Renal disease as a predictor of increased mortality among patients with rheumatoid arthritis.
OBJECTIVE
Mortality among RA patients and controls was analyzed with special attention to renal disease in population-based material (originally screened in 1988) of 604 patients with RA (470 females, 134 males) and 457 age- and sex-matched controls (352 females, 105 males). In the original RA population, isolated hematuria (HU) was observed in 54, isolated proteinuria (PU) in 27, combined hematuria and proteinuria (HUPU) in 7, chronic renal failure (CRFtot) in 36 and isolated chronic renal failure without HU or PU (CRFisol) in 15 patients. Among the controls, HU was observed in 39, PU in 11, CRFtot in 32 and CRFisol in 16 subjects. HUPU was not observed in any of the controls. Microalbuminuria (20-200 microg/min) was observed in 34 RA patients and in 27 controls. Histologically confirmed amyloidosis was found in 13 RA patients and mesangial glomerulonephritis (MesGN) in 17 patients. The mortality was evaluated in 1999 from data of the Statistical Office of Finland. Statistical analysis was performed by Cox regression analysis.


RESULTS
Mortality was significantly increased in the RA population as compared to controls: hazard ratio (HR) 1.78 (95% CI 1.34-2.31) for all RA patients; HR 2.12 (1.52-2.94) for females; HR 1.15 (0.75-1.77) for males. In the RA material, increased mortality was detected in patients with HUPU (HR 4.45; 1.54-12.84), PU (HR 3.54; 1.88-6.65), CRFtot (HR 3.74; 2.55-5.56) or microalbuminuria (HR 2.77; 1.64-4.69) when compared to those with normal clinical renal findings, whereas HU (HR 1.49; 0.88-2.52), CRFisol (HR 1.71; 0.82-3.54), bacteriuria (HR 0.96; 0.35-2.59) or pyuria (HR 0.65; 0.09-4.65) did not predict mortality. Renal amyloidosis was associated with an over twofold mortality rate (HR 2.31; 1.03-5.15), whereas mortality was within expected limits in RA patients with MesGN (HR 1.61; 0.49-5.24).


CONCLUSIONS
Our results show that nephropathy presenting with combined hematuria and proteinuria, proteinuria, microalbuminuria or histologically confirmed amyloidosis is associated with increased mortality in RA patients, whereas mortality is within expected limits in those with isolated hematuria or mesangial glomerulonephritis.
Sihvonen
S
S
Department of Internal Medicine, Tampere University Hospital, Tampere, Finland. susanna.sihvonen@fimnet.fi
Korpela
M
M
Mustonen
J
J
Laippala
P
P
Pasternack
A
A
D000419:Albuminuria / Q000209:etiology; D000686:Amyloidosis / Q000150:complications; D000704:Analysis of Variance; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000401:mortality*; D016022:Case-Control Studies; D002423:Cause of Death; D003430:Cross-Sectional Studies; D005260:Female; D006417:Hematuria / Q000209:etiology; D006801:Humans; D007674:Kidney Diseases / Q000150:complications* / Q000401:mortality; D007676:Kidney Failure, Chronic / Q000150:complications; D008297:Male; D009026:Mortality; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011507:Proteinuria / Q000209:etiology