| WELCOME TO THE
SELF CONTROLLED CASE SERIES METHOD
The self-controlled case series (SCCS) method is an alternative study method for investigating the association between a transient exposure and an adverse event. The method was developed to study adverse reactions to vaccines. The method uses only cases, no separate controls are required as the cases act as their own controls. Each case's given observation time is divided into control and risk periods. Risk periods are defined during or after the exposure. Then the method finds a relative incidence, that is, the incidence in risk periods relative to the incidence in control periods. Time-varying confounding factors such as age can be allowed for by dividing up the observation period further into age categories. An advantage of the method is that confounding factors that do not vary with time, such as genetics, location, socio-economic status are controlled for implicitly.
A good place to start is by reading the following two articles:
Whitaker HJ, Farrington CP and Musonda P. Tutorial in Biostatistics: The self-controlled case series method. Statistics in Medicine 2006, 25(10): 1768-1797.
Petersen I, Douglas I and Whitaker H. Self-controlled case series methods – an alternative to standard epidemiological study designs. British Medical Journal. 2016; 354: i4515. DOI:10.1136/bmj.i4515
The Statistics in Medicine paper walks through the theory and gives a practical guide; examples given for STATA, GENSTAT, SAS, R and GLIM on this web site all relate to this tutorial. The British Medical Journal paper offers a general overview and a more gentle introduction, it is also more up-to-date and points readers to methodological advances published after the Statistics in Medicine paper.
Click here for a fuller list of papers on the method.