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Clinical research of kidney diseases V: extended analytic models
1 Divisione di Nefrologia e Dialisi, Azienda Instituti Ospitalieri di Cremona, Cremona, Italy 2 Clinical Epidemiology Unit 3 Division of Community Health and Humanities, Faculty of Medicine, Memorial University of Newfoundland, Canada
Correspondence and offprint requests to: Pietro Ravani, Divisione di Nefrologia, Azienda Istituti Ospitalieri di Cremona, Italy, Largo priori 1, Cremona, 26100, Italy. E-mail: pietro.ravani@med.mun.ca
| The first 150 words of the full text of this article appear below. |
| Introduction |
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In some study designs the same epidaemiological unit is observed more than once. For example, in a cross-sectional study of the radial artery flow rate, several outcome values can be recorded on the same subject under different experimental conditions (e.g. exposure to different vasoactive substances). Some longitudinal studies typically monitor participants over time and both predictors (e.g. blood pressure) and outcomes (e.g. left ventricular mass index) are measured on different occasions in the same subject. In other designs, observations can fall into groups (clustered data), such as single measurements taken on a paired organ (e.g. the eye or the kidney) or single observations on different members of the same hospital/region or family. More complex designs may lead to a combination of clustering and repeated/longitudinal measurements (Table 1). All these designs generate correlated outcome data (Figure 1).
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| Extended generalized linear models |
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Fixed and random effects modelling
Variance correction
Model choice
| Extended survival models |
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Correlated survival times
Risk sets for survival analysis
Variance-corrected models
Frailty models
Model choice
Time-dependent effects and time-varying covariates
| Special topics |
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| Conclusion |
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