The compression of morbidity hypothesis: promise and pitfalls of using record-linked data bases to assess secular trends in morbidity and mortality.

Individuals who are 65 years of age and older have exhibited unprecedented declines in mortality over the past few decades in the United States. Whether this increased survival has been accompanied by delays in the onset of disease or greater age-specific morbidity remains unanswered because of a paucity of reliable information on secular trends in age-specific disease incidence and survival. The Rochester Epidemiology Project (REP) is one of a few existing medical record linkage systems that offer promise of providing some of the necessary information. Several examples are presented that illustrate the potential of medical record-linked data bases for examining secular trends in the association between age at onset of disease and age at death.