Centripetal bias

The reputations of certain clinicians and institutions cause individuals with specific disorders or exposures to gravitate toward them.

Background

Centripetal bias as defined by Sackett in his 1979 indicates that the number of cases recorded at different institutions may be biased because patients might seek out clinicians or institutions with a good reputation in that clinical area, thus artificially inflating the numbers recorded. This may impact estimates of prevalence and the population under investigation may not reflect the characteristics of the wider population. (see Spectrum bias)

Example

Sackett uses the examplee.g. the striking rate of posterior fossa cerebral aneurysms reported from the University of Western Ontario.” (Sackett 1979)

Impact

The impact of centripetal bias has not formally been evaluated. In prognostic studies, if a particular centre has more severe cases (due to its good reputation for treating the condition, for example), this may affect the results of the prognostic study. Economic factors might also influence these effects if more well-off patients can access these centres, but poorer patients are unable to do so. (See selection bias)

Preventive steps

Surveys should use sampling techniques that aim to account for known and unknown differences in the distribution of factors affecting the condition of interest.

Sources

Sackett DL. Bias in analytic research. J Chron Dis 1979; 32: 51-63

Delgado-Rodríguez MLlorca J Bias

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