Gout : its epidemiology and therapeutic effect of urate-lowering agent

Abstract

Gout is chronic inflammatory arthritis characterised by monosodium urate crystal deposition in peripheral joints. The global prevalence of gout is increasing except Taiwan and the United States. However, there was no updated epidemiological data of gout as well as the utilisation of urate-lowering agent in Hong Kong and the United States (US). The risk factor of gout is essential. The association between high blood lead level and gout has been shown in previous studies. However, the toxicity effect of lead at low blood lead level was inconclusive. The association between gout and depression was inconclusive. Whether the use of urate-lowering agent would increase depression was not investigated. Therefore, this thesis aimed to study the epidemiology of gout in Hong Kong and the US, risk factor analysis of urate control,3 toxicity effect of lead at low exposure level as well as the effect of urate control on depression. The Clinical Data Analysis and Report System was used to study the epidemiology of gout in Hong Kong in 2006-2017. Patients who used the service in a public hospital in Hong Kong in 2005 were included in this study. Patients who died before 2006 were excluded. The incidence and prevalence of gout are increasing in Hong Kong. However, the management of gout is suboptimal. Only one in four patients prescribed urate-lowering agents. Adult participants in the US National Health Nutrition and Examination Survey 2007-2016 were included to study the prevalence of gout, utilisation of urate-lowering agents, the association between blood lead level and gout as well as the association between urate control and depression. Gout was defined as self-reported gout. Urate-lowering agent prescription was defined using a pill bottle review. Serum urate level >6 mg/dL was used to define treatment failure. There was no significant increase in the prevalence of gout. However, the utilisation of urate-lowering agent was suboptimal. One in three patients with gout prescribed ULT. Stage 2-5 chronic kidney disease and thiazide diuretics prescription were the predictors of treatment failure. Blood lead level was associated with increased prevalence of gout. Gout was associated with an increased prevalence of depression. The use of uratelowering agent was not associated with increased depression. Given that the incidence and prevalence of gout increased over the past eleven years in Hong Kong, the control for the risk factors, including lead exposure is important. The suboptimal control of urate-lowering agent should be promoted for better management of gout. Patients should be screened for depression.