ORLANDO – Elderly patients who answer unenthusiastically when asked how long they would like to live may have a dramatically increased risk of dying within 2 years if this attitude is combined with even minor or subthreshold depression, according to some unexpected findings from the Philadelphia Quality of Life of Elders Study.
The findings highlight the importance of even subthreshold depression in this population, said Jana M. Mossey, Ph.D. “From a clinical perspective, when you ask a person how they are doing today you should be really paying attention to the answer,” she said in an interview.
The study, which she presented as a poster at the annual meeting of the Gerontological Society of America, analyzed self-rated health, depression, and years of desired life (YDL) among 600 community-living elderly people (mean age 77 years) and compared this with their mortality rates within the 2 years following the interviews.
Predictably, among the 12% of subjects who died during this period, both poor self-rated health and depressive symptoms were risk factors for mortality, said Dr. Mossey, professor at Drexel University's School of Public Health in Philadelphia.
Although below-average YDL was not a risk factor by itself, it was a factor in the highest mortality risk when combined with depressive symptoms.
“Once you identify someone who is at increased risk [based on depressive symptoms], it's important to delve a bit further and find out what they're thinking about in terms of how they see themselves in the future and how long they want to go on the way they are. This is all information that's going to tell the doctor that here is a person who has high mortality risk and needs to be looked at through a different lens,” she said.
After controlling for objective health status, poor self-rated health increased mortality risk by about 3.5 times, compared with excellent self-rated health. And presence of depressive symptoms (measured using the Centers for Epidemiological Studies Depression scale) doubled mortality, compared with absence of depressive symptoms.
YDL was measured by asking subjects the following question: “Thinking of yourself today–your health and how you manage things–if you were going to be just like you are now for the rest of your life, please tell me the longest time you'd want to live? How many more years or days?” Responses were categorized according to norms established for each age group.
Although 22% of subjects had below-average YDL, this characteristic in itself did not increase their mortality risk, compared with those that had above-average YDL, said Dr. Mossey. But the combination of below-average YDL with depressive symptoms dramatically increased mortality risk by more than eightfold.
“This tells us that depressive symptoms, even when they are minor or subthreshold, need to be taken more seriously than we had thought in the past,” she said.
In a recent paper on subthreshold depression, Dr. Mossey wrote that unlike major depression, which occurs in between 2% and 6% of the population, subthreshold depression is significantly more common, with a prevalence of up to 25%, and rates in excess of 50% among hospitalized patients (Advance for Nurses 2005;7:37–9).
With growing evidence that subthreshold depression compromises quality of life, physical and social functioning, and recovery from illness and injury, and is associated with a disproportionate use of health services, this form of depression represents “a disease state that warrants treatment,” she wrote.