The fraction of long-term sickness absence attributable to work environmental factors: prospective results from the Danish Work Environment Cohort Study

Objective

To examine the fraction of long‐term sickness absence periods attributable to physical and psychosocial work environmental risk factors.

Method

A random population sample was followed for 18 months in a national register of social transfer payments. Mutually adjusted hazard ratios for onset of long‐term sickness absence and aetiological fractions were computed.

Results

After mutual adjustment, no significant effect of psychosocial work environment factors remained. In men, 23% and 28% of long‐term sickness absence were attributable to working mainly standing or squatting, and lifting or carrying loads, respectively. In women, 27% of long‐term sickness absence was attributable to bending or twisting of the neck or back.

Conclusions

Physical work environment exposures explained between 10% and 30% of long‐term sickness absence. The potential for reducing long‐term sickness absence is substantial.Long‐term sickness absence is a major public health problem.¹ In previous studies we identified five psychosocial and four physical work environment factors that were independent risk factors of long‐term sickness absence.^2,3 The psychosocial risk factors associated with long‐term sickness absence were the demands of hiding emotions and emotional demands for men, and management quality, role conflicts, and reward among women.² In both genders, the physical work environment risk factors associated with long‐term sickness absence were extreme bending or twisting of the neck or back, working mainly standing or squatting, lifting or carrying loads, and pushing or pulling loads.³In the present study, the relative contribution of these risk factors, and thus the potential for reducing long‐term sickness absence, is studied by computation of aetiological fractions.⁴     

Sickness absence as a risk factor for job termination, unemployment, and disability pension among temporary and permanent employees

Objectives

This study examined sickness absence as a risk factor for job termination, unemployment, and disability pension among temporary and permanent workers.

Methods

Prospective cohort study with data on employment contract and sickness absence in 1996, job termination by 1997, and employment status in 1997 and 2000 for 19 093 temporary and 41 530 permanent public sector employees.

Results

For women aged 40 years or less and for women over 40, a high sickness absence increased the risk of job termination among temporary employees (OR 1.52 (95% CI 1.36 to 1.71) and OR 1.70 (95% CI 1.36 to 2.13) respectively). High absence was not associated with job termination among men in temporary employment. Among permanent employees, high sickness absence predicted job termination among older, but not among younger employees. Temporary employees with high sickness absence were at the highest risk of immediate unemployment and unemployment three years later. Among older permanent employees, high sickness absence was associated with subsequent work disability pension.

Conclusions

A high rate of sickness absenteeism increases the risk of job termination and unemployment among women in temporary public sector jobs. For permanent employees, secure employment provides protection against unemployment even in the case of high sickness absence.     

Burnout as a predictor of self-reported sickness absence among human service workers: prospective findings from three year follow up of the PUMA study

Aim

To investigate whether burnout predicts sickness absence days and sickness absence spells in human service workers.

Method

A total of 824 participants from an ongoing prospective study in different human service sector organisations were eligible for the three year follow up analysis. Burnout was measured with the work related burnout scale of the Copenhagen Burnout Inventory. Sickness absence was measured with self‐reported number of days and spells during the last 12 months before the baseline and the follow up survey. A Poisson regression model with a scale parameter was used to account for over dispersion. A linear regression model was used for analysing changes in burnout and absence between baseline and follow up.

Results

Burnout was prospectively associated with both sickness absence days and sickness absence spells per year. Differences in sickness absence days varied from a mean of 5.4 days per year in the lowest quartile of the work related burnout scale to a mean of 13.6 in the highest quartile. An increase of one standard deviation on the work related burnout scale predicted an increase of 21% in sickness absence days per year (rate ratio 1.21, 95% CI 1.11 to 1.32) after adjusting for gender, age, organisation, socioeconomic status, lifestyle factors, family status, having children under 7 years of age, and prevalence of diseases. Regarding sickness absence spells, an increase of one standard deviation on the work related burnout scale predicted an increase of 9% per year (rate ratio 1.09, 95% CI 1.02 to 1.17). Changes in burnout level from baseline to follow up were positively associated with changes in sickness absence days (estimate 1.94 days/year, SE 0.63) and sickness absence spell (estimate 0.34 spells/year, SE 0.08).

Conclusion

The findings indicate that burnout predicts sickness absence. Reducing burnout is likely to reduce sickness absence.     

Self-reported health problems and sickness absence in different age groups predominantly engaged in physical work

Objectives

To study the associations between self‐reported health problems and sickness absence from work.

Methods

The results of a questionnaire survey were combined with archival data of sickness absence of 1341 employees (88% males; 62% blue‐collar) in the construction, service and maintenance work within one corporation in Finland. Sex, age and occupational grading were controlled as confounders. A zero‐inflated negative binomial (ZINB) regression model was used in the statistical analysis of sickness absence data.

Results

The prevalence of self‐reported health problems increased with age, from 23% in 18–30‐year‐olds to 54% in 55–61‐year‐olds. However, in those aged 18–30 years, 71% had been absent from work and in those aged 55–61 years this proportion was 53%. When health problems and occupational grading were accounted for in the ZINB model, age as such was not associated with the number of days on sick leave, but the young workers still had higher propensity for (any) sickness absence than the old. Self‐rated future working ability and musculoskeletal impairment were strong determinants of sickness absence. Among those susceptible to taking sick leave, the estimated mean number of absence days increased by 14% for each rise of 1 unit of the impairment score (scale 0–10).

Conclusions

Young subjects had surprisingly high probability for sickness absence although they reported better health than their older colleagues. A higher total count of absence days was found among subjects reporting health problems and poorer working ability, regardless of age, sex and occupational grade. These findings have implications for both management and the healthcare system in the prevention of work disability.Sickness absence means non‐attendance by an employee at work due to a (certified) health complaint when the employer expects attendance. Despite the straightforward definition, sickness absence has proved to be a complex phenomenon. In addition to illness, it has been associated with, for example, demographical and socioeconomic factors, organisational features, job content and attitudes to work.¹ The key psychosocial predictors of sickness absence include individuals'' own perceptions of health and working ability.^2,3It is a common belief that older (supposedly in poorer health) employees are more absent from work than their younger (supposedly healthier) colleagues.^4,5 However, the young seem to stay out of work due to minor health complaints more than older workers. Also some earlier studies have found that older age increases the risk of overall sickness absences, but decreases that of one‐day absences.⁶We investigated how age and self‐reported health problems are associated with sickness absence within a cohort predominantly employed in physical work.     

Does enhanced information exchange between social insurance physicians and occupational physicians improve patient work resumption? A controlled intervention study

Background

Patient work resumption after sickness absence varies even among patients with similar pathologies and characteristics. Explanations remain uncertain. One newly investigated field is “information asymmetry”, a situation in which critical information is not appropriately exchanged between stakeholders in disability management. It is hypothesised that information asymmetry between social insurance physicians and occupational physicians prolongs sickness absence.

Objectives

To assess the influence of enhanced information exchange between these physicians on patient outcome.

Methods

Non‐randomised controlled intervention study. The setting was the work inability assessment consultation of social insurance physicians in Belgium. Inclusion criteria were: employee, age 18–50, and subacute (more than one month) sickness absence. The intervention was a structured information exchange (through the use of a communication form) between the patient''s social insurance physician and occupational physician. The intervention started when the patient''s sickness absence reached the subacute stage, and ended when the sickness absence benefit was ceased or the duration exceeded one year. The primary outcome measure was the sickness absence benefit status of the patient assessed one year after benefit onset.

Results

Of the 1883 patients asked to enrol in the study, 1564 (84%) participated; 505 (32%) of 1564 patients were assigned to the intervention group and 1059 (68%) to the control group; 1553 (99%) of 1564 patients completed the study. In the intervention group, 86% received no sickness absence benefit at the end of the study, versus 84% in the control group (95% CI 0.91–1.15). No significant differences in other outcome parameters were obtained.

Conclusions

Information exchange between physicians may not be enough to influence work resumption among patients on sickness absence. Further research on stakeholders'' information asymmetry and its effect on the outcome of patients are necessary. The complexity of information asymmetry in disability management cannot be underestimated.     

Long hours in paid and domestic work and subsequent sickness absence: does control over daily working hours matter?

Objectives

To explore the associations of working hours (paid, domestic, commuting, and total) with sickness absence, and to examine whether these associations vary according to the level of employee control over daily working hours.

Methods

Prospective cohort study among 25 703 full‐time public sector employees in 10 towns in Finland. A survey of working hours and control over working hours was carried out in 2000–01. The survey responses were linked with register data on the number of self‐certified (⩽3 days) and medically certified (>3 days) sickness absences until the end of 2003. Poisson regression analyses with generalised estimating equations were used to take into account the fact that the employees were nested within work units. Adjustments were made for work and family characteristics and health behaviour. The mean follow‐up period was 28.1 (SD 8.1) months.

Results

Long domestic and total working hours were associated with higher rates of medically certified sickness absences among both genders. In contrast, long paid working hours were associated with lower rates of subsequent self‐certified sickness absences. Long commuting hours were related to increased rates of sickness absence of both types. Low control over daily working hours predicted medically certified sickness absences for both the women and men and self‐certified absences for the men. In combinations, high control over working hours reduced the adverse associations of long domestic and total working hours with medically certified absences.

Conclusions

Employee control over daily working hours may protect health and help workers successfully combine a full‐time job with the demands of domestic work.     

Why are manual workers at high risk of upper limb disorders? The role of physical work factors in a random sample of workers in France (the Pays de la Loire study)

Objective

To investigate the reasons for the excess risk of upper limb musculoskeletal disorders among manual workers compared with other workers in a random sample of 2656 French men and women (20–59 years old) participating in a study on the prevalence of work related upper limb disorders conducted by France''s National Institute of Health Surveillance.

Methods

Prevalence ratios (PR) of physician‐diagnosed musculoskeletal disorders of the shoulder, elbow, wrist, and hand (any of six leading disorders, rotator cuff syndrome, carpal tunnel syndrome) in manual versus non‐manual workers were calculated using Cox regression models with a constant time of follow up and robust variance.

Results

11.3% of men and 15.1% of women were diagnosed with an upper limb disorder. The risk was especially high in manual workers (PRs: 1.40 to 2.10). Physical work factors accounted for over 50% of occupational disparities overall, 62% (men) to 67% (women) for rotator cuff syndrome, and 96% (women) for carpal tunnel syndrome. The authors calculated that under lower levels of physical work exposures, up to 31% of cases among manual workers could have been prevented.

Conclusions

In working men and women, upper limb musculoskeletal disorders are frequent. Physical work exposures, such as repetitive and forceful movements, are an important source of risk and in particular account for a large proportion of excess morbidity among manual workers.     

Reducing sick leave by minimal postal intervention: a randomised, controlled intervention study

Background

The lack of efficient medical interventions for combating increasing sickness absence rates has lead to the introduction of alternative measures initiated by the Norwegian National Insurance Service or at workplaces.

Aim

To determine whether minimal postal intervention had any effect on the length of sick leave.

Methods

Randomised, controlled trial with a one year follow up in Northern Norway in 1997 and 1998; 990 consecutive newly sick‐listed persons with musculoskeletal or mental disorders were studied. Within the intervention group, 495 eligible sick‐listed persons received a general information letter and a questionnaire as their sick leave passed 14 days. Possible intervention effects were analysed by survival analysis of the probability of returning to work within one year, and logistic regressions with benefits at one year as the dependent variable.

Results

The overall reduction of 8.3 (95% CI −22.5 to 6.0) calendar days in mean length of sick leaves in the intervention group compared to controls, was not statistically significant. However, intervention significantly reduced length of sick leaves in subgroups with mental disorders, and with rheumatic disorders and arthritis, and overall for sick leaves lasting 12 weeks or more. Young people with low back pain showed an adverse effect to intervention. The overall relative risk of receiving benefits due to sickness after one year in the intervention group was 0.69 (95% CI 0.51 to 0.93) compared to controls.

Conclusion

The results should encourage employers, insurance institutions, and authorities to initiate challenges as questions on the length of sick leave and possible modified work measures, during the first few weeks of sick leave, for at least some groups of sick‐listed persons.     

A 12 year prospective study of circulatory disease among Danish shift workers

Background

Previous studies of the risk of heart disease after shift work reached different estimates and review authors disagree about the validity of some of the studies. A cross sectional study showed that shift workers had a higher prevalence of nearly every unfavourable work environment factor investigated. Conflicts at work and low decision latitude were more frequent among shift workers, and all‐day walking or standing work and part‐time jobs were more often found among female shift workers.

Objectives

To estimate the risk of circulatory disease in a prospective follow up of a representative sample of gainfully employed Danes, considering known or suspected confounding factors.

Methods

A cohort of 5517 people who were gainfully employed in 1990 were followed up for all hospital treatments due to circulatory diseases (390–458, ICD‐8; I00–I99, ICD‐10) from 1991 to 2002 inclusive. A log linear Poisson regression model was applied to control confounding factors and calculate the relative risk for 927 men and women working nights, evenings, or other non‐day shifts compared to 4579 day workers.

Results

Non‐day workers compared to day workers had a relative risk (RR) for all circulatory diseases of 1.31 (95% CI 1.06–1.63). Without control for BMI and smoking, the RR estimate was 1.33 (95% CI 1.07–1.65). For a subgroup of workers with at least three years'' seniority, the RR was 1.40 (95% CI 1.09–1.81). The population based aetiological fraction of shift work was estimated to 5%.

Conclusion

This study adds to a growing body of evidence suggesting that shift work carries an excess risk of circulatory diseases.     

Work-family conflict as a risk factor for sickness absence

Objectives

(1) To study both cross‐sectional and prospective relationships between work–family conflict and sickness absence from work; (2) to explore the direction of the relationships between the different types of conflict (work–home interference and home–work interference) and sickness absence; and (3) to explore gender differences in the above relationships.

Methods

Data from the Maastricht Cohort Study were used with six months of follow up (5072 men and 1015 women at T6). Work–family conflict was measured with the Survey Work–Home Interference Nijmegen (SWING). Sickness absence was assessed objectively through individual record linkage with the company registers on sickness absence.

Results

In the cross‐sectional analyses, high levels of work–family conflict, work–home interference, and home–work interference were all associated with a higher odds of being absent at the time of completing the questionnaire, after controlling for age and long term disease. Differences in average number of absent days between cases and non‐cases of work–home interference were significant for men and most pronounced in women, where the average number of absent days over six months follow up was almost four days higher in women with high versus low–medium work–home interference.

Conclusions

A clear relation between work–family conflict and sickness absence was shown. Additionally, the direction of work–family conflict was associated with a different sickness absence pattern. Sickness absence should be added to the list of adverse outcomes for employees struggling to combine their work and family life.     

Risk of affective and stress related disorders among employees in human service professions

Objectives

To examine the risk of affective and stress related disorders among men and women employed in human service professions.

Methods

Population based case‐control study using data from national registers. Cases (n = 28 971) were identified in the Danish Psychiatric Central Research Register among all hospitalised patients and outpatients aged 18–65 who received a first time ever diagnosis of affective (ICD‐10, F30–39) or stress related (ICD‐10, F40–48) disorder from 1 January 1995 to 31 December 1998. Each case was assigned five never admitted referents (n = 144 855) of the same gender and age, randomly drawn from a 5% sample of the Danish population obtained from Statistics Denmark''s Integrated Database for Labour Market Research. Occupation held the year before matching was classified according to the Danish version of the International Classification of Occupation. Health care, education, social work, and customer services were defined as human service professions and constituted 21% of all employed in the study. Adjusted risks (hazard ratios) relative to all other occupations were calculated for 24 human service occupations.

Results

The relative risk of depression in human service professions was 1.35 (95% CI 1.24 to 1.47) for women and 1.49 (95% CI 1.29 to 1.73) for men. The risk of stress was 1.18 (95% CI 1.11 to 1.26) for women and 1.49 (95% CI 1.32 to 1.67) for men. Specific professions contributed differentially to the magnitude of risk, with education and social services displaying the highest risks. No increase in risks was found in customer service occupations. Gender was a significant modifying factor with the highest risk levels in men.

Conclusions

There was a consistent association between employment in human service occupations and the risk of affective and stress related disorders. Risks were highest for men working in these typically female professions. More work is needed to distinguish work hazards from effects attributable to selection mechanisms and personality characteristics.     

How consistently distributed are the socioeconomic differences in severe back morbidity by age and gender? A population based study of hospitalisation among Finnish employees

Aims

To study the socioeconomic distribution of severe back morbidity by age and gender, and to examine to what extent the differences in back morbidity between socioeconomic groups are particularly related to manual work in different age groups.

Methods

Hospital admissions in 1996 for back disorders of 25–64 year old men (3123 of a total 743 961) and women (3043 of 773 936) from the Finnish Hospital Discharge Register were linked with demographic and socioeconomic data from the 1995 population census. Poisson regression analysis was used to calculate the rate ratios for back related hospitalisation by occupational class and education. The distribution of cases according to occupational status and education was presented in relation to the whole occupationally active workforce by age and gender.

Results

Blue‐collar (manual) workers had a higher risk of being hospitalised because of back disorders compared with white‐collar employees (non‐manual) in all age groups among both genders. Manual work versus non‐manual work was associated with a 1.3 to 1.4‐fold risk (95% CI 1.0 to 1.8) among women and a 1.3 to 1.6‐fold risk (95% CI 1.1 to 2.2) among men. The risk of hospitalisation was further inversely associated with educational level within manual and non‐manual work in all other age groups except in those aged 55–64 years. Gender related differences were much smaller compared with the socioeconomic ones.

Conclusions

Socioeconomic differences in back morbidity leading to hospitalisation were consistent by age and gender. The results suggest that not only the physical strenuousness of work, but also other causes of severe back disorders are clustered around a subject''s socioeconomic status, indicated by formal education. This may have implications for prevention and the planning of rehabilitation.     

Validation of an asthma questionnaire for use in healthcare workers

Background

Previous studies have described increased occurrence of asthma among healthcare workers, but to our knowledge there are no validated survey questionnaires with which to study this occupational group.

Aims

To develop, validate, and refine a new survey instrument on asthma for use in epidemiological studies of healthcare workers.

Methods

An initial draft questionnaire, designed by a multidisciplinary team, used previously validated questions where possible; the occupational exposure section was developed by updating health services specific chemical lists through hospital walk‐through surveys and review of material safety data sheets. A cross‐sectional validation study was conducted in 118 non‐smoking subjects, who also underwent bronchial challenge testing, an interview with an industrial hygienist, and measurement of specific IgE antibodies to common aeroallergens.

Results

The final version consisted of 43 main questions in four sections. Time to completion of the questionnaire ranged from 13 to 25 minutes. Test–retest reliability of asthma and allergy items ranged from 75% to 94%, and internal consistency for these items was excellent (Cronbach''s α ⩾ 0.86). Against methacholine challenge, an eight item combination of asthma related symptoms had a sensitivity of 71% and specificity of 70%; against a physician diagnosis of asthma, this same combination showed a sensitivity of 79% and specificity of 98%. Agreement between self‐reported exposures and industrial hygienist review was similar to previous studies and only moderate, indicating the need to incorporate more reliable methods of exposure assessment. Against the aerollergen panel, the best combinations of sensitivity and specificity were obtained for a history of allergies to dust, dust mite, and animals.

Conclusions

Initial evaluation of this new questionnaire indicates good validity and reliability, and further field testing and cross‐validation in a larger healthcare worker population is in progress. The need for development of more reliable occupational exposure assessment methods that go beyond self‐report is underscored.     

A higher risk of congenital anomalies in the offspring of personnel who served aboard a Norwegian missile torpedo boat

Background

In the 1990s, congenital anomalies were reported among children whose fathers had served aboard a Norwegian missile torpedo boat (MTB). The Royal Norwegian Navy asked the University of Bergen to look into this problem as one part of a general health and work environment surveillance.

Aims

To estimate any increased risk of having children with congenital anomalies and having stillborn children among the offspring of workers that had served aboard the MTB and to investigate possible differences in exposure and other risk factors between these groups.

Methods

Data from a cross‐sectional study among all current employees of the Norwegian Navy (n = 2265, response rate 58%) were analysed.

Results

The prevalence ratio of having a child with congenital malformations associated with working on the ship was 4.0 (95% CI 1.9 to 8.6). The prevalence ratio of having a child who was stillborn or died within one week was 4.1 (95% CI 1.7 to 9.9).

Conclusion

Service aboard the MTB was associated with an increased risk of having children with congenital birth defects and having children that were stillborn. The causes of these findings are unknown.     

Characteristics of work related asthma: results from a population based survey

Objectives

Many risk factors for asthma have been investigated, one of which is the workplace. Work related asthma is a frequently reported occupational respiratory disease yet the characteristics which distinguish it from non‐work related asthma are not well understood. The purpose of this study was to examine differences between work related and non‐work related asthma with respect to healthcare use and asthma control characteristics.

Methods

Data from the Massachusetts Behavioral Risk Factor Surveillance System for 2001 and 2002 were used for this analysis. Work related status of asthma was determined by self‐report of ever having been told by a physician that asthma was work related. Healthcare measures evaluated were emergency room visits and physician visits for worsening asthma and for routine care. Characteristics of asthma control evaluated were frequency of asthma symptoms, asthma attacks, difficulty sleeping, and asthma medication usage in the last 30 days and limited activity in the past 12 months.

Results

The prevalence of lifetime and current asthma in Massachusetts were 13.0% and 9.2%, respectively. Approximately 6.0% (95% CI 4.8 to 7.3) of lifetime and 6.2% (95% CI 4.7 to 7.8) of current asthma cases were work related. In the past 12 months, individuals with work related current asthma were 4.8 times (95% CI 2.0 to 11.6) as likely to report having an asthma attack, 4.8 times (95% CI 1.8 to 13.1) as likely to visit the emergency room at least once, and 2.5 times (95% CI 1.1 to 6.0) as likely to visit the doctor at least once for worsening asthma compared to individuals with non‐work related asthma.

Conclusions

Work related asthma is associated with increased frequency of asthma attacks and use of healthcare services. A better understanding of factors that contribute to differences in healthcare use and asthma control is needed to improve prevention and control strategies for individuals suffering from the disease.     

The French National Mesothelioma Surveillance Program

Objectives

The French National Mesothelioma Surveillance Program (NMSP) was established in 1998 by the National Institute for Health Surveillance (InVS). Its objectives are to estimate the trends in mesothelioma incidence and the proportion attributable to occupational asbestos exposure, to help improve its pathology diagnosis, to assess its compensation as an occupational disease, and to contribute to research.

Methods

The NMSP records incident pleural tumours in 21 French districts that cover a population of approximately 16 million people (a quarter of the French population). A standardised procedure of pathological and clinical diagnosis ascertainment is used. Lifetime exposure to asbestos and to other factors (man made mineral fibres, ionising radiation, SV40 virus) is reconstructed, and a case‐control study was also conducted. The proportion of mesothelioma compensated as an occupational disease was assessed.

Results

Depending on the hypothesis, the estimated number of incident cases in 1998 ranged from 660 to 761 (women: 127 to 146; men: 533 to 615). Among men, the industries with the highest risks of mesothelioma are construction and ship repair, asbestos industry, and manufacture of metal construction materials; the occupations at highest risk are plumbers, pipe‐fitters, and sheet‐metal workers. The attributable risk fraction for occupational asbestos exposure in men was 83.2% (95% CI 76.8 to 89.6). The initial pathologist''s diagnosis was confirmed in 67% of cases, ruled out in 13%, and left uncertain in the others; for half of the latter, the clinical findings supported a mesothelioma diagnosis. In all, 62% applied for designation of an occupational disease, and 91% of these were receiving workers'' compensation.

Conclusions

The NMSP is a large scale epidemiological surveillance system with several original aspects, providing important information to improve the knowledge of malignant pleural mesothelioma, such as monitoring the evolution of its incidence, of high risk occupations and economic sectors, and improving pathology techniques.     

Medical downgrading, self-perception of health, and psychological symptoms in the British Armed Forces

Objective

To investigate the contribution of psychological symptoms to limited employability for medical reasons in the British Armed Forces.

Methods

A sample of 4500 military personnel was randomly selected to receive either a full or an abridged questionnaire. The questionnaires asked whether the participant was medically downgraded and if yes, the reason for it. The full questionnaire included the General Health Questionnaire‐12 (GHQ‐12), the post‐traumatic stress disorder (PTSD) checklist, 15 symptoms to assess somatisation, and selected items of the quality of life SF‐36 questionnaire. The abridged questionnaire included the GHQ‐4, a 14 item PTSD checklist, five symptoms, and the item on self‐perception of health from the SF‐36. Subjects above a threshold score for GHQ, PTSD, and symptoms were considered to have psychological symptoms.

Results

12.4% of the participants were medically downgraded. The majority (70.4%) had social or work limitations. Medically downgraded personnel had higher odds ratios in comparison to non‐downgraded personnel for psychological distress 1.84 (95% CI 1.43 to 2.37), PTSD 3.06 (95% CI 1.82 to 5.15), and number of symptoms 2.37 (95% CI 2.37 1.62 to 3.47). GHQ, PTSD, and symptoms scores were mainly, but not exclusively, related to chronic physical injury.

Conclusions

Psychological symptoms are common among medically downgraded personnel. Although the mechanisms involved are unclear, tackling issues of psychological symptoms among these subjects could contribute to faster restitution to full employability in the Armed Forces.     

Predicting the long term course of low back pain and its consequences for sickness absence and associated work disability

Background

Low back pain is characterised by a dynamic pattern of episodes and recovery but little is known about the long term course of back pain due to lack of cohort studies with sufficiently long follow up periods.

Methods

A cohort of 523 workers in nursing homes and homes for the elderly was followed for two years. Physical load was measured by observations at the workplace. Psychosocial factors at work, individual characteristics, and low back pain were determined by questionnaire once a year. The effect of work load on low back pain and the transition of low back pain into sickness absence was calculated with logistic regression analysis. A Markov model was used to construct a hypothetical cohort of workers with follow up of 40 years (40 cycles of 1 year) with transitional probabilities between no complaints, low back pain, and sickness due to low back pain. Permanent disability was used as end state of health.

Results

The transitional probability from no complaints to low back pain varied between p = 0.25 and p = 0.29, from low back pain to sickness absence between p = 0.09 and p = 0.25, and recurrence of sickness absence varied between p = 0.27 and p = 0.50, depending on the level of physical load. During a 40 year career, total sickness absence due to low back pain was approximately 140 weeks (6.6%) among workers with high physical load and about 30 weeks (1.4%) among those with low physical load.

Conclusion

The Markov approach illustrated the potential impact of physical load on (permanent) disability due to low back pain among workers with exposure to physical load. These consequences may go unnoticed in cohort studies with follow up periods of a few years.     

Associations between temporary employment and occupational injury: what are the mechanisms?

Objective

To determine whether observed higher risks of occupational injury among temporary workers are due to exposure to hazardous working conditions and/or to lack of job experience level.

Methods

Data systematically recorded for 2000 and 2001 by the Spanish Ministry of Labour and Social Affairs on fatal and non‐fatal traumatic occupational injuries were examined by type of employment and type of accident, while adjusting for gender, age, occupation, and length of employment in the company. In the study period there were 1500 fatal and 1 806 532 non‐fatal traumatic occupational injuries that occurred at the workplace. Incidence rates and rate ratios (RR) were estimated using Poisson regression models.

Results

Temporary workers showed a rate ratio of 2.94 for non‐fatal occupational injuries (95% CI 2.40 to 3.61) and 2.54 for fatal occupational injuries (95% CI 1.88 to 3.42). When these associations were adjusted by gender, age, occupation, and especially length of employment, they loose statistic significance: 1.05 (95% CI 0.97 to 1.12) for non‐fatal and 1.07 (95% CI 0.91 to 1.26) for fatal.

Conclusions

Lower job experience and knowledge of workplace hazards, measured by length of employment, is a possible mechanism to explain the consistent association between temporary workers and occupational injury. The role of working conditions associated with temporary jobs should be assessed more specifically.     

Association of ventricular arrhythmias detected by implantable cardioverter defibrillator and ambient air pollutants in the St Louis, Missouri metropolitan area

Background

It has previously been reported that the risk of ventricular arrhythmias is positively associated with ambient air pollution among patients with implantable cardioverter defibrillators (ICD) in Boston.

Aims

To assess the association of community exposures to air pollution with ventricular arrhythmias in a cohort of ICD patients in metropolitan St Louis, Missouri.

Methods

ICD detected episodes reported during clinical follow up were abstracted and reviewed by an electrophysiologist to identify ventricular arrhythmias. A total of 139 ventricular arrhythmias were identified among 56 patients. A case‐crossover design was used with control periods matched on weekday and hour of the day within the same calendar month. Conditional logistic regression models were adjusted for temperature, barometric pressure, and relative humidity in the 24 hours preceding the event.

Results

There was a significant (24%, 95% CI 7% to 44%) increase in risk of ventricular arrhythmias associated with each 5 ppb increase in mean sulphur dioxide and non‐significantly increased risk (22%, 95% CI −6% to 60%; and 18%, 95% CI −7% to 50%) associated with increases in nitrogen dioxide (6 ppb) and elemental carbon (0.5 μg/m³), respectively in the 24 hours before the arrhythmia.

Conclusions

These results provide evidence of an association between ventricular arrhythmias and ambient air pollutants in St Louis. This is consistent with previous results from Boston, although the pollutants responsible for the increased risk are different.