Diagnosis of illness presentation in the elderly.

In the standard medical model of diagnosis, there is a 1:1 correspondence between clinical symptoms and signs and a pathological disease process. However, it is believed that this model does not accurately define many illness presentations in elderly patients. The frequency with which the medical model is diagnostically accurate, and the other models that might more effectively diagnose geriatric illness, are unknown. This study was designed to ascertain the frequency with which the medical model of diagnosis pertains in a clinical population of older adults and to develop and validate alternative models for diagnosis of illness presentation in this population. Using a retrospective chart review (n = 86) and a prospective validation in a second sample (n = 56) of geriatric assessment clinic patients, it was found that the medical model of illness fit less than half of the patients. To describe the illness presentations of the remaining patients, four new diagnostic models of illness presentation were identified which incorporate comorbidity, functional, and psychosocial factors. Use of these new models along with the medical model of illness diagnosis may assist in more accurate and complete diagnosis in elderly patients and enhance teaching of effective diagnosis in geriatric medicine.