Additional file 1 of Identifying individuals at risk of needing CKD associated medications in a European kidney disease cohort

Supplementary material 1

Patient characteristics.

<p>PCR: urinary protein to creatinine ratio; ACEi/ARBs: angiotensin converting enzyme inhibitors/angiotensin receptor blockers. WHO anemia: Hb <13 g/dL for men and <12 g/dL for women.</p

Multivariate analyses of hepcidin levels according to different definitions of iron status.

<p><i>Abbreviations: TSAT, Transferrin saturation; CRP, C-reactive protein; BIC, Bayesian Information Criterion; AIC, Akaike information Criterion; Ref, reference class.</i></p><p><b>β±sd</b> Regression coefficients for the different iron indexes in the linear regression models of hepcidin values (square-root transformed).</p>1<p>Models were adjusted for measured glomerular filtration rate, gender, age, body mass index, albuminemia, erythropoietin, oral iron and centre.</p>2<p>Models for Lipschitz’s iron index and the four-class iron index were also adjusted for C-reactive protein (CRP) in two classes (≤8 vs >8 ng/mL).</p

Hepcidin concentration according to quintiles of ferritin (A), transferrin saturation (B) and total iron-binding capacity (C).

<p>Hepcidin concentration according to quintiles of ferritin (A), transferrin saturation (B) and total iron-binding capacity (C).</p

Distribution of patients according to the TSAT-ferritin index [10] (rows), the TSAT-TIBC index (columns) and the combined TSAT-TIBC-ferritin index (cells).

<p>Data are expressed as n (%).</p><p>Cells include numbers (%) for the five iron profiles defined by the combined ferritin-TSAT-TIBC index : normal, absolute ID, noninflammatory functional ID, inflammatory functional ID, and hypotransferrinaemia.</p><p><i>Abbreviations:</i> ID, iron deficiency; TSAT, transferrin saturation; TIBC, transferrin iron-binding capacity.</p><p><i>TSAT-Ferritin index:</i> normal iron status defined as TSAT≥20%, absolute ID as TSAT<20% and ferritin<40 ng/ml, and functional ID as TSAT<20% and ferritin≥40 ng/ml.</p><p><i>TSAT-TIBC index:</i> normal iron status defined as TIBC≥50 µmol/L and TSAT≥20%, ID as TIBC≥50 µmol/L and TSAT<20%, inflammatory syndrome as TIBC<50 µmol/L and TSAT<20%, and hypotransferrinaemia as TIBC<50 µmol/L and TSAT≥20%.</p

Multivariate analyses of haemoglobin changes (in g/dL) according to different definitions of iron status profile, stratified by mGFR classes.

<p><i>Abbreviations:</i> BIC Bayesian Information Criterion; AIC, Akaike information Criterion. TSAT, transferrin saturation; TIBC, transferrin iron-binding capacity; ID, iron deficiency; Ref, reference class.</p>1<p>See BOX 1 for definitions of iron indexes.</p>2<p>BIC and AIC were given for the multivariate model taking into account the interaction term between mGFR and iron tests. Best values for BIC and AIC are underlined.</p>3<p>Regression coefficients for the different iron indexes in the linear regression models of Hb levels, stratified by mGFR classes. Models are adjusted for age, gender, ethnicity, smoking, diabetic nephropathy, renin angiotensin system inhibitors and oral iron use, C-reactive protein, serum folic acid, serum albumin, and centre.</p

Flowchart of study sample.

<p>Flowchart of study sample.</p

Hepcidin level according to categorial factors.

<p>CRP: C reactive protein; ACE/ARBs: angiotensin converting enzyme inhibitors/angiotensin receptor blockers.</p

Iron status index combining ferritin, transferrin saturation (TSAT) and total iron-binding capacity (TIBC).

<p><i>Each combination of iron marker and their threshold values is tested in this study.</i></p><p>Total iron-binding capacity (TIBC) in µmol/L was calculated as 25×transferrin (g/L).</p><p>Transferrin saturation (TSAT) was calculated as serum iron/TIBC×100%.</p

Iron profiles distribution according to gender (2a) and mGFR (2b).

<p>Iron profiles distribution according to gender (2a) and mGFR (2b).</p