Adjusting for Non-Compliance and Contamination in Randomized Clinical Trials

Cuzick, Jack; Edwards, Robert R.; Segnan, Nereo

doi:10.1002/(sici)1097-0258(19970515)16:9<1017::aid-sim508>3.0.co;2-v

Cited by 278 publications

(237 citation statements)

References 5 publications

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“…The NHSBSP was established in the counties of Norfolk, Suffolk, and Cambridgeshire in 1989. For sample size, assuming a relative risk of 0.68 (Cuzick et al, 1997), and a 70% coverage, 264 cases and 528 matched controls would detect a significant effect with 80% power at the 5% level with a two-sided test (Breslow and Day, 1987). We therefore aimed for 300 cases and 600 controls as a fail-safe measure.…”

Section: Methodsmentioning

confidence: 99%

A case–control study of the impact of the East Anglian breast screening programme on breast cancer mortality

et al. 2007

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Although breast cancer screening has been shown to work in randomised trials, there is a need to evaluate service screening programmes to ensure that they are delivering the benefit indicated by the trials. We carried out a case -control study to investigate the effect of mammography service screening, in the NHS breast screening programme, on breast cancer mortality in the East Anglian region of the UK. Cases were deaths from breast cancer in women diagnosed between the ages of 50 and 70 years, following the instigation of the East Anglia Breast Screening Programme in 1989. The controls were women (two per case) who had not died of breast cancer, from the same area, matched by date of birth to the cases. Each control was known to be alive at the time of death of her matched case. All women were known to the breast screening programme and were invited, at least once, to be screened. There were 284 cases and 568 controls. The odds ratio (OR) for risk of death from breast cancer in women who attended at least one routine screen compared to those who did not attend was 0.35 (CI: 0.24, 0.50). Adjusting for self-selection bias gave an estimate of the breast cancer mortality reduction associated with invitation to screening of 35% (OR ¼ 0.65, 95% CI: 0.48, 0.88). The effect of actually being screened was a 48% breast cancer mortality reduction (OR ¼ 0.52, 95% CI: 0.32, 0.84). The results suggest that the National Breast Screening Programme in East Anglia is achieving a reduction in breast cancer deaths, which is at least consistent with the results from the randomised controlled trials of mammographic screening.

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Section: Methodsmentioning

confidence: 99%

A case–control study of the impact of the East Anglian breast screening programme on breast cancer mortality

et al. 2007

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“…To achieve nonbiased, exposure specific estimates the method described by Cuzick et al, 22 modified for application to a Poisson distribution, was used.…”

Section: Studied Exposuresmentioning

confidence: 99%

Effectiveness of population‐based service screening with mammography for women ages 40 to 49 years with a high or low risk of breast cancer: Socioeconomic status, parity, and age at birth of first child

Hellquist

Czene

Hjälm

et al. 2014

Cancer

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BACKGROUND: Invitation to mammography screening of women aged 40 to 49 years is a matter of debate in many countries and a cost-effective alternative in countries without screening among women aged 40 to 49 years could be inviting those at higher risk. The relative effectiveness of mammography screening was estimated for subgroups based on the breast cancer risk factors parity, age at time of birth of first child, and socioeconomic status (SES). METHODS: The SCReening of Young Women (SCRY) database consists of all women aged 40 to 49 years in Sweden between 1986 and 2005 and was split into a study and control group. The study group consisted of women residing in areas in which women aged 40 to 49 years were invited to screening and the control group of women in areas in which women aged 40 to 49 years were not invited to screening. Rate ratio (RR) estimates were calculated for 2 exposures: invitation and attendance. RESULTS: There were striking similarities noted in the RR pattern for women invited to and attending screening and no statistically significant difference or trend in the RR was noted by risk group. The RR estimates increased by increasing parity for parity of 0 to 2 and ranged from 0.55 (95% confidence interval [95% CI], 0.38-0.79) to 0.79 (95% CI, 0.65-0.95) for attending women. The RR for women with high SES was lower than that for women with low SES (RR, 0.72 [95% CI, 0.79 [95% CI,], respectively). For women aged 20 to 24 years at the time of the birth of their first child, the RR was 0.73 (95% CI, 0.58-0.91) and estimates for other ages were similar. CONCLUSIONS: There was no statistically significant difference noted in the relative effectiveness of mammography screening by parity, age at the time of birth of the first child, or SES. Cancer 2015;121:251-8.

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“…The Clean Animal Policy, which was introduced in 1996, prevents visibly dirty animals from being slaughtered and aims to reduce the risk of E. coli O157 along with other zoonotic pathogens contaminating meat 2 . Since 2000, between 1-7 commercial cattle farms have been traced annually in England and Wales as potential sources of human outbreaks and investigated by the authorities.…”

Section: Introductionmentioning

confidence: 99%

“…The RCT examined the effect of farm practice changes on reduction of E. coli O157 burden in groups of young cattle. The objectives were (1) to establish the effect of three control packages of on-farm 2 management practices to reduce E. coli O157 in young-stock; (2) to assess the effect of observed compliance with intervention measures on the result and (3) to establish the relative impact of various control measures within potentially effective control packages.…”

Section: Introductionmentioning

confidence: 99%

Farm practices to controlE. coliO157 in young cattle - A randomised controlled trial

Ellis‐Iversen¹,

Smith²,

Winden

et al. 2007

Vet. Res.

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-A randomised controlled trial was used to investigate the effect of three complex management intervention packages to reduce the burden of E. coli O157 in groups of young-stock on cattle farms in England and Wales. All intervention farms were assigned measures to avoid buying in new animals and having direct contact or sharing water sources with other cattle. Furthermore, package A (7 farms) aimed to keep a clean environment and closed groups of young-stock; package B (14 farms) aimed for improved water and feed hygiene, whilst package C was assigned both A and B. The control farms (26 farms) were asked not to alter their practices. Farms, which were assigned intervention package A, exhibited a 48% reduction in E. coli O157 burden over the 4.5 months (average) of observation, compared to 18% on the control farms. The effect of package A compared to the control farms in a crude intention-to-treat model was RR = 0.26 (p = 0.122). When the risk ratio was adjusted for actual application of the different measures, the effect of intervention package A became stronger and statistically significant (RR = 0.14 p = 0.032). Statistical evidence (p < 0.05) showed that dry bedding and maintaining animals in the same groups were the most important measures within the package and weak evidence (p < 0.1) showed that a closed herd policy and no contact with other cattle may also be of importance. Compliance with the other measures in package A had no influence on the effect of the package. No evidence of effect of the other two intervention packages was found.VTEC (STEC) E. coli O157 / randomised controlled trial / prevention / zoonotic control in cattle

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Adjusting for Non-Compliance and Contamination in Randomized Clinical Trials

Cited by 278 publications

References 5 publications

A case–control study of the impact of the East Anglian breast screening programme on breast cancer mortality

A case–control study of the impact of the East Anglian breast screening programme on breast cancer mortality

Effectiveness of population‐based service screening with mammography for women ages 40 to 49 years with a high or low risk of breast cancer: Socioeconomic status, parity, and age at birth of first child

Farm practices to controlE. coliO157 in young cattle - A randomised controlled trial

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