Capture-Recapture
Capture-Recapture methods were originally developed by animal scientists for estimating wildlife populations but are now being used increasingly in epidemiology and public health. The general idea is to use two separate methods to identify cases of enquiry (e.g., maternal deaths) and to examine the proportion of cases identified by the second method that were also identified by the first. From this, it is then possible to estimate the coverage of the first method and hence to estimate the total number of cases. For example, Buescher et al (2001; see below) used capture-recapture to identify pregnancy-related deaths by using death certificates and enhanced surveillance with birth-death record linkage. Capture-recapture has been used to look at maternal mortality in the USA, Indonesia and Bangladesh.
For capture-recapture estimates, each death included must be confirmed (no false positives) and it must be clear which method ‘identified’ the death. The identification must be independent and the method assumes all cases are equally likely to be identified. Missing some cases is not a serious concern, but it decreases precision.
Capture-recapture can be used to assist in monitoring trends over time. Trends can be problematic to interpret if there are changes in coverage of deaths identified as well as in the risks of death. Capture-recapture approaches estimate coverage, and hence population totals, even when coverage changes.
General:
An example for maternal mortality:
