Observational studies: going beyond the boundaries of randomized controlled trials

Yang, Wenying; Zilov, Alexey; Soewondo, Pradana; Bech, Ole Molskov; Sekkal, F.; Home, Philip

doi:10.1016/s0168-8227(10)70002-4

Cited by 123 publications

(114 citation statements)

References 17 publications

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“…Such studies are usually characterized by lower costs, higher patient numbers, more rapid accrual, and consequently a shorter time for identification and dissemination of results [15,16]. However, despite statistical controls, selection bias may affect results from single-and multi-institutional series [16,17]. In addition, most observational studies generally include men treated at high-volume tertiary referral centers.…”

Section: A Role For Pca Registriesmentioning

confidence: 99%

“…These registries collect a standardized set of variables for every case of the disease in question occurring within a well-defined population. Developed in the first half of the 20th century to provide an understanding of the scale and profile of cancer within communities, and to elucidate causes of variations between and within populations over time, population-based cancer registries in higher-income settings have evolved and frequently measure and assess patterns and quality of care, as well as longitudinal patient outcomes [4,17,[25][26][27]. Clinical registries dedicated to specific cancers exist in the USA, Asia, Australia, and several European countries.…”

Section: Types Of Pca Registriesmentioning

confidence: 99%

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Prostate Cancer Registries: Current Status and Future Directions

Gandaglia¹,

Bray

Cooperberg

et al. 2016

European Urology

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Context: Disease-specific registries that enroll a considerable number of patients play a major role in prostate cancer (PCa) research. Objective: To evaluate available registries, describe their strengths and limitations, and discuss the potential future role of PCa registries in outcomes research. Evidence acquisition: We performed a literature review of the Medline, Embase, and Web of Science databases. The search strategy included the terms prostate cancer, outcomes, statistical approaches, population-based cohorts, registries of outcomes, and epidemiological studies, alone or in combination. We limited our search to studies published between January 2005 and January 2015. Evidence synthesis: Several population-based and prospective disease-specific registries are currently available for prostate cancer. Studies performed using these data sources provide important information on incidence and mortality, disease characteristics at presentation, risk factors, trends in utilization of health care services, disparities in access to treatment, quality of care, long-term oncologic and health-related quality of life outcomes, and costs associated with management of the disease. Although data from these registries have some limitations, statistical methods are available that can address certain biases and increase the internal and external validity of such analyses. In the future, improvements in data quality, collection of tissue samples, and the availability of data feedback to health care providers will increase the relevance of studies built on population-based and disease-specific registries. Conclusions: The strengths and limitations of PCa registries should be carefully considered when planning studies using these databases. Although randomized controlled trials still provide the highest level of evidence, large registries play an important and growing role in advancing PCa research and care. Patient summary: Several population-based and prospective disease-specific registries for prostate cancer are currently available. Analyses of data from these registries yield information that is clinically relevant for the management of patients with prostate cancer.

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Section: A Role For Pca Registriesmentioning

confidence: 99%

Section: Types Of Pca Registriesmentioning

confidence: 99%

Prostate Cancer Registries: Current Status and Future Directions

Gandaglia¹,

Bray

Cooperberg

et al. 2016

European Urology

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“…1,2 While RCTs are the standard approach for regulatory approval of new therapeutic agents, observational studies are valuable when there are multiple available treatments and comparative RCTs are not feasible. 6 Observational studies also allow assessment of larger numbers of patients and may better reflect treatment effects in a real-world clinical setting. 6 However, observational studies are prone to confounding and bias, and approaches are needed to limit baseline imbalances in disease characteristics before direct comparisons are made.…”

Section: Introductionmentioning

confidence: 99%

Comparative efficacy and discontinuation of dimethyl fumarate and fingolimod in clinical practice at 12-month follow-up

Hersh

Love

Cohn

et al. 2016

Multiple Sclerosis and Related Disorders

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Background: Dimethyl fumarate and fingolimod are oral disease-modifying therapies approved to treat relapsing multiple sclerosis. Prior observational studies and our previous 12-month investigation showed comparable clinical efficacy. Objective: The purpose of this study was to assess real-world efficacy and discontinuation of dimethyl fumarate and fingolimod over 24 months in patients with multiple sclerosis. Methods: Patients treated with dimethyl fumarate (n ¼ 395) or fingolimod (n ¼ 264) completed 24-month follow-up in a large academic multiple sclerosis center. Discontinuation rates and measures of disease activity were compared after propensity score weighting. The primary outcome was on-treatment annualized relapse rate ratio. Other measures included rate of drug discontinuation and brain magnetic resonance imaging activity defined as new T2 and/or gadolinium-enhancing lesions. Results: Propensity score weighting showed excellent covariate balance. At 24 months, dimethyl fumarate demonstrated comparable annualized relapse rate (rate ratio ¼ 1.45, 95% confidence interval 0.53 3.99) and brain magnetic resonance imaging activity (odds ratio ¼ 1.38, 95% confidence interval 0.83 2.32). Dimethyl fumarate patients discontinued therapy earlier compared to fingolimod (hazard ratio ¼ 1.40, 95% confidence interval 1.11 1.77) and were more likely to discontinue therapy due to intolerability (odds ratio ¼ 1.98, 95% confidence interval 1.18 3.23). Conclusion: Dimethyl fumarate and fingolimod had similar reductions in annualized relapse rate in clinical trials, and our real-world experience supports this observation. Dimethyl fumarate-treated patients had higher likelihood of early discontinuation, and this was mostly due to intolerability.

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“…By definition, observational studies have greater heterogeneity of medical interventions and patient populations that are closer to clinical practice. 2 Other advantages of observational studies are that they are usually cheaper than RCTs and can be used to investigate rare outcomes and to detect unusual side effects, and that some designs are easily and quickly performed.…”

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confidence: 99%

Observational studies: why are they so important?

Mariani

Pêgo‐Fernandes

2014

Sao Paulo Med. J.

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Randomized clinical trials (RCTs) are known to be the gold standard for medical research, and this study design is preferred for investigating the efficacy of new interventions. Many authors and editors believe that the RCT design always surpasses other research designs. However, this is not an unquestionable truth.The main advantage of RCTs is that they provide better control over possible bias through randomization and blinding. In other words, the great strength of an RCT is its high internal validity. On the other hand, rigid design control could reduce the ability to generalize the results.1 Another issue relating to RCTs is the fact that recruitment, randomization and blinding are not always possible because of technical issues (e.g. surgical procedures) or ethical issues (e.g. in a hypothetical trial to prove the association between smoking and lung cancer, it would be unethical to randomly assign a group to smoke).But what should be done when RCTs are unfeasible or unethical? The answer could be a well-designed observational study. This term describes a range of study designs that includes cross-sectional, case-control, prospective and retrospective cohort studies. The main characteristic of observational studies is that any intervention is not determined by the protocol, but by clinical practice. Cross-sectional studies are used to estimate prevalence. They are relatively quick and cheap, and can be used to study multiple outcomes. However, they do not differentiate between cause and effect or within the sequence of events. They are useful for identifying associations that can then be more rigorously studied using a cohort study or randomized controlled study. The most important problem with this type of study is in differentiating between cause and effect from a simple association. Case-control studies are considered to be simple to organize and useful for hypothesis generation. They retrospectively compare two groups in order to identify predictors of an outcome.They allow calculation of odds ratios. The disadvantages are that they can only evaluate one outcome and that the presence of bias is usually high and difficult to assess. The major difficulty could lie in determining an adequate control group. Cohort studies are excellent for estimating the incidence and natural history of a condition.They may be prospective or retrospective and sometimes two cohorts are compared. They analyze predictors (risk factors) that enable relative risk calculation. Since they measure events in temporal sequence, they can distinguish causes from effects. Retrospective cohorts are considered to be cheaper and quicker, but may have fragile results, particularly if the database is inadequate. Prospective cohorts are more accurate and, with a good protocol (with adequate sample size and follow-up) can have results that are as reliable as those of RCTs. 3The main problem in observational studies is the presence of confounders and selection bias (which are prevented in RCTs through randomization and blinding). A confounder ...

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Observational studies: going beyond the boundaries of randomized controlled trials

Cited by 123 publications

References 17 publications

Prostate Cancer Registries: Current Status and Future Directions

Prostate Cancer Registries: Current Status and Future Directions

Comparative efficacy and discontinuation of dimethyl fumarate and fingolimod in clinical practice at 12-month follow-up

Observational studies: why are they so important?

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