Associations between depressive complaints and indicators of labour participation among older Dutch employees: a prospective cohort study.

PURPOSE: European policy measures have led to an increased net labour participation of older employees. Yet, via different routes (for instance disability schemes) employees still often leave the labour market early. Mental health may be an important factor hindering labour participation. Aims of this study are twofold: first, to examine the relationship between mental health-particularly depressive complaints-and indicators of labour participation among older employees over a 2-year follow-up period and second, to explore the impact of different work contexts when studying this relation. METHODS: A subsample of older employees (aged > 45 years; n = 1253) from the Maastricht Cohort Study was studied. Depressive complaints were assessed using the Hospital Anxiety and Depression scale. Logistic and Cox regression analyses covered 2 years of follow-up and were also stratified for relevant work-related factors. RESULTS: Employees with mild depressive complaints showed statistically significantly higher risks for poor mental workability (HR 2.60, 95% CI 1.14-5.92) and high psychological disengagement levels (HR 2.35, 95% CI 1.21-4.57) over time compared to employees without depressive complaints. Within various work contexts, for instance in which employees perform physically demanding work or have high psychological job demands, significantly stronger associations were found between depressive complaints and poor mental workability over time. CONCLUSIONS: This study shows strong longitudinal associations between depressive complaints and indicators of labour participation, also within different work contexts over time. Results provide valuable input for developing preventive measure aiming to enhance sustainable labour participation of older employees.

Need for recovery and different types of early labour force exit: a prospective cohort study among older workers.

PURPOSE: This study examines the relationship between need for recovery (NFR) and labour force exit (LFE) among older workers. Different types of LFE (early retirement, work disability and unemployment) are considered, and the role of potential confounding and modifying factors, including the availability of early LFE schemes, is examined. Also, associations between NFR and the intention and ability to prolong one's working life, which are known determinants of LFE, are assessed. METHODS: A subsample of older workers from the Maastricht Cohort Study was examined (n = 2312). The relationship between NFR and LFE was investigated by means of Cox regression analyses. Logistic regression analyses were performed to investigate cross-sectional associations between NFR and the intention and ability to prolong working life. RESULTS: Elevated NFR was associated with a higher risk of overall LFE during a 4-year follow-up period (HR 1.39, 95% CI 1.09-1.78), and specifically with a higher risk of leaving the labour force through early retirement and work disability. When early retirement schemes were available, strong and significant associations between NFR and LFE were observed (HR 2.79, 95% CI 1.29-6.02), whereas no significant associations were found when such schemes were unavailable. Older workers with a higher NFR also had earlier retirement intentions and lower self-assessed abilities (both physical and mental) to prolong their working life until the mandatory retirement age. CONCLUSIONS: Because this study shows that NFR is a precursor of LFE among older workers, monitoring NFR is important for timely interventions aimed at reducing NFR to facilitate extended labour participation.

Prevalence of lymphoedema more than five years after breast cancer treatment.

AIM: A lack of consistency in the definition of breast cancer related lymphoedema (BCRL) and of uniform measurement criteria contribute to the wide prevalence range found in current literature. This report aims to describe the long-term prevalence of BCRL and secondly, to compare the long-term prevalence of BCRL when assessed by two objective measures and one subjective measure. METHODS: The upper-limbs of 145 post-surgical breast cancer patients were evaluated for the presence of lymphoedema using the water displacement method. Two circumference methods and patient perceived swelling were applied secondarily for comparison. Limb measurements were performed once, more than five years after surgery. RESULTS: The long-term prevalence of BCRL using water displacement was 8%. Prevalence varied when the sum of arm circumference (SOAC), the arm circumference and the self-report methods were used: 16, 31 and 17% [P < 0.001], respectively. Of the women identified with BCRL using the water displacement technique, 82% were detected with the SOAC method, 82% with the arm circumference method and 91% by self-report. Using water displacement as the gold standard the methods with the highest specificities were the SOAC (90%) and self-report method (89%), arm circumference resulted in a low specificity of 73%. CONCLUSION: The prevalence of BCRL more than five years after surgical treatment differs depending on the measuring method used. Our data underlines the necessity for consensus on the diagnostic criteria for BCRL.

Radiation exposure and cause specific mortality among nuclear workers in Belgium (1969-1994).

Cause specific mortality was studied in nuclear workers from five nuclear facilities in Belgium and compared to the general population. For the 1969-1994 period, mortality in male nuclear workers is significantly lower for all causes of death and for all cancer deaths. The same conclusions are reached if one assumes a latency period of 20 y between the first irradiation and cancer induction. In female workers, mortality due to all causes and all cancer deaths is not different from that of the general population. Analysis of cause specific mortality was performed for male and female workers for three endpoints: specific cancer sites, cardiovascular and respiratory diseases. No significant increase in mortality was observed. In male workers, the influence of cumulative dose was also investigated using four dose levels: no significant correlation was found. Smoking habits may be a confounding factor in smoking related health conditions.

Psychosocial work characteristics as risk factors for being injured in an occupational accident.

The aim of this study was to investigate the relationship between psychosocial work characteristics and the risk for being injured in an occupational accident. We performed this study within the framework of the Maastricht Cohort Study of Fatigue at Work, a prospective cohort study on employees (n = 7051) from a wide range of companies and organizations. One hundred eight workers reported being injured in an occupational accident for which the subject consulted a physician or physiotherapist. Adjustments were made for work environment and demographic variables. High psychologic job demands were a risk factor for being injured in an occupational accident. Low decision latitude had a crude relative risk for being injured in an occupational accident of 2.02 (95% confidence interval [CI] = 1.23-3.39). This relationship almost completely disappeared after adjustment for the confounders mentioned here. Coworker and supervisor support were inversely related to the risk of being injured in an occupational accident but did not reach statistical significance. Other psychosocial work characteristics that had a significant effect on the risk for being injured in an occupational accident were conflicts with the supervisor (relative risk [RR] = 2.49; 95% CI = 1.42-4.37) or colleagues (RR = 2.62; 95% CI = 1.58-4.35), job satisfaction (RR = 1.43; 95% CI = 1.08-1.91), and high emotional demands (RR = 2.45; 95% CI = 1.52-3.94). We conclude that after adjustment for demographic variables, fatigue, and factors that describe the type of work environment that high psychologic job demands, emotional demands, and conflicts with the supervisor and/or colleagues are risk factors for being injured in an occupational accident.

Dose dependent increased mortality risk in COPD patients treated with oral glucocorticoids.

Systemic corticosteroids are often administered in COPD patients. The relationship between systemic glucocorticoids and mortality in patients with moderate to severe chronic obstructive pulmonary disease (COPD) was retrospectively analysed. Baseline characteristics of the patients, in stable clinical condition, were collected on admission to a pulmonary rehabilitation centre. Overall mortality was asessed at the end of follow-up. The Cox proportional hazards model was used to quantify the relationship between glucocorticoid use, distinguishing administration route (oral/inhalation) and oral dose, and overall mortality, adjusted for the influence of age, sex, smoking, lung function, resting arterial blood gases and body mass index. On multivariate analysis, oral glucocorticoid use at a (prednisone equivalent) dose of 10 mg x day(-1) without inhaled glucocorticoids, was associated with an increased risk (RR=2.34, 95% confidence interval (CI) 1.24-4.44) while 15 mg x day(-1) carried a relative risk of 4.03, CI = 1.99-8.15). A significant interaction was observed between inhaled and oral glucocorticoid use. Combined with inhaled glucocorticoids, the relative risk of oral glucocorticoid use appeared to be significantly smaller. It is concluded that in severe chronic obstructive pulmonary disease, maintenance treatment with oral glucocorticoids is associated with increased mortality in a dose-dependent manner. Since the present study design cannot exclude the possibility of bias by indication, further prospective studies are indicated using a broader patient characterization.

Mortality update of workers exposed to acrylonitrile in The Netherlands.

A retrospective cohort study investigating the cause-specific mortality patterns of 2842 workers occupationally exposed to acrylonitrile for at least 6 months before 1 July 1979 was updated. The comparison group consisted of 3961 workers from a nitrogen fixation plant during the same time interval. Industrial hygiene assessments quantified past exposure to acrylonitrile, the use of personal protective equipment, and exposure to other potential carcinogenic agents. All 6803 workers were followed for mortality until 1 January 1996. The follow-up was almost complete (99.6%), and for 99.3% the cause of death was ascertained. Age distribution, follow-up period, and temporal changes in background mortality rates were adjusted for in calculations of standardized mortality ratios for separate causes of death. Cumulative dose-effect relations were determined for 3 exposure categories and 3 latency periods. The results showed that, although cancer mortality fluctuated slightly, no cancer excess seems related to exposure to acrylonitrile.

[Cognitive and psychotic effects after cessation of chronic cannabis use]. / Cognitieve effecten en psychotische effecten na stopzetting van chronisch cannabisgebruik.

Establishment of residual cognitive and psychotic effects (effects present at the time that all active cannabinoids are eliminated from the body) putatively produced by prolonged heavy cannabis use is difficult, because of many confounding variables like slow elimination of active cannabinoids, lack of supervision during abstinence, poor use of well-matched control groups and the presence of withdrawal symptoms. Residual cognitive effects were observed in some but not in all tests after prolonged heavy cannabis use. The effects were mostly mild. The relationship of cannabis use, psychotic effects and schizophrenia was unclear; the cannabis conceivably gave relief, but it also appeared that cannabis caused schizophrenia in young people and (or) enhanced the symptoms, especially in young people poorly able to cope with stress or in whom the antipsychotic therapy was unsuccessful.

Weight loss is a reversible factor in the prognosis of chronic obstructive pulmonary disease.

The objective of the study was to further unravel the prognostic significance of body weight changes in patients with COPD. Two survival analyses were performed: (1) a retrospective study, including 400 patients with COPD none of whom had received nutritional therapy; (2) a post hoc analysis of a prospective study, including 203 patients with COPD who had participated in a randomized placebo-controlled trial. There was no overlap between the patient groups. Baseline characteristics of all patients were collected on admission to a pulmonary rehabilitation center in stable clinical condition. In the prospective randomized placebo-controlled trial, the physiologic effects of nutritional therapy alone (n = 71) or in combination with anabolic steroid treatment (n = 67) after 8 wk was studied in patients with COPD prestratified into a depleted group and a nondepleted group. Mortality was assessed as overall mortality. The Cox proportional hazards model was used to quantify the relationship between the baseline variables age, sex, spirometry, arterial blood gases, body mass index (BMI), smoking, and subsequent overall mortality. Additionally, the influence of treatment response on mortality was investigated in the prospective study. The retrospective study revealed that low BMI (p < 0.001), age (p < 0.0001) and low PaO2 (p < 0.05) were significant independent predictors of increased mortality. After stratification of the group into BMI quintiles a threshold value of 25 kg/m2 was identified below which the mortality risk was clearly increased. In the prospective study, weight gain (> 2 kg/8 wk) in depleted and nondepleted patients with COPD, as well as increase in maximal inspiratory mouth pressure during the 8-wk treatment, were significant predictors of survival. On Cox regression analysis weight change entered as a time-dependent covariate remained an independent predictor of mortality in addition to all variables that were entered in the retrospective study. The combined results of the two survival analyses provide evidence to support the hypothesis that body weight has an independent effect on survival in COPD. Moreover the negative effect of low body weight can be reversed by appropriate therapy in some of the patients with COPD.

Mortality of workers exposed to dieldrin and aldrin: a retrospective cohort study.

OBJECTIVE: To investigate the occurrence of long term health effects in humans exposed to aldrin and dieldrin, with an update of an earlier retrospective cohort mortality study. METHODS: A group of 570 workers employed between 1 January 1954 and 1 January 1970 either in a production or formulation plant were followed up for mortality until 1 January 1993. There were extensive industrial hygiene data available and biological monitoring data of aldrin and dieldrin for most of the workers. From these data individual estimates were made of the total intake of dieldrin. A total number of 2539.37 person-years at risk was added to the original study. RESULTS: 118 deaths were observed compared with 156 expected. No increase in mortality from liver cancer was found. However, there was an excess in mortality from rectal cancer. This excess was inversely related to the dose gradient. An analysis by job title did not show any excess cancer in any particular job. CONCLUSION: The study does not support a carcinogenic effect of dieldrin and aldrin in humans.

Mortality of Dutch coal miners in relation to pneumoconiosis, chronic obstructive pulmonary disease, and lung function.

OBJECTIVES: To analyse the mortality patterns of former Dutch coal miners, focusing on coal workers' pneumoconiosis (CWP) and chronic obstructive pulmonary diseases (COPD) in relation to pre-existing impairment of lung function. METHODS: 3790 selected miners, medically examined between 1952 and 1963, were followed up to the end of 1991 with the municipal population registries and the causes of death from the death certificates were ascertained and converted to the codes from the ninth revision of the international classification of diseases (ICD-9). Mortality comparisons were made with the male population in The Netherlands, resulting in standardised mortality ratios (SMRs). 3367 miners had radiological manifestation of CWP at medical examinations. RESULTS: 80% of the miners died during the follow up period. Excess mortalities from CWP (SMR 4523) and COPD (SMR 179) were found. Coal miners without CWP also showed an increased mortality from COPD (SMR 2913). A diminished lung function (forced expiratory volume in one second (FEV1), or FEV1/FVC (forced vital capacity) ratio) at medical examination resulted in a significantly increased SMR for COPD (322 and 212 respectively) whereas normal lung function yielded expected mortalities from COPD. A positive correlation also emerged between diminished lung function and the SMR due to CWP. The body mass index (BMI) at the moment of medical examination was correlated with the risk of dying of COPD and CWP: a decreasing BMI resulting in an increased SMR. CONCLUSIONS: Not only infectious diseases and CWP but also COPD is an important cause of occupational mortality in miners with extensive exposure to coal mine dust. No obvious connection between pre-existing CWP and the COPD mortality exists. Impaired FEV1 and FEV1/FVC ratios are predictors of an increased risk of COPD death. The BMI seems to indicate the severity of the COPD, resulting in premature death.

Mortality in a group of tar distillery workers and roofers.

OBJECTIVE: A retrospective cohort mortality study was conducted to assess long-term health risk in a group of tar distillery workers and roofers in order to investigate the existence of carcinogenic effects related to the occupational exposures. METHODS: The study population consisted of 907 tar distillery workers and 866 roofers, employed at least one half-year between January 1947 and January 1980. This group was followed for mortality until January 1988. For the deceased workers the cause of death was provided by the Central Bureau of Statistics. The observed cause-specific mortality was compared with the expected cause-specific mortality calculated by means of the national mortality rates of The Netherlands. RESULTS: Mortality from cancer of the lungs and trachea was higher than expected in both groups, but not statistically significant. In addition the roofers had experienced an excess mortality rate from external causes. CONCLUSIONS: The study provides some additional support for the carcinogenicity of coal tar exposures, but the findings were not statistically significant.

Mortality and lung cancer in ceramic workers in The Netherlands: preliminary results.

A retrospective cohort study in 1794 male ceramic workers in the Netherlands was carried out to analyze the lung cancer risk in relation to crystalline silica exposure and silicosis. They had all been employed for two years or longer in ceramic industries between 1972 and 1982. During a health survey, 124 cases of simple pneumoconiosis were diagnosed; after 14 years of follow-up, 161 deaths had occurred. No increased overall and cause-specific mortality was found in the total group of ceramic workers, and a statistically significant cumulative dose-response relation for silica exposure and lung cancer did not emerge. An excess lung cancer mortality appeared among workers with simple pneumoconiosis. The authors conclude that the disease process resulting in silicosis in the ceramic industry carries an increased risk of lung cancer, which is supportive of a nongenotoxic pathway.

Effects of infusion of cholinergic drugs into the prefrontal cortex area on delayed matching to position performance in the rat.

Rats trained on a Delayed Matching To Position (DMTP) task displayed mediating behavior during delays to solve the task. Infusion of the cholinergic antagonist scopolamine into the medial Prefrontal Cortex area (mPFC), dose dependently impaired performance independent of delay. These results indicate that scopolamine does not specifically affect working memory. Infusion of the cholinesterase inhibitor physostigmine, muscarinic subtype receptor antagonists, the dopamine (D1) antagonist SCH23390, and of the GABA-A receptor antagonist bicuculline, did not affect performance in the DMTP task. In a post-hoc analysis scopolamine was found to impair discriminability in a delay-dependent manner only in animals that used mediating behavior in the majority of the trials. Furthermore, a time sampling method indicated that scopolamine infusions into the mPFC disrupted mediating behavior during the task. Results suggest that cholinergic systems in the mPFC play a role in directing attention to task relevant behavior.

Investigation of a cluster of ten cases of Hodgkin's disease in an occupational setting.

The objective of this study was to identify occupational exposures that might be etiologically linked to an unusual cluster of ten cases of Hodgkin's disease. The cases were identified within the active workforce of a large chemical manufacturing firm over a 23-year period by the medical director of the facilities. Based on comparison with regional cancer incidence rates, the standardized incidence ratio for Hodgkin's disease was 497 (95% confidence interval: 238-915) for the period from the construction of the facilities in 1966 through early 1992. A nested case-control study was undertaken with 200 controls selected according to case-cohort sampling. Simultaneously, efforts were initiated to confirm and characterize each case more fully. Occupational exposures were identified and categorized using process, work history, medical record, and industrial hygiene data. Tissue slides were available for eight cases and a second review confirmed the diagnosis of Hodgkin's disease. For one case, a final diagnosis of large-cell anaplastic lymphoma was determined after histology review. Among 214 different chemical agents studied, eight were identified to which three or more of the cases had been exposed prior to the date of their initial diagnosis. Exposure odds ratios were statistically elevated for five of these agents; dose-response evaluations for two of the agents, ethylene oxide and benzene, failed to provide additional support for a causal relationship. In conclusion, although several statistical associations were identified, no substance emerged as a likely candidate for explaining the observed Hodgkin's disease cluster.

Effects of oxazepam on event-related brain potentials, EEG frequency bands, and vigilance performance.

Eighteen males performed two vigilance tasks with static and dynamic stimuli under the influence of oxazepam (20 and 40 mg) in a placebo-controlled, double blind, crossover design. Oxazepam dose-dependently impaired overall level of performance and aggravated the decrement with time in measures of accuracy and sensitivity relative to placebo. The drug reduced the amplitudes of the P1, N1, P2N2, and P3 (dose-dependently) waves of event-related potentials (ERPs). Oxazepam aggravated the linear decline with time of the P3 amplitude only. Oxazepam impaired accuracy was related to deterioration of central processing involved in stimulus discrimination (P2N2). Impairment of response-related performance measures (RT and RI) was associated with processing manifest in the P1, N1, and P3 waves. Oxazepam effects on the amplitudes of N1 and P3 correlated with drug effects on power in alpha 1 (8-10 Hz). Drug effects on overall performance and alpha were also related; the drug effect on response speed correlated only with the drug effect on beta 1 (12.5-21 Hz). Effects of time-on-task on performance and EEG were unrelated, but oxazepam induced performance declines with time may have been caused by declines in resource allocation, as manifest in the amplitude of P3. Time effects on EEG power bands and ERP amplitudes were not significantly related to the time course of oxazepam activity. A curious dissociation emerged: both oxazepam and time-on-task impaired performance, but the drug induced a decrease of theta and alpha 1 power, whereas time-on-task increased power. Various processes play a role in performance decrements with time, and various aspects of processing may be involved in signal-detection measures which makes terms such as sensitivity quite meaningless. So-called computational processing was indistinguishable from energetic processes, which questions the validity of the distinction between these two domains. Explanations of EEG activity in terms of a unidimensional theory of arousal are untenable.

Relation between stimulus discriminability and response bias in a delayed conditional discrimination task in the rat.

The present study investigated whether changes in response bias (log b) affect discriminability (log d) in a delayed conditional discrimination (DCD) task. Eight rats were trained on an DCD task and response bias was manipulated by changing the reinforcement ratio (RR) for correct responding on the two response alternatives. Three findings emerged. First, changes in RR produced changes in log b and the magnitude of these changes was related to the value of the RR. Second, log d was affected by changing RRs. Third, the effect of changes in RR on log b was larger after longer delays. These results suggest that log d and log b are not independent and it is concluded that changes in response bias (log b) may affect the discriminability measure log d. This implies that changes in log d may be mediated by changes in response bias and it is therefore recommended that log d and log b values are both reported when investigating effects of, for example, pharmacological manipulations on DCD performance.

The object delayed non-matching to sample task in rats does not depend on working memory.

Four rats were trained on an object delayed non-matching to sample task to measure working memory (WM). On separate trials a sample object was presented to the rat, which was presented again along with another object after a 3 s delay rats were rewarded with food if they chose the novel object. In this procedure the choice objects are positioned in a fixed order (the novel object was positioned at first, followed by the sample object). When the order of placement of the choice objects was reversed performance dropped from 87% to 28% correct, showing that the rats always chose the object that was first positioned into the choice area. When the order of positioning of the choice objects was randomized during training, rats were not able to learn the task. It is suggested that performance is based on a discrimination between choice objects instead of WM.

Risk of gastric cancer in pneumoconiotic coal miners and the effect of respiratory impairment.

OBJECTIVES: This study was carried out to investigate the mortality patterns in a group of 3790 coal miners. The study population had abnormal chest x ray films at a routine medical examination that was performed in the 1950s. METHODS: The total group of 3790 coal miners were followed up for mortality up to 1 January 1992. Causes of death, determined and coded at time of death, were traced with help from the Central Bureau of Statistics. RESULTS: Total mortality in this group of coal miners with abnormal chest x ray films was significantly higher than expected (SMR 127.1, 95% CI 122.5-131.6), mainly a reflection of the increase in mortality from non-malignant respiratory disease (SMR 411.0, 95% CI 382.3-441.3). Mortality from gastric cancer was also significantly increased (SMR 147.5, 95% CI 122.3-176.3). This risk of mortality from gastric cancer was confined to workers with no pneumoconiosis or only a mild form. Despite the strong relation to duration of employment and pneumoconiosis the group of workers with more severe manifestations of pneumoconiosis did not experience an excess in mortality from gastric cancer. CONCLUSION: This study confirms the earlier reported risk of gastric cancer in coal miners. Also it confirms the hypothesis that this risk of gastric cancer is limited to workers with a mild degree of pneumoconiosis or none. In workers with severe forms of pneumoconiosis the pulmonary clearance system is impaired in such a way that the inhaled coal dust does not reach the digestive tract.

Cholinergic drug effects on a delayed conditional discrimination task in the rat.

The centrally acting cholinergic antagonist scopolamine (0.025-0.10 mg/kg ip) and the peripherally acting cholinergic antagonist methyl-scopolamine (0.01-0.10 mg/kg) dose dependently impaired discriminability independent of delay in a delayed conditional discrimination task that precludes use of mediating behavior. This indicates that scopolamine does not specifically affect working memory. Drugs that enhance cholinergic transmission neither improved discriminability nor attenuated scopolamine-induced impairments. In a post hoc analysis scopolamine was found to impair discriminability in a delay-dependent manner in rats that performed at a high level in pretest sessions. Methyl-scopolamine impaired performance independently of delay in these rats. The authors suggest that a ceiling effect at short delays produced this Drug x Delay interaction of scopolamine in the best performing rats.