Zotero for mac word 2016 full#
Zotero for mac word 2016 series#

Having identified cases, the next step in setting up the data for SCCS is to define observation periods-these are the study periods for each individual, over which a full history on the timing of events and exposures are available.

Only those who have experienced an event (cases) can contribute any information on when the event occurred, so only data on these individuals need to be collected. Precise timings are needed, so the SCCS method is best suited to acute events and transient exposures for which periods of exposure risk can be clearly defined. Asking “when?” rather than “who?” becomes the key question. The SCCS method aims to estimate a relative incidence, which compares the incidence of adverse events within periods of hypothesised excess risk due to exposure with incidence during all other times. We discuss these and identify the key limitations and potential biases. As for any epidemiological study design, the SCCS method has some assumptions. In this paper we provide an overview of SCCS methodology and some examples of how the method has been applied, in order to give an idea of the potentials of SCCS. The SCCS method is a case only method it has the advantages that no separate controls are required and any fixed confounder is automatically controlled for.

Zotero for mac word 2016 series#

In these situations the self controlled case series (SCCS) method provides an alternative epidemiological study design to investigate the association between a transient exposure and an outcome event. Likewise, studies on hospital data may not have information on the exact catchment areas and hence it is a struggle to find suitable controls for cases of a particular event. For example, in the research of adverse effects of vaccines it can be difficult to identify suitable comparison groups (eg, if most of the population receives the vaccine). There are several situations, however, where standard epidemiological study designs fall short. 1 Since then, epidemiological study designs, such as cohort and case-control studies, have been widely applied in medical research (see supplementary web table w1). This research was groundbreaking as they were one of the first teams to demonstrate a link between smoking and various diseases. In 1951, Richard Doll and Austin Bradford Hill wrote to all registered doctors in the United Kingdom to obtain information about their smoking habits. SCCS is best suited to acute recurrent or non-recurrent events and transient exposures for which precise timings are availableĮstimation is within individuals and no separate controls are required, hence the method is self controlled, and time invariant factors are cancelled outįollow-up is not censored at the event, so when events can impact on subsequent exposure, care must be taken to ensure analyses are carried out that eliminate or minimise bias The self controlled case series (SCCS) method provides an alternative to established epidemiological designs