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Comparison of the mortality of a cohort with the mortality of a reference population in a prognostic study
Author(s) -
Hill Catherine,
Laplanche Agnes,
Rezvani Ali
Publication year - 1985
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780040308
Subject(s) - cohort , medicine , demography , population , proportional hazards model , cohort study , mortality rate , statistics , environmental health , mathematics , sociology
It is standard practice in epidemiological studies to compare the observed mortality of a cohort to the mortality expected in a reference population of the same age and sex distributions computed from national statistics. The same methods can be used in a prognostic study where the effects on survival of potential prognostic factors are studied in a cohort of patients with a given disease. Writing the hazard function in the cohort as the product of the hazard function in the reference population and a function of some characteristics of the patients, one can derive simple estimates and statistical tests of the standardised mortality ratios (Breslow et al. 1 ). The study of a cohort of patients with thyroid cancer will provide an example.