Wednesday, 21 August 2013

Follow-up and assessment of self reports of work-related illness in the Labour Force Survey

Prepared by the Health and Safety Executive 2013 (J R Jones, J T Hodgson and S Webster (Statistics and Epidemiology Unit))

Executive summary

The Labour Force Survey (LFS) is the Health and Safety Executive’s primary source of data on work-related illness, but it relies on respondents’ perceptions of medical matters and their own assessment of whether their illness was caused or made worse by work. There is also very little scope within the LFS to explore the perceived causes and the impact of these conditions on the daily lives of those affected.

In the Work-Related Illness Survey (WRIS), a sample of respondents reporting a work-related illness in the 2010 LFS were re-interviewed and asked to provide more details about their illness and its connection with work. With their permission, their doctor was also contacted and asked to complete a short questionnaire to provide further information on the reported illness and give their view of its link to work. Finally, a panel of experts reviewed all the information provided and assessed the link between work and the illness.

The survey findings, case review and the outcome of the doctors’ survey were together used to address two primary study objectives: to assess the nature and degree of work-relatedness of illnesses reported in the LFS and to measure the impact of these conditions on the daily lives of those affected.

In 77% of cases, it was accepted by the case review panel that the link with work was plausible, either as a main cause or a contributory cause of the illness. In a further 10% of cases, the review concluded that work did not contribute to the underlying disease process but may have exacerbated the disease symptoms. A medical opinion was only available for about a quarter of cases but where information was provided, in 57% of cases the doctor agreed that the work was definitely or probably a main or contributory cause of the illness, and in a further 27% of cases they reported that it was possibly a main or contributory cause. In only 3.6% of cases did the respondent’s doctor give the opinion that the illness was unlikely to be or definitely not work-related. The degree of consistency between the doctors and the case review panel was good, with the same decision made in 80% of the cases where both the doctors and the review panel felt they had sufficient information available to make an informed decision.

For 13% of cases, the case review panel judged that a link between work and the illness was unlikely. It was of interest to determine what leads to these cases being reported as work-related and whether there are any common factors which should be taken into account when assessing the true scale of work-related ill health. Statistical models were constructed to investigate which variables were most strongly associated with a judgement of an unlikely link between work and illness. The strongest association was with the individual’s occupation, with differing levels of plausibility across all of the occupational groups. In particular, the link with work was regarded as less plausible on the whole for individuals working in elementary occupations and more plausible on the whole for individuals working in skilled trades. The other important factor was the length of time which had passed since the end of their exposure to the work they believed had made them unwell. Where the exposure had ended a long time ago, there was significantly more chance that the review panel would judge the link between work and ill health to be unlikely. Although individuals’ psychological characteristics appeared to be an important factor when assessed in isolation, the effect disappeared in the full model and there is therefore little evidence that reports from individuals with a somatisation tendency were more likely to be judged as having an unlikely link to work.

With regard to the impact of work-related ill health on the daily lives of those affected, it was unsurprising to find that the general physical and mental health of those individuals tends not to be good, with almost four in five respondents saying they suffered from moderate or worse pain or discomfort and almost three in five that they suffered from moderate or worse anxiety or depression. Although causality is impossible to demonstrate, the majority of respondents believed that their general health would be considerably better were it not for the work-related illness. The impact of these work-related ill health conditions also appears to be strong with WRIS respondents holding negative views of the extent to which the illness affects their lives, in comparison with other study populations suffering from various illnesses.

Our conclusion from the results of this investigation are that self-reports of work-related ill health are broadly reliable. The level of possibly mistaken reports will be to some extent counter-balanced by opposite biases. In particular just as there are individuals who make an implausible ascription to work, there will be others who do not recognise a genuine connection with work activities. Given this and the fact there is no available measure without problems, we believe that it is better to continue to work with the estimate as it emerges from the LFS, rather than apply a series of adjustments. When sensibly interpreted, such surveys provide valid information not available from other sources.

Full text (PDF 66pp)

I found this to be a fascinating read.

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