Does response propensity bias stress audits?

BACKGROUND: Non-response bias in surveys occurs when non-respondents differ from respondents. Methods of dealing with this include measuring 'response propensity'. We propose that response propensity has a trait-like component, measurable within the survey. Covariance of this component with survey items could indicate non-response bias. AIMS: To measure and validate trait-like response propensity, to test whether it co-varied with survey items during a routine stress audit and to test whether a prior staff attitude survey may have been biased. METHODS: Stress survey sent to government employees during a routine audit. We designed two new items to measure trait-like response propensity and completion of a prior staff survey. We calculated an odds ratio, correlations and Mann-Whitney U-tests to assess relationships between trait response propensity, completion of the prior staff survey and current stress survey scores. RESULTS: There were 71 respondents; response rate 68%. The trait response propensity item predicted completion of a prior staff survey (odds ratio 8.75, 95% confidence interval 2.32-33.08). Trait response propensity significantly correlated with two of the 40 survey items and did not significantly correlate with any of the eight 'stressor' sub-scales. Non-respondents to the prior staff survey had a significantly lower risk of stress on two of the eight stressor scales. CONCLUSIONS: Trait response propensity seems to be a valid construct. The weight of evidence does not provide an indication of non-response bias (yet neither does it assure freedom from non-response bias). The prior staff survey may have been affected by non-response bias.

Sustaining person-environment fit with a changing workforce.

Data on health and lifestyle from the Naval service cohort study of occupational stress form the background to a discussion of employee health and the sustainability of a healthy workforce in relation to secular changes - in particular, the increasing prevalence of obesity. One thousand two hundred and forty-one Naval personnel returned questionnaires in 2007 and 2011 and reported their body mass index (BMI), alcohol consumption and smoking, general health and health conditions such as back pain and high blood pressure on both occasions. Health risk due to high BMI and waist circumference in 2011 was predicted by low participation in exercise in 2007. Those performing physically demanding work in 2007 were more likely to be in the 'no risk' category in 2011. High BMI in 2007 was associated with the development of back pain, musculoskeletal conditions and high blood pressure in 2011. The findings are discussed in relation to two aspects of sustainability: the sustainability of current ergonomics practice in relation to health and safety; and the role of ergonomics in sustaining a healthy and productive workforce. PRACTITIONER SUMMARY: Evidence is presented for the benefits of exercise in sustaining employee health and for an association between a high BMI and a number of common health complaints that have traditionally been tackled through workplace ergonomics. This evidence can be used to support the development of workplace design concepts that promote physical activity.

Two year follow-up study of stressors and occupational stress in submariners.

BACKGROUND: Submariners are an occupational group within the Royal Navy (RN) who work in isolated and extreme conditions. This preliminary study forms part of a longitudinal study of occupational stress in the RN. AIMS: To compare stress prevalence in submariners with matched controls and to identify predictors of occupational stress in submariners over a 2 year follow-up period. METHODS: Participants completed a Work and Well-Being Questionnaire to measure occupational stressors and the General Health Questionnaire-12 (GHQ-12) to measure stress at time point 1, and a follow-up GHQ-12 2 years later. Demographically matched controls from the surface fleet of the RN were identified for each submariner. Regression models were developed for submariners and their controls to predict future stress at time point 2 using psychosocial predictors from time point 1. RESULTS: Participants comprised 144 submariners and 144 general service controls. There were no differences between submariners and their surface fleet counterparts in the prevalence of occupational stress. Nevertheless, different predictors for the development of stress were found between the two groups. For submariners, over-commitment and rank were the main predictors; whereas for controls, the predictors were length of service, body mass index and physical work. CONCLUSIONS: Submariners were not more likely to suffer from occupational stress than surface fleet controls in the RN. However, the psychosocial predictors of stress were significantly different for this RN specialist group, demonstrating the importance of developing individual models of stress for different occupational groups.

Vessel motion thresholds for maintaining physical and cognitive performance: a study of naval personnel at sea.

Methods and results are reported from a study of ships companies' exposure to low-frequency motions on three vessels of the Royal Navy. The aim of the study was to investigate relationships between deck accelerations and the incidence of problems such as difficulties with physical tasks, cognitive activities, motion sickness, and work effort. Ship motions were recorded continuously during sea patrols of 10-14 days. The data collected from the three vessels comprised 105 days of ship motions over 12 patrols, with 779 associated daily diaries from 78 participants. Problems most strongly associated with vessel motions were related to the difficulties with physical tasks. Some cognitive aspects of task performance and motion sickness were associated with vertical acceleration magnitudes, but the correlations were less strong than with physical tasks. Practitioner Summary: Little is known about the severity of ship motions that degrade physical and mental performance. The paper offers preliminary estimates of the motion threshold values below which the performance will not be degraded by motion.

Age and BMI interact to determine work ability in seafarers.

BACKGROUND: Seafaring is known to be a demanding occupation but the implications of ageing in seafarers are poorly understood. AIMS: To investigate task demands and work ability in merchant seamen at sea and to identify factors predicting work ability. METHODS: This was a cross-sectional study carried out on a single vessel during a summer deployment. Instantaneous heart rate (HR) was recorded at 5-s intervals during representative 8-h shifts in 41 merchant seamen. Participants completed the work ability index and also rated their daily task demands using the National Aeronautics and Space Administration Task Load Index (NASA-TLX). Body mass index (BMI), waist circumference and demographic details were recorded. RESULTS: Work demands were found to be moderate according to both HR data and TLX scores. The mean BMI was 27.5 kg/m(2) (standard deviation 3.3) and the mean age was 47 years. The majority of participants rated their work ability as 'good' to 'excellent'. The best predictor of work ability was the interaction between BMI and age, whereas there was a statistically significant negative correlation between HR and age. CONCLUSIONS: Work ability in this group of seafarers was found to be high and the work was shown to be moderately demanding, on average. Although work ability declined with age and with BMI independently, the best predictor of work ability was the interaction between BMI and age, with increased BMI having a deleterious effect on work ability in older employees doing moderately demanding work.

Work demands and need for recovery from work in ageing seafarers.

This study was conducted on a population of seafarers serving in the Royal Fleet Auxiliary (RFA), the organisation providing support at sea to the Royal Navy. An investigation into work-related fatigue in RFA personnel onboard ships was carried out following changes to the regulations concerning maximum retirement age, to determine whether age was associated with recovery from work demands. A total of 322 personnel aged from 19 to 61 years were interviewed onboard seven RFA ships. The Need for Recovery scale was used to measure fatigue and work demands exposure was measured using the Baecke questionnaire and the NASA Task Load Index. It was found that older personnel did not have higher work-related fatigue than younger personnel. A measure of frustration at work was found to be most strongly related to work-related fatigue, even in seafarers who carried out physically demanding jobs. Work-related fatigue was found to accumulate over time in personnel who continued to be exposed to work demands onboard a ship. Finally, a relatively high level of work-related fatigue was found in the RFA sample as a whole, which may hold implications for management interventions. It was concluded that older personnel in the RFA can cope with the day-to-day demands of working life as well as younger personnel, possibly due to a 'survivor effect', whereby those personnel who do not cope as well with work demands leave and find a different job, leaving only those who successfully deal with the demands of working life at sea. STATEMENT OF RELEVANCE: In order to manage work demands in seafarers, it is important to identify the most fatiguing demands. Age is of interest because of the demographic ageing of the workforce. Age was not associated with a higher need for recovery. Psychological work demands had a greater effect on need for recovery than physical work demands.

Chronic and acute psychological strain in naval personnel.

BACKGROUND: Previous surveys have shown that there is a greater prevalence of psychological strain in Naval personnel than in the general population and have described the main psychosocial stressors associated with strain. AIMS: To determine the prevalence of acute strain and of repeated episodes of strain over 6- and 12-month periods. METHODS: Six and twelve months after completing a Phase I Work and Well-Being questionnaire, 2596 personnel were reassessed using a follow-up General Health Questionnaire-12. RESULTS: The response rates at 6 and 12 months ranged from 51 to 60%. There was no evidence of response bias at follow-up. The prevalence of acute strain was 31% at Phase I. After 6 months, approximately half of strain cases had recovered. Only 10% had strain over the entire period. Change in strain was linked to change in work role. CONCLUSIONS: Accumulation of strain and recovery occur within 6 months depending on change in work role. Management of strain might best be achieved by management of work demands and deployment length. Further studies will investigate the rate of accumulation of strain over the course of demanding deployments. Exposure to psychosocial stressors such as effort reward imbalance accounted for much of the difference between chronic strain sufferers and those with no strain.

Work-related stress indicator surveys in UK Ministry of Defence.

INTRODUCTION: UK Ministry of Defence (MOD) policy and strategy recommend the use of a 'Defence MODified' version of the Health and Safety Executive Management Standards Indicator Tool to help managers identify risks of work-related stress among Defence personnel. The Defence MODified Tool ('Stress Indicator Survey') asks personnel to rate their perceptions of eight working conditions known to be significantly associated with work-related stress. MOD psychologists are developing a Defence norm group against which future survey scores can be compared. This article describes the use of the Stress Indicator Survey in MOD and gives an overview of findings from 2016 to 2018. METHOD: MOD psychologists conducted 27 Stress Indicator Surveys in 2016-2018. Data were collated from 6227 personnel for the Defence norm group and comparisons were conducted between Service personnel and MOD civil servants, and between Services (Royal Navy/Royal Marines (RN/RM), Army and Royal Air Force (RAF)). RESULTS: Service personnel had significantly more favourable perceptions than MOD civil servants of most working conditions. The RN/RM had significantly more favourable perceptions than either the Army or the RAF of all working conditions. These findings indicate differential risks of work-related stress in different groups of personnel. DISCUSSION: Possible explanations for the observed differences in risk of work-related stress are discussed, including the nature of military life and planned changes to Defence civilian headcount. Examples of managerial actions to improve working conditions based on individual survey findings are given.

Occupational stress and strain in the Royal Navy 2007.

BACKGROUND: Previous surveys of psychological strain in the Naval Service (NS) have shown higher than expected levels of strain when compared to the general population. AIM: To repeat the survey last carried out in 2004 and to obtain further information on the nature of the occupational stressors associated with strain. METHODS: General Health Questionnaire-12 strain rates and job/life stressors were measured using a Work and Well-Being Questionnaire. Models of strain were developed for male and female personnel in the Royal Navy (RN) and males in the Royal Marines (RM). RESULTS: The response rate was 57%. The psychological strain rate was 31.5% overall. Personnel suffering from strain tended to be 'overcommitted' to work, had low levels of commitment to the NS and had suffered stressful life events (SLEs) in the previous 12 months. Strain rates declined with age and rank in males, but not in females. Strain was significantly positively correlated with levels of overcommitment, effort-reward imbalance (ERI), role conflict, work-family conflict, organizational commitment and exposure to SLEs. Models of strain in the males and females in the RN and in the RM accounted for between 37 and 44% of the variance in strain. CONCLUSIONS: The survey provides evidence for both the demand control and ERI models-components of these models contribute independently to strain. High levels of commitment to the organization were associated with lower strain and exposure to SLEs to higher strain.

Naval Service cohort study of occupational stress: background to the research and a review of the latest findings.

The Naval Service has been actively involved in research on occupational stress for almost 10 years. Three cross-sectional studies have been completed during this time period. It has been shown that the prevalence rate of psychological strain amongst personnel is relatively constant at 31-34%. Several smaller studies, of personnel at sea and of the availability of support services have also been completed. In general, the research has shown that the prevalence rate of strain is higher in the NS than in the general population and is comparable to that found in similar uniformed service organisations, such as the Police. Recognising the limitations of cross-sectional research methods, the decision was made, in 2006, to follow a cohort of personnel over a 6-year period in order to gain better understanding of the processes by which work demands impact on psychological health and to determine whether psychological ill-health has an adverse impact on factors such as premature voluntary retirement and medical downgrading. The paper presents the history of the research and some of the work in progress.

Effect of lumbar traction on stature.

Ten subjects were given lumbar traction for each of three time periods. Traction forces of one third of body weight were used. Stature was measured before and after traction and before and after three control periods of crook lying (lying supine with the knees flexed at 90 degrees and the feet resting on the traction table). ANOVA was used to test the hypotheses that traction and time in traction were significantly related to stature increase. Traction had significant effects on stature. The mean stature increase was 8.94 mm after 25 minutes traction compared with 3.33 mm after 25 minutes crook lying. Time in traction also had significant effects on stature increase which was most rapid during the first 15 minutes of traction. These findings can be related to the use of stature measurement as an index of spinal loading and the possible implications for treatment. However, since only healthy, young subjects were used and only one magnitude of traction was applied, the findings should be interpreted with caution. Further investigations would overcome these limitations.

Task and postural factors are related to back pain in helicopter pilots.

BACKGROUND: A previous survey by Shear et al. revealed a high prevalence of back pain in Royal Navy helicopter aircrew, compared with controls. It was recommended that a second survey be undertaken, taking account of flying tasks and cockpit ergonomics. This was the purpose of the present investigation. METHOD: A questionnaire containing items on back pain and posture was circulated to all 246 acting pilots, with returns of 75%. The questionnaire sought information on pain in both the flying pilot and co-pilot/instructor roles. RESULTS: The 12-mo prevalence of back pain was 80%. Task-related back pain was greatest in instrument flying (72%) and least in the co-pilot and instructor roles (24%). Self-ratings of posture indicated that forward flexed trunk postures predominated in the flying roles and were most extreme in instrument flying. In non-flying roles, symmetrical, reclining postures were more often reported. No demographic or psychosocial variables were significantly related to back pain prevalence or disability. CONCLUSIONS: Much of the back pain experienced by helicopter pilots appears to be due to the posture needed to operate the cyclic and collective controls. In instrument flying, it is suggested that the visual demands of scanning the displays may exacerbate the pain by causing the pilot to lean further forward.

Anthropometric variability, equipment usability and musculoskeletal pain in a group of nurses in the Western Cape.

This study examined the anthropometry and anthropometric fit of a group of nurses in Western Cape private hospitals. Anthropometric variables were measured using a sample of nurses and a correlation matrix generated. All nurses were given a questionnaire concerned with operational problems in the work environment and musculoskeletal pain. The nurses reported numerous problems in the working environment, including lumbar backache, inadequate space and equipment that caused bodily discomfort. There were consistent, statistically significant associations between the frequency of occurrence of these problems and the anthropometric data indicating that the problems were caused or amplified by body size variability and were not simply general usability problems which would affect all nurses irrespective of their body dimensions.

Job stressors in naval personnel serving on ships and in personnel serving ashore over a twelve month period.

Sixty one percent of respondents to a questionnaire survey of occupational stress (Phase I) returned follow-up questionnaires twelve months later (Phase II). The Phase I questionnaire measured psychological strain resulting from exposure to occupational stressors, and measured the presence of stress buffers and demographic, psychological and lifestyle-related confounding factors, including age, rank and gender, mood state and the occurrence of stressful life events outside of work. The prevalence of strain was 31% at Phase I and 33% at Phase II. Fifty percent of personnel had no strain on either occasion, 15% had strain on both occasions and the remainder had strain on one occasion. The main stressor associated with strain at Phase I was an inability to disengage from work and this stressor accounted for a greater proportion of the variance in strain in personnel serving on ships than those serving ashore. The twelve-month follow-up questionnaire (Phase II) re-assessed psychological strain. A multiple linear regression analysis was conducted to identify factors measured at Phase I that predicted strain at Phase II in previously strain-free individuals. A lack of autonomy and control and dissatisfaction with living conditions predicted strain twelve months later in those serving on ships. Of the living conditions assessed, lack of privacy was the most strongly associated with strain twelve months later in those serving on ships. These stressors were not associated with strain twelve months later in those serving ashore. The findings suggest that improvements to the design of the environment on ships may have benefits for the psychological health of personnel.

Hip joint mobility and spinal angles in standing and in different sitting postures.

The spinal angles of 25 female subjects were measured in standing and in four different sitting postures with various trunk-thigh angles. Additionally, measurements of hip and lumbar mobility were made in an attempt to relate mobility to spinal curvature in the different sitting postures. Lumbar curvature was observed to decrease as the trunk-thigh angle decreased across the different sitting postures, and reduction in curvature was associated with hip mobility. An exploratory analysis of interrelationships among hip mobility, spinal mobility, and spinal curvature was also carried out. A significant correlation between lumbar and thoracic angular deviations in standing and hip flexion/extension range was obtained. The findings are discussed with reference to theories of sitting posture and the influence of hip joint mobility on postural adaptations to furniture. Further investigations, including studies of male subjects, are indicated.

Effects of seat slope and hip flexion on spinal angles in sitting.

Lumbar and thoracic spinal angles of 25 male and 25 female subjects were measured in four sitting postures, with standing angles used as reference. Subjects sat with either 90 deg or 65 deg of hip flexion on either flat or forward-sloping seats. Lumbar kyphosis was greatest when the flat seat/90-deg posture was adopted and least when the sloping seat/65-deg posture was adopted. The opposite was observed for the thoracic angles, and intermediate results were observed for the other two sitting postures. No statistically significant interactions were observed among seat slope, hip flexion, and subject sex. The findings are discussed with reference to the anatomy of sitting and factors influencing pelvic tilt and the implications for the ergonomic design of chairs.

Development of observational methods for estimation of exposure to workplace postural stress.

Several recent studies have illustrated the need for a simple observational instrument for the estimation of exposure to postural stress in epidemiological studies of musculoskeletal disorders. Such an instrument is particularly necessary in developing countries. This paper describes the development of an observational instrument across a spectrum of industrial occupations in South Africa. The instrument was derived from adaptations to previously published observational methods and was specifically adapted to the measurement and application constraints identified during empirical development work in various industries. The final instrument fulfilled its aims of being applicable across a broad spectrum of jobs, including a broad spectrum of exposure variables and being reasonably cost- and time-effective. Some construct validity is indicated by the fact that two out of the three main exposure variables of interest showed significant associations with neck and shoulder pain in an epidemiological analysis. These variables were the score of summed estimates of the duration of time in sustained postures in a working day and the score of estimated overall repetitiveness based on cycle-time criteria. Further investigations are needed for pain at other anatomical sites. The measurement and scoring problems identified are discussed with reference to some aspects of these results.

Work related musculoskeletal disorders and ergonomic stressors in the South African workforce.

OBJECTIVES: The main objective of this study was to investigate exposure-response relations between adverse musculoskeletal outcomes and ergonomic exposure variables. METHODS: A cross sectional analytical study was conducted in 11 factories from seven sectors of manufacturing industry in South Africa. Exposure to workplace ergonomic stressors was assessed in factory floor jobs (n = 46) with a simple low technology observational model. Repetition, force, static posture, dynamic movement, and other job exposures were measured. Data of adverse musculoskeletal outcome and data on potential confounders and effect modifiers were obtained from subjects (n = 401) randomly sampled from each job category with a questionnaire given by interviewers. RESULTS: High prevalences of regional musculoskeletal pain were found with substantial variability between industries. Sex was the only individual risk factor (after adjustment for potential confounders and effect modifiers) that was significantly associated with regional pain. Ergonomic exposures in the workplace were significantly associated with musculoskeletal pain of the neck and shoulders odds ratio (OR) 5.38 (95% confidence interval (95% CI) 1.16 to 25.0) for repetition, and OR 3.91 (95% CI 1.11 to 13.7) for seated compared with standing work; pain of the wrists and hands OR 10.2 (95% CI 1.39 to 75.6) for high summed score of dynamic postures of the wrist). CONCLUSIONS: This study indicates good predictive ability to reduce ergonomic stress with the exposure model, simple surveillance methods, and educational programmes in the workplace. Further study on sampling strategies and refinement of dimensions of ergonomic stressors are needed.

Postural adaptations to workbench modifications in standing workers.

Surveys have shown that many workers operate under conditions that require constrained standing. The aim of this study was to investigate postural adaptations in constrained standing to facilitate the development of design guidelines for standing workspaces. Standing postures were observed in six different workspaces that were designed using combinations of task distance (which was either constrained or unconstrained) and foot position (which was constrained, unconstrained or employed a footrest). Subjects at work were recorded stereophotogrammetrically and postural variables were obtained in three dimensions. Postural adaptation to increased task distance was found to be characterized by increased trunk flexion and increased hip flexion while adaptation to close work was found to be characterized by increased neck flexion and increased thoracic kyphosis. Constrained foot position resulted in increased hip flexion accompanied by increased plantar flexion. Although use of the footrest resulted in some reduced lumbar lordosis, it increased trunk flexion and was not associated with significantly less discomfort than any of the other workspaces.