Depression is common among diabetes patients and has been linked to negative health outcomes such as heart disease and death. And there may be more.
A recent study found that symptoms of major depression were associated with an increased risk of kidney failure in diabetes patients.
The researchers believe that more research is needed to see if treatment for depression can help improve kidney outcomes in diabetes patients.
The lead authors of this study were Margaret K. Yu, MD, MS, and Bessie A. Young, MD, MPH, from the Veterans Affairs Puget Sound Health Care System, the University of Washington School of Medicine, the University of Washington School of Public Health and the Kidney Research Institute — all in Seattle, Washington.
The study included 3,886 adults with diabetes who were outpatients from primary care clinics of a large health maintenance organization in Washington. Of these participants, 12 percent had major depression symptoms and 8 percent had minor depression symptoms.
Twelve percent of the participants had major depression symptoms and 8 percent had minor depression symptoms.
Major depression is defined as having at least five of the following symptoms for at least two weeks, and minor depression is defined as having two to four of these symptoms for at least two weeks:
- low or irritable mood
- loss of enjoyment in usual activities
- trouble sleeping or sleeping too much
- significant change in appetite
- lack of energy
- feelings of worthlessness, self-hate or guilt
- difficulty with concentration
- unusually slow or fast movements
- feeling hopeless or helpless
- continuous thoughts of death or suicide
Follow-up for this study was conducted for an average of nine years. There were a total of 26,397 patient-years (number of participants multiplied by number of years with diabetes).
The findings showed that 87 (2 percent) of the patients had developed kidney failure.
The overall rate of kidney failure was 3.30 cases per 1,000 patient-years.
The researchers determined that the rate of kidney failure among the patients with major depression symptoms was 6.65 cases per 1,000 patient-years.
The rate for those with minor depression symptoms and no depression symptoms was 4.30 cases per 1,000 patient-years and 2.78 cases per 1,000 patient-years, respectively.
The patients with major depression symptoms had an 85 percent increased risk for kidney failure compared to those with no depression symptoms, even after controlling for factors such as age, sex, race/ethnicity, marital status, education, smoking, body mass index (height to weight ratio), diabetes duration, baseline kidney function, high blood pressure, medication use and adherence to diabetes self-care.
The findings revealed that the participants with major depression symptoms were generally younger, female and non-Hispanic black and had lower levels of education and salary compared to those without depression symptoms.
Minor depression symptoms were not associated with kidney failure.
The authors noted some limitations of their study. First, depression symptoms were self-reported in a questionnaire rather than clinically diagnosed. Second, depression status was only considered at the start of the study and not over the entire length of the study. Third, the findings were not adjusted for blood pressure because that data was not available. Fourth, the researchers did not have data on medication adherence. Fifth, the study population was all insured so the findings may not be generalizable to uninsured diabetes patients.
This study was published on March 27 in the Clinical Journal of the American Society of Nephrology.
The National Institute of Mental Health Services, the American Kidney Fund and the Veterans Affairs Puget Sound Health Care System provided funding.