Journal of critical care
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Estimating the required sample size for a study is necessary during the design phase to ensure that it will have maximal efficiency to answer the primary question of interest. Clinicians require a basic understanding of the principles underlying sample size calculation to interpret and apply research findings. This article reviews the critical components of sample size calculation, including the selection of a primary outcome, specification of the acceptable types I and II error rates, identification of the minimal clinically important difference, and estimation of the error associated with measuring the primary outcome. The relationship among confidence intervals, precision, and study power is also discussed.
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Journal of critical care · Mar 2005
ReviewA systematic review of the Charlson comorbidity index using Canadian administrative databases: a perspective on risk adjustment in critical care research.
The Charlson index is commonly used for risk adjustment in critical care health services research. However, the literature supporting this methodology has not been thoroughly explored. We systematically reviewed the literature related to administrative database adaptations of the Charlson index. ⋯ Time and cost barriers prevent widespread use of physiology-based risk adjustment in population-based research. The decreased predictive ability of the Charlson index must be weighed against the advantages of using this instrument for population-based research. Future research should focus on updating the Charlson index for recent changes in the prognosis of comorbid diseases and introduction of International Statistical Classification of Diseases, 10th Revision coding of discharge abstracts.
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Journal of critical care · Mar 2005
ReviewA systematic review of the Charlson comorbidity index using Canadian administrative databases: a perspective on risk adjustment in critical care research.
The Charlson index is commonly used for risk adjustment in critical care health services research. However, the literature supporting this methodology has not been thoroughly explored. We systematically reviewed the literature related to administrative database adaptations of the Charlson index. ⋯ Time and cost barriers prevent widespread use of physiology-based risk adjustment in population-based research. The decreased predictive ability of the Charlson index must be weighed against the advantages of using this instrument for population-based research. Future research should focus on updating the Charlson index for recent changes in the prognosis of comorbid diseases and introduction of International Statistical Classification of Diseases, 10th Revision coding of discharge abstracts.