Supplementary Material for: Awareness of Chronic Kidney Disease and Depressive Symptoms: National Health and Nutrition Examination Surveys 2005-2010

Background: Depressive symptoms are common in patients with chronic kidney disease (CKD) and may stem from distress associated with CKD awareness. So far, no studies have examined this association. The objective of this study was to evaluate the association between awareness of CKD and depressive symptoms. Methods: We included adults with stages 1-4 CKD (estimated glomerular filtration rate 15-60 ml/min/1.73 m2 or urine albumin-to-creatinine ratio ≥30 mg/g) using the National Health and Nutrition Examination Surveys from 2005 to 2010. Depressive symptoms were categorized as minimal (9-item Patient Health Questionnaire (PHQ-9) score 0-4), subthreshold (PHQ-9 score 5-14) and severe (PHQ-9 score ≥15). Participants were classified as aware of CKD if they answered yes to the question: ‘Have you ever been told you have weak or failing kidneys?' Multivariable logistic regression was used to identify variables independently associated with at least subthreshold depressive symptoms (PHQ-9 ≥5). Results: In 2,500 participants with CKD, the weighted prevalence was 21.4% for subthreshold and 3.1% for severe depressive symptoms. The weighted prevalence of CKD awareness was 6.4%. Independent predictors of depressive symptoms included younger age, female gender, never been married, less than high-school education, annual family income <$20,000, obesity, smoking, cardiovascular comorbidity and mental health visit in the past year. CKD awareness was independently associated with a 1.66 greater odds of depressive symptoms (95% CI 1.01-2.74, p < 0.05). Conclusions: Awareness of CKD is significantly associated with depressive symptoms independent of known confounding factors. Future studies should examine mediators of this association, especially in light of national efforts to promote CKD awareness.