Prospective Cohort Study Of Industrial Employees

Questions : 1.Provide one paragraph of summary of the study youve chosen and I approved (200 words Max) in your OWN WORDS to show the reader (me) that you have understood the study and you everything about it because you read it few times 2.What is the research question? Provide the full version? 3.Was the study design appropriate and how else can it be done (give details of another alternative design in relation to the same objectives and study settings)? 4.What are the comparison groups in this study?Were they clearly defined?5.Are the study population representative of the general population? Explain your answer.6.What analytical strategy was used to assess results?7.What measure was used to assess the relationship between risk factor and outcome? Where these objective or subjective?8.What are the types of bias that may affect this study? Explain these specifically and in relation to Study population ,Recruitment process ,Measurements used and Follow up issues. 9.How do you think issues (Bias) in the previous question can influence the results (discuss this in details and in relation to the above processes and parameters)?10.Comment on external validity of the results.11.What confounders did the authors adjust for? In your opinion, couldhave there been any other confounders in his study that could have influenced the results (i.e. the association between exposure and outcome? Answers : 1.Work stress has been considered to be causing various degrees of health related problems in several working domains. On the other hand cardiovascular disorders are one of the leading causes of mortality worldwide. The study by Kivimki et al. (2002) aims to evaluate the correlation between wok related stress defined by certain models and cardiovascular mortality. The authors aim to identify different features of a workplace and work organisation that might play an important role in the occurrence of cardiovascular disorders related deaths. The study population was comprised of workers employed for at least 15 months by Valmet factories. The participants were stratified based on age sex and occupational role including mangers, office staff, skilled and semi-skilled workers. A cohort study design was utilised. The components of two different work stress models, the job strain model and the effort reward imbalance model were measured using relevant questionnaire. The cardiovascular mor tality data for each participant was obtained from Statistics Finland national mortality register. Demographic and behavioural factors were measured initially and biological factors were measured both at the beginning of the study and after a five year follow up. The relationship between the work stress variables and the biological factors were assessed statistically. The study found that there was twofold increases risk of cardiovascular mortality rate for workers with high job-strain and effort-reward imbalance, which was consistent with other similar study findings. 2.The research question: To find whether work stress as defined by the job strain as well as effort-reward imbalance model is related to risk of mortality caused due to cardiovascular disease. 3.The study design utilised by Kivimki et al. (2002) is a Cohort study where 812 employees participated (545 men and 267 women). Several personal attributes, demographic data and biological factors related to cardiovascular diseases were measured as baseline variants as well as after a 5 year and 10 year follow up. The cohort study design is appropriate in this case as it can measure the association of the selected risk factors with cardiovascular disease related mortality. However, a control group was not selected which may have influenced the study results. Another study design that could have been adopted for the purpose of this research is a Case-control design. In a case control study design two groups could have been selected, one consisting of people who died from cardiovascular diseases and one with death caused by other causes. The groups have to be adjusted for age, sex and occupational posts. The precepts history could have been studied for prior work related stress during their tenure as employees by examining the work they performed. Conclusions regarding the relationship between work stress and cardiovascular diseases could have been drawn by comparing the study results obtained from the two groups. 4.There was no comparison group designed for this study. Employees that were categorised in the most favourable third of the work stress parameters were considered as a reference group. No separate group without work stress was considered. 5.The study population is only representative of employees from particular manufacturing industries like paper machines, tractors, firearms, gauges and so on. Work related stress was measured for jobs ranging from heavy and precision engineering, clerical and administrative jobs. Hence, the study results are representative to this certain jobs and industry as the work stress risk factor for cardiovascular diseases was measured only for these areas of work. 6.The primary aim was to measure the correlation between age, sex, occupation, smoking status and other biological baseline parameters indicative of cardiovascular diseases such as physical activity, systolic blood pressure, serum cholesterol and body mass index, with mortality caused by cardiovascular diseases. Secondly the association between work stress variables like job strain, effort-reward imbalance and its related components with cardiovascular mortality was measured. Finally, to relate the direct biological parameters to cardiovascular mortality the authors examined the relationship between blood pressure, cholesterol concentration and body mass index with the same. Cox proportional hazard models were used for the initial assessment. Analysis of variance was used for other assessments after adjustments of the baseline values for these factors for the particular study group. SAS 8.12 statistical program package was used for the purpose of the analyses. 7.The risk factors provided in the job strain model and effort-reward imbalance model were measured by self-assessment of the employees using questionnaire. Hence, measurement of risk factors was subjective. However, the classification of cause of death of the participants followed an objective measurement provided by International Classification of Diseases (ICD). 8. Firstly, the study did not have a control group. The resulting scales for the questionnaires that determined the work stress was dived into thirds and the participants reporting to be in the most favourable third was considered to be a reference group. A lack of control group was a bias in regard to study groups. The recruitment process lack any bias as the authors tried to participants from all the occupational levels and the age, gender and employment period related biases were also avoided by adopting efficient recruitment parameters. The measurement of work stress was subjective and hence prevalence of certain bias cannot be ruled out. Although standard assessment scales were utilised a subjective measurement is always prone to bias in any study model. At a follow up study after five years systolic pressure and a serum total cholesterol concentration was measured and at a ten year follow up only body mass index was measured. All the biological parameters that were measured at baseline were not measured at the follow up which is biased from the perspective of efficient results. 9.A lack of control group, subjective stress factors measurements and lack of sufficient measurements can all lead to bias in the study finding by inaccurate association and interpretation of the causes of death. It might have produced false positive observations all elucidated by the findings of the study. 10.The external validity of the results cannot be assured as the study participants were confined in terms of location, work industry and occupation. Hence, the stress factors cannot be extrapolated to other work industries and occupations. 11.Confounding factors like age, sex, occupational group and biological factors were adjusted for cardiovascular mortality rates. However, race and ethnicity and family history on cardiovascular disease were not studied during the research. This can have influence on the genetic predisposition of the participants and hence affect the study results and interpretations. References Kivimki, M., Leino-Arjas, P., Luukkonen, R., Riihimi, H., Vahtera, J., Kirjonen, J. (2002). Work stress and risk of cardiovascular mortality: prospective cohort study of industrial employees.Bmj,325(7369), 857.