Role of depressive and cognitive status in self-reported evaluation of quality of life in older people: comparing proxy and physician perspectives.

OBJECTIVE: To assess the quality of life (QOL) of older adults aged over 65 years, who were healthy or suffering from depressive syndrome (DS) and/or Alzheimer's disease (AD); to analyse agreement between participants' and proxies' QOL ratings; to evaluate the association between participants' depressive and cognitive symptoms and QOL rating; to correlate participants' health ratings and the severity of physician assessment.

METHODS: 138 non-institutionalised older people of both genders and their respective caregiver and treating doctor were consecutively recruited (response rate 74.6%). Forty suffered from AD, 36 from DS, 35 from both conditions and 27 had neither. All participants were evaluated by Mini Mental State Examination, Geriatric Depression Scale and World Health Organization Quality of Life (WHOQOL) questionnaire. The caregiver filled out QOL-Proxy and the physician filled out the 'Health and Severity of Illness' form.

RESULTS: The four groups scored significantly differently in all areas of WHOQOL-100 (WHOQOL questionnaire with 100 items). Participants with DS perceived their QOL as poorer than did healthy and AD subjects. Participants with AD and DS obtained intermediate scores. Severity of depression correlated with worsening QOL. Subjects with DS--but not those with AD, AD and DS, and, in some areas, healthy participants--had similar perception of their QOL to their proxies. Poor physical health ratings by the physician corresponded to poorly perceived QOL by the patient.

CONCLUSION: Older people with AD perceive their own QOL similarly to and, in some areas, even better than healthy people of the same age. The opposite was observed among the depressed. Informants do not always evaluate QOL in the same way as healthy elders and those with AD, while there is more agreement with depressed patients. Informant evaluation may be helpful but is not necessarily reliable.