Purely wavelength- and amplitude-modulated quartz-enhanced photoacoustic spectroscopy.

We report here on a quartz-enhanced photoacoustic (QEPAS) sensor employing a quantum cascade laser (QCL) structure capable of operating in a pure amplitude or wavelength modulation configuration. The QCL structure is composed of three electrically independent sections: Gain, Phase (PS) and Master Oscillator (MO). Selective current pumping of these three sections allows obtaining laser wavelength tuning without changes in the optical power, and power modulation without emission wavelength shifts. A pure QEPAS amplitude modulation condition is obtained by modulating the PS current, while pure wavelength modulation is achieved by modulating simultaneously the MO and PS QCL sections and slowly scanning the DC current level injected in the PS section.

How much do preexisting chronic conditions contribute to age differences in health care expenditures after a work-related musculoskeletal injury?

OBJECTIVES: To estimate the contribution of preexisting chronic conditions on age differences in health care expenditures for the management of work-related musculoskeletal injuries in British Columbia. METHODS: A secondary analysis of workers' compensation claims submitted over the 5-year period between January 1, 2002 and December 31, 2006 (N = 55,827 claims among men and 32,141 claims among women). Path models examined the relationships between age and health care expenditures, and the extent to which age differences in health care expenditures were mediated by preexisting chronic conditions. Models were adjusted for individual, injury, occupational, and industrial covariates. RESULTS: The relationship between age and health care expenditures differed for men and women, with a stronger age gradient observed among men. Preexisting osteoarthritis and coronary heart disease were associated with elevated health care expenditures among men and women. Diabetes was associated with elevated health care expenditures among men only, and depression was associated with elevated health care expenditures among women only. The percentage of the age effect on health care expenditures that was mediated through preexisting chronic conditions increased from 12.4% among 25-34-year-old men (compared with 15-24 y) to 26.6% among 55+-year-old men; and 14.6% among 25-34-year-old women to 35.9% among women 55 and older. CONCLUSIONS: The results of this study demonstrate that differences in preexisting chronic conditions have an impact on the relationship between older age and greater health care expenditures after a work-related musculoskeletal injury. The differing prevalence of preexisting osteoarthritis, coronary heart disease, and to a lesser extent diabetes (among men) and depression (among women) across age groups explain a nontrivial proportion of the age effect in health care expenditures after injury. However, approximately two thirds or more of the age effect in health care expenditures remains unexplained.

Are age-related differences in the consequence of work injury greater when occupational physical demands are high?

BACKGROUND: To examine if age differences in the consequences of work injury are exacerbated when occupational physical demands are higher. METHODS: A secondary analysis of workers' compensation claims in British Columbia (N = 373,672). Regression models examined the relationship between age and health care expenditures, days of wage replacement and the occurrence of long-term-disability following a work-related injury in occupations with lower and higher physical demands. Models were adjusted for individual and injury related covariates. RESULTS: Older age and higher occupational physical demands were associated with worse work-injury outcomes. The relationship between age and each outcome was not exacerbated when occupational physical demands were higher compared to when they were lower. Counter to our hypotheses age differences in health care expenditures were smaller among women in more demanding occupations. CONCLUSIONS: In this study, we found no evidence that the relationship between age and the consequences of work injury is exacerbated when physical occupational demands are high.

Distributed learning on 20 000+ lung cancer patients - The Personal Health Train.

BACKGROUND AND PURPOSE: Access to healthcare data is indispensable for scientific progress and innovation. Sharing healthcare data is time-consuming and notoriously difficult due to privacy and regulatory concerns. The Personal Health Train (PHT) provides a privacy-by-design infrastructure connecting FAIR (Findable, Accessible, Interoperable, Reusable) data sources and allows distributed data analysis and machine learning. Patient data never leaves a healthcare institute. MATERIALS AND METHODS: Lung cancer patient-specific databases (tumor staging and post-treatment survival information) of oncology departments were translated according to a FAIR data model and stored locally in a graph database. Software was installed locally to enable deployment of distributed machine learning algorithms via a central server. Algorithms (MATLAB, code and documentation publicly available) are patient privacy-preserving as only summary statistics and regression coefficients are exchanged with the central server. A logistic regression model to predict post-treatment two-year survival was trained and evaluated by receiver operating characteristic curves (ROC), root mean square prediction error (RMSE) and calibration plots. RESULTS: In 4 months, we connected databases with 23 203 patient cases across 8 healthcare institutes in 5 countries (Amsterdam, Cardiff, Maastricht, Manchester, Nijmegen, Rome, Rotterdam, Shanghai) using the PHT. Summary statistics were computed across databases. A distributed logistic regression model predicting post-treatment two-year survival was trained on 14 810 patients treated between 1978 and 2011 and validated on 8 393 patients treated between 2012 and 2015. CONCLUSION: The PHT infrastructure demonstrably overcomes patient privacy barriers to healthcare data sharing and enables fast data analyses across multiple institutes from different countries with different regulatory regimens. This infrastructure promotes global evidence-based medicine while prioritizing patient privacy.

Occupational Gradients in Work-Related Insecurity and Health: Interrogating the Links.

Traditional work-related securities that constitute the career-job model of employment have been in steep decline for several decades, affecting workers across industries and occupations. Still, insecure employment remains unequally distributed across the working population according to the major axes of social stratification, namely age, gender, race, and socioeconomic class. This study investigates patterns of exposure to work-related insecurity across the occupational hierarchy and whether these contribute to occupational gradients in health outcomes. Drawing on data from a national panel survey of the Canadian workforce, a multilevel growth curve modeling approach is used to examine the relationship between work-insecurity exposures and workers' self-rated health trajectories over 5 years. Findings show that work-related insecurity is associated with declines in self-rated health, although the type of insecurity as well as the magnitude, direction, and duration of the effect varies by occupational status-position. The application of pseudo-R2 tests confirmed this study's central hypothesis that gradients in health outcomes across occupational hierarchies are due, in part, to differences in exposure to work-related insecurity. Going forward, the development of effective health promotion interventions that can modify work-related health gradients, must work toward mitigating the risk of exposure to adverse work circumstances that is systemic to occupational hierarchies.

The impact of temporary employment and job tenure on work-related sickness absence.

OBJECTIVES: To investigate the impact of temporary employment and job tenure on work-related sickness absence of 1 week or more. METHODS: A longitudinal analysis was undertaken of the time to work-related sickness absence from the start of a job using the Canadian Survey of Labour and Income Dynamics. The sample consisted of 4777 individuals who experienced 7953 distinct job episodes and 167 absences. There were 114,488 person-job-month observational units. The major variables of interest in this study were a variable identifying whether the job was temporary or permanent, and tenure on the job. RESULTS: Individuals in temporary jobs were as likely to have a work-related sickness absence as individuals in permanent jobs. Individuals with job tenure of 4-6 months were 64% less likely to have an absence than individuals with longer tenures. Individuals in a union were more likely to have an absence. Firm size was not associated with absence. CONCLUSIONS: Previous studies have suggested that temporary employment and job tenure are associated with work-related health risk exposures and the ability to take a sickness absence, but these studies have not considered the nature of the employment contract in a longitudinal framework. This analysis did not find temporary employment to be associated with differential absence rate after controlling for tenure, prior health status, and several other individual and job characteristics. Short tenure is negatively related to the probability of work-related sickness absence, union membership is positively related, and firm size is not related to this variable.

Labor market and health trajectories during periods of economic recession and expansion in the United States, 1988‒2011.

Objectives We examined associations between labor market and health (LM-H) trajectories in the United States between 1988 and 2011 and whether associations differed across macroeconomic expansion/recession periods. Methods Working-age cohorts, derived from the US Panel Study of Income Dynamics, were followed over time to characterize LM-H trajectories. Poisson regression provided relative risks (RR) with robust 95% confidence intervals (CI) for the association between trajectories, adjusting for demographic and socioeconomic variables. Results LM trajectories ending in unemployment (RR 1.7‒2.5 across periods) or inactivity (RR 2.3-3.2) had a greater risk of worsening health trajectories, compared to stable employment. In contrast, RR for individuals returning to work following an intermediary period of unemployment/inactivity were attenuated across most periods. Stable-employed individuals had the highest probability of remaining in good health, whereas trajectories ending in unemployment or inactivity had the lowest probability. These overall relationships were consistent across macroeconomic periods. Conclusions We found strong and consistent relationships between LM-H trajectories across macroeconomic periods. The attenuated (but not eliminated) risk among individuals returning to work following a period of unemployment/inactivity suggests that health outcomes are not only dependent on the LM end-state, but also on the distinct pattern over time.

Precarious employment experiences and their health consequences: towards a theoretical framework.

Fundamental shifts in the structure of labour markets, work systems, and employment relations of industrialized countries have outpaced changes in legislative, social and political mechanisms. As a result, a growing number of workers are exposed to precarious employment experiences, which we define as experiences that give rise to instability, lack of protection, insecurity, and social and economic vulnerability. These experiences represent a potentially significant occupational health risk. Our central objective is to develop a detailed framework that outlines the key aspects of work experiences that makes them precarious, and to consider links between these aspects and downstream health effects.

Long-term mortality risk in individuals with permanent work-related impairment.

OBJECTIVES: Recent estimates indicate that at least one in five activity-limiting injuries occurs at work. Of individuals who suffer these injuries approximately 10% experience some degree of functional impairment. We were interested in investigating long-term mortality risk in individuals with permanent impairment from work injury and to examine whether work disability is a significant explanatory factor. METHODS: We used a retrospective matched cohort methodology to examine differences in mortality rates between individuals with permanent impairment from a work injury and a group of non-injured controls over a 19-year period. We used a sample of impaired workers to investigate the impact of work disability on mortality risk using percentage of earnings recovery after injury as the key proxy measure. All analyses were stratified by sex. RESULTS: Permanent impairment from a work injury was predictive of premature mortality in both male and female claimants, though the risk was slightly higher among women. Work disability was a key explanatory factor in the rate of death among impaired workers, the effects being more pronounced in men. We also found that higher impairment level was associated with mortality in men but not in women. CONCLUSION: The study demonstrates the impact of permanent work-related impairment on longevity and identifies work disability as an important determinant of mortality risk. Given the disconnect between impairment ratings derived from standard diagnostic tools and labour-market activity after accident, more research is needed on the specific factors that contribute to work disability, particularly those related to psycho-social health and well-being.

Impact of pre-existing chronic conditions on age differences in sickness absence after a musculoskeletal work injury: a path analysis approach.

OBJECTIVES: This study aims to examine the extent to which a greater prevalence of pre-existing chronic conditions among older workers explains why older age is associated with longer duration of sickness absence (SA) following a musculoskeletal work-related injury in British Columbia. METHODS: A secondary analysis of workers' compensation claims in British Columbia over three time periods (1997-1998; 2001-2002, and 2005-2006), the study comprised 102 997 and 53 882 claims among men and women, respectively. Path models examined the relationships between age and days of absence and the relative contribution of eight different pre-existing chronic conditions (osteoarthritis, rheumatoid arthritis, hypertension, coronary heart disease, diabetes, thyroid conditions, hearing problems, and depression) to this relationship. Models were adjusted for individual, injury, occupational, and industrial covariates. RESULTS: The relationship between age and length of SA was stronger for men than women. A statistically significant indirect effect was present between older age, diabetes, and longer days of SA among both men and women. Indirect effects between age and days of SA were also present through osteoarthritis, among men but not women, and coronary heart disease, among women but not men. Depression was associated with longer duration of SA but was most prevalent among middle-aged claimants. Approximately 70-78% of the effect of age on days of SA remained unexplained after accounting for pre-existing conditions. CONCLUSIONS: Pre-existing chronic conditions, specifically diabetes, osteoarthritis and coronary heart disease, represent important factors that explain why older age is associated with more days of SA following a musculoskeletal injury. Given the increasing prevalence of chronic conditions among labor market participants (and subsequently injured workers) moderate reductions in age differences in SA could be gained by better understanding the mechanisms linking these conditions to longer durations of SA.

Marital formation in individuals with work-related permanent impairment.

BACKGROUND: Prior studies on the impact of disabling work injury have neglected social support as a key mediating factor. This study investigates how permanent impairment from a work injury affects marital formation, an indicator of social support and integration with the potential to affect psychosocial adjustment and the resumption of productive social roles following work injury. HYPOTHESES: Adjusting for socio-demographic and economic factors associated with marriage ability, we expect that individuals with a work-related permanent impairment will have a lower rate of marital formation compared to their non-injured counterparts. METHODS: Drawing on a linkage of workers' compensation claims data with income tax information, we undertake a duration modeling analysis comparing workers who have sustained a workplace injury with a matched sample of non-injured controls to examine time to marital formation in each group. RESULTS: Women who suffered a disabling work injury were 17% less likely to marry relative to controls. High levels of physical impairment reduced the rate of marriage in women by 22%. We did not find an effect of impairment on marriage probability in models adjusted for income in men. CONCLUSIONS: Our findings underscore the importance of examining the social and interpersonal consequences of work injury, factors not currently addressed by the occupational rehabilitation system.

The Relationship between Age and Work Injury in British Columbia: Examining Differences across Time and Nature of Injury.

OBJECTIVE: The aim of this study was to examine the relationship between age and the lost-time workers' compensation claims in British Columbia, Canada, over three time periods (1997-98, 2001-02 and 2005-06). We examined if the relationship between age and risk of lost-time claims is consistent over time and for different nature of injury categories. METHODS: Secondary analyses of lost-time workers' compensation claims combined with estimates of person-years of exposure generated from the Canadian Labour Force Survey were performed. Analyses examined the relationship between age and claim risk using sex-stratified regression models, adjusting for time period, occupational characteristics and whether the claimant was employed in the goods or service industry. Multiplicative interaction terms were used to examine if the relationship between age and lost-time claim risk changed over time. Seven separate regression models were generated to explore the variation in the effect of age across nature of injury groups. RESULTS: We observed important differences in the relationship between age and risk of injury depending on the nature of injury examined. A negative relationship was observed between age and lost-time claims for open wounds, while a positive relationship was observed for traumatic injuries to bones, nerves and the spinal cord. We found no evidence that the relationship between age and risk of lost-time claims changed over time periods. CONCLUSIONS: The association between age and risk of lost-time claims depends on the nature of injury under investigation. We found no evidence that the relationship between age and overall lost-time claim risk has changed over time in British Columbia.

'Rapid Learning health care in oncology' - an approach towards decision support systems enabling customised radiotherapy'.

PURPOSE: An overview of the Rapid Learning methodology, its results, and the potential impact on radiotherapy. MATERIAL AND RESULTS: Rapid Learning methodology is divided into four phases. In the data phase, diverse data are collected about past patients, treatments used, and outcomes. Innovative information technologies that support semantic interoperability enable distributed learning and data sharing without additional burden on health care professionals and without the need for data to leave the hospital. In the knowledge phase, prediction models are developed for new data and treatment outcomes by applying machine learning methods to data. In the application phase, this knowledge is applied in clinical practice via novel decision support systems or via extensions of existing models such as Tumour Control Probability models. In the evaluation phase, the predictability of treatment outcomes allows the new knowledge to be evaluated by comparing predicted and actual outcomes. CONCLUSION: Personalised or tailored cancer therapy ensures not only that patients receive an optimal treatment, but also that the right resources are being used for the right patients. Rapid Learning approaches combined with evidence based medicine are expected to improve the predictability of outcome and radiotherapy is the ideal field to study the value of Rapid Learning. The next step will be to include patient preferences in the decision making.

The health consequences of precarious employment experiences.

OBJECTIVE: This study provides a test of a conceptual framework of the stress-related health consequences of "precarious" employment experiences defined as those associated with instability, lack of protection, insecurity across various dimensions of work, and social and economic vulnerability. METHODS: Data were drawn from the Canadian Survey of Labor and Income Dynamics (SLID), a nationally representative longitudinal labor-market survey (1999-2004). Logistic regression analysis estimated the impact of several dimensions of precarious employment on two health outcomes: low health status and low functional health. PARTICIPANTS: For each calendar year we selected a subsample of individuals with close ties to the labor-market--i.e., aged 25 to 54, not full-time students, and employed at least 9 months of the year. We excluded individuals who were self-employed, those in management-level positions, and individuals who reported less than good health at the beginning of the year. RESULTS: Certain work characteristics (low earnings, the lack of an annual wage increase, substantial unpaid overtime hours, the absence of pension benefits, manual work) predict an increased risk of adverse general and/or functional health outcomes. CONCLUSIONS: Proactive regulatory initiatives and all-encompassing benefits programs are urgently required to address emerging work forms and arrangements that present risks to health.

Social protection and the employment contract: the impact on work absence.

OBJECTIVE: This study investigates the impact of temporary employment on all-cause sickness absence of one week or more with a focus on how this relationship is moderated by factors related to social protection (job tenure, union membership and firm size). PARTICIPANTS: A sample of 5,307 individuals who experienced 9,574 distinct job episodes was drawn from a longitudinal Canadian labour market survey (2000-2004). METHODS: Duration analysis was undertaken to model the time from the start of a job to the first sickness absence. Specifically, a proportional hazard model was estimated using a complementary log-log function for continuous time processes. RESULTS: Findings showed that temporary employment was associated with a lower rate of sickness absence after controlling for tenure, prior health status, and several other individual and job characteristics. CONCLUSIONS: The results suggest that the lack of social protection in temporary jobs is a powerful determinant of absence taking, even in the case of serious health conditions that require an absence of one week or more.