Hypertension and Afro-descendant ethnicity: a bad interaction for lupus nephritis treated with cyclophosphamide?
Hypertension and ethnicity are important prognostic factors in evolution of lupus nephritis. A cohort of 75 patients with lupus nephritis treated with cyclophosphamide was conducted to investigate the evolution of creatinine levels between Caucasians and Afro-descendants. A multiple linear model was used to evaluate the combined effects of ethnicity and hypertension over delta creatinine controlling confounders. Sample characteristics were: 85% females; mean (+/-SD) age of 33.6 +/- 12.0 years; 77% Caucasians; 40% hypertensive at renal biopsy; 91% WHO class IV; mean basal creatinine: 1.5 +/- 1.3 mg/dL; mean final creatinine: 2.1 +/- 2.5 mg/dL; 40% anaemia; proteinuria: 5.4 +/- 4.8 g/day. Comparing Caucasians and Afro-descendants, it was found: 28.1% versus 72.2% for hypertension (P = 0.002); 31.6% versus 66.7% for anaemia (P = 0.018); 5.9 +/- 5.0 versus 3.8 +/- 4.0. g/day (P = 0.02) for proteinuria. Other comparisons including basal creatinine did not reach statistical significance. Comparing outcomes between Caucasians and Afro-descendants, it was found: 10.5% versus 22.2% for doubling of creatinine (P = 0.24); 0.41 +/- 2.03 versus 1.05 +/- 2.41 for delta creatinine ( P = 0.29); 8.8% versus 22.2% for haemodialysis (P = 0.21) and 3.5% versus 5.6% for death (P = 0.99). Analysing delta creatinine with multiple linear regression showed that hypertension had a significant overall effect (b = 0.80; SE = 0.32; P = 0.015), ethnicity alone was not significant (b = 0.35; SE = 0.29; P = 0.228); however, the effect of hypertension on delta creatinine was more intense among Afro-descendants than among Caucasians (interaction term b = - 0.83; SE = 0.37; P = 0.027). Afro-descendants lupus patients experience worst prognosis of renal function probably due to the effect of hypertension and not ethnicity per se.
de Castro
W P
WP
Post-Graduation Program in Medical Sciences: Nephrology, Faculdade de Medicina da Universidade Federal do Rio Grande do Sul, Brazil. wcastro@portoweb.com.br
Morales
J V
JV
Wagner
M B
MB
Graudenz
M
M
Edelweiss
M I
MI
Gonçalves
L F
LF
D000328:Adult; D000740:Anemia / Q000209:etiology; D044383:Black People / Q000208:ethnology; D001938:Brazil / Q000208:ethnology; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D003520:Cyclophosphamide / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications*; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D016014:Linear Models; D008181:Lupus Nephritis / Q000188:drug therapy / Q000208:ethnology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011507:Proteinuria / Q000209:etiology; D006435:Renal Dialysis; D012189:Retrospective Studies; D044465:White People / Q000208:ethnology
D007166:Immunosuppressive Agents; D003520:Cyclophosphamide; D003404:Creatinine