Clinical prognostic factors in lupus nephritis. The importance of hypertension and smoking.

BACKGROUND: Many previous studies of the influence of sociodemographic and clinical factors on the development of renal failure in patients with lupus nephritis have been based on selected subgroups of patients and have yielded conflicting results. We sought to determine the prognostic importance of patient demographic characteristics (age, gender, race, and socioeconomic status), smoking status, and hypertension in the development of end-stage renal disease (ESRD) among patients with lupus nephritis.
METHODS: This retrospective cohort study followed an inception cohort of 160 adults with lupus nephritis. The outcome measure was the development of ESRD, defined as the institution of maintenance dialysis or measurement of a creatinine clearance of 10 mL/min or less. Life-table analysis was used to determine differences between patient subgroups in the time to development of ESRD.
RESULTS: End-stage renal disease developed in 41 (26%) of 160 patients followed up for a median of 6.4 years. Hypertension and smoking status at the onset of nephritis were strongly associated with differences in the time to development of ESRD. The median time to ESRD among patients with moderate to severe hypertension (diastolic blood pressure, greater than or equal to 105 mm Hg) was 7 months, among patients with mild hypertension (diastolic blood pressure, 90 to 104 mm Hg) it was 146 months, and among normotensive patients it was greater than 273 months. The median time to ESRD among smokers was 145 months and among nonsmokers it was greater than 273 months. These effects persisted in multivariable analyses adjusting for differences among patients in age, gender, socioeconomic status, renal histology, and immunosuppressive treatment. The independent effects of hypertension and smoking resulted in shorter times to renal failure among patients who were both hypertensive and smoking, compared with nonsmoking hypertensive patients. The development of ESRD did not differ among patient demographic subgroups.
CONCLUSION: Patient demographic characteristics had no detectable impact on the rate of progression to ESRD in this cohort. Hypertension and smoking appear to be important, potentially modifiable, factors influencing the prognosis of patients with lupus nephritis.