Non-randomized controlled studies refers mainly to quasi- experimental studies. They do not, however, provide an organizing framework for your report. See the suggested CJNR framework below. State the overall study intention or research question as well as specific objectives or hypotheses that clearly emanate from the framework and the related literature.
Identify the type of non-randomized study, such as between-subject e. Describe how the participants were assigned to the experimental and comparison groups e. Describe the strategy used to minimize bias, such as a matching procedure, and the selected variables and rules used in the matching process. Identify the approach for providing a standardized or tailored mode of delivery e.
Describe the professional qualifications of the interventionists and the training provided to them. State whether the participants in this group received no treatment at all no-treatment control or comparison treatment e.
Describe the components, mode of delivery, and dose of comparison treatment as well as the qualifications of the health professionals who provided the treatment. Describe the data-collection procedures at each time point before, during, and after treatment :.
Identify statistics used to evaluate the effects of the interventions on outcomes, moderator and mediator effects, and the influence of adherence to the intervention on outcomes. Describe the methods used for secondary and adjusted in the case of baseline differences analyses.
Participants are then recruited and randomly assigned to either the intervention or the comparator group. This is often ensured by using automated randomization systems e. RCTs are often blinded so that participants and doctors, nurses or researchers do not know what treatment each participant is receiving, further minimizing bias.
RCTs can be analyzed by intentionto-treat analysis ITT; subjects analyzed in the groups to which they were randomized , per protocol only participants who completed the treatment originally allocated are analyzed , or other variations, with ITT often regarded least biased.
All RCTs should have pre-specified primary outcomes, should be registered with a clinical trials database and should have appropriate ethical approvals. RCTs can have their drawbacks, including their high cost in terms of time and money, problems with generalisabilty participants that volunteer to participate might not be representative of the population being studied and loss to follow up.
While expensive and time consuming, RCTs are the gold-standard for studying causal relationships as randomization eliminates much of the bias inherent with other study designs. To provide true assessment of causality RCTs need to be conducted appropriately i. Disclosures: The authors have no financial interests to disclose.
National Center for Biotechnology Information , U. Author manuscript; available in PMC Dec 1. Four strategies for case-mix adjustment were evaluated: none adequately adjusted for bias in historically and concurrently controlled studies.
Logistic regression on average increased bias. Propensity score methods performed better, but were not satisfactory in most situations. Detailed investigation revealed that adequate adjustment can only be achieved in the unrealistic situation when selection depends on a single factor.
Conclusions: Results of non-randomised studies sometimes, but not always, differ from results of randomised studies of the same intervention. Non-randomised studies may still give seriously misleading results when treated and control groups appear similar in key prognostic factors. Standard methods of case-mix adjustment do not guarantee removal of bias. Residual confounding may be high even when good prognostic data are available, and in some situations adjusted results may appear more biased than unadjusted results.
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