The findings add to growing evidence describing a strong relationship between physical symptoms and psychological distress among patients with chronic conditions.
Reviewed by Evette J. Ludman, PhD

Evette J. Ludman, PhD, from the Center for Health Studies at the Group Health Cooperative in Seattle and colleagues reporting in General Hospital Psychiatry said that patients with major depression were two to five times more likely to report each of the 10 symptoms of diabetes assessed, after controlling for disease severity measures.

The investigators mailed surveys to all patients with diabetes from nine primary care clinics of the nonprofit health maintenance organization Group Health Cooperative in Western Washington State. The Patient Health Questionnaire was used to diagnose major depression and the Self-Completion Patient Outcome instrument measured nine diabetes symptoms. These nine symptoms included cold hands and feet, numb hands and feet, polyuria, excessive hunger, abnormal thirst, shakiness, blurred vision, feeling faint and feeling sleepy.

IMPORTANT ITEM ADDED

“We added one item, pain in hands and feet, based on perceived importance of this common symptom,” Dr. Ludman said.

Three distinct components of diabetes severity – diabetes complications, treatment intensity and glycemic control – were measured from automated medical records data from an 18-month period prior to survey completion, Dr. Ludman said. Lab tests were used to identify patients with nephropathy based on the presence of microalbuminuria.

TWO OR MORE COMPLICATIONS

“Approximately one-third of patients had two or more complications,” Dr. Ludman and colleagues wrote. Pharmacy data regarding the use of oral hypoglycemic agents and insulin were used to indicate treatment intensity. HbA1c was used to measure glycemic control and automated data were used to identify the HbA1c test that was closest in time to the return date of the questionnaire. Investigators used HbA1c to divide patients into two groups describing glycemic control (<8% and ≥8%).

Demographics including age, gender, race, years of education, employment status, race/ethnicity and marital status were identified by the questionnaire. Clinical status questions were asked such as age at onset of diabetes, weight and height; and medical comorbidities were also measured.

Among the 4,168 patients with diabetes who responded, those 487 with major depression reported significantly more diabetes symptoms (mean =4.40) than patients without depression (mean =2.46) after adjusting for demographic characteristics, objective measures of diabetes severity and medical comorbidity [F(1,4029)=339.31, P<.0001], Dr. Ludman and colleagues found.

SIGNIFICANT RELATIONSHIP

“The overall number of diabetes symptoms was related to the number of depressive symptoms endorsed by participants (P<.0001),” Dr. Ludman said. “Logistic regression analyses found that depression was significantly related to each of the 10 diabetes symptoms (all P<.0001).”

While depressed patients were approximately two to five times more likely to report each of the 10 symptoms of diabetes assessed in this study, patients with elevated Hb1Ac levels were 1.7 to 1.34 times more likely to report 4 of the 10 diabetes symptoms. Dr. Ludman and colleagues said that patients with two or more diabetes complications were 1.27 to about 2 times more likely to report nine symptoms.

NEUROPATHY SYMPTOMS

The researchers said that, as would be expected, having a greater number of diabetic complications increased the odds of reporting diabetes symptoms including numbness and pain in one’s hands or feet that are associated with diabetic neuropathy.

“It was more surprising that having depression was associated with similarly large or larger odds ratios for these diabetic symptoms, even after controlling for complications,” Dr. Ludman and colleagues wrote. “It should be noted that none of the elevated diabetes symptoms other than daytime sleepiness or hunger could be considered neurovegetative signs of depression.”

They wrote that depression can be viewed as an integral part of any chronic disease that is accompanied by significant physical symptoms. Patients with comorbid chronic medical conditions and depression who report higher levels of physical symptoms than other patients with comparable severity of the disease may puzzle treating clinicians.

ASSESS FOR DEPRESSION

“High levels of symptoms that do not correlate with physical or laboratory assessments should prompt the clinician to assess for depression, so that inappropriate testing or treatment recommendations are avoided,” Dr. Ludman said.

It will be important for future studies to test whether identifying and treating depression in patients with major diabetes and comorbid depression will result in decreased diabetes symptom burden.

Evette J. Ludman, PhD, is from the Center for Health Studies, Group Health Cooperative, Seattle. She can be reached at ludman.e@ghc.org.

Ludman EJ, Katon W, Russo J, et al. Depression and diabetes symptom burden. General Hospital Psychiatry. 2004;26:430-436.