Psychological distress and C-reactive protein in a South African national survey

OBJECTIVE: To examine the association of psychological distress with serum C-reactive protein (CRP) in a South African cohort. METHODS: Data were analysed on individuals aged ≥15 years from the South African National Health and Nutrition Examination Survey (SANHANES) of 2012. Psychological distress was evaluated using the Kessler Psychological Distress Scale. Linear regression models assessed the association of psychological distress with serum CRP, adjusting for possible confounding factors. RESULTS: The analytic sample comprised n = 3944 individuals (mean age = 40 and sex = 36% males). Psychological distress was significantly associated with increased serum CRP levels (B = 0.31 and p = 0.001). This association was no longer significant after adjusting for demographic variables, lifestyle factors, cardiac disease, diabetes, hypertension, trauma and anti-inflammatory medication use (B = 0.15 and p = 0.062). CONCLUSION: Psychological distress was associated with elevated levels of CRP among South African adults. However, the association was confounded by a range of factors, with demographic variables (age, sex and population group) having the largest confounding effect. These findings indicate that CRP is not a useful biomarker of psychological distress, and that additional work is needed on the underlying psychobiology of psychological distress.