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Recent eLetters

Displaying 1-10 letters out of 254 published

  1. How stakeholder participation could increase inequities. The inverse equity hypothesis lens.

    Recent review from Harris et al [1] sets the alternative hypothesis that greater degree of stakeholders participation can produce a contextually valid synthesis. Aware of the importance of stakeholders in healthcare, a null hypothesis may come to mind: Stakeholders increase inequity by biasing synthesis. Let us give you some theoretical framework. Research on public health interventions should include academic researchers and local stakeholders to ensure that results are relevant to, and useful for, decision-makers. The idea is that stakeholders involvement also increases transparency and truthfulness of research process [2]. Thus, the partnership "researcher-stakeholder" may be successful in improving health outcomes. Given its goal, the scope of stakeholders involvement is wide, including patients, caregivers, clinicians, researchers, advocacy groups, professional societies, businesses, policymakers, or others. These people that emerge from general population are also vulnerable to health inequalities. Then, what if there is a gap, within stakeholder, between the most and the least disadvantaged? This scenario can lead to biased results because of two reasons: 1) Marginalization of vulnerable populations that are valuable for the researcher-stakeholder partnership, and 2) Unfairness selection of stakeholders that reproduces inequality in a particular way by allowing some people to mobilize capital for their own benefit, blending self-interest and public interest which is a difficult enterprise [3]. Allowing some individuals to have greater probability of become stakeholder could, as I already mention, produce biased results. Biased results leads to wrong decision-making and to interventions that initially benefit only those with higher socio-economic status and therefore inadvertently increase inequities, a situation called "the inverse equity hypothesis" [4] Thus, one can easily conclude one big issue in the role of stakeholders in research: we must assure significant inclusion of the most disadvantaged. How? Using proper procedures for obtaining persons from the target population to build the stakeholder team. Finally, based on this short dissertation a question emerges to pose to Dr. Harris: Did you use special procedures to assure a significant inclusion of individuals to stakeholder team? In other words: do you think is important to consider selection bias when setting up the stakeholder team? Acknowledgments: Victor C. Kok MD. PhD. Asia University Conflict of interest: No one to declare. References:

    1 Harris J, Croot L, Thompson J, et al. How stakeholder participation can contribute to systematic reviews of complex interventions: Figure 1. J Epidemiol Community Health 2015;70:jech - 2015- 205701. doi:10.1136/jech-2015-205701 2 AHRQ. Stakeholder Guide 2014. Stakehold Guid 2014 2014;:15- 6.http://www.ahrq.gov/research/findings/evidence-based- reports/stakeholderguide/stakeholdr.pdf 3 Klenk NL, Meehan K, Pinel SL, et al. GLOBAL CHANGE SCIENCE. Stakeholders in climate science: Beyond lip service? Science 2015;350:743- 4. doi:10.1126/science.aab1495 4 Victora CG, Vaughan JP, Barros FC, et al. Explaining trends in inequities: evidence from Brazilian child health studies. Lancet (London, England) 2000;356:1093-8. doi:10.1016/S0140-6736(00)02741-0

    Conflict of Interest:

    None declared

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  2. Options in Breech Delivery: the woman's choice?

    Hehir (2015) gives an interesting account on the current trends in breech delivery and gives discusses several large studies whose findings suggest that differences in mortality between vaginal breech delivery and elective cesarean section are minimal. Considering the down sides of cesarean delivery, such as increased risks during future pregnancies and births, what is the best option for women? And who should make that decision?

    Vaginal breech delivery rates are decreasing, with more obstetricians opting for cesarean delivery and some even using a 'no- option' approach when it comes to vaginal breech delivery (Hehir, 2015). This 'no-option' approach means that women are not given the chance to make informed decisions about their own healthcare- a principle which is fundamental to current medical practice (Dyer, 2015). Of course there are challenges, and the fast pace and anxiety provoking environment of an emergency breech delivery is not the ideal situation to be making these decisions. It is therefore important that women are given information about their options early on in their pregnancy so that a plan can be agreed between the patient and the rest of the medical team.

    References Dyer. C. 2015. Doctors should not cherry pick what information to give to patients, court rules. British Medical Journal. 350.

    Hehir. M. 2015. Trends in Vaginal Breech Delivery. Journal of epidemiology and Community Health. 69:12.

    Conflict of Interest:

    None declared

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  3. a cup of tea

    It appears somewhat bizarre that authorities have ignored a widely consumed source of fluoride from tea although insisting on community water fluoridation (CWF) to reduce dental decay. Notably, black tea in commercial teabags contains significant levels of fluoride. This is especially so when sourced from Kenya with volcanic soils compounded by fluoride from superphosphate fertilisers. Mechanical harvesting then includes older leaves with higher fluoride content than the young hand- picked tips. Habitual tea drinkers with a daily consumption of 3 cups of tea could already be obtaining more than adequate or safe fluoride intake based on the WHO (2002) upper limit recommendations of 2mg/day for children and 4mg for adults. Peckham's multicentre GP study revealing 30% higher hypothyroidism in areas where the water supply exceeded 0.3ppm of fluoride must raise serious questions regarding HFSA toxicity as nationwide, the British are traditionally tea drinkers. Thus all areas would already be getting fluoride from tea yet only those with CWF had increased hypothyroidism rates.

    Conflict of Interest:

    None

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  4. Potential Challenges to Using Paternal Education as a Proxy for SES

    Oksuzyan et al. report an association between race/ethnicity and two subtypes of childhood leukemia: acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML).1 Accordingly, the researchers suggest that there are genetic, cultural, and environmental factors involved in the etiology of childhood leukaemia [1].

    Importantly, Oksuzyan et al. made a significant effort to examine and control for the potential role of socioeconomic status (SES) on this association. In particular, the authors used paternal education levels used as a proxy for SES given that a significant percentage of information on maternal education was missing from the birth registry used [1]. This strategy faces several challenges given the complex association of race, education, and SES.

    The use of paternal education might not appropriately account for the adverse health effects which might result (at least in part) from residing in single-parent homes. It has been widely documented that children frequently exhibit poor health outcomes in single-parent homes due to causal chain of effects related to parent's education, SES, and income [2]. Moreover, the information regarding paternal education as a proxy for SES was obtained from the California Birth Registry [1]. It is possible that this data does not adequately represent the SES of the cases used in the study given that the father identified might not have provided financial support for the child.

    In addition, the use of parental education as a proxy for SES may not be an appropriate method as average income frequently varies in jobs requiring similar education levels [3]. It is possible that these variations occur more frequently among different ethnic/racial groups; potentially as a result of systemic prejudice and/or unequal employment opportunities [3].

    Oksuzyan et al. report an association between race/ethnicity and childhood leukaemia [1]. Due to potential challenges in using paternal education as a proxy for SES, the inclusion of maternal education and a discussion regarding SES in single-parent homes would have been valuable.

    References

    1 Oksuzyan S, Crespi CM, Cockburn M, Mezei G, Vergara X, Kheifets L. Race/ethnicity and the risk of childhood leukaemia: A case-control study in California. J Epidemiol Community Health Published Online First: 19 March 2015. doi:10.1136/jech-2014-204975

    2 Gucciardi E, Celasun N, Stewart DE. Single-mother families in Canada. Can J Public Health 2004;95(1):70-73.

    3 Williams DR. Race, socioeconomic status, and health. The added effects of racism and discrimination. Ann N Y Acad Sci 1999;896:173-188.

    Conflict of Interest:

    None declared

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  5. Sleep duration by actigraphy in relation to perceived health among older adults

    Lauderdale et al. examined the association between perceived fair/poor health and sleep duration by several methods [1]. The authors concluded that U-shaped relationship between sleep duration and prevalence of fair/poor health was observed only with measuring sleep with survey sleep hours and survey calculated sleep time. In contrast, there was no association between long sleep duration and increased prevalence of fair/poor health by actigraphy. However, I am not fully convinced by their arguments.

    First, the authors well understand the limitation of actigraphy, named Actiwatch Spectrum, for sleep evaluation and the need of validation study of actigraphy against sleep polysomnography. There is a difference between brain activity and physical movement during sleep, and the discrepancy of sleep parameters between polysomnography and actigraphy is obvious for insomniacs [2]. When calculating total sleep time by actigraphy, the authors selected default sleep/awake sensitivity setting (40 counts per minutes), and also carried out a sensitivity analysis with a lower threshold of 20. Although the correlation coefficient between sleep duration with different threshold setting was greater than 0.99, actual sleep duration differs 18 minute in an average. Kushida et al. reported the best sleep/awake threshold of Actiwatch for detecting wakefulness as "high-sensitivity" setting (20 counts per minutes) [3]. Peterson et al. adopted default sleep/awake sensitivity setting of Actiwatch, and described the overestimation of total sleep time and underestimation of wake-after sleep onset [4]. These reports present that level of sleep/awake threshold is important for estimating sleep duration by actigraphy.

    Second, the numbers of subjects in each category of sleep duration seems useful information in their study. The authors described the mean value of sleep duration by survey sleep hours and by actigraph total sleep time were 7.5 hours and 7.2 hours, but the prevalence of fair/poor health in subjects with sleep duration >9 hours by survey sleep hours was two- fold higher than that by actigraph total sleep time. The correlation coefficient between sleep duration by survey sleep hours and by actigraph total sleep time was 0.29, and I suspect that some subjects with long sleep duration by actigraphy do not actually keep enough sleep duration.

    Anyway, sleep polysomnography study is required to confirm the lack of U-shaped association between sleep duration and prevalence of fair/poor health.

    References

    1 Lauderdale DS, Chen JH, Kurina LM, et al. Sleep duration and health among older adults: associations vary by how sleep is measured. J Epidemiol Community Health 2015 Nov 3. doi: 10.1136/jech-2015-206109

    2 Natale V, Leger D, Martoni M, et al. The role of actigraphy in the assessment of primary insomnia: a retrospective study. Sleep Med 2014;15:111-5.

    3 Kushida CA, Chang A, Gadkary C, et al. Comparison of actigraphic, polysomnographic, and subjective assessment of sleep parameters in sleep- disordered patients. Sleep Med 2001;2:389-96.

    4 Peterson BT, Chiao P, Pickering E, et al. Comparison of actigraphy and polysomnography to assess effects of zolpidem in a clinical research unit. Sleep Med 2012;13:419-24.

    Conflict of Interest:

    None declared

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  6. It is important that selecting appropriate reporting guidance

    Dear editor, We have read with great interest the meta-analysis submitted by Li and colleagues1, which investigated the association between fish consumption and depression risk. We warmly and greatly congratulate and applaud for their important work. However, an issue existed in this study should be noted. These authors stated that observational study including cross-sectional, case-control, and cohort study was eligible for their inclusion criteria in inclusion criteria subsection. However, the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA)2 was used to guide reporting their meta-analysis. Important is that the PRISMA is designed to use mainly in systematic review and meta-analysis with randomized controlled trials (RCTs) rather than meta-analysis with observational studies in epidemiology. Controversially, the Meta-analysis of Observational Studies in Epidemiology (MOOSE)3 is developed for reporting this given meta-analysis. And thus, the authors should adopted the MOOSE to guide reporting their meta-analysis on this given topic preferably we suggested in order to further improve reporting quality. 1. Li F, Liu X, Zhang D. Fish consumption and risk of depression: a meta-analysis. J Epidemiol Community Health 2015; doi: 10.1136/jech-2015-206278. 2. Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meya-analyses: the PRISMA statement. J Clin Epidemiol 2009; 62:1006-1012. 3. Stroup DF, Berlin JA, Moton SC, et al. Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis of Observational Studies in Epidemiology (MOOSE) group. JAMA 2000; 283:2008-2012.

    Conflict of Interest:

    None declared

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  7. Stressful psychosocial work and exit from the labour market

    Hintsa et al. examined the effect of effort, reward and job control on the exit from the labour market by a 6-year follow-up study in workers at the age of 61 years or younger [1]. The author adopted binary logistic regression analysis by adjusting several variables, and concluded that effort-reward imbalance (ERI), effort and job control were significant predictors for exit from the labour market. In contrast, reward was not selected as a significant predictor. I have some concerns on their study.

    First, the authors did not use effort, reward and job control simultaneously as independent variables for predicting exit from the labour market. Schmidt et al. recently reported that the sum score of effort significantly increased and the sum score of reward significantly decreased as ERI increased in 4141 samples in Germany [2]. If multicollinearity among independent variables cannot be solved, the simultaneous use of ERI, effort and reward should be handled with caution, because ERI was simply calculated as the logarithmic value of [(sum score of effort)*7]/[(sum score of reward)*3]. But inset of effort and reward simultaneously as independent variables into logistic model seems appropriate, because the authors measured stressful psychological work environment by ERI model, and each factor has a different dimension for psychometry. In addition, simultaneous use of job control from another theoretical stress model should also be considered in combination with ERI model after evaluating multicollinearity.

    Second, statistical results differed by different combination of adjusting variables in their study. The adjusting variables were selected to know the net association between exit from the labour market and effort, reward or job control, and I recommend selecting full-adjudging model in their study. If discrepancies of statistical results by selecting different combination of adjusting variable exist, stability of significance cannot be guaranteed in the statistical model.

    Finally, there are other reasons of exit from the labour market than the causes of working environment. On this point, explanation rate of exit from the labour market by factors form ERI model and job control should be presented. The authors selected workers at the age of 61 years or younger, and cause of exit by family support is suspected especially in women. This would partly be related to the sex differences in the average age of withdrawal from the labour market. Anyway, further study is commended to confirm the causal association.

    References

    1 Hintsa T, Kouvonen A, McCann M, et al. Higher effort-reward imbalance and lower job control predict exit from the labour market at the age of 61 years or younger: evidence from the English Longitudinal Study of Ageing. J Epidemiol Community Health 2015;69:543-9.

    2 Schmidt B, Bosch JA, Jarczok MN, et al. Effort-reward imbalance is associated with the metabolic syndrome - findings from the Mannheim Industrial Cohort Study (MICS). Int J Cardiol 2015;178:24-8.

    Conflict of Interest:

    None declared

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  8. Abnormal liver enzymes and diabetes risk: potential contribution of chronic viral hepatitis was underplayed

    Sir,

    Xu et al report an association between deranged liver enzymes e.g. alanine transaminase (ALT) in Chinese people residing in Southern China and the incidence of diabetes [1].

    The authors examined multiple potential confounding factors which could influence liver enzymes e.g. alcohol consumption & adiposity. However, although the authors briefly mentioned chronic viral hepatitis infections i.e. chronic hepatitis B virus (HBV) & hepatitis C virus (HCV), I think they did not give this confounder sufficient weight and did not report HBV/HCV prevalence data in the cohort studied. This is a significant shortcoming of this study.

    As the authors acknowledged, chronic HBV & HCV are relatively common in China, with the prevalence of chronic HBV of 11.3% for males, 8.2% for females & for chronic HCV 3.1% for males, 3.3% for females [2].

    Therefore, as these are common infections in China, the underlying population prevalence of chronic HBV & HCV infection in the study cohort could account for at least some of the deranged liver enzymes in the study population. Unfortunately, the lack of data on these infections prevents quantitative analysis of the effect these hepatitides may have on the liver enzyme profiles in this cohort.

    The authors acknowledged a possible association between HCV and diabetes, but there is also emerging evidence that chronic HBV infection is associated with insulin resistance [3]. Furthermore, chronic HBV complicated by cirrhosis may be associated with diabetes mellitus [4]. The apparent association between deranged liver enzymes and the development of diabetes may not be due to hepatitis/transaminitis per se, but may reflect underlying specific pathologies such as chronic HBV and HCV.

    The high prevalence of chronic HBV and HCV in the Chinese population and the associations of these infections with insulin resistance & diabetes mellitus means that the authors' conclusions underplay the possible contribution of chronic viral hepatitis to the development of diabetes. Thus, the conclusions should perhaps have included recommendations that patients with deranged liver enzymes should be screened for these viral hepatitis infections, so that they can be considered for antiviral treatment which would be beneficial not just in terms of future diabetes risk, but also the well-known risks of cirrhosis & hepatocellular carcinoma in these patients.


    References:
    1. Xu L, Jian CQ, Schooling CM et al. Liver enzymes and incident diabetes in China: a prospective analysis of 10764 participants in the Guangzhou Biobank Cohort Study. J Epidemiol Community Health 2015;69:1040-1044
    2. Huang H, Hu XF, Zhao FH et al. Estimation of cancer burden attributable to infection in Asia. J Epidemiol 2015 doi:10.2188/jea.JE20140215
    3. Lee JG, Lee S, Kim YJ et al. Association of chronic viral hepatitis B with insulin resistance. World J Gastro 2012;18(42):6120-6126
    4. Zhang J, Shen Y, Cai H et al. Hepatitis B virus infection status and risk of type 2 diabetes mellitus: A meta-analysis. Hepatol Res 2015 doi:10.1111.hepr.12481

    Conflict of Interest:

    None declared

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  9. Potential Challenges to Using Paternal Education as a Proxy for SES

    Oksuzyan et al. report an association between race/ethnicity and two subtypes of childhood leukemia: acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML).1 Accordingly, the researchers suggest that there are genetic, cultural, and environmental factors involved in the etiology of childhood leukaemia [1].

    Importantly, Oksuzyan et al. made a significant effort to examine and control for the potential role of socioeconomic status (SES) on this association. In particular, the authors used paternal education levels used as a proxy for SES given that a significant percentage of information on maternal education was missing from the birth registry used [1]. This strategy faces several challenges given the complex association of race, education, and SES.

    The use of paternal education might not appropriately account for the adverse health effects which might result (at least in part) from residing in single-parent homes. It has been widely documented that children frequently exhibit poor health outcomes in single-parent homes due to causal chain of effects related to parent's education, SES, and income [2]. Moreover, the information regarding paternal education as a proxy for SES was obtained from the California Birth Registry [1]. It is possible that this data does not adequately represent the SES of the cases used in the study given that the father identified might not have provided financial support for the child.

    In addition, the use of parental education as a proxy for SES may not be an appropriate method as average income frequently varies in jobs requiring similar education levels [3]. It is possible that these variations occur more frequently among different ethnic/racial groups; potentially as a result of systemic prejudice and/or unequal employment opportunities [3].

    Oksuzyan et al. report an association between race/ethnicity and childhood leukaemia [1]. Due to potential challenges in using paternal education as a proxy for SES, the inclusion of maternal education and a discussion regarding SES in single-parent homes would have been valuable.

    References

    1 Oksuzyan S, Crespi CM, Cockburn M, Mezei G, Vergara X, Kheifets L. Race/ethnicity and the risk of childhood leukaemia: A case-control study in California. J Epidemiol Community Health Published Online First: 19 March 2015. doi:10.1136/jech-2014-204975

    2 Gucciardi E, Celasun N, Stewart DE. Single-mother families in Canada. Can J Public Health 2004;95(1):70-73.

    3 Williams DR. Race, socioeconomic status, and health. The added effects of racism and discrimination. Ann N Y Acad Sci 1999;896:173-188.

    Conflict of Interest:

    None declared

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  10. Evidence of a lack of beneficial effect of outdoor physical exercise

    Dear sir

    The author commented on the paucity of research on the point where physical exercise in polluted air becomes more harmful than beneficial. I would like to share our research findings conducted more than 10 years ago in Hong Kong (Yu et al, 2004). We compared the physical fitness of school children who regularly performed physical exercise with those who did not. In a less polluted district (annual mean PM10=44.9 ug/m3), children who regularly did physical exercise had significantly better cardiopulmonary fitness (with a higher predicted maximum oxygen update of 1.8 mL/Kg/min among children who did regular exercise). By contrast, among children in a 'high pollution district' (PM10=57.6 ug/m3), there was no significant difference in their cardiopulmonary fitness whether they exercised regularly or not (the difference in VO2 max between children with regular physical exercise and those without was insignificant, at 0.6 mL/Kg/min). The concentration of PM10 in mainland Chinese cities are much higher than our 'high pollution district', and outdoor physical exercise may be more harmful than beneficial.

    Tze Wai Wong

    Reference: Yu ITS, Wong TW, Liu HJ. Impact of air pollution on cardiopulmonary fitness of schoolchildren. Journal of Occupational and Environmental Medicine 2004; 46:946-954.

    Conflict of Interest:

    None declared

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