P6225Uric acid visit-by-visit variability is an independent risk factor of CHD - and all-cause mortality
Abstract Variability of serum uric acid (SUA) has been seldom examined in connection with long-term morbidity and mortality. We present results from a study of male civil servants and municipal employees, estimating associations of visit-by-visit variability of SUA with long-term all-cause as well as cause-specific mortality. Patients and methods There were 10,059 men, aged 40–65, tenured civil servants and municipal employees in the territories of the three most populated urban areas. Of these, 8822 participated in three extensive examinations in 1963, 1965 and 1968 and underwent assessment of diabetes and coronary morbidity status. We conducted analysis examining whether the standard deviations of Z-scores of SUA (SUA-Z), across the three study visits, predicted fatal outcomes. SUA-Z was defined as the difference between the individual SUA and the mean of SUA, divided by the standard deviation (SD) for the pertinent examination, namely separately for the 1963, 1965 and 1968 means and SD. Hazard ratios (HR) associated with the SD of SUA-Z were calculated for 18-yr stroke and CHD mortality (1968 to 1986) and the 18-yr all-cause mortality associated with quartiles of the above variability. The lowest quartile served as the referent, adjusting for age. A subsequent model adjusted additionally for the baseline value of SUA as well as for baseline frequency of diabetes mellitus and coronary heart disease (CHD) Results Multivariate analysis of 18-yr CHD mortality (1968–1986, 906 deaths among 8822 men) yielded a significant association with the 1963–1968 SD of SUA-Z with age adjusted HR of CD mortality of 0.99, 1.12 and 1.43 for quartiles 2 to 4 respectively (P using Mantel trend test=0.0002). Further adjustment for baseline prevalence of diabetes and CHD somewhat decreased the above HR estimates to 0.98, 1.04 and 1.29, respectively, with a HR=1.15 (95% CI, 1.07–1.23) per 1 mg/Dl increment of the 1963 SUA serum level. The results for the 18-yr all-cause mortality (2836 deaths, 1968–1986) strongly indicated increasing age-adjusted mortality risk with increasing SD of SUA-Z: HRs= 1.08 (95% CI,0.97–1.21), 1.15 (1.03–1.28), and 1.37 (1.23–1.51). No association was observed between the SD of SUA-Z and 18 years stroke mortality. Sensitivity analysis, incorporating the last (1968) SUA levels assessed, rather than the 1963 ones, yielded virtually identical HRs. Conclusion In this cohort of tenured male workers, with diverse occupation, higher variability of SUA measurement taken in 1963–5-8 were clearly predictive of 18-year CHD and all-cause mortality, above and beyond the SUA levels proper.