: Exercise evaluation was conducted in a laboratory setting. PARTICIPANTS: Sixteen female workers (aged 26-55 years) without serious musculoskeletal diseases and with a mean neck and shoulder pain intensity of 7.8 on a 100-mm visual analog scale participated in the study. MEASUREMENTS: Electromyographic (EMG) activity was measured in 5 selected muscles during the exercises of lateral raise, wrist extension, and shoulder external rotation during graded loadings with dumbbells (2-7.5 kg) and elastic tubing (Thera-Band, red to silver resistance). The order of exercises and loadings was randomized for each individual. Electromyographic amplitude was normalized to the absolute maximum EMG amplitude obtained during maximal voluntary isometric contraction and exercise testing. Immediately after each set of exercise, the Borg CR10 scale was used to rate perceived loading during the exercise. RESULTS: Resistance exercise with dumbbells as well as elastic tubing showed increasing EMG amplitude and perceived loading with increasing resistance. At the individually maximal level of resistance for each exercise-defined as the 3 repetitions maximum-normalized EMG activity of the prime muscles was not significantly different between dumbbells (59%-87%) and elastic tubing (64%-86%). Perceived loading was moderately to very strongly related to normalized EMG activity (r=.59-.92). Limitations The results of this study apply only for exercises performed in a controlled manner (ie, without sudden jerks or high acceleration). CONCLUSIONS: Comparably high levels of muscle activation were obtained during resistance exercises with dumbbells and elastic tubing, indicating that therapists can choose either type in clinical practice. The Borg CR10 can be a useful aid in estimating intensity of individual rehabilitation protocols.

Effect of physical exercise interventions on musculoskeletal pain in all body regions among office workers: a one-year randomized controlled trial.

This study investigated effects of physical exercise on musculoskeletal pain symptoms in all regions of the body, as well as on other musculoskeletal pain in association with neck pain. A single blind randomized controlled trial testing a one-year exercise intervention was performed among 549 office workers; specific neck/shoulder resistance training, all-round physical exercise, or a reference intervention. Pain symptoms were determined by questionnaire screening of twelve selected body regions. Case individuals were identified for each body region as those reporting pain intensities at baseline of 3 or more (scale of 0-9) during the last three months. For neck cases specifically, the additional number of pain regions was counted. Intensity of pain decreased significantly more in the neck, low back, right elbow and right hand in cases of the two exercise groups compared with the reference group (P<0.0001-0.05). The additional number of pain regions in neck cases decreased in the two exercise groups only (P<0.01-0.05). In individuals with no or minor pain at baseline, development of pain was minor in all three groups. In conclusion, both specific resistance training and all-round physical exercise for office workers caused better effects than a reference intervention in relieving musculoskeletal pain symptoms in exposed regions of the upper body.

Smoking and height as risk factors for prevalence and 5-year incidence of hearing loss. A questionnaire-based follow-up study of employees in Denmark aged 18-59 years exposed and unexposed to noise.

This paper investigated whether smoking and short stature in adulthood were independent risk factors for hearing loss. We reanalyzed data from the Danish Work Environment Cohort Study (an existing cohort study), on prevalence of self-reported hearing loss among 7,221 employees and on five-year incidence among 4,610 employees. We found that smoking predicted hearing loss incidence and prevalence. Smoking did not predict incidence at noise exposure during half or more of a worker's hours. Very short stature predicted prevalence in the total adult population only weakly, but strongly among employees born before 1951. These prospective findings indicate that smoking is an independent risk factor for incidence of hearing loss. Very short stature predicted prevalence of hearing loss only in a subpopulation.

Adjuvant effect of quaternary ammonium compounds in a murine model.

It has been suggested that occupational exposure to quaternary ammonium compounds (QACs) may promote the development of allergic airway diseases. In this study, hazard identifications of the adjuvant effect of cetylpyridinium chloride (CPC), dimethyldioctadecylammonium bromide (DDA), hexadecyltrimethylammonium bromide (HTA), and tetraethylammonium chloride (TEA) were performed in a screening bioassay. Female BALB/c mice were injected subcutaneously with the model allergen ovalbumin (OVA) alone or together with different quantities of one of the QAC test compounds. After one or two boosters, levels of OVA-specific IgE, IgG1 and IgG2a antibodies were measured in sera. CPC and DDA increased IgE and IgG1 antibody production, respectively, compared to the OVA control group, whereas HTA and TEA showed no adjuvant effect. Nevertheless, when TEA was given in combination with DDA, the adjuvant effect was up to six-fold higher than the adjuvant effect of DDA alone. Only DDA had a statistically significant adjuvant effect on IgG2a antibody levels.

IgE-mediated asthma and rhinitis I: a role of allergen exposure?

Exposures to airborne protein antigens, aeroallergens, may cause sensitization with production of Th2-dependent antibodies, including IgE. The IgE antibodies and associated cellular responses are responsible for the allergic airway diseases, allergic rhinitis and allergic asthma, which are increasing in societies with Western life style. Aeroallergens may have different potential to sensitize exposed subjects. Thus, there are only a limited number of important groups of aeroallergens, which are those from house dust mites, cockroaches, pets, pollens, and moulds. Allergy follows to a certain extent the pharmacological/toxicological paradigm of dose-response relationship. Unlike effects of pharmacologically and toxicologically active substances, allergens elicit their adverse effects in a two-stage process. In the first stage the immunologically naïve individual is sensitized to the allergen. In the second stage renewed exposure to the allergen elicits the disease response. Also, high concentrations of aeroallergens may induce immunological tolerance. The scientific literature suggests that many environmental factors contribute to the increase in sensitization and development of airway allergies. Nevertheless, the dose-response relationships apply (within certain limits) both to the sensitization itself and to the exacerbation of the diseases. This suggest that exposure reduction may be one of the methods for reduction of risk, in relation to control of the allergic airway diseases.

Adjuvant effect of di-n-butyl-, di-n-octyl-, di-iso-nonyl- and di-iso-decyl phthalate in a subcutaneous injection model using BALB/c mice.

During the last decades, the prevalence of the allergic airway diseases, asthma and rhinitis, has increased world-wide. Introduction of environmental chemicals with adjuvant effect may play a role in this increase. In the present study, the adjuvant effects of di-n-butyl-, di-n-octyl-, di-iso-nonyl- and di-iso-decyl phthalate are studied in a screening model. Ovalbumin, used as the model antigen, was injected subcutaneously in the neck region of BALB/cJ mice with the selected phthalate in concentrations from 2-2000 microg/ml. Additionally, the mice were boosted once or twice with ovalbumin alone. Immunization with ovalbumin alone, the ovalbumin control group, served as the baseline for antibody production, whereas aluminium hydroxide served as the positive control. The levels of ovalbumin-specific IgE, IgG1 and IgG2a antibodies in sera were determined. Adjuvant effect was accepted to be present if a statistical increase in antibody production occurred in a test group as compared to an ovalbumin control group together with the fulfillment of dose-response relationships. Adjuvant effect varied strongly between the phthalates investigated. Phthalates with 8 or 9 carbon atoms in the alkyl side chains were the stronger adjuvants whereas phthalates with shorter or longer alkyl side chains possessed less adjuvant activity. Adjuvant effects were apparent either from the IgE or the IgG1 response or both, whereas no effect was seen on the IgG2a response. Additional studies with airborne exposure are required to establish whether the hazards also result in a significant risk for the development of allergy in man.