Methodology used in studies reporting chronic kidney disease prevalence: a systematic literature review

Background

Many publications report the prevalence of chronic kidney disease (CKD) in the general population. Comparisons across studies are hampered as CKD prevalence estimations are influenced by study population characteristics and laboratory methods.

Methods

For this systematic review, two researchers independently searched PubMed, MEDLINE and EMBASE to identify all original research articles that were published between 1 January 2003 and 1 November 2014 reporting the prevalence of CKD in the European adult general population. Data on study methodology and reporting of CKD prevalence results were independently extracted by two researchers.

Results

We identified 82 eligible publications and included 48 publications of individual studies for the data extraction. There was considerable variation in population sample selection. The majority of studies did not report the sampling frame used, and the response ranged from 10 to 87%. With regard to the assessment of kidney function, 67% used a Jaffe assay, whereas 13% used the enzymatic assay for creatinine determination. Isotope dilution mass spectrometry calibration was used in 29%. The CKD-EPI (52%) and MDRD (75%) equations were most often used to estimate glomerular filtration rate (GFR). CKD was defined as estimated GFR (eGFR) <60 mL/min/1.73 m² in 92% of studies. Urinary markers of CKD were assessed in 60% of the studies. CKD prevalence was reported by sex and age strata in 54 and 50% of the studies, respectively. In publications with a primary objective of reporting CKD prevalence, 39% reported a 95% confidence interval.

Conclusions

The findings from this systematic review showed considerable variation in methods for sampling the general population and assessment of kidney function across studies reporting CKD prevalence. These results are utilized to provide recommendations to help optimize both the design and the reporting of future CKD prevalence studies, which will enhance comparability of study results.

[Hospital prevalence of kidney failure. Consequences and reflections for the planning of nephrology services]

A prospective prevalence study of Renal Failure (RF) in inhospital patients (creatinine > = 1.7 mg/dl) was carried out during March 1994, in two hospitals covering well defined and mutually exclusive populations. Cases were selected by screening all urea and creatinine blood tests performed in both laboratories, and registered in an individual form for daily follow-up of their nephrologic outcome. We registered 242 RF cases among 3525 patients admitted (6.8%), with an A.R.F. prevalence of 5.2%, 46% of all patients had a serum creatinine > 3 mg/dl and 71% were older than 65 years. In 55% RF was acquired inside the hospital. The most frequent cause of A.R.F. was pre-renal failure with 37%, followed by 32% of ischemic acute tubular necrosis and 13% toxic ATN. Nephrology was consulted in only 29% of all hospital RF cases. Only 17% of the RF patients were submitted to dialysis procedures, overall mortality was 31%, and 30% had normal renal function at discharge. Our results provide a data base to rethink the organization, staffing and role of nephrology departments inside general hospitals.

Mixed cryoglobulinemia in a heroin addict

Several forms of glomerulopathies have been described in patients who use intravenous heroin, including focal glomerulosclerosis, membranous nephropathy associated with chronic hepatitis B antigenemia, and immune complex proliferative glomerulonephritis. This report describes a patient who was a heroin addict for 15 years and who developed membranoproliferative glomerulonephritis and cutaneous vasculitis due to mixed cryoglobulinemia; he also had a positive hepatitis C virus (HCV) antibody. Recently, an association has been described between "essential" mixed cryoglobulinemia and chronic HCV infection, which has a high prevalence in intravenous drug addict population. It is possible that mixed cryoglobulinemia-associated glomerulonephritis, occurring with chronic HCV infection, came to be considered a major cause of renal disease in heroin abusers. The possibility that HCV infection can be responsible for other types of renal involvement in intravenous drug addicts deserves further attention.

[Hemostatic changes associated with recombinant human erythropoietin (rHu Epo) treatment]

End-stage chronic renal failure (CRF) is often associated with platelet' disfunction and therefore with impaired hemostasis. Several investigators have reported that rHu Epo, used in the treatment of CRF anaemia, is able to activate a broad spectrum of hematopoietic stem cells, and therefore is able to increase the number of platelets and to induce correction of platelet disfunction. In order to investigate hemostasis changes associated with rHu Epo we studied 8 dialysis patients before and 12 weeks after rHu Epo. RHu Epo did not induce any change in the number of platelets (187710 +/- 52690 vs 204430 +/- 68710; p = NS), but seemed to improve its function (MI% of aggregation with ADP: 46.3 +/- 4.4% vs 49.1 +/- 5.3%; p less than 0.05). There was an improvement in PT (79.0 +/- 3.0% vs 87.5 +/- 8.9%; p less than 0.02) and aPTT (33.3 +/- 5.9" vs 29.3 +/- 2.1"; p less than 0.05) suggesting an improvement in platelet coagulant activities. These preliminary results indicate that rHu Epo does not increase the number of platelets but can induce a correction of platelet disfunction.

[Treatment of anemia in patients with chronic kidney insufficiency in hemodialysis with erythropoietin]

A group of 50 patients (26 men and 24 women, mean age 50 +/- 19 years and range 21 to 67) on chronic hemodialysis (HD) and with basal levels of hemoglobin (Hb) less than or equal to 8 g/dl was treated with recombinant human erythropoietin (r-HuEpo) during 3 months. r-HuEpo was started at 50 U/kg I.V. 3 times a week, immediately after each session of HD, for 4 weeks, and this dose was increased in steps of 25 U/kg until a Hb level of 12 g/dl or a maximum dose of 100 U/kg were reached. Complete blood counts and biochemical profile were performed before the first dose of r-HuEpo and once weekly and monthly respectively during the period of treatment. In 8 patients the red-cell life span was studied with cromium 51 labelled erythrocytes just before and after treatment. One patient had a grand mal seizure and the r-HuEpo was discontinued. In 44 patients the mean hematocrit increased from 21.8% to 32.1% and in the other 5 there were no response because of iron deficiency. There were no changes in leucocytes and platelets counts and consistent decreases in iron and ferritin serum concentrations were observed despite oral supplementation of iron. In the 8 patients studied the shortened erythrocyte survival did not suffer any significant variation with r-HuEpo. Predialysis creatinine, urea and phosphorus blood levels increased significantly at 3th month of treatment but there was no increase in potassium. In 32.6% of previously normotensive and hypertensive patients an increase in blood pressure was founded. Thrombosis of arteriovenous fistulas and other severe clinical side effects were not observed.(ABSTRACT TRUNCATED AT 250 WORDS)