Abstract:
OBJECTIVE:To examine whether the association of inadequate or unclear allocation concealment and lack of blinding with biased estimates of intervention effects varies with the nature of the intervention or outcome. DESIGN:Combined analysis of data from three meta-epidemiological studies based on collections of meta-analyses. DATA SOURCES:146 meta-analyses including 1346 trials examining a wide range of interventions and outcomes. MAIN OUTCOME MEASURES:Ratios of odds ratios quantifying the degree of bias associated with inadequate or unclear allocation concealment, and lack of blinding, for trials with different types of intervention and outcome. A ratio of odds ratios <1 implies that inadequately concealed or non-blinded trials exaggerate intervention effect estimates. RESULTS:In trials with subjective outcomes effect estimates were exaggerated when there was inadequate or unclear allocation concealment (ratio of odds ratios 0.69 (95% CI 0.59 to 0.82)) or lack of blinding (0.75 (0.61 to 0.93)). In contrast, there was little evidence of bias in trials with objective outcomes: ratios of odds ratios 0.91 (0.80 to 1.03) for inadequate or unclear allocation concealment and 1.01 (0.92 to 1.10) for lack of blinding. There was little evidence for a difference between trials of drug and non-drug interventions. Except for trials with all cause mortality as the outcome, the magnitude of bias varied between meta-analyses. CONCLUSIONS:The average bias associated with defects in the conduct of randomised trials varies with the type of outcome. Systematic reviewers should routinely assess the risk of bias in the results of trials, and should report meta-analyses restricted to trials at low risk of bias either as the primary analysis or in conjunction with less restrictive analyses.
journal_name
BMJjournal_title
BMJ (Clinical research ed.)authors
Wood L,Egger M,Gluud LL,Schulz KF,Jüni P,Altman DG,Gluud C,Martin RM,Wood AJ,Sterne JAdoi
10.1136/bmj.39465.451748.ADsubject
Has Abstractpub_date
2008-03-15 00:00:00pages
601-5issue
7644eissn
0959-8138issn
1756-1833pii
bmj.39465.451748.ADjournal_volume
336pub_type
杂志文章abstract:OBJECTIVE:To evaluate the association between use of hormone replacement therapy and the risk of idiopathic venous thromboembolism. DESIGN:Population based case-control study. SETTING:Population enrolled in the General Practice Research Database, United Kingdom. SUBJECTS:A cohort of 347,253 women aged 50 to 79 witho...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.314.7083.796
更新日期:1997-03-15 00:00:00
abstract:OBJECTIVE:To examine the effectiveness of post-diagnosis dementia treatment and coordination of care by memory clinics compared with general practitioners. DESIGN:Multicentre randomised controlled trial. SETTING:Nine memory clinics and 159 general practitioners in the Netherlands. PARTICIPANTS:175 patients with a ne...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,多中心研究,随机对照试验
doi:10.1136/bmj.e3086
更新日期:2012-05-15 00:00:00
abstract:OBJECTIVE:To assess treatment related changes in quality of life up to 15 years after diagnosis of localised prostate cancer. DESIGN:Population based, prospective cohort study with follow-up over 15 years. SETTING:New South Wales, Australia. PARTICIPANTS:1642 men with localised prostate cancer, aged less than 70, an...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.m3503
更新日期:2020-10-07 00:00:00
abstract:OBJECTIVES:To determine clinical correlates and outcome of hypoxaemia in children admitted to hospital with an acute lower respiratory tract infection. DESIGN:Prospective cohort study. SETTING:Paediatric wards of the Royal Victoria Hospital and the hospital of the Medical Research Council's hospital in Banjul, the Ga...
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.318.7176.86
更新日期:1999-01-09 00:00:00
abstract:OBJECTIVE:To assess the cost effectiveness of different screening strategies for abdominal aortic aneurysm in men, from the perspective of a national health service. SETTING:Screening units at regional hospitals. PARTICIPANTS:Hypothetical cohort of 65 year old men from the general population. MAIN OUTCOME MEASURES:C...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.e4276
更新日期:2012-07-05 00:00:00
abstract:OBJECTIVE:To synthesise the views of patients and carers in decision making regarding treatment for chronic kidney disease, and to determine which factors influence those decisions. DESIGN:Systematic review of qualitative studies of decision making and choice for dialysis, transplantation, or palliative care, and them...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,评审
doi:10.1136/bmj.c112
更新日期:2010-01-19 00:00:00
abstract:OBJECTIVE:To determine the risk of chronic kidney disease in patients with psoriasis. DESIGN:Population based cohort study and nested cross sectional study. SETTING:Electronic medical records database based in United Kingdom. PARTICIPANTS:Cohort study: patients with psoriasis aged 18-90 each matched to up to five pa...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.f5961
更新日期:2013-10-15 00:00:00
abstract:OBJECTIVE:To estimate the effectiveness of delivering an anthelmintic through a community child health programme on the weight gain of preschool children in Uganda. DESIGN:Cluster randomised controlled trial. SETTING:Eastern Uganda. PARTICIPANTS:48 parishes participating in a new programme for child health: 24 offer...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,随机对照试验
doi:10.1136/bmj.38877.393530.7C
更新日期:2006-07-15 00:00:00
abstract:PROBLEM:Zimbabwe has one of the highest rates of HIV seroprevalence in the world. In 2001 only 4% of women and children in need of services for prevention of mother to child transmission of HIV were receiving them. DESIGN:Pilot implementation of the first programme for prevention of mother to child transmission of HIV...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.329.7475.1147
更新日期:2004-11-13 00:00:00
abstract::Managed care has entered the lexicon of healthcare reform, but confusion and ignorance surround its meaning and purpose. It seeks to cut the costs of health care while maintaining its quality, but the evidence that it is able to achieve these aims is mixed. As well as raising awareness and understanding of the issues ...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,评审
doi:10.1136/bmj.314.7097.1823
更新日期:1997-06-21 00:00:00
abstract:OBJECTIVE:To explore the suitability of a screening based intervention for excessive alcohol use by describing the experiences of general practitioners who tried such an intervention in their everyday practice. DESIGN:Qualitative interviews with general practitioners who had participated in a pragmatic study of a comb...
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.325.7369.870
更新日期:2002-10-19 00:00:00
abstract:OBJECTIVE:To assess the impact of Stepping Stones, a HIV prevention programme, on incidence of HIV and herpes simplex type 2 (HSV-2) and sexual behaviour. DESIGN:Cluster randomised controlled trial. SETTING:70 villages (clusters) in the Eastern Cape province of South Africa. PARTICIPANTS:1360 men and 1416 women aged...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,多中心研究,随机对照试验
doi:10.1136/bmj.a506
更新日期:2008-08-07 00:00:00
abstract:PROBLEM:Prophylactic treatment and follow-up after exposure to HIV, hepatitis B, and hepatitis C outside hospital needs to be improved. BACKGROUND AND SETTING:Until January 2000, people in Amsterdam could report exposure outside hospital to either a hospital or the municipal health service. If they reported to the mun...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.330.7495.825
更新日期:2005-04-09 00:00:00
abstract:OBJECTIVES:To investigate the claim that 90% of episodes of low back pain that present to general practice have resolved within one month. DESIGN:Prospective study of all adults consulting in general practice because of low back pain over 12 months with follow up at 1 week, 3 months, and 12 months after consultation. ...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.316.7141.1356
更新日期:1998-05-02 00:00:00
abstract:OBJECTIVE:Detailed analysis of primary cutaneous melanoma first diagnosed in Scotland in patients aged 65 and over. DESIGN:Comparison of changing incidence, sex distribution, site, histogenetic type, tumour thickness, and prognosis of all primary cutaneous melanomas in patients aged 65 and over diagnosed in Scotland i...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.304.6829.746
更新日期:1992-03-21 00:00:00
abstract:OBJECTIVE:To examine the extent of uptake of medication for secondary prevention of coronary heart disease in older British men and women before (1998-2001) and after (2003) the implementation of the national service framework. DESIGN:Two population based, longitudinal studies of men and women aged 60-79 in 1998-2001,...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,多中心研究
doi:10.1136/bmj.38704.770127.BE
更新日期:2006-01-21 00:00:00
abstract:OBJECTIVE:To investigate estimation of calorie (energy) content of meals from fast food restaurants in adults, adolescents, and school age children. DESIGN:Cross sectional study of repeated visits to fast food restaurant chains. SETTING:89 fast food restaurants in four cities in New England, United States: McDonald's...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.f2907
更新日期:2013-05-23 00:00:00
abstract:OBJECTIVE:To determine whether a decision aid designed for adults with low education and literacy can support informed choice and involvement in decisions about screening for bowel cancer. DESIGN:Randomised controlled trial. SETTING:Areas in New South Wales, Australia identified as socioeconomically disadvantaged (lo...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,随机对照试验
doi:10.1136/bmj.c5370
更新日期:2010-10-26 00:00:00
abstract:OBJECTIVE:To compare incidences of perinatal mortality and severe perinatal morbidity between low risk term pregnancies supervised in primary care by a midwife and high risk pregnancies supervised in secondary care by an obstetrician. DESIGN:Prospective cohort study using aggregated data from a national perinatal regi...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.c5639
更新日期:2010-11-02 00:00:00
abstract::In a series of papers published during the past decade Richard Wilkinson has advanced the view that income inequality is the key determinant of variations in average life expectancy at birth among developed countries. Yet a careful examination of the two sources of data on income distribution most often used by Wilkin...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.311.7015.1282
更新日期:1995-11-11 00:00:00
abstract:OBJECTIVE:To determine if trimethoprim use for urinary tract infection (UTI) is associated with an increased risk of acute kidney injury, hyperkalaemia, or sudden death in the general population. DESIGN:Cohort study. SETTING:UK electronic primary care records from practices contributing to the Clinical Practice Resea...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.k341
更新日期:2018-02-09 00:00:00
abstract:OBJECTIVE:To compare ultrasonography with intravenous urography in the investigation of adults with haematuria. DESIGN:Prospective study entailing the examination of all patients with both investigations concurrently. The investigations were performed independently on routine lists by different duty radiologists. Each...
journal_title:BMJ (Clinical research ed.)
pub_type: 临床试验,杂志文章
doi:10.1136/bmj.301.6760.1074
更新日期:1990-11-10 00:00:00
abstract:OBJECTIVE:To assess the effect of screening for cervical intraepithelial neoplasia on the incidence of and mortality from invasive squamous cell carcinoma of cervix in north east Scotland and to discover why cases of invasive cancer still occur. DESIGN:(a) Analysis of data on cases of cervical intraepithelial neoplasi...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.308.6941.1407
更新日期:1994-05-28 00:00:00
abstract::A committee of French bishops has contradicted the Vatican's condemnation of all methods of contraception by acknowledging that condom use may be necessary in order to prevent the spread of HIV and protect against AIDS. The Social Commission of the French Episcopate made this statement in a book entitled AIDS: Societ...
journal_title:BMJ (Clinical research ed.)
pub_type: 新闻
doi:10.1136/bmj.312.7029.462a
更新日期:1996-02-24 00:00:00
abstract::A study was performed to assess whether the existing differential capitation fees for general practitioners accurately assess differential workloads. Data from the third morbidity study in general practice were used to compare capitation fees with relative workload in differing age and sex groups. The population mix w...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.297.6654.966
更新日期:1988-10-15 00:00:00
abstract:OBJECTIVE:To assess the association between genitourinary infections in the month before conception to the end of the first trimesterand gastroschisis. DESIGN:Case-control study with self reported infections from a computer assisted telephone interview. SETTING:National birth defects prevention study, a multisite, po...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,多中心研究
doi:10.1136/bmj.39567.509074.25
更新日期:2008-06-21 00:00:00
abstract:STUDY OBJECTIVE:Comparison of four layer bandage system with traditional adhesive plaster bandaging in terms of (a) compression achieved and (b) healing of venous ulcers. DESIGN:Part of larger randomised trial of five different dressings. SETTING:Outpatient venous ulcer clinic in university hospital. PATIENTS:(a) Pr...
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.297.6657.1159
更新日期:1988-11-05 00:00:00
abstract:OBJECTIVE:To examine the association between warfarin treatment and longitudinal outcomes after ischemic stroke in patients with atrial fibrillation in community practice. DESIGN:Observational study. SETTING:Hospitals (n = 1487) participating in the Get With The Guidelines (GWTG)-Stroke program in the United States, ...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章
doi:10.1136/bmj.h3786
更新日期:2015-07-31 00:00:00
abstract:OBJECTIVE:To compare the functional results after displaced fractures of the femoral neck treated with internal fixation or hemiarthroplasty. DESIGN:Randomised trial with blinding of assessments of functional results. SETTING:University hospital. PARTICIPANTS:222 patients; 165 (74%) women, mean age 83 years. Inclusi...
journal_title:BMJ (Clinical research ed.)
pub_type: 杂志文章,随机对照试验
doi:10.1136/bmj.39399.456551.25
更新日期:2007-12-15 00:00:00
abstract:OBJECTIVE:To assess whether sleep apnoea syndrome is an independent risk factor for hypertension. DESIGN:Population study. SETTING:Sleep clinic in Toronto. PARTICIPANTS:2,677 adults, aged 20-85 years, referred to the sleep clinic with suspected sleep apnoea syndrome. OUTCOME MEASURES:Medical history, demographic da...
journal_title:BMJ (Clinical research ed.)
pub_type: 评论,杂志文章
doi:10.1136/bmj.320.7233.479
更新日期:2000-02-19 00:00:00