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In a
clinic-based SS disease population, a patient arrives to clinic after disease onset. This
phenomenon is known as ‘late-entry’, and is quantified by the period between birth and
clinic arrival (1;2). Alternatively, an SS disease patient may never be recruited to the
study, due to either early life mortality without clinic attendance, or mild disease
expression not requiring clinical care. References
(1) Simon R. Length biased sampling in etiologic studies. American
Journal of Epidemiology 1980; 111(4):444-452.
(2) Brookmeyer R, Gail MH. Biases in prevalent cohorts. Biometrics
1987; 43(4):739-749. |