Abstract:
OBJECTIVE:To determine whether failure to adequately adjust for a reported 40% misclassification of use of in vitro fertilisation (IVF) as reported in a Swedish study could have led to a false finding that folic acid increases dizygotic twinning. DESIGN:Modelling with population based data. SETTING:Swedish vital records for 1995-9. MAIN OUTCOME MEASURES:Rates of twinning calculated according to whether women used IVF to become pregnant. Estimated unadjusted and adjusted odds ratios of the association between use of folic acid and twinning by use of IVF. RESULTS:In 1995-9, Swedish women who used IVF had an almost 20 times the chance of having twins than women who did not use IVF (rate ratio 19.7, 95% confidence interval 18.7 to 20.6). In the absence of a true effect of folic acid, the use of a 40% misclassified surrogate variable to adjust for use of IVF would have resulted in a false finding that folic acid was associated with a more than twofold increase in twinning. CONCLUSION:Use of IVF is a strong confounder because it is associated with both use of folic acid and twinning. Even when misclassification of IVF was reduced to 5%, this bias persisted in the adjusted model. Using a 40% misclassified surrogate to adjust for IVF, as reported in the Swedish study, probably led to a false finding that folic acid increased dizygotic twinning.
journal_name
BMJjournal_title
BMJ (Clinical research ed.)authors
Berry RJ,Kihlberg R,Devine Odoi
10.1136/bmj.38369.437789.82keywords:
subject
Has Abstractpub_date
2005-04-09 00:00:00pages
815issue
7495eissn
0959-8138issn
1756-1833pii
bmj.38369.437789.82journal_volume
330pub_type
杂志文章abstract::A randomised controlled trial of two management regimens was carried out in women patients over 65 years of age with hip fractures. Ninety seven patients were admitted to a designated orthopaedic geriatric unit and 125 to orthopaedic wards. No difference was observed in mortality, length of stay, or placement of patie...
journal_title:BMJ (Clinical research ed.)
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1136/bmj.297.6656.1116
更新日期:1988-10-29 00:00:00
abstract:OBJECTIVE:To obtain information about the computerisation of general practice in Wales, and to enable more effective planning of educational provision for doctors and other primary health care workers. DESIGN:Postal questionnaire sent to all general practices in Wales. SUBJECTS:553 general practices, of which 401 (73...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.303.6794.93
更新日期:1991-07-13 00:00:00
abstract:OBJECTIVE:To provide a comprehensive survey of the content and quality of intervention studies relevant to the treatment of schizophrenia. DESIGN:Data were extracted from 2000 trials on the Cochrane Schizophrenia Group's register. MAIN OUTCOME MEASURES:Type and date of publication, country of origin, language, size o...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.317.7167.1181
更新日期:1998-10-31 00:00:00
abstract:OBJECTIVES:To relate cancer since entry into the Framingham Heart Study with the risk of incident Alzheimer's disease and to estimate the risk of incident cancer among participants with and without Alzheimer's disease. DESIGN:Community based prospective cohort study; nested age and sex matched case-control study. SET...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.e1442
更新日期:2012-03-12 00:00:00
abstract::Physical examination of the cardiovascular system is central to contemporary teaching and practice in clinical medicine. Evidence about its value focuses on its diagnostic accuracy and varies widely in methodological quality and statistical power. This makes collation, analysis, and understanding of results difficult ...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,评审
doi:10.1136/bmj.i3309
更新日期:2016-07-27 00:00:00
abstract:OBJECTIVE:To study prevalence of Turner's syndrome in Denmark and to assess validity of prenatal diagnosis. DESIGN:Study of data on prenatal and postnatal Turner's syndrome in Danish Cytogenetic Central Register. SUBJECTS:All registered Turner's syndrome karyotypes (100 prenatal cases and 215 postnatal cases) during ...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.312.7022.16
更新日期:1996-01-06 00:00:00
abstract:OBJECTIVE:To evaluate the effectiveness of dietary antioxidants in the primary prevention of age related macular degeneration (AMD). DESIGN:Systematic review and meta-analysis. DATA SOURCES:Search of seven databases without limits on year or language of publication, and retrieval of references in pertinent reviews an...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,meta分析,评审
doi:10.1136/bmj.39350.500428.47
更新日期:2007-10-13 00:00:00
abstract:OBJECTIVE:To assess the ability of ultrasonography to identify reflux nephropathy in children after urinary tract infection. DESIGN:Ten experienced radiologists performed a total of 240 ultrasonographic examinations of kidneys in a one day study. The examiners were unaware of the results of previous radiological and c...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.309.6949.235
更新日期:1994-07-23 00:00:00
abstract:OBJECTIVE:To assess the efficacy of a newly developed system for applying continuous or intermittent negative (subatmospheric) extrathoracic pressure in respiratory failure. DESIGN:Uncontrolled clinical trials in infants deteriorating or failing to improve despite standard medical treatment. SETTING:Paediatric and ne...
journal_title:BMJ (Clinical research ed.)
pub_type: 临床试验,杂志文章
doi:10.1136/bmj.299.6710.1253
更新日期:1989-11-18 00:00:00
abstract::The first call for applications to the NHS research and development programme on the interface between primary and secondary care was advertised in February 1994. A total of 674 outline proposals were submitted and 54 (8%) secured funding. Projects have been commissioned in 16 of the 21 priority areas and around 6m po...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.311.7012.1080
更新日期:1995-10-21 00:00:00
abstract:OBJECTIVE:To compare the mortality of patients in a palliative care unit on working days with that on weekends and public holidays. DESIGN:Retrospective database study. SETTING:Palliative care unit in Germany. POPULATION:All admissions to palliative care unit between 1 January 1997 and 31 December 2008. MAIN OUTCOM...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.g7370
更新日期:2014-12-16 00:00:00
abstract::Care in the community for insane people today is more a matter of expert provision than communal support. In consequence, although they are no longer confined to hospital, mentally ill people largely remain marginalised in a society that does not have the resources, nor often the inclination, to take responsibility fo...
journal_title:BMJ (Clinical research ed.)
pub_type: 历史文章,杂志文章
doi:10.1136/bmj.311.7021.1708
更新日期:1995-12-23 00:00:00
abstract:OBJECTIVE:To compare perinatal outcomes in births of women with versus without a history of bariatric surgery. DESIGN:Population based matched cohort study. SETTING:Swedish national health service. PARTICIPANTS:1,742,702 singleton births identified in the Swedish medical birth register between 1992 and 2009. For eac...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.f6460
更新日期:2013-11-12 00:00:00
abstract:OBJECTIVE:To evaluate the association between migraine and cognitive decline among women. DESIGN:Prospective cohort study. SETTING:Women's Health Study, United States. PARTICIPANTS:6349 women aged 65 or older enrolled in the Women's Health Study who provided information about migraine status at baseline and particip...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.e5027
更新日期:2012-08-08 00:00:00
abstract::Monocycline is the most widely prescribed systemic antibiotic for acne largely because it needs to be given only once or twice a day and seems not to induce resistance. Up to April 1994 11 cases of minocycline induced systemic lupus erythematosus and 16 cases of hepatitis had been reported to the Committee on Safety o...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.312.7024.169
更新日期:1996-01-20 00:00:00
abstract:OBJECTIVE:To determine the global capacity (availability, accessibility, quality, and affordability) to deliver kidney replacement therapy (dialysis and transplantation) and conservative kidney management. DESIGN:International cross sectional survey. SETTING:International Society of Nephrology (ISN) survey of 182 cou...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.l5873
更新日期:2019-10-31 00:00:00
abstract:OBJECTIVE:To assess the effectiveness of health checks by nurses in reducing risk factors for cardiovascular disease in patients from general practice. DESIGN:Randomised controlled trial. SETTING:Five urban general practices in Bedfordshire. SUBJECTS:2136 patients receiving an initial health check in 1989-91 and sch...
journal_title:BMJ (Clinical research ed.)
pub_type: 临床试验,杂志文章,随机对照试验
doi:
更新日期:1994-01-29 00:00:00
abstract:OBJECTIVE:To study the comparative importance of environment and genes in the development of islet cell autoimmunity associated with insulin dependent diabetes mellitus. DESIGN:Population based study of diabetic twins. SETTING:Danish population. SUBJECTS:18 monozygotic and 36 dizygotic twin pairs with one or both pa...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.314.7094.1575
更新日期:1997-05-31 00:00:00
abstract::The import of the HIV or AIDS epidemic for heterosexuals in Britain is difficult to evaluate at this stage. By June 1988, only 60 cases of heterosexually acquired AIDS are known, out of 1598 reported AIDS cases. Of these, only 6 women and 4 men presumably were infected in Britain, the rest abroad. But, judging from...
journal_title:BMJ (Clinical research ed.)
pub_type: 社论
doi:10.1136/bmj.298.6671.401
更新日期:1989-02-18 00:00:00
abstract:OBJECTIVE:To investigate the association between treatment induced change in high density lipoprotein cholesterol and total death, coronary heart disease death, and coronary heart disease events (coronary heart disease death and non-fatal myocardial infarction) adjusted for changes in low density lipoprotein cholestero...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,meta分析,评审
doi:10.1136/bmj.b92
更新日期:2009-02-16 00:00:00
abstract:OBJECTIVE:To determine medical students' self awareness and ability to discriminate right from left; to identify characteristics associated with this ability; and to identify any techniques used to aid discrimination. DESIGN:Questionnaire and psychometric study. SETTING:Undergraduate medical school, Northern Ireland....
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.a2826
更新日期:2008-12-16 00:00:00
abstract:OBJECTIVE:To compare blood pressure control, satisfaction, and adherence to drug treatment in patients with treated hypertension followed up by their family physicians either every three months or every six months for three years. DESIGN:Randomised equivalence clinical trial. Settings 50 family practices in south east...
journal_title:BMJ (Clinical research ed.)
pub_type: 临床试验,杂志文章,多中心研究,随机对照试验
doi:10.1136/bmj.37967.374063.EE
更新日期:2004-01-24 00:00:00
abstract:OBJECTIVES:To examine the prospective associations between consumption of sugar sweetened beverages, artificially sweetened beverages, and fruit juice with type 2 diabetes before and after adjustment for adiposity, and to estimate the population attributable fraction for type 2 diabetes from consumption of sugar sweete...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,meta分析,评审
doi:10.1136/bmj.h3576
更新日期:2015-07-21 00:00:00
abstract:OBJECTIVES:To assess, as part of wider inspections by HM Inspectorate of Prisons, the extent and quality of health care in prisons in England and Wales. DESIGN:Inspections based on a set of "expectations" derived mainly from existing healthcare quality standards published by the prison service and existing ethical gui...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.315.7120.1420
更新日期:1997-11-29 00:00:00
abstract:OBJECTIVES:To assess the feasibility and effectiveness of a general practice based, proactive system of asthma care in children. DESIGN:Randomised controlled trial with cluster sampling by general practice. SETTING:General practices in the northern region of the Australian Capital Territory. PARTICIPANTS:174 childre...
journal_title:BMJ (Clinical research ed.)
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1136/bmj.327.7416.659
更新日期:2003-09-20 00:00:00
abstract::The studyEveritt H, Landau G, Little P. Therapist telephone-delivered CBT and web-based CBT compared with treatment as usual in refractory irritable bowel syndrome: the ACTIB three-arm RCT. Health Technol Assess 2019;23:1-154.This project was funded by the NIHR Health Technology Assessment Programme (project number 11...
journal_title:BMJ (Clinical research ed.)
pub_type: 评论,杂志文章
doi:10.1136/bmj.l4962
更新日期:2019-11-04 00:00:00
abstract:OBJECTIVES:To investigate the feasibility of obtaining signed consent for submission of patient identifiable data to a national clinical audit database and to identify factors influencing the consent process and its success. DESIGN:Feasibility study. SETTING:Seven paediatric intensive care units in England. PARTICIP...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,多中心研究
doi:10.1136/bmj.38404.650208.AE
更新日期:2005-04-16 00:00:00
abstract:OBJECTIVE:To estimate the prevalence of emotionalism after stroke, to assess its relation with other mood disorders, and to identify clinical variables with which it is associated. DESIGN:Descriptive study of a cohort of patients consecutively entered on a community stroke register. SETTING:Community based research p...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.298.6679.991
更新日期:1989-04-15 00:00:00
abstract:OBJECTIVES:To estimate survival after a diagnosis of dementia in primary care, compared with people without dementia, and to determine incidence of dementia. DESIGN:Cohort study using data from The Health Improvement Network (THIN), a primary care database. SETTING:353 general practices in the United Kingdom providin...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,多中心研究
doi:10.1136/bmj.c3584
更新日期:2010-08-05 00:00:00
abstract:OBJECTIVE:To compare the rate of moderate to severe exacerbations between triple therapy and dual therapy or monotherapy in patients with chronic obstructive pulmonary disease (COPD). DESIGN:Systematic review and meta-analysis of randomised controlled trials. DATA SOURCES:PubMed, Embase, Cochrane databases, and clini...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,meta分析
doi:10.1136/bmj.k4388
更新日期:2018-11-06 00:00:00