Heart disease and the risk of allopurinol-associated severe cutaneous adverse reactions: a general population-based cohort study.

BACKGROUND: Allopurinol is commonly prescribed for gout, and its clinical use may expand with ongoing trials assessing its potential cardiorenal benefits. Because heart disease has been suggested to be a risk factor for allopurinol-associated severe cutaneous adverse reactions, we sought to confirm this association in a Canadian general population cohort. METHODS: We used population data from British Columbia, Canada, to identify all incident allopurinol users between 1997 and 2015. We examined the association between heart disease (ischemic heart disease and heart failure) and the risk of hospital admission for severe cutaneous adverse reactions, adjusting for known and purported risk factors. We also evaluated the joint effects of combined clinical and demographic risk factors. RESULTS: Among 130 325 allopurinol initiators, 109 hospital admissions occurred for allopurinol-associated severe cutaneous adverse reactions. The multivariable relative risk among those with heart disease was 1.55 (95% confidence interval 1.01-2.37). Patients with heart disease and chronic kidney disease who were started on an allopurinol dosage of greater than 100 mg/d had an 11-fold higher risk. Allopurinol initiation at a lower dosage among patients with heart disease and chronic kidney disease resulted in a fivefold reduction in risk. Older women with heart disease from regions with large Asian populations had a 23-fold higher risk of allopurinol-associated severe cutaneous adverse reactions than younger men without heart disease from other regions. INTERPRETATION: Heart disease is independently associated with risk of allopurinol-associated severe cutaneous adverse reactions, similar to chronic kidney disease, and low-dosage allopurinol initiation may substantially mitigate this risk. Risk factors for these rare but serious reactions should be considered when initiating allopurinol.

Contemporary Prevalence of Gout and Hyperuricemia in the United States and Decadal Trends: The National Health and Nutrition Examination Survey, 2007-2016.

OBJECTIVE: To estimate the current prevalence rates and decadal trends of gout and hyperuricemia in the US, as well as the prevalence of urate-lowering therapy (ULT) among gout patients, using 2007-2016 data from a nationally representative survey of American men and women (the National Health and Nutrition Examination Survey [NHANES]). METHODS: Using data from 5,467 participants in the NHANES 2015-2016, we estimated the most recent prevalence rates of gout and hyperuricemia. When the NHANES was conducted, all participants were asked about their history of gout (as diagnosed by a health professional) and medication use. Hyperuricemia was defined as having a serum urate level of >7.0 mg/dl in men and >5.7 mg/dl in women. We examined decadal trends in these estimates using data from the NHANES 2007-2016 and investigated ULT usage trends using the NHANES 2007-14 (the most recent data available to date). RESULTS: In 2015-2016, the prevalence of gout was 3.9% among adults in the US (9.2 million people), with 5.2% [5.9 million] in men and 2.7% [3.3 million] in women. Mean serum urate levels were 6.0 mg/dl in men and 4.8 mg/dl in women, and hyperuricemia prevalence rates were 20.2% and 20.0%, respectively. The prevalence rates of gout and hyperuricemia remained stable between 2007 and 2016 (P for trend > 0.05). The prevalence of ULT use among patients with gout was 33% in 2007-2014 and remained stable over time (P for trend > 0.05). CONCLUSION: In this nationally representative survey sample of adults in the US, the prevalence rates of gout and hyperuricemia remained substantial, albeit unchanged, between 2007 and 2016. Despite these rates, only one-third of gout patients were receiving ULT.

Hydroxychloroquine prescription trends and predictors for excess dosing per recent ophthalmology guidelines.

BACKGROUND: Hydroxychloroquine (HCQ) retinopathy may be more common than previously recognized; recent ophthalmology guidelines have revised recommendations from ideal body weight (IBW)-based dosing to actual body weight (ABW)-based dosing. However, contemporary HCQ prescribing trends in the UK remain unknown. METHODS: We examined a UK general population database to investigate HCQ dosing between 2007 and 2016. We studied trends of excess HCQ dosing per ophthalmology guidelines (defined by exceeding 6.5 mg/kg of IBW and 5.0 mg/kg of ABW) and determined their independent predictors using multivariable logistic regression analyses. RESULTS: Among 20,933 new HCQ users (78% female), the proportions of initial HCQ excess dosing declined from 40% to 36% using IBW and 38% to 30% using ABW, between 2007 and 2016. Among these, 47% of women were excess-dosed (multivariable OR 12.52; 95% CI 10.99-14.26) using IBW and 38% (multivariable OR 1.98; 95% CI,1.81-2.15) using ABW. Applying IBW, 37% of normal and 44% of obese patients were excess-dosed; however, applying ABW, 53% of normal and 10% of obese patients were excess-dosed (multivariable ORs = 1.61 and 0.1 (reference = normal); both p < 0.01). Long-term HCQ users showed similar excess dosing. CONCLUSION: A substantial proportion of HCQ users in the UK, particularly women, may have excess HCQ dosing per the previous or recent weight-based guidelines despite a modest decline in recent years. Over half of normal-BMI individuals were excess-dosed per the latest guidelines. This implies the potential need to reduce dosing for many patients but also calls for further research to establish unifying evidence-based safe and effective dosing strategies.

Racial/ethnic variation and risk factors for allopurinol-associated severe cutaneous adverse reactions: a cohort study.

OBJECTIVES: To examine associations of race/ethnicity and purported risk factors with hospitalised allopurinol-associated severe cutaneous adverse reactions (AASCARs). METHODS: We used US Medicaid data to identify incident allopurinol users between 1999 and 2012. We examined the risk of hospitalised AASCARs according to race/ethnicity and purported key risk factors and calculated relative risks (RR). RESULTS: Among 400 401 allopurinol initiators, we documented 203 hospitalised AASCAR cases (1 in 1972 initiators). The average AASCAR hospitalisation was 9.6 days and 43 individuals (21%) died. The multivariable-adjusted RRs for AASCARs among blacks, Asians and Native Hawaiians/Pacific Islanders compared with whites or Hispanics were 3.00 (95% CI 2.18 to 4.14), 3.03 (95% CI 1.72 to 5.34) and 6.68 (95% CI 4.37 to 10.22), respectively. Female sex, older age (≥60 years), chronic kidney disease and initial allopurinol dose (>100 mg/day) were independently associated with a 2.5-fold, 1.7-fold, 2.3-fold and 1.9-fold higher risk of AASCAR, respectively. In our combined demographic analysis, older women (≥60 years) of a high-risk race/ethnicity (blacks, Asians or Native Hawaiians/Pacific Islanders) had over a 12-fold higher risk of hospitalised AASCARs than younger men of a low-risk race/ethnicity (whites or Hispanics) (multivariable-adjusted RR, 12.25; 95% CI 6.46 to 23.25). CONCLUSIONS: This racially diverse (yet mostly white) cohort study indicates that the risk of hospitalised AASCAR is rare overall, although blacks, Asians and Native Hawaiians/Pacific-Islanders have a substantially higher risk of hospitalised AASCARs, particularly among older women. These data also support the practice of initiating allopurinol at a low dose (eg, ≤100 mg/day).

The rising prevalence and incidence of gout in British Columbia, Canada: Population-based trends from 2000 to 2012.

OBJECTIVES: Gout is increasingly recognized as the most common form of inflammatory arthritis worldwide; however, no Canadian data on the disease burden of gout are available. We estimated the prevalence, incidence, prescription patterns, and comorbidity burden of gout in an entire Canadian province [British Columbia (BC)] over the last decade. METHODS: We utilized PopulationData BC, a province-wide database, to estimate temporal trends in the prevalence and incidence of gout from 2000 to 2012, as well as according to age category. Annual estimates were age-sex-standardized using 2012 as the reference. We also examined annual trends in prescription patterns of common gout medications and assessed the comorbidity burden among gout patients in 2012. RESULTS: The 2012 prevalence of gout was 3.8% among the overall population, and the incidence rate was 2.9 per 1000 person-years. Both gout prevalence and incidence increased substantially over the study period. This burden additionally increased according to age category, affecting over 8% of those ages 60-69 years in 2012. Approximately 22% of gout patients received a prescription for urate-lowering therapy (ULT), which remained stable over the study period, while colchicine and oral glucocorticoid use both increased modestly. By 2012, 72%, 52%, and 18% of prevalent gout patients had been diagnosed with hypertension, hyperlipidemia, and diabetes, respectively. CONCLUSIONS: The burden of gout in BC, Canada, is substantial, and both the prevalence and incidence have increased over the past decade, while prescription of ULT remains low. These data support the need to improve gout prevention and care.

Improved survival in rheumatoid arthritis: a general population-based cohort study.

OBJECTIVE: Mortality trends of rheumatoid arthritis (RA) are largely unknown over the past decade when new drugs and management strategies have been adopted to effectively treat RA. METHODS: Using The Health Improvement Network, an electronic medical record database representative of the UK general population, we identified patients with incident RA and up to five individuals without RA matched for age, sex and year of diagnosis between 1999 and 2014. The RA cohort was divided in two sub-cohorts based on the year of RA diagnosis: the early cohort (1999-2006) and the late cohort (2007-2014). We compared mortality rates, HRs (using a Cox proportional hazard model) and rate differences (using an additive hazard model) between RA and non-RA cohorts adjusting for potential confounders. RESULTS: Patients with RA diagnosed between 1999 and 2006 had a considerably higher mortality rate than their comparison cohort (ie, 29.1 vs 18.0 deaths/1000 person-years), as compared with a moderate difference in patients with RA diagnosed between 2007 and 2014 and their comparison cohort (17.0 vs 12.9 deaths/1000 years). The corresponding absolute mortality rate differences were 9.5 deaths/1000 person-years (95% CIs 7.5 to 11.6) and 3.1 deaths/1000 person-years (95% CI 1.5 to 4.6) and the mortality HRs were 1.56 (95% CI 1.44 to 1.69) and 1.29 (95% CI 1.17 to 1.42), respectively (both p values for interaction <0.01). CONCLUSION: This general population-based cohort study indicates that the survival of patients with RA has improved over the past decade to a greater degree than in the general population. Improved management of RA and its associated comorbidities over recent years may be providing a survival benefit.

Trends in Gout and Rheumatoid Arthritis Hospitalizations in Canada From 2000 to 2011.

OBJECTIVE: Gout and rheumatoid arthritis (RA) are the 2 most common forms of inflammatory arthritis worldwide. As hospitalizations for both conditions lead to substantial health resource use, contemporary inpatient trends and associated costs may provide important benchmarks of disease burden. However, relevant data are limited. METHODS: We used PopulationData BC, a population-based administrative data set from Canada. We examined trends in the annual hospitalization and surgery rate of gout and RA from 2000 to 2011. Additionally, we examined annual trends in the inpatient cost burden of both conditions. We assessed annual trends in hospitalization and surgery rates using Poisson regression models and cost trends using linear regression models. RESULTS: From 2000 to 2011, the annual hospitalization rate for RA declined by 49% from 15.4 to 7.9 per 100,000 Canadian adults (P < 0.001), whereas that for gout doubled from 3.8 to 7.6 per 100,000 Canadian adults (P < 0.001). Approximately 31% of RA admissions were associated with hip or knee replacement surgery; the trend of these surgeries paralleled the declining trend in RA hospitalizations (P = 0.0097). The inpatient costs also reflected the hospitalization trends, with a 40% decrease in RA hospital costs, while gout costs more than doubled over the study period. CONCLUSION: Our findings indicate that hospitalization rates for gout have doubled over the past decade, while those for RA have decreased considerably. While these data provide an encouraging benchmark for RA care, they also highlight the critical need to improve gout management and prevention to mitigate its rising disease burden in Canada and beyond.

Racial disparities in the risk of Stevens-Johnson Syndrome and toxic epidermal necrolysis as urate-lowering drug adverse events in the United States.

OBJECTIVES: HLA-B*5801 allele carriage (a strong determinant of allopurinol hypersensitivity syndrome) varies substantially among races, which may lead to racial disparities in the risk of Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN) in the context of urate-lowering drug adverse events (ULDAEs). We examined this hypothesis in a large, racially diverse, and generalizable setting. METHODS: Using a database representative of US hospitalizations (2009-2013), we investigated the racial distribution of hospitalized SJS/TEN (principal discharge diagnosis) as ULDAEs (ICD-9-CM Classification of External Causes). Our reference groups included the US Census population, US allopurinol users, and ULDAE hospitalizations without SJS/TEN. RESULTS: We identified 606 cases hospitalized for SJS/TEN as ULDAEs (mean age = 68 years; 44% male), among which there was an overrepresentation of Asians (27%) and Blacks (26%), and an underrepresentation of Whites (29%) and Hispanics (% too-low-to-report), compared with the US Census population (5%, 12%, 67%, and 15%, respectively). The hospitalization rate ratios for SJS/TEN among Asians, Blacks, and Whites were 11.9, 5.0, and 1.0 (referent), respectively. These associations persisted using other national referents. According to the NHANES 2009-2012, allopurinol constituted 96.8% of urate-lowering drug use, followed by probenecid (2.1%). CONCLUSIONS: These national data indicate that Asians and Blacks have a substantially higher risk of SJS/TEN as ULDAEs than Whites (or Hispanics), correlating well with corresponding frequencies of HLA-B*5801 in the US population (i.e., 7.4%, 4%, 1%, and 1%, respectively). Given its market dominance and established association with SJS/TEN, our findings support the use of vigilance in these minorities when considering allopurinol.

Gout and the risk of Alzheimer's disease: a population-based, BMI-matched cohort study.

OBJECTIVE: While gout is associated with cardiovascular (CV)-metabolic comorbidities and their sequelae, the antioxidant effects of uric acid may have neuroprotective benefits. We evaluated the potential impact of incident gout on the risk of developing Alzheimer's disease (AD) in a general population context. METHODS: We conducted an age-matched, sex-matched, entry-time-matched and body mass index (BMI)-matched cohort study using data from The Health Improvement Network, an electronic medical record database representative of the UK general population, from 1 January 1995 to 31 December 2013. Up to five non-gout individuals were matched to each case of incident gout by age, sex, year of enrolment and BMI. We compared incidence rates of AD between the gout and comparison cohorts, excluding individuals with prevalent gout or dementia at baseline. Multivariate hazard ratios (HRs) were calculated, while adjusting for smoking, alcohol use, physician visits, social deprivation index, comorbidities and medication use. We repeated the same analysis among patients with incident osteoarthritis (OA) as a negative control exposure. RESULTS: We identified 309 new cases of AD among 59 224 patients with gout (29% female, mean age 65 years) and 1942 cases among 238 805 in the comparison cohort over a 5-year median follow up (1.0 vs 1.5 per 1000 person-years, respectively). Univariate (age-matched, sex-matched, entry-time-matched and BMI-matched) and multivariate HRs for AD among patients with gout were 0.71 (95% CI 0.62 to 0.80) and 0.76 (95% CI 0.66 to 0.87), respectively. The inverse association persisted among subgroups stratified by sex, age group (<75 and ≥75 years), social deprivation index and history of CV disease. The association between incident OA and the risk of incident AD was null. CONCLUSIONS: These findings provide the first general population-based evidence that gout is inversely associated with the risk of developing AD, supporting the purported potential neuroprotective role of uric acid.