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Recent eLetters

Displaying 1-10 letters out of 322 published

  1. Comparing the incomparable may be erroneous .

    Dear Editor: We peruse with interest the interesting study by Meng Lee et al (1). We would like to share the followings:

    1.One of the strengths of any retrospective data analysis is the acceptance/compliance with therapy in the real-life situation ( whatever the compliance rate may be).The exclusion of 1632 patients ( 42% of the total) because of medication possession ratio <80% has limited the external validity of the study.

    2.Excluding 355 patients (9% of the total) further because of Atrial fibrillation, valvular heart diseases or coagulopathy may not be justified ( if they were put either on aspirin or clopidogrel ,they should have been included).

    3.During the follow-up period, statin and diuretics were used more frequently ( statistically significant) in the clopidogrel group. It is well known that statin and diuretics reduce ischemic strokes (2,3).Thus tilting the balance in favor of clopidogrel.

    4.Much less patients were put on clopidogrel (384 patients) versus aspirin (1500 patients),even the best statistical model may not be able to completely nullify the bias as the disparity is substantial.

    As the above mentioned limitations are influential, the results of the study may be biased and should be interpreted with caution.

    References

    1.Meng Lee, Yi-Ling Wu, Jeffrey L Saver, Hsuei-Chen Lee, Jiann-Der Lee,Ku-Chou Chang, Chih-Ying Wu, Tsong-Hai Lee, Hui-Hsuan Wang, Neal M Rao, and Bruce Ovbiagele.Is clopidogrel better than aspirin following breakthrough strokes while on aspirin? A retrospective cohort study. BMJ Open 2014 4:e006672; doi:10.1136/bmjopen-2014-006672

    2.Pierre Amarenco, Julien Labreuche.Lipid management in prevention of stroke:review and updated meta-analysis od statin for stroke prevention.The Lancet Neurology. 2009;8(5):453-463.doi:1016/s1474-4422(09) 70058-4

    3.PROGRESS Collaborative group. Randomised trial of a perindopril- based blood pressure-lowering regimen among 6105 individuals with previous stroke or transient ischemic attack.The Lancet. 2001;358:9287,1033-1041. doi:10.1016/s014-6736(01)06178-5

    Conflict of Interest:

    None declared

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  2. RE: Low-fats and not low-carbs for better diabetes control in Indians

    Dear Editor

    I wish to address the eLetter responding to our recently published article in BMJ Open (Joshi SR, et al. Results from a dietary survey in an Indian T2DM population: a STARCH study. BMJ Open. 2014 Oct 31;4(10):e005138.) Firstly, thank you to Prof.Vishnupriya R Paturi for taking the time to read our article and providing feedback. We believe that the impact and relative importance that the type or source of carbohydrate has on postprandial glucose level has continued to be an area of debate. However, many studies highlights that the dietary carbohydrate determines the postprandial blood glucose response. Garg A & Parillo M reported that dietary carbohydrate increases blood glucose concentrations, particularly in the postprandial period. Therefore, in diabetic patients, particularly those treated with insulin or who have more severe forms of type 2 diabetes, a carbohydrate-rich diet can have detrimental effects on glycemic control, which plays a major role in the development of coronary artery disease and other macrovascular and microvascular complications (1,2). In parallel with the plasma glucose rise, plasma insulin and triacylglycerol concentrations also tend to increase with a high- carbohydrate diet, along with other cardiovascular disease risk factors(3). Although, it is known that not all carbohydrate-rich foods are equally hyperglycemic: differences in the postprandial blood glucose response to various carbohydrate-containing foods have been shown in both healthy subjects and diabetic patients, even when consumed in portion sizes containing identical amounts of carbohydrate. It was observed that carbohydrate-rich foods represent a heterogeneous category and, therefore, may have a variable effect on energy and substrate metabolism in humans. (4-6). The American Diabetes Association reviewed the available scientific data regarding the effect of the type or source of carbohydrate on the prevention and management of diabetes and suggested the following statements: [7] * The component of the diet that has the greatest influence on blood glucose is carbohydrate. However, other macronutrients in the diet, i.e., fat and protein, can influence the postprandial blood glucose level. * Regulation of blood glucose to achieve near-normal levels is a primary goal in the management of diabetes, and, thus, dietary techniques that limit hyperglycemia following a meal are likely important in limiting the complications of diabetes. * Low-carbohydrate diets are not recommended in the management of diabetes. Although dietary carbohydrate is the major contributor to postprandial glucose concentration, it is an important source of energy, water-soluble vitamins and minerals, and fiber. * Both the amount (grams) of carbohydrate as well as the type of carbohydrate in a food influence blood glucose level. * The maintenance of a healthy body weight is strongly recommended as a means of preventing this disease, because much of the risk of developing type 2 diabetes is attributable to obesity,

    Also most experts agree that the total carbohydrate intake from a meal or snack is a relatively reliable predictor of postprandial blood glucose. Thus in addition to advice fat proportions in diets, monitoring total grams of carbohydrate, whether by use of exchanges or carbohydrate counting, remains a key strategy in achieving glycemic control.In our study, we suggested the need to investigate further the benefit of various therapeutic interventions in high carbohydrate-consuming Indian type-2 diabetes mellitus participants in a prospective randomised controlled study.

    References: 1.Garg A, Bonanome A, Grundy SM, et al. Comparison of a high carbohydrate diet with a high-monounsaturated-fat diet in patients with noninsulin- dependent diabetes mellitus. N Engl J Med 1988;319:829 -34. 2.Parillo M, Giacco R, Ciardullo AV, et al. Does a high carbohydrate diet have different effects in NIDDM patients treated with diet alone or hypoglycemic drugs? Diabetes Care 1996;19:498 -500. 3.Rivellese A, Giacco R, Genovese S, et al. Effects of changing amount of carbohydrate in diet on plasma lipoproteins and apolipoproteins in type II diabetic patients. Diabetes Care 1990;13:446-8. 4.Coulston AM, Hoolenbeck CB. Swislocki AML, et al. Deleterious metabolic effects of high carbohydrate, sucrose containing diets in patients with NIDDM. Am J Med 1987;82:213-20. 5.O'Dea K, Nestel R, Autonoff L. Physical factors influencing postprandial glucose and insulin responses to starch. Am J Clin Nutr 1980;33:760-5. 6.Liljeberg H, Granfeldt Y, Bjorck I. Metabolic responses to starch in bread containing intact kernels versus milled flour. Eur J Clin Nutr 1992;46:561-5. 7.Nancy F. Sheard, et al. Dietary Carbohydrate (Amount and Type) in the Prevention and Management of Diabetes. Diabetes Care 2004; 27(9):2266- 2271

    Conflict of Interest:

    Competing interests SRJ: Author: Bayer Zydus Pharma; Speaker: Sanofi, Abbott, USV, Franco Indian, Ranbaxy, PHFI, MSD, Novartis, J & J, Roche Diagnostics, Novo Nordisk, Marico, Emcure; Consultant, Investigator: Bayer Zydus Pharma; Research Support: Bayer Zydus Pharma; AB: Research Grant: Bayer Zydus Pharma

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  3. NCCAM

    CAM includes both complementary and alternative practices. Alternative practices, by definition, either have not been proven to work, or have been proven not to work. Complementary practices have always been mainstream and many are evidence-based. There is no sound scientific or medical justification for analysing the two together. Alternative practitioners may prefer them to be considered together, as this may provide a halo effect of legitimacy from being considered alongside obviously valid concepts such as diet and exercise, but in analysing the cost-effectiveness of these interventions it seems to me rather important to unpick the two.

    For example, any judgment of the validity of medical training in nutrition cannot possibly shed light on the validity of training in a refuted dogma such as homeopathy or reiki.

    It is plausible that autohypnosis may be able to materially benefit patients with anxiety disorders. It is wholly implausible that homeopathy would deliver any objectively provable benefit at all. To consider the two jointly, is to needlessly muddy the waters.

    The authors reference the US National Center for Complementary and Alternative Medicine (NCCAM), a body set up at the instigation of a pro- CAM legislator to investigate and produce evidence around CAM interventions.

    Dr. David Gorski has been looking closely at NCCAM for some years, along with several colleagues. They have noted that NCCAM has spent in excess of one billion dollars since its inception in 1993. To date, they have failed to validate a single alternative intervention. They have produced supportive evidence for massage therapy (which is scarcely controversial), but not for any of the alternative therapies tested - many of which are by now considered refuted though still doggedly promoted by believers.

    I would suggest the authors do their best in future to unpick the effects of legitimate and medically plausible complementary therapies, from those of alternative therapies. This will reduce the risk of their research being abused by advocates as support for therapies which, of themselves, have little or no provable validity.

    In the light of surveys showing that large numbers of doctors knowingly prescribe placebos, it would also be valuable to understand how many of the doctors using CAM therapies consider them to be valid interventions and administer them on that basis.

    Conflict of Interest:

    None declared

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  4. Prevention of Risk Factors: Eat and Have Physical Activity What Our Grandparents Used to Have.

    "Let food be thy medicine and medicine be thy food." Hippocrates

    We read with interest the study by T.Sekhri,R.S.Kanwar et al(1).The authors needs to be congratulated for such a meticulous and unique study involving subjects from all over India.The study is first of its kind in India and an eye-opener. However,the following issues we shall like to share:

    1.As it was a non-interventional and free-of-cost to the participating subjects study.Why only 14,500 subjects( 55%) gave the informed consent out of approximately 26,000.It may be worth mentioning some important reasons of this rather less acceptance for the study.This low level of participation compromises the external validity of the study.

    2.The subjects with known coronary artery disease (CAD) were excluded.It would have been interesting to know how many subjects with newly discovered CAD were detected,including silent old MI pattern in ECG.

    3.As mentioned in the introduction of the study(1),over 60% of CAD in native Indians remain unexplained by conventional risk factors,why only conventional risk factors were considered in the study.

    4.Gainfully,in the protocol,disease history is included,it would have been relevant to know about the other diseases and if any correlation with the risk factors could have been made. Like patients with depression/psychiatric morbidity (common diseases these-days)and obstructive sleep apnea have much worse risk factor profile and are increasing recognized as novel risk factors per se. Interestingly in women( obstetric history was ascertained),any correlation with adverse obstetric history and risk factor profile was observed?.The data is rapidly accumulating between adverse obstetric history and development of cardiovascular disease in future(2).

    5.In the present study interestingly only 27% of hypertensives were aware about their condition ( 73% were newly discovered).A rather lower percentage particularly for civilian government employee,having free access to the medical services.

    6.78.6% of the subjects had two or more risk factors is a disturbing fact.In Prabhakaran's study(3) in 2005 amongst industrial workers of north India 47% subjects had atleast two risk factors.Is it a temporal trend or the difference is due to the location of the subjects in the study,needs to be explained.

    The study emphasized the disturbing trend in the health status in India and serious thoughts and actions are needed to contain this unabated epidemic.What will be the peak of the epidemic is anybody's guess. However, we have the following suggestions to offer:

    1.When the epidemic reaches this gigantic proportion,secondary and tertiary prevention have very limited impact at a community level.

    2.The primordial and primary prevention assume huge importance. As they are much more cost-effective and result yielding.

    3.For Primordial prevention and primary prevention ,in a nutshell the message is : to eat and try to assume the level of physical activity and lifestyle ( may not be possible for everyone) similar to what our grandparents used to have.

    4.To counteract the adverse health consequences of modern life .We advocate three levels of prevention: health education, health education and health education of the entire world ( in particular developing world), with emphasis upon educating health policy - makers.

    References

    1.T Sekhri, R S Kanwar, R Wilfred, P Chugh, M Chhillar, R Aggarwal, Y K Sharma, J Sethi, J Sundriyal, K Bhadra, S Singh, N Rautela, Tek Chand, M Singh, and S K Singh.Prevalence of risk factors for coronary artery disease in an urban Indian population. BMJ Open 2014 4:e005346; doi:10.1136/bmjopen-2014-005346

    2.Bellamy L,Casas JP,Hingorani AD,Williams DJ.Pre-eclampsia and risk of cardiovascular disease and cancer in later life:Systematic review and meta-analysis.BMJ.2007;335:974

    3.Prabhakaran D, Shah P, Chaturvedi V, et al. Cardiovascular risk factor prevalence among men in a large industry of northern India. Natl Med J India 2005;18:59-65.

    Conflict of Interest:

    None declared

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  5. Cause of the nodding syndrome

    Landis et al. describe a temporal association between wartime conflict, internal displacement, and Nodding syndrome (NS)(1). They raise infectious, nutritional and neuropsychiatric elements as possible causal factors. The authors, however, do not mention a key factor that may have played a major role during the NS epidemic in northern Uganda: a lack of ivermectin treatment in onchocerciasis endemic areas.

    Mass-distribution of ivermectin is routinely used to interrupt onchocerciasis transmission in endemic foci, and an association between NS and onchocerciasis has repeatedly been reported (2). NS only occurs in onchocerciasis hyperendemic areas, and other forms of epilepsy are also thought to be highly prevalent in many of these regions(3).

    During the civil war in northern Uganda (1986-2006/2008), there was no access to ivermectin in districts affected by NS, and it was only after the war that ivermectin treatment programmes were established. Ivermectin has been distributed annually in NS-affected districts since 2008, and biannually since 2012 (2). This has coincided with a dramatic drop in the number of new NS cases, and no new cases were officially reported in 2013 (4). The ivermectin distribution programme in northern Uganda was supplemented by control measures targeting blackflies (Simuliidae), the vectors of onchocerciasis, in late-2012. The Achwa and Pager rivers were initially treated with larvicides applied from boats and light aircraft, and larval breeding sites are now being treated with the organophosphate, temephos, at predefined points along the rivers (2). We believe that this integrated approach, targeting both the vectors of onchocerciasis and the parasite in the human population, has contributed to the reduction of NS cases in northern Uganda.

    The link between NS and onchocerciasis appears to be further reinforced by a recent study which suggests that an antibody-mediated autoimmune response to leiomodin-1 may be involved in the etiology of NS. Johnson et al. have demonstrated that antibodies against leiomodin-1 are more likely to be present in NS cases than in controls (5). These antibodies are also present in the cerebrospinal fluid of certain patients with NS, are neurotoxic in vitro, and cross-react with Onchocerca volvulus -specific proteins.

    We do not believe that NS can be explained by events only related to war. In the Mahenge NS-focus in Tanzania, there is no recent history of conflict or household internment. Hypotheses regarding NS etiology should be based on information from all affected regions.

    Further research is needed to explore whether NS is caused by an auto -immune reaction in response to Onchocerca volvulus infection; whether the species or strain of Onchocerca is unique in NS-affected areas, or whether NS is caused by a currently unidentified agent transmitted by blackflies (6).

    R. Colebunders, K. Coudere, N. Van der Moeren, A Hendy

    Reference List

    (1) Landis JL, Palmer VS, Spencer PS. Nodding syndrome in Kitgum District, Uganda: association with conflict and internal displacement. BMJ Open 2014;4(11):e006195.

    (2) Colebunders R, Post R, O'Neill S, Haesaert G, Opar B, Lakwo T et al. Nodding syndrome since 2012: recent progress, challenges and recommendations for future research. Trop Med Int Health 2014 October 28.

    (3) Pion SD, Kaiser C, Boutros-Toni F, Cournil A, Taylor MM, Meredith SE et al. Epilepsy in onchocerciasis endemic areas: systematic review and meta-analysis of population-based surveys. PLoS Negl Trop Dis 2009;3(6):e461. (4) Ministry of Health, Uganda. Weekly epidemiological bulletin. 2014.

    (5) Johnson T, Tyagi R, Lee PR, Leea M-h, Johnson KR, Kowalak J, Medynets M, Hategan A, Nutman TB, Sejvar J, Makumbi I, Aceng JR, Dowell SF, Nath A. Detection of auto-antibodies to leiomodin-1 in patients with nodding syndrome. j.jneuroim , 103. 2014.

    (6) Colebunders R, Hendy A, Nanyunja M, Wamala JF, van OM. Nodding syndrome-a new hypothesis and new direction for research. Int J Infect Dis 2014 August 23;27C:74-7.

    Conflict of Interest:

    None declared

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  6. Reply to Ole Olsen (2)

    Thanks to statistician Ole Olsen who again expresses his concern about the validity of the data in the National Birth Registry, and the inconsistent reporting of these data on the official on-line sites. This time Ole Olsen, however, goes one step further. Now he demands the editors of BMJ open to ensure "documentation of the validity of all variables for all years in the study period".

    To validate all recorded birth related diagnosis and procedural codes over a time span of 13 years, during which more 829,000 women have delivered, would require providing the clinical notes of a representative sample of these deliveries to see first, if all the relevant codes were recorded appropriately, and secondly, if any non-relevant codes had been recorded. Fortunately such validation studies have been made, demonstrating a general high validity of the recorded obstetrical diagnosis and procedural codes in the National Health Registry, which feeds the Danish Birth Registry (1).

    The main variables used for our study were calendar years, the gestational age of delivering women, and the codes assessing stillbirth. As reported, the gestational age was recorded in 99.4 % of all deliveries, and has been found to have a high validity (1). The same applies to the codes for stillbirths, which is generally considered as a "hard" end point. We have previously indicated how we assessed stillbirths (2).

    So the remaining question is whether other circumstances than the earlier induction practice could explain the encouraging substantial decline in stillbirths - not whether such a decrease actually occurred. Considering the dramatic increase in risk of stillbirth with increasing gestational age, it is not surprising that moving deliveries from high- risk post-term weeks to earlier weeks with substantial lower risk of intrauterine death would decrease the overall stillbirth rate from 37 gestational weeks. This is possibly not a very welcome message for people like Ole Olsen, who for many years has argued for home deliveries, but it does not make the scientific evidence less valid. Ole Olsen indicates specifically, that the recording of induction of labour may have had a lower validity than ideal. However this variable was used only for descriptive purposes in our study, to demonstrate the increasing proportion of inductions of deliveries from 12.4% to 25.2% during the study period. If some of the codes used to assess labour induction have been prone to variation between departments, which is not unlikely, these circumstance would not change anything in our analysis or in our conclusion.

    As Ole Olsen also demonstrates, there have been several attempts to ensure the validity and standardisation of obstetrical coding in Denmark. This has been done through national guidelines elaborated by the Danish Society of Obstetrics and Gynaecology (DSOG)(3), and by annual meetings where these registration rules are discussed and posted solid. These attempts are expected generally to have improved the registration practice in Denmark by time.

    The experiences Ole Olsen and his midwife collaborators Rydahl and Clausen have had by getting access to data in the Danish Birth Registry, and the inconsistencies in the official online statistics are - again - not our responsibility and should be addressed to the relevant bodies.

    About data sharing, one of the strengths about Danish registry research is that these registry data are available for all scientists, including Ole Olsen, who want to investigate any obstetrical question.

    Based on the high validity of the diagnosis codes used in our study, we are still confident with our analyses, and with the conclusions drawn.

    1) Langhoff-Roos J, Rasmussen S. [Validation of the National Health Registry concerning obstetrical research and quality assurance][In Danish]. National Health Board 2003. Page 1-193.

    2) Lidegaard O. Reply to Rydahl and Clausen. BMJ open 2014, October 13, 2014.

    3) https://dsog.squarespace.com/obstetrik/. Accessed December 4, 2014.

    Conflict of Interest:

    See original article

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  7. Re:Response to the A population-based observational study of diabetes during pregnancy in Victoria, Australia article

    Dear Editor

    I wish to address the eLetter responding to our recently published article in BMJ Open (Abouzeid M, Versace VL, Janus ED, et al. A population -based observational study of diabetes during pregnancy in Victoria, Australia, 1999-2008). Firstly, thank you to Wigdan Farah for taking the time to read our article and providing positive feedback. Specifically they suggest that we add the variable 'socio-economic status' (SES) to our analysis. They cite the paper by Nomura Y, Marks DJ, Grossman B, et al. (2012) in Archives of Pediatrics & Adolescent Medicine as an example of the influence of SES on health outcomes. We are pleased to advise that we have just had an article accepted by PLoS One entitled 'Socio-cultural disparities in GDM burden differ by maternal age at first delivery' (accepted December 2nd, 2014, Abouzeid M, Versace V, Janus E, et al.). We encourage Wigdan Farah to access this article once it appears online in the near future.

    Kind regards

    Abouzeid M, Versace VL, Janus ED, M-A Davey M-A, Philpot B, Oats J, and Dunbar JA

    Articles cited

    1. Abouzeid M, Versace VL, Janus ED, et al. A population-based observational study of diabetes during pregnancy in Victoria, Australia, 1999-2008. BMJ Open. 2014;4(11):e005394.

    2. Nomura Y, Marks DJ, Grossman B, et al. Exposure to gestational diabetes mellitus and low socioeconomic status: effects on neurocognitive development and risk of attention-deficit/hyperactivity disorder in offspring. Arch Pediatr Adolesc Med. Apr 2012;166(4):337-343.

    3. Abouzeid M, Versace VL, Janus ED, et al. Socio-cultural disparities in GDM burden differ by maternal age at first delivery.(Accepted December 2nd, 2014). PLoS One.

    Conflict of Interest:

    None declared

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  8. Re:Is self-identification as 'obese' really a public health solution?

    Dr Ian Brown rightly highlights the potential dangers of an atmosphere of stigma around weight, and suggests that rejection of the term 'obese' may be protective of body self-esteem (1). This is an important point, as the term 'obese' is clearly perceived as stigmatising by many, and perceived stigma has been associated with poorer weight outcomes as well as psychological distress (2). However, our perspective is that the specific terminology used to discuss body weight may be less important than there being a common language shared between health professionals, the research community, media and the public. At present, clinically descriptive approaches to weight classification are severely out of kilter with the way in which the public perceives body weight, which must impede individuals' ability to access information and make informed decisions about their own health and lifestyle.

    Meanwhile, a valuable asset in tackling weight stigma could be a far greater public understanding that there is no level playing field when it comes to body weight. It is well recognised in the research community that there are strong genetically-mediated predispositions that mean that some individuals are more susceptible to weight gain, and make the challenge of weight management in an obesogenic environment far greater for them. This fact does not seem widely understood by the public or discussed in the media (3, 4), and greater awareness of this could contribute to less judgemental (and self-blaming) attitudes towards difficulties with weight control (5).

    Ultimately the best solution to the problem of high levels of population obesity lies in reversing the trajectory of the food environment, but progress toward this is minimal at present. In the meantime, the lack of effective channels of communication about weight must be a formidable obstacle to fostering the knowledge and skills required to manage the difficulties of living in an obesogenic society.

    1. Brown, I. Is self-identification as 'obese' really a public health solution? BMJ Open. 2014 Letter (Response to Johnson F, et al. BMJ Open 2014; 4(11):e005561. doi: 10.1136/bmjopen-2014-005561) 2. Jackson SE, Beeken RJ, Wardle J. Perceived weight discrimination and changes in weight, waist circumference, and weight status. Obesity (Silver Spring). 2014 Dec;22(12):2485-8. 3. Beeken RJ, Wardle J. Public beliefs about the causes of obesity and attitudes towards policy initiatives in Great Britain. Public Health Nutr. 2013 Dec;16(12):2132-7. 4. Sikorski C, Luppa M, Kaiser M, Glaesmer H, Schomerus G, K?nig HH, Riedel-Heller SG. The stigma of obesity in the general public and its implications for public health - a systematic review. BMC Public Health. 2011 Aug 23;11:661. doi: 10.1186/1471-2458-11-661. 5. Meisel SF, Wardle J. 'Battling my biology': psychological effects of genetic testing for risk of weight gain. J Genet Couns. 2014 Apr;23(2):179 -86.

    Conflict of Interest:

    Authors of the original research article

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  9. Still need for validation of the data

    I am still concerned about the validity of the data used in the paper "Reduction in stillbirths at term after new birth induction paradigm: results of a national intervention" (1). The paper covers the time period 2000-2012. Lack of validity of the used registry data was documented in 2003 (2) and serious concern about the validity of the data in the registries still exist.

    For the year 2001 the validity of the data in the registers was thoroughly investigated for all Danish births during one specific week by comparing register data with data extracted from patient records by two senior obstetricians (2). In a 192 page report in Danish the authors conclude that "you cannot use the registered interventions to calculate the rates of induction of birth [my translation]" (2) and they note that "the use of the codes in the register is different from one hospital to the other" (2). The work in the report had been initiated because "Since the medical birth registration [...] was transferred to electronic reporting to the National Patient Register (LPR), there has been uncertainty about the quality of the reported data and a growing need for a current validation and a prospective quality improvement of registration practice" (2). Particularly "the lack of feedback from the Board of Health gave uncertainty about the validity of the data reported among health professionals, who entered data, and clinical researchers who used the data" (2). I would appreciate if the authors of the paper (1) could explain how they have overcome this problem for the early years of their study period.

    For the more recent years in the study period I have previously documented several large inconsistencies in annual stillbirth rates between the paper published in this journal (1) and the official published national statistics (comment published 10th September 2014) and Rydahl and Clausen have brought attention to unexplained and dramatic retrospective changes in the online electronic register that supplied data to the paper (7th October). In a joint newspaper commentary leading Danish obstetricians and midwives state "access to the data has been difficult, costly and time consuming" (3), and they add that "[u]nfortunately, we are no longer able to use the data to navigate in everyday clinical practice. Data not used regularly lose their immediate value - proper registration requires motivation and ongoing feedback" (3). The latter concern is identical to the concern issued ten years earlier (2). I would appreciate if the authors of the paper (1) could explain in sufficiently transparent detail how they have overcome the inconsistencies, variability and motivational problems for the middle and late years of their observation period and ensured validity of their data.

    Editors are responsible for everything published in their journals and should ensure the quality of the material they publish (4). I thus ask the editors of BMJ Open to ensure transparent documentation of the validity of all variables for all years in the study period. I also propose that the authors publish and share data and documentation with other researchers on the web as it is encouraged by The BMJ (5).

    1. Hedegaard M, Lidegaard O, Skovlund CW, M?rch LS, Hedegaard M. Reduction in stillbirths at term after new birth induction paradigm: results of a national intervention. BMJ Open. 2014 Aug 14;4(8)

    2. Sundhedsstyrelsen, Center for Evaluering og Medicinsk Teknologivurdering. Validering af Landspatientregistret (LPR) med henblik p? obstetrisk forskning og kvalitetssikring - et kvalitetsudviklingsprojekt [Validation of the National Patient Register (LPR) in relation to obstetric research and quality - a quality development project]. Sundhedsstyrelsen, Copenhagen 2003.

    3. Krebs L, Langhof-Roos J, Petersen KR, Bondo L. Sundhedsstyrelsen gemmer vigtig viden om f?dsler [National Board of Health hides important information on births]. Politiken, 14. okt. 2013 [at http://politiken.dk/debat/debatindlaeg/ECE2102941/sundhedsstyrelsen-gemmer -vigtig-viden-om-foedsler/; accessed 25. Nov 2014].

    4. Kleinert S & Wager E (2011) Responsible research publication: international standards for editors. A position statement developed at the 2nd World Conference on Research Integrity, Singapore, July 22-24, 2010. Chapter 51 in: Mayer T & Steneck N (eds) Promoting Research Integrity in a Global Environment. Imperial College Press / World Scientific Publishing, Singapore (pp 317-28). (ISBN 978-981-4340-97-7)

    5. The BMJ. Data sharing [at http://www.bmj.com/about-bmj/resources- authors/article-types/research; accessed 25. Nov 2014].

    Conflict of Interest:

    None declared

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  10. Responce to the A population-based observational study of diabetes during pregnancy in Victoria, Australia article

    Dear Editor,

    I am writing to support the author in their outcomes and to add one point to their article "A population-based observational study of diabetes during pregnancy in Victoria, Australia 'from the British Medical Journal on November 14th, 2014 1

    It is an interesting article specially with the significant side effect of diabetes during pregnancy and I suggest the author to add the socioeconomic status as one of the study variable, depending on the Exposure to Gestational Diabetes Mellitus and Low Socioeconomic Status Effects on Neurocognitive Development and Risk of Attention-Deficit Hyperactivity Disorder in Offspring study 2,which showed that maternal gestational diabetes and low socioeconomic status were associated with an approximately 2-fold increased risk for ADHD at age 6 years, impaired neurobehavioral functioning, including lower IQ, poorer language, and impoverished behavioral and emotional functioning.

    Sincerely, Wigdan Farah Research Trainee Preventive Medicine Department Mayo Clinic Rochester, MN

    References: 1. Abouzeid M, Versace VL, Janus ED, et al. A population-based observational study of diabetes during pregnancy in Victoria, Australia, 1999-2008. BMJ Open. 2014;4(11):e005394.

    2. Nomura Y, Marks DJ, Grossman B, et al. Exposure to gestational diabetes mellitus and low socioeconomic status: effects on neurocognitive development and risk of attention-deficit/hyperactivity disorder in offspring. Arch Pediatr Adolesc Med. Apr 2012;166(4):337-343.

    Conflict of Interest:

    None declared

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