A comparison of alternative strategies for choosing control populations in observational studies.

ABSTRACT: Various approaches have been used to select control groups in observational studies: (1) from within the intervention area; (2) from a convenience sample, or randomly chosen areas; (3) from areas matched on area-level characteristics; and (4) nationally. The consequences of the decision are rarely assessed but, as we show, it can have complex impacts on confounding at both the area and individual levels. We began by reanalyzing data collected for an evaluation of a rapid response service on rates of unplanned hospital admission. Balance on observed individual-level variables was better with external than local controls, after matching. Further, when important prognostic variables were omitted from the matching algorithm, imbalances on those variables were also minimized using external cont

SUBMITTER: Steventon A 

PROVIDER: S-EPMC4565881 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature