About the self-controlled case series method

What is 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. 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.

Suggested reading

A good place to start is:

Whitaker HJ, Farrington CP and Musonda P. Tutorial in Biostatistics: The self-controlled case series method. Statistics in Medicine 2006, 25(10): 1768-1797.

The examples given for STATA, GENSTAT, SAS, R and GLIM on this web site all relate to this tutorial.

These two papers compare the SCCS method with alternative methods, the first with cohort and case-control methods, and the second with other case-only methods:

Farrington CP, Nash J and Miller E. Case series analysis of adverse reactions to vaccines: a comparative evaluation. American Journal of Epidemiology 1996, 143:1165-1173.

Farrington CP. Control without separate controls: evaluation of vaccine safety using case-only methods. Vaccine 2004, 22: 2064-2070.

A more advanced paper describing the SCCS method is:

Farrington CP. Relative incidence estimation from case series for vaccine safety evaluation. Biometrics 1995, 51:228-235.

Click here for a list of all papers on the method and applications.

The self-controlled case series method / Heather Whitaker / updated April 2010