CKD STAGE DISTRIBUTION IN AN ITALIAN PROVINCE; SEVEN YEARS OF FOLLOW UP

Abstract Background and Aims Chronic kidney disease (CKD) is a chronic illness with important implications for the health of the population and for the commitment of resources by public health services. CKD staging makes it possible to assess the severity of the disease and its distribution in the population. The distribution of the stages of CKD diagnosed through hospitalization were analyzed using administrative database of the Local Health Authority of a province with a population of about 1 million inhabitants in northern Italy. Method Patients with hospital discharge with a diagnosis of CKD (ICD9CM 5851, 5852, 5853, 5854) in 2011- 2012 years, without dialysis treatment, neither transplantation procedure nor acute renal failure were selected. Demographic characteristics, comorbidities, dialysis treatment, drugs prescription and nephrological follow-up were investigated. This cohort of patients was examined over a 7-year period (2011-2017). Stage five was not considered to avoid possible misunderstanding with five D stage. Results 1808 patients diagnosed with CKD were extracted from the 2011-2017 administrative database; of these, 1267 had a diagnosis with the CKD stage specification. The distribution of 1267 patients in the CKD stages at the first hospital discharge was as follows: 7.4% stage 1, 30.9% stage 2, 42.3% stage 3, 19.3% stage 4. The 832 patients described in the study were still alive as of Jan. 1, 2013 while 435 (34.3%) died by Dec. 31, 2012. Until Dec. 31, 2017, 503 of the 832 patients died representing the 52.8% of stage 1 patients, 62% of stage 2 patients, 58.2% of stage 3 patients, 66.4% of stage 4 patients. Males were the most prevalent gender (58.5%), without any significant difference into CKD stages. Our patients have a fairly high age as can be seen from the table 1. The presence of co-morbidities was assessed either directly for the main risk factors or by the modified Charlson index (MCI) for CKD patients. The average value of the MCI is 3.8 ± 3.1 for all patients and 3.4 ±3.0 for stage 1, 4.1 ± 3.3 for stage 2, 3.7 ± 3.1 for stage 3, 3.7 ± 2.9 for stage 4, with maximum values of 12.0, 17.0, 16.0 and 14.0 respectively. About 40% of patients had diabetes mellitus, with the highest prevalence in stage 4 (49.3%) and the lowest in stage 1 (25%). Cardiovascular disease was distributed almost equally among all patients with a value between 82% in stage 1 and 86.3% in stage 4. Cancer were present in 26.3% of patients with similar values in all stages. Just about 9% of patients underwent dialysis treatment for achieving ESRD, with a percentage of 5.6% among patients in stage 1 and 17.1% among those in stage 4. Hemodialysis represented first choice treatment (86%) compared with peritoneal one (14%). Time from the diagnosis of CKD to the first dialysis was variable with an average of 3.4 ±1.7 years; the longest interval for patients in stage 1 (5.1±1.8) and the shortest (3.0 ±1.6) for patients in stage 4. The number of nephrological visits at renal units was analyzed for an assessment of the extent of follow-up and prevention upon reaching the ESRD (table2). More than 90% of patients had prescribed drugs antagonists of the renin angiotensin system, in all stages of CKD; other antihypertensive drugs (Ca channel blockers and peripheral vasodilators) had a similar prescription level. Anemia control drugs (ESA and iron) had an incremental prescription with stages of the disease from 51.4% in stage 1 to 74% in stage 4, similarly to Ca-P metabolism control drugs ranging from 44.4% in stage 1 to 67.8% in stage 4. Conclusion Correct staging of CKD is very important to assess the prognosis of patients, but the major determinants of outcome are comorbidities and age of the patients. The cohort examined has a high mortality rate, far higher than reported in the literature for CKD. It should be noted that the sample was identified by hospitalization for cardiovascular diseases more than 50% complicated by diabetes and hypertension, so death represents the main outcome and not ESRD.