A Systematic Review of the Evidence on Inflammation in Depressive Illness and Symptoms, in Chronic and End Stage Kidney Disease

BackgroundDepressive illness and symptoms are known to be common in physical health problems and are present in at least a third of people with chronic kidney disease and end stage renalfailure (CKD/ESKD). Depressive illness and symptoms in CKD/ESKD complicates care, is associated with a shorter life expectancy, and may arise in response to inflammation.MethodsWe undertook a systematic review of studies including measures of depression and inflammatory markers in CKD/ESKD. The protocol was pre-registered with PROSPERO: CRD42019141305. Data base searches were completed in 2019 and repeated in May 2020. We assessed study quality, and undertook a narrative synthesis as well as meta-analyses of cross-sectional and longitudinal studies, examining associations between depressive states and inflammatory markers.ResultsThere was significant heterogeneity in study quality, comorbidities, samples, depression measures, and study design, as well as in the specific measured inflammatory markers.Overall, there is some evidence for associations of IL6 and CRP with depressive illness and symptoms, with inconclusive or contradictory evidence for other inflammatory markers. There were few intervention studies. Studies of samples with physical comorbidity and higher rated quality were more likely to show positive associations. There were few longitudinal studies.ConclusionsThere is some evidence of inflammation being an important correlate of depressive illness and symptoms in the presence of physical health comorbidities. Better research designs areneeded including a range of inflammatory markers.