Serum urate is associated with baseline renal dysfunction but not survivalor deterioration in renal function in malignant phase hypertension

Background There has been speculation whether serum uric acid levels are an independent prognostic factor in patients with hypertension. Objective To investigate the clinical associations and prognostic value of serum urate in patients with malignant phase hypertension (MHT), by compari ng clinical features in patients with serum urate levels above and below th e median levels for this population, and secondly, by performing a survival analysis in these patients. Patients and methods Review of the data on 153 patients (98 males; mean age 50.3 years, SD 13.5) with MHT on the west Birmingham MHT register. Median uric acid levels in this population was 0.41 mmol/l (6.9 mg/dl), with an in terquartile range of 0.34-0.50 mmol/l (5.7-8.4 mg/dl). Clinical characteris tics of patients with a serum urate < 0.41 mmol/l (group 1) were compared t o those with levels above the median (0.41 mmol/l, group 2). Results Mean duration of follow-up was similar in both groups. The mean dia stolic blood pressure at presentation and both mean systolic and diastolic blood pressures at follow-up were significantly higher in group 2 (that is, those with high serum urate levels) (unpaired t test, P = 0.039), There wa s also more renal dysfunction in group 2 patients with MHT, with higher mea n serum urea and creatinine levels, both at presentation and at follow-up ( unpaired t test, P < 0.01). The commonest causes of death were myocardial i nfarction (n = 7), heart failure (n = 4), stroke (n = 10) and renal failure (n = 5). There was no difference in mean survival duration between groups 1 and 2 (Kaplan-Meier, 64.6 versus 66.8 months; log-rank test, P = 0.519). Serum urate levels also did not predict the rise in serum creatinine levels (log-rank test, P = 0.84) or urea (P = 0.4033) amongst these patients. Usi ng a multivariate Cox proportional hazards analysis, the only independent p redictors of outcomes (death or the need for dialysis) were age (P = 0.007) and serum creatinine levels at presentation (P = 0.0046). Conclusion Our analysis of a large series of patients with MHT shows that t hose with high urate levels had higher diastolic blood pressures and greate r renal impairment at baseline. At follow-up, patients with median serum ur ate > 0.41 mmol/l showed a greater deterioration in renal function and high er blood pressures, but no significant difference in survival. Serum urate levels also do not appear to be predictive of the deterioration in renal fu nction or overall survival in patients with MHT. J Hypertens 2000, 18:97-10 1 (C) Lippincott Williams & Wilkins.