[Multimorbidity and the Kidney]

Multimorbidity, i.e. the simultaneous presence of 2 or more diseases, is common in patients with chronic kidney disease (CKD). Cardiovascular diseases such as coronary heart disease, heart failure, stroke or vascular dementia are of particular importance. CKD and comorbidities influence each other, which is why the current KDIGO guidelines emphasize the need for personalized treatment approaches. This applies in particular to older patients, who are especially frequently affected by CKD. The diagnosis of CKD patients should not only include typical comorbidities, but also a comprehensive risk assessment and an evaluation to avoid polypharmacy.Recognising CKD is of particular importance for patients with chronic diseases in old age, as kidney disease can have a profound effect on or worsen the course of other diseases and the limitation of kidney function has a significant influence on the treatment approach. Particular attention must be paid to the correct assessment of kidney function in older people in terms of determining the estimated glomerular filtration rate (eGFR). Here, a measurement of serum creatinine is not always sufficient due to lower muscle mass and may need to be supplemented by additional parameters to estimate the glomerular filtration rate, such as cystatin C.Depending on the eGFR, kidney disease is categorized into the stages CKD G1-G5. In addition, if kidney disease is suspected, a test for proteinuria should also be performed, preferably as a measurement of albumin excretion in spontaneous urine (albumin-to-creatinine ratio, ACR). Geriatric screening and assessment are also crucial to recognize the multimorbidity, frailty and psychosocial aspects of older patients.The treatment of multimorbidity in CKD patients focusses on progression reduction and secondary and tertiary prevention, whereby a healthy lifestyle, regular exercise and a balanced diet are also important. The prevention of cardiovascular disease, particularly in the case of high blood pressure and diabetes mellitus, requires individualized therapy, in which the choice and dosage of medication must also be taken into account, particularly in the case of advanced renal impairment. If heart failure and/or atrial fibrillation are also present, close interdisciplinary collaboration between nephrologists, cardiologists and GPs is helpful in order to optimize treatment. In addition, CKD patients with dementia face particular challenges in terms of medication and the avoidance of delirium and mental symptoms.