Validity of gout diagnosis in Swedish primary and secondary care - a validation study

Empagliflozin and Risk of Incident Gout: Analysis from the EMPagliflozin Comparative Effectiveness and SafEty (EMPRISE) Cohort Study

BACKGROUND

Hyperuricemia is frequently observed in patients with type 2 diabetes (T2D) and is associated with increased risk of gout and cardiovascular disease (CVD). Empagliflozin lowers serum urate levels by enhancing its urinary excretion.

OBJECTIVE

To compare initiators of empagliflozin vs dipeptidyl peptidase-4 inhibitor (DPP4i) and initiators of empagliflozin vs glucagon-like peptide-1 receptor agonist (GLP-1RA) with respect to the risk of incident gout events.

DESIGN AND PARTICIPANTS

Using three claims-based datasets from 08/2014 to 09/2019, we generated two cohorts (cohort 1: empagliflozin vs DPP4i; cohort 2: empagliflozin vs GLP-1RA) of adult patients with T2D and without prior history of gout or gout-specific medication dispensing separately in each dataset. To assess the risk of incident gout, we estimated hazard ratios (HR) and rate differences (RD) per 1000 person-years (PY) with their 95% confidence intervals (CI) before and after 1:1 propensity score (PS) matching adjusting for 141 baseline covariates.

KEY RESULTS

We identified 102,262 pairs of 1:1 propensity score-matched adults in cohort 1 and 131,216 pairs in cohort 2. Over a mean follow-up period of 8 months on treatment, the risk of gout was lower in patients initiating empagliflozin compared to DPP4i (HR = 0.69: 95% CI (0.60-0.79); RD =  - 2.27: 95% CI (- 3.08, 1.46)) or GLP-1RA (HR = 0.83: 95% CI (0.73-0.94); RD =  - 0.99: 95% CI (- 1.66, - 0.32)). Results were consistent across subgroups (sex, age, body mass index, chronic kidney disease, heart failure, cardiovascular disease, and concurrent diuretic use) and sensitivity analyses.

CONCLUSIONS

Among adults with T2D, the initiation of empagliflozin vs a DPP4i or GLP-1RA was associated with lower risk of incident gout, complementing results from a post hoc analysis of the EMPA-REG OUTCOME trial and previously published observational research focusing on the sodium-glucose co-transporter-2 inhibitor class in more narrowly defined study populations.

Development and validation of a self-updating gout register from electronic health records data

OBJECTIVE

To develop an automatic gout register from electronic health records (EHRs) data.

METHODS

We analysed the EHR of all patients >18 years old from a tertiary academic hospital (2013-2022) based on six criteria: International Classification of Diseases 10 gout diagnosis, urate-lowering therapy prescription, monosodium urate crystals in joint aspiration and gout-related terms in problem lists, clinical or imaging reports. We assessed the positive and negative predictive value (PPV and NPV) of the query by chart reviews.

RESULTS

Of 2 110 902 outpatients and inpatients, 10 289 had at least one criterion for gout. The combination of joint aspiration OR diagnostic in the problem list OR≥2 other criteria created a register of 5138 patients, with a PPV of 92.4% (95% CI 88.5% to 95.0%) and an NPV of 94.3% (95% CI 91.9% to 96.0%). PPV and NPV were similar among outpatients and inpatients. Incidence was 2.9 per 1000 person-year and dropped by 30% from the COVID-19 pandemic onward. Patients with gout were on average 71.2 years old (SD 14.9), mainly male (76.5%), overweight (69.5%) and polymorbid (mean number of comorbidities of 3, IQR 1-5). More than half (57.4%) had received a urate-lowering treatment, 6.7% had a gout that led to a hospitalisation or ≥2 flares within a year and 32.9% received a rheumatology consultation.

CONCLUSION

An automatic EHR-based gout register is feasible, valid and could be used to evaluate and improve gout management. Interestingly, the register uncovered a marked underdiagnosis or under-reporting of gout since the COVID-19 pandemic.

Validation of gout diagnosis in electronic primary care medical records: A population-based study

OBJECTIVE

The main objective of the study was to see the concordance between the diagnosis of gout recorded in primary care electronic medical records and the ACR/EULAR 2015 classification criteria.

METHODS

A cross-sectional study was conducted using electronic medicals records in 7 primary care centres of Barcelona. Patients' data to study clinical diagnose and management was gathered from the primary care electronic medical records of the Catalonian health institute (Institut Català de la Salut, ICS) and phone interview. Patients were considered to have gout if they scored 8 or more points on the EULAR/ACR 2015 classification criteria for gout.

RESULTS

In total, 70.9% of the patients with a gout diagnosis met ACR/EULAR 2015 criteria. Adding a hyperuricemia in a blood test in the EMR increased the percentage to 78.9%. 29.8% of the gout patients were not receiving urate-lowering therapy. 62.3% of the treated patients did not achieve the target uricemia (< 6mg/dL).

CONCLUSIONS

The majority of gout patients from primary care electronic medical records fulfil ACR/EULAR gout criteria. This database can be used for observational studies. In most of the gout patients the urate target was not achieved.

Gout in Dalarna, Sweden - a population-based study of gout occurrence and compliance to treatment guidelines

OBJECTIVE

This study aimed to describe the incidence and prevalence of gout, describe the use of allopurinol among prevalent gout cases, and determine persistence with allopurinol and degree of compliance with treat-to-target recommendations before and after the publication of Swedish national guidelines in 2016.

METHOD

Prospectively registered data on gout diagnoses and allopurinol prescriptions were used to calculate incidence and prevalence, and the proportion of prevalent patients on allopurinol. Gout patients starting allopurinol during 2013-2015 versus 2016-2018 were compared regarding persistence and compliance with treat-to-target principles.

RESULTS

The incidence of gout was 221-247 per 100 000 person-years during 2014-2019, prevalence in 2018 was 2.45%. Among prevalent cases, the proportion on allopurinol ranged from 21% to 25%. Allopurinol persistence was better for individuals starting therapy during 2016-2018 compared with 2013-2015 (45% vs 39%, p = 0.031), as were several outcomes related to treat-to-target principles, e.g. measuring baseline serum urate (SU) (84% vs 77%, p < 0.001), follow-up SU (50% vs 36%, p < 0.001), and the proportion of patients reaching an SU level < 360 µmol/L (45% vs 30%, p < 0.001).

CONCLUSION

Incidence and prevalence were slightly higher than in previous Swedish reports. Allopurinol use among prevalent gout patients did not increase during 2014-2019. Only a minor improvement in persistence was seen, and a moderate increase in compliance with guidelines, suggesting a need for improved management and extended patient involvement to increase and optimize the use of urate lowering therapy.

Gender differences in illness perceptions and disease management in patients with gout, results from a questionnaire study in Western Sweden

BACKGROUND

Aims were to examine gender differences in patients with gout with regard to a) self-reported gout severity, b) illness perceptions (IP), c) impact on daily activities and Quality of Life (QoL), d) advice from healthcare professionals, e) having changed dietary- or alcohol habits.

METHODS

Adult patients with gout identified in primary and secondary care in Sweden between 2015 and 2017 (n = 1589) were sent a questionnaire about demographics, gout disease severity, IP (using the Brief Illness Perception Questionnaire, (B-IPQ)) and disease management. T-tests, Chi square tests, ANalysis Of VAriance (ANOVA) and linear regression models were used for gender comparisons.

RESULTS

Eight hundred sixty-eight patients responded to the questionnaire. Women, n = 177 (20%), experienced more severe gout symptoms (p = 0.011), albeit similar frequencies of flares compared to men. Women experienced modest but significantly worse IP with regard to consequences, identity, concerns and emotional response (p < 0.05) as well as daily activities such as sleeping (p < 0.001) and walking (p = 0.042) and QoL (p = 0.004). Despite this and a higher frequency of obesity in women (38 vs 21%, P < 0.001) and alcohol consumption in men (p < 0.001), obese women had received significantly less advice regarding weight reduction (47 vs 65%, p = 0.041) compared to obese men. On the other hand, women reported having acted on dietary advice to a larger degree.

CONCLUSIONS

Despite only modestly worse gout severity and perception, women appear to have been given less information regarding self-management than men. These gender differences should be given attention and addressed in clinical care.

Increased risk of incident gout in young men with metabolic syndrome: A nationwide population-based cohort study of 3.5 million men

Background

To date, few studies have focused on risk factors for gout in young people, and large-scale studies on the relationship between metabolic syndrome (MetS) and gout are lacking. We aimed to investigate the association between gout and MetS in a large nationwide population-based cohort of young men who participated in national health examination.

Materials and methods

Cohort included men aged 20–39 years who participated in a health check-up in 2009–2012. A total of 3,569,104 subjects was included in the study, excluding those who had a previous diagnosis of gout or had renal impairment. The outcome was the occurrence of gout, which was defined using the diagnosis code of gout in the claims database. Cox proportional hazard model was used to evaluate the association between MetS and incident gout.

Results

Mean follow-up duration was 7.35 ± 1.24 years and the incidence rate of gout was 3.36 per 1,000 person-years. The risk of gout in subjects with MetS was 2.4-fold higher than subjects without MetS. Among the components of MetS, hypertriglyceridemia and abdominal obesity showed the greatest association with gout. As the number of MetS components increased, the risk of gout increased. The association between gout and MetS was more pronounced in relatively young subjects and in low- or normal-weight subjects.

Conclusion

Metabolic syndrome is an important risk factor for the gout in young men. In particular, the association between MetS and gout was greater in young and non-obese men. Management of MetS in young men will be important for future gout prevention.

Incident Gout and Risk of First-Time Acute Coronary Syndrome: A Prospective, Population-Based Cohort Study in Sweden

OBJECTIVE

To investigate the risk of first-time acute coronary syndrome (ACS) in a large cohort of primary and secondary care patients with incident gout compared to the general population.

METHODS

Using register data for the period 2007-2017, we conducted a prospective, population-based cohort with 20,146 patients with incident gout (mean age 65.6 years; 67.4% male) and 83,517 matched population controls without prior history of coronary heart disease. We calculated incidence rates (IRs) and hazard ratios (HRs) adjusted for baseline comorbidities and dispensed prescriptions. In a sensitivity analysis, we included gout cases and controls with no previously diagnosed comorbidity (6,075 cases and 44,091 controls).

RESULTS

The IR of first-time ACS was significantly increased in the gout cohort compared to controls (9.1 versus 6.3 of 1,000 person-years). Unadjusted Cox regression showed that gout patients had higher risk of first-time ACS compared to controls (HR 1.44 [95% confidence interval (95% CI) 1.33-1.56]), with a higher HR in women (HR 1.64 [95% CI 1.41-1.90]) than in men (HR 1.36 [95% CI, 1.24-1.50]). In multivariable analysis, the risk diminished but remained significant (HR 1.15 [95% CI 1.06-1.25]). The risk was similar in the sensitivity analysis (HR 1.20 [95% CI 1.01-1.44]) and still higher in women (HR 1.34 [95% CI 0.86-2.08]) than in men (HR 1.18 [95% CI 0.97-1.44]).

CONCLUSION

Patients with incident gout have a 44% increased risk of first-time ACS, higher in women than in men. This risk is largely explained by the underlying comorbidities, but there is still a modestly increased risk that may be due to gout-related factors.

Gout increases length of stay in patients hospitalized for heart failure exacerbation

Background:

It is unclear whether patients with a history of gout have longer hospitalizations in general, or only when suffering a flare. This study examines the effect of gout diagnosis and gout flare on the length of stay (LoS) in patients admitted for heart failure (HF) exacerbation.

Methods:

We conducted a matched retrospective cohort study and searched electronic medical records for patients admitted for HF with a prior diagnosis of gout from 1 July 2012 to 30 June 2017 and matched them to patients admitted for HF without gout. Cases who had a gout flare during the admission were identified. The log of the length of stay (log LoS) was utilized for normalization of the data. We used a linear mixed-effect model to compare the adjusted LoS of gout patient with flare, gout patient without flare, and controls.

Results:

A total of 978 admissions for HF exacerbation in 738 patients, including 246 individual with gout and 492 matched controls, were identified and included in the analysis. The log LoS was significantly longer in cases (1.86 ± 0.95) compared with controls (1.72 ± 0.94; p = 0.0278). The log LoS was significantly longer in those with gout who flared (2.41 ± 0.96) compared to those without gout (1.72 ± 0.94, p < 0.0001). After adjusting for potential confounders, the log LoS of patients who flared (p < 0.0001) remained significantly longer than controls, as well as those who did not flare (p = 0.042), but to a lesser extent.

Conclusion:

HF patients with gout had significantly longer hospitalizations than those without gout, a finding driven primarily by gout flare during hospitalization.

Incident Gout: Risk of Death and Cause-Specific Mortality in Western Sweden: A Prospective, Controlled Inception Cohort Study

Background

Excess mortality in gout has been attributed to cardiovascular diseases (CVD). Considering the decline in CVD mortality in the general population, we wanted to evaluate overall mortality in gout and cause-specific contributions to mortality beyond CVD and temporal trends.

Methods

All incident cases of gout between 2006 and 2015 in western Sweden and 5 population controls per case matched for age, sex, and county were identified. Comorbidities were identified for 5 years preceding the index date. Follow-up ended at death, migration, or end of study on December 2017. Effect of gout on death risk was calculated using COX regression on the whole population and stratified by sex, adjusted for demographics, and comorbidities. Death incidence rates were compared between the two time periods, 2006-2010 and 2011-2015.

Results

We identified 22,055 cases of incident gout and 98,946 controls, median age (Q1, Q3) 69-68 (57, 79/56, 78) years and 67.6-66.5% males. Except for dementia, all comorbidities were significantly more common at baseline among gout cases. Overall, the risk for death in incident gout was neither increased overall nor in men, but women had a 10% elevated risk. In adjusted models for cause-specific mortality, death from CVD, renal disease, and digestive system diseases were significantly increased in the total gout population while death from dementia, cancer, and lung diseases were significantly decreased. There were no significant differences in overall incident death rate ratios between cases and controls in the two time periods examined.

Conclusions

An increased risk for CVD, renal disease, and diseases of the digestive system in patients with gout highlights the importance of addressing CVD risk factors in gout management. Gout was associated with reduced mortality from dementia, which may have implications on urate lowering therapy and possible effects on dementia risk.

Lifestyle factors and comorbidities in gout patients compared to the general population in Western Sweden: results from a questionnaire study

OBJECTIVE

This study aimed to identify lifestyle factors associated with gout in patients with prevalent gout compared to the general population.

METHOD

Adult patients with gout identified in primary and secondary care in Western Sweden between 2015 and 2017 were sent a questionnaire asking about demographics, lifestyle, and comorbidities. Five age- and gender-matched controls were identified in a random sample of 52 348 individuals aged 16-84 years who participated in the National Public Health survey in Sweden, year 2015. Logistic regression models were used to compare cases and controls with regard to lifestyle factors and comorbidities.

RESULTS

Of the 1589 invited gout patients, 868 (55%) responded. After matching for age and gender, 728 were included in the analysis (82.4% male; mean ± sd age 69.3 ± 10.5 years for men and 71.8 ± 9.9 years for women with gout). Male and female gout patients were significantly more likely to be overweight or obese (men 79% vs 66%; women 78.5% vs 65.3%), to have binge-drinking behaviour (men 29.9% vs 11%; women 13.7% vs 2.9%), and to be ex-smokers, compared to controls. Moreover, male gout patients reported lower levels of physical activity, while diabetes and hypertension were more common in both genders with gout than in controls.

CONCLUSION

In this questionnaire study, gout patients reported significantly more obesity and binge-drinking behaviour and less physical activity than controls. This suggests that there are great unmet needs for the management of lifestyle factors, particularly regarding overweight/obesity and binge drinking, in patients with gout.

Association between perinatal factors and future risk for gout-a nested case-control study

Background

Increased level of urate is the strongest risk factor for gout development but since only a minority of hyperuricemics are affected by gout, other pathogenic factors must be considered. Low birth weight is associated with future morbidities causing hyperuricemia, such as diabetes and renal disease. The purpose of this study was to investigate if, and to what extent, maternal and perinatal factors, including birth weight, are associated with future risk of being diagnosed with gout.

Methods

A population-based retrospective nested case-control registry study based on regional and national health care registers in Sweden. All incident cases of gout born in 1973 and onward who had received ≥1 diagnosis of gout from 2000 through 2019 in the region of western Sweden were included. Up to 5 non-gout controls were matched to each case by age, sex, and county at the year of first gout diagnosis. A range of maternal, gestational, and perinatal factors were analyzed for their potential association to future gout development. This included the health of the mother, gestational length, birth weight, number of siblings, and congenital malformations.

Results

Maternal diabetes, any congenital malformation, and being small for gestational age were factors that significantly increased the risk for future gout development, odds ratio (95% CI) 3.1 (1.3 to 7.4) (p=0.01), 1.33 (1.04 to 1.7) (p=0.02), and 1.75 (1.3 to 2.3) (p<.0001), respectively.

Conclusions

In this study, maternal diabetes and being small for gestational age increased the risk for future gout development in young adults. As of today, these conditions are becoming more prevalent and may contribute to the ongoing gout epidemic. These results require both confirmation and further delineation of underlying mechanisms.

Association of Sodium-Glucose Transport Protein 2 Inhibitor Use for Type 2 Diabetes and Incidence of Gout in Taiwan

IMPORTANCE

The use of sodium-glucose transport protein 2 (SGLT2) inhibitors is currently a standard intervention in patients with type 2 diabetes (T2DM) and exerts favorable pleiotropic effects to consistently lower blood urate levels. However, to date, no association between SGLT2 inhibitor use and the incidence of gout have been established.

OBJECTIVE

To investigate whether prescribed SGLT2 inhibitors are associated with lower gout incidence in patients with T2DM.

DESIGN, SETTING, AND PARTICIPANTS

In a cohort study, all patients with incident T2DM in Taiwan National Health Institution databases between May 1, 2016, and December 31, 2018, were retrospectively analyzed. As a comparator, patients using dipeptidyl peptidase 4 (DPP4) inhibitors were included. A total of 47 905 individuals receiving an SGLT2 inhibitor and 183 303 receiving a DPP4 inhibitor were evaluated, along with 47 405 pairs of patients using an SGLT2 inhibitor or DPP4 inhibitor in 1:1 propensity score-matched analyses. Data analysis was conducted from April 1 to June 30, 2021.

MAIN OUTCOMES AND MEASURES

A gout diagnosis was based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and the International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM). Multiple Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% CIs.

RESULTS

In total, 231 208 patients with T2DM were included in the population; 113 812 individuals (49.22%) were women, and the mean (SD) age was 61.53 (12.86) years. The overall gout incidence was 20.26 per 1000 patient-years for SGLT2 inhibitor users and 24.30 per 1000 patient-years for DPP4 inhibitor users. When potential risk factors were adjusted in the propensity score-matched population, use of SGLT2 inhibitors was associated with a lower risk of gout (HR, 0.89; 95% CI, 0.82-0.96) compared with DPP4 inhibitors, particularly for patients receiving dapagliflozin (HR, 0.86; 95% CI, 0.78-0.95). A sensitivity analysis, performed when a gout diagnosis was ascertained using the ICD-9-CM or ICD-10-CM code with gout-related medication, also showed a significantly lower risk for gout incidence of 15% with SGLT2 inhibitors (HR, 0.85; 95% CI, 0.74-0.97). Subgroup analysis indicated that SGLT2 inhibitor benefits in patients with T2DM to achieve a lower gout risk were not different across subgroups.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that patients with T2DM who are receiving SGLT2 inhibitors may have a lower risk for gout compared with those receiving DPP4 inhibitors.

Serious Infections in Patients With Gout in the US: A National Study of Incidence, Time Trends, and Outcomes

OBJECTIVE

To study the epidemiology of serious infections in patients hospitalized with gout.

METHODS

We identified patients with gout hospitalized with a primary diagnosis of pneumonia, sepsis/bacteremia, urinary tract infection (UTI), skin and soft tissue infections (SSTIs), or opportunistic infections (OIs) in a US National Inpatient Sample from 1998 to 2016 and examined factors associated with utilization and mortality.

RESULTS

We noted 1,140,085 hospitalizations of patients with serious infections and gout (11% of all hospitalizations of patients with gout; 1998-2000 [8.9%], 2015-2016 [14.5%]). Compared to patients without gout, patients with gout hospitalized with serious infections were older (median age 65 versus 74 years), more of them had a Charlson-Deyo comorbidity index score ≥2 (42% versus 65%), and fewer were female (53% versus 35%) or non-White (40% versus 35%), respectively. The most common infection was pneumonia (52%) in 1998-2000 and sepsis (52%) in 2015-2016. Median hospital charges and hospital stays were higher for patients with sepsis and OIs in 2015-2016 ($41,000-$42,000; 5.1-5.5 days) versus those with UTI, pneumonia, or SSTIs ($15,000-$17,000; 3.0-3.9 days). Compared to patients with sepsis, the multivariable-adjusted odds of health care utilization and in-hospital mortality were significantly lower for patients with UTI, SSTIs, and pneumonia, and non-home discharge or in-hospital mortality were lower in patients with OIs. Among patients hospitalized with infections, older age, Medicaid coverage, a higher Charlson-Deyo comorbidity index score, Black race, and Northeast and nonrural hospital location were associated with significantly higher health care utilization and mortality, while female sex, Medicare insurance, and lower income were associated with higher utilization.

CONCLUSION

Given an increasing rate of serious infections, especially sepsis and pneumonia, in individuals with gout, development of effective interventions targeting factors associated with health care utilization and mortality will improve outcomes and reduce burden.

Clinical implications of synovial fluid specimen handling for crystal associated arthritides: A systematic review

AIM

To identify the appropriate methods of synovial fluid (SF) specimen storage, manipulation and handling for crystal associated arthritides (CAA) diagnosis.

METHOD

A systematic literature review was conducted using 5 medical databases to identify diagnostic studies assessing SF specimen handling for calcium pyrophosphate (CPP) and monosodium urate (MSU) crystals identification. All included studies were rated for quality using the Quality Assessment of Diagnostic Accuracy Studies 2.

RESULTS

Fifteen studies, including 2 non-English language manuscripts, were included. Eight studies examined both types of crystals, while 3 studies examined CPP and 4 studies examined MSU crystals only. Overall, MSU crystals were more stable over time compared to CPP crystals. MSU stability was generally independent of time, preservative and temperature. CPP crystals deteriorated with time and were more stable if refrigerated. Ethylenediaminetetraacetic acid (EDTA) was a suitable preservative. Re-examining an initially negative SF sample at 24 hours facilitated detection of additional cases. Very few studies had an overall low risk of bias and applicability.

CONCLUSION

Monosodium urate crystals remain stable over time independent of storage time, temperature and preservative. CPP crystals are mostly stable for 24-48 hours but can deteriorate with time. Overall, SF crystal examination should ideally be done within 24-48 hours. They may be stored at room temperature without any preservative. Otherwise, refrigeration (4°C/39°F) and EDTA preservation is reasonable. Stored SF re-examination, at 24 hours, helps identify a small number of additional MSU and CPP cases. Centrifugation techniques allow better and easier crystal identification, particularly CPP. Most studies were of unclear or low quality.

The absolute risk of gout by clusters of gout-associated comorbidities and lifestyle factors-30 years follow-up of the Malmö Preventive Project

Background

Gout is predicted by a number of comorbidities and lifestyle factors. We aimed to identify discrete phenotype clusters of these factors in a Swedish population-based health survey. In these clusters, we calculated and compared the incidence and relative risk of gout.

Methods

Cluster analyses were performed to group variables with close proximity and to obtain homogenous clusters of individuals (n = 22,057) in the Malmö Preventive Project (MPP) cohort. Variables clustered included obesity, kidney dysfunction, diabetes mellitus (DM), hypertension, cardiovascular disease (CVD), dyslipidemia, pulmonary dysfunction (PD), smoking, and the use of diuretics. Incidence rates and hazard ratios (HRs) for gout, adjusted for age and sex, were computed for each cluster.

Results

Five clusters (C1–C5) were identified. Cluster C1 (n = 16,063) was characterized by few comorbidities. All participants in C2 (n = 750) had kidney dysfunction (100%), and none had CVD. In C3 (n = 528), 100% had CVD and most participants were smokers (74%). C4 (n = 3673) had the greatest fractions of obesity (34%) and dyslipidemia (74%). In C5 (n = 1043), proportions with DM (51%), hypertension (54%), and diuretics (52%) were highest. C1 was by far the most common in the population (73%), followed by C4 (17%). These two pathways included 86% of incident gout cases. The four smaller clusters (C2–C5) had higher incidence rates and a 2- to 3-fold increased risk for incident gout.

Conclusions

Five distinct clusters based on gout-related comorbidities and lifestyle factors were identified. Most incident gout cases occurred in the cluster of few comorbidities, and the four comorbidity pathways had overall a modest influence on the incidence of gout.

Occupational exposure to inorganic dust and risk of gout: a population-based study

Background

Risk factors operating independently of hyperuricemia could be of importance in determining why only a minority of people with hyperuricemia develop gout. Exposure to inorganic dust has been linked to other inflammatory diseases and could influence the development of gout.

Objectives

To evaluate if occupational exposure to inorganic dust increases the risk of gout.

Methods

Individuals aged 30–65 years with a first gout diagnosis in 2006–2012 in the population-based healthcare database of the Western Swedish Healthcare Region (VEGA) and population controls matched by age and sex were included. Data on occupation was collected from the Swedish occupational register. Exposure status was assigned by means of a job exposure matrix. Data on gout-related comorbidities was collected from VEGA. Alcohol use disorder and obesity were related both to gout and exposure to inorganic dust and were adjusted for in multivariate analyses. ORs were calculated using conditional logistic regression.

Results

5042 gout cases and 20 682 controls were included. Exposure to inorganic dust was associated with gout in both unadjusted (OR 1.12, 95% CI 1.04 to 1.20) and multivariate (OR 1.08, 95% CI 1.00 to 1.16) analyses of the whole population. In sex-stratified multivariate analyses, dust exposure was significantly associated with gout in women (adjusted OR 1.26, 95% CI 1.05 to 1.51), but not in men (adjusted OR 1.05, 95% CI 0.97 to 1.13).

Conclusions

We describe for the first time an association between exposure to inorganic dust and gout. After adjusting for confounders, the findings were statistically significant for women but not for men.

A Retrospective Cohort Study of the Effect of Gout on Mortality Among Patients with a History of Kidney Transplantation

Background

Kidney transplantation is associated with increased prevalence of gout. However, evidence of the effect of gout on long-term kidney transplantation outcomes is mixed. This study examined mortality risk among patients with a history of kidney transplantation with vs. without gout.

Material/Methods

A retrospective study was conducted using Medicare Fee-for-Service administrative claims of patients with a history of kidney transplantation. Cox proportional hazards models determined the effect of gout on all-cause mortality, controlling for confounders, including comorbid mortality risk, via the Charlson Comorbidity Index. Because the relationships between gout and components of the Charlson Comorbidity Index are also debated, 3 different model assumptions were used: 1) gout shares a common cause with these comorbidities, 2) gout is upstream of these comorbidities, 3) the effect of gout on mortality is modified by these comorbidities.

Results

Gout increased the risk of all-cause mortality in the unadjusted model (hazard ratio: 1.44, 95% CI 1.27–1.63) and after adjustment for demographics and transplant vintage (hazard ratio: 1.16, 95% CI 1.02–1.32). Gout was not a significant risk after adjustment for baseline Charlson Comorbidity Index (hazard ratio: 1.03, 95% CI 0.90–1.17). Gout was associated with greater mortality among patients without baseline comorbidities (Charlson Comorbidity Index=0; hazard ratio: 3.48, 95% CI 1.27–9.57) in the stratified model.

Conclusions

Among patients with a history of kidney transplantation, gout did not have an independent effect on all-cause mortality. However, gout was a predictor of mortality among patients with no comorbidities, suggesting that gout is an early warning sign of poor health in kidney transplantation patients.

Assessing the Risk for Gout With Sodium-Glucose Cotransporter-2 Inhibitors in Patients With Type 2 Diabetes: A Population-Based Cohort Study

BACKGROUND

Hyperuricemia is common in patients with type 2 diabetes mellitus and is known to cause gout. Sodium-glucose cotransporter-2 (SGLT2) inhibitors prevent glucose reabsorption and lower serum uric acid levels.

OBJECTIVE

To compare the rate of gout between adults prescribed an SGLT2 inhibitor and those prescribed a glucagon-like peptide-1 (GLP1) receptor agonist.

DESIGN

Population-based new-user cohort study.

SETTING

A U.S. nationwide commercial insurance database from March 2013 to December 2017.

PATIENTS

Persons with type 2 diabetes newly prescribed an SGLT2 inhibitor were 1:1 propensity score matched to patients newly prescribed a GLP1 agonist. Persons were excluded if they had a history of gout or had received gout-specific treatment previously.

MEASUREMENTS

The primary outcome was a new diagnosis of gout. Cox proportional hazards regression was used to estimate hazard ratios (HRs) of the primary outcome and 95% CIs.

RESULTS

The study identified 295 907 adults with type 2 diabetes mellitus who were newly prescribed an SGLT2 inhibitor or a GLP1 agonist. The gout incidence rate was lower among patients prescribed an SGLT2 inhibitor (4.9 events per 1000 person-years) than those prescribed a GLP1 agonist (7.8 events per 1000 person-years), with an HR of 0.64 (95% CI, 0.57 to 0.72) and a rate difference of -2.9 (CI, -3.6 to -2.1) per 1000 person-years.

LIMITATION

Unmeasured confounding, missing data (namely incomplete laboratory data), and low baseline risk for gout.

CONCLUSION

Adults with type 2 diabetes prescribed an SGLT2 inhibitor had a lower rate of gout than those prescribed a GLP1 agonist. Sodium-glucose cotransporter-2 inhibitors may reduce the risk for gout among adults with type 2 diabetes mellitus, although future studies are necessary to confirm this observation.

PRIMARY FUNDING SOURCE

Brigham and Women's Hospital.

Dual energy CT findings in gout with rapid kilovoltage-switching source with gemstone scintillator detector

Background

A definite diagnosis of gout requires demonstration of monosodium urate crystals in synovial fluid or in tophi, which in clinical practice today seldom is done. Dual energy CT (DECT) has repeatedly been shown to be able to detect monosodium urate crystals in tissues, hence being an alternative method to synovial fluid microscopy. The vast majority of these studies were performed with CT scanners with two X-ray tubes. In the present study we aim to investigate if and at what locations DECT with rapid kilovoltage-switching source with gemstone scintillator detector (GSI) can identify MSU crystals in patients with clinically diagnosed gout. We also performed a reliability study between two independent readings.

Methods

Patients with new or established gout who had been examined with DECT GSI scanning of the feet at Sahlgrenska University Hospital, Mölndal between 2015 and 2018 were identified. Their medical records were sought for gout disease characteristics using a structured protocol. Urate deposits in MTP1, MTP 2–5, ankle/midfoot joints and tendons were scored semiquantatively in both feet and presence of artifacts in nail and skin as well as beam hardening and noise were recorded. Two radiologists performed two combined readings and scoring of the images, thus consensus was reached over the scoring at each occasion (Espeland et al., BMC Med Imaging. 2013;13:4). The two readings were compared with kappa statistics.

Results

DECT GSI could identify urate deposits in the feet of all 55 participants with gout. Deposits were identified in the MTP-joints of all subjects but were also present in ankle/midfoot joints and tendons in 96 and 75% respectively. Deposition of urate was predicted by longer disease duration (Spearman’s Rho 0.64, p < .0001) and presence of tophi (p = 0.0005). Artifacts were common and mostly found in the nails (73%), a minority displayed skin artifacts (31%) while beam hardening and noise was rare. The agreement between the two readings was good (Κ = 0.66, 95% CI = 0.61–0.71).

Conclusion

The validity of DECT GSI in gout is supported by the identification of urate in all patients with clinical gout and the good correlations with clinical characteristics. The occurrence of artifacts was relatively low with expected locations.

Prevalence and incidence of non-gout crystal arthropathy in southern Sweden

Objective

To estimate the prevalence and incidence of non-gout crystal arthropathy in relation to socioeconomic factors in southern Sweden.

Methods

All patients (age ≥ 18 years) with at least one visit to a physician with the diagnosis of interest in the Skåne region (population of 1.3 million) in 1998–2014 were identified. Non-gout crystal arthropathy (ICD-10 codes M11.0–M11.9) was subclassified in four different groups: calcium pyrophosphate crystal deposition related arthropathy (CPPD), unspecified non-gout arthropathies, chondrocalcinosis, and hydroxyapatite crystal deposition disease. The crude and age-adjusted point prevalence on December 31, 2014, and the cumulative incidence during 2014 were calculated for all non-gout crystal arthropathies, CPPD, and other unspecified non-gout arthropathies overall and in relation to occupation, income, and level of education.

Results

The crude 2014 point prevalence (95% CI) and 2014 cumulative incidence (95% CI) of all non-gout crystal arthropathies were 0.23% (0.23–0.24) and 21.5 (19–25) cases/100,000 persons. Mean age (range) among all prevalent cases in 2014 was 71 (20–102) years and 56% were males. The point prevalence and cumulative incidence of CPPD were 0.09% (0.08–0.09) and 8 (7–10)/100,000 persons, respectively. The corresponding data for unspecified non-gout crystal deposition disease was 0.16% (0.16–0.17) and 15.6 (13–18)/100,000 persons, respectively. The prevalence and incidence of CPPD and unspecified non-gout crystal arthropathies were slightly higher in men and increased with age irrespective of gender. Unspecified non-gout crystal arthropathy but not CPPD was less prevalent in persons with ≥ 15 years of education, whereas there were no clear associations with occupation and income.

Conclusion

The prevalence of all diagnosed non-gout crystal arthropathies was 0.23%, thus considerably less prevalent than gout in southern Sweden. CPPD and other unspecified non-gout crystal arthropathies are the predominant diagnoses, increasing with age and in men. With the exception for unspecified non-gout crystal arthropathies being inversely correlated to a higher level of education, no convincing association with the socioeconomic factors was found.

The Validity of Gout Diagnosis in Primary Care: Results from a Patient Survey

OBJECTIVE

Validate primary care diagnosis of gout by the Mexico and the Netherlands classification criteria.

METHODS

Questionnaires on gout characteristics were sent to all individuals aged ≥ 18 with ≥ 1 International Classification of Diseases, 10th ed. diagnosis of gout at 12 primary care centers.

RESULTS

Positive predictive values for gout diagnosis ranged from 71% for the Netherlands criteria to 80% for the Mexico criteria. Maximum inflammation within 24 h was the most common reported symptom (86%).

CONCLUSION

The vast majority of gout cases in primary care fulfill classification criteria and are valid for research purposes.

Associations between urate-lowering therapy and the risk of type 2 diabetes mellitus

Background

Gout is independently associated with increased risk of type 2 diabetes mellitus (T2DM). Urate-lowering therapy (ULT) might be beneficial in lowering the risks of T2DM. Therefore, we conducted a nested case-control study to evaluate the associations between ULT and T2DM.

Methods

This study retrieved the data of 29,765 gout patients from the period of 1998–2010 by using data from Taiwan’s National Health Insurance Research Database. Controls (n = 59,530) were matched at a 1:2 ratio by age, sex, and region. Multivariate Cox proportional hazards regression were performed to examine the dose-dependent relationship between ULT and T2DM.

Results

The adjusted Hazard ratio (HR) for the association of T2DM with allopurinol or benzbromarone exposure was 1.17 (95% confidence interval (CI) 1.07–1.28) and1.09 (95% CI 1.03–1.15), respectively. The HR for the cumulative allopurinol dose was 0.87 (95% CI 0.71–1.07) for patients with dose ≤1.3 mg/day and was 1.31 (95% CI 1.13–1.52) for those with a dose >15.2 mg/day. Similarly, the HR for the cumulative benzbromarone dose was 0.85(95% CI 0.75–0.96) for patients with a dose ≤1.3 mg/day and 1.42 (95% CI 1.30–1.55) for patients with a dose>9.4 mg/day, respectively. Moreover, the average exposure dose of >100 mg/day for allopurinol and >100 mg/day for benzbromarone was associated with a 1.28-fold (95% CI 1.11–1.48) and 1.47-fold (95% CI 1.23–1.76) T2DM risk respectively. The HR for patients in aged >50 years group with cumulative dose ≤1.3 mg/day of allopurinol or benzbromarone had lower risk of T2DM (HR = 0.74, 95% CI 0.58–0.94 for allopurinol; HR = 0.79, 95% CI 0.69–0.90 for benzbromarone).

Conclusion

Gout patients with prolonged ULT and a high dose of ULT were associated with a significant increase in T2DM risk. Although gout patients with age greater than 50 years and a lower dose of ULT may be beneficial in lowering T2DM risk, further clinical studies need to be confirmed these associations.

Comorbidity in gout at the time of first diagnosis: sex differences that may have implications for dosing of urate lowering therapy

Background

The aim of this study is to examine the occurrence of comorbidities at the time of first diagnosis of gout compared with matched population controls, overall and by sex, as well as to examine the crude and age-standardized prevalence of these comorbidities in men and women with gout at first diagnosis.

Methods

A population-based study used data from Swedish national and regional registers, including 14,113 gout patients aged ≥ 20 years, with a first recorded diagnosis of gout between 1 January 2006 and 31 December 2012, and 65,782 population controls, matched by age, sex and county. Prevalence ratios (95% confidence intervals) comparing gout cases and controls were calculated, overall and by sex. Crude and age-standardized prevalence (95% confidence interval) of all comorbidities in gout patients were calculated, to show differences between sexes, taking also the higher age at diagnosis in women into account.

Results

All examined comorbidities were 1.2–2.5-fold more common in gout patients at diagnosis than in population controls in both sexes. Women with gout were on average 6 years older than men at first gout diagnosis and most comorbidities, including obesity and diuretic use, were or tended to be more frequent in women than in men. When standardizing for age, women had a higher prevalence of thromboembolism (6.6% vs 5.2%) and chronic obstructive pulmonary disease (3.1% vs 2.4%). Men, on the other hand, had a higher prevalence of coronary heart disease (9.4% vs 6.4%), atrial fibrillation (9.0% vs 6.0%), congestive heart failure (7.7% vs 6.6%) and stroke (4.1% vs 3.3%).

Conclusions

The occurrence of most comorbidities was significantly increased at first diagnosis of gout in both sexes. Women were older at diagnosis and had higher occurrence of most comorbidities, including obesity and diuretic use, factors that increase serum urate, and this needs to be taken into account when starting and optimizing urate lowering therapy. These sex differences were attenuated when standardizing for age and the occurrence of cardiovascular diseases was actually higher in men.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1596-x) contains supplementary material, which is available to authorized users.

Work disability in gout: a population-based case–control study

Objectives

To examine the extent and cost of work disability among patients with gout compared with matched population controls and to analyse predictors of work disability.

Methods

A regional cohort study using data from Swedish national and regional registries from January 2000 through December 2012, including 4571 patients with gout of working age, with a first recorded diagnosis of gout in the years 2003–2009 and 22 482 population controls, matched by age, sex and place of residence. Differences in baseline characteristics (educational level, income, previous employment and comorbidities) and the number of work-loss days (absenteeism) due to sick leave and disability pension for 3 years after identification were calculated. Predictors for new-onset work absenteeism (>90 days/year) in a subset were determined by conditional logistic regression.

Results

Patients with gout (median age 53 years) had significantly more comorbidities, lower income and lower level of education than matched controls. The average work absentee rate during the 3-year follow-up period was higher among patients with gout than controls, 22% and 14%, respectively (P<0.0001). New-onset absenteeism was in multivariate analyses significantly predicted by gout (OR 1.47; 95% CI 1.23 to 1.75). Other variables independently related to new-onset absenteeism were education ≤12 years, previous unemployment and history of sick leave, in addition to several comorbidities (renal disease, cardiovascular disease, alcohol abuse and obesity).

Conclusions

Gout is associated with substantially higher work absenteeism and costs for society due to productivity loss, after adjusting for associated comorbidities and socioeconomic differences. Whether more intensive treatment of gout is cost-effective needs to be addressed in future studies.

Incidence of and risk factors for nephrolithiasis in patients with gout and the general population, a cohort study

BACKGROUND

Nephrolithiasis (NL) is known to be associated with gout, although there are few comparative studies on risk and risk factors for NL in gout compared to population cohorts. In this cohort study we investigated: (1) overall incidence of NL in gout (cases) and general population controls; (2) risk and risk factors (common comorbidities and medications) for first-time NL in cases and controls separately.

METHODS

Cases (n = 29,968) and age-matched and sex-matched controls (n = 138,678) were identified from the regional healthcare database in western Sweden (VEGA). The analyzed risk factors (comorbidities and current medication use) for first-time NL, and socioeconomic factors were retrieved from VEGA and other national Swedish registers. For cases, follow up began on 1 January 2006 or on the first diagnosis of gout if this occurred later, and for controls on their index patient's first diagnosis of gout. Follow up ended on death, emigration or 31 December 2012. Incidence rates (IR) per 1000 person-years and hazard ratios (HR) were calculated. The incidence calculations were performed for cases (regardless of prior NL) and their controls. HRs with first occurrence of NL as outcome were calculated only in those without previous NL.

RESULTS

In cases there were 678 NL events (IR: 6.16 events per 1000 person-years (95% CI: 5.70-6.64) and in controls 2125 NL events (IR 3.85 events per 1000 person-years (95% CI: 3.69-4.02), resulting in an age-sex-adjusted incidence rate ratio of 1.60 (95% CI:1.47-1.74). Point estimates for predictive factors were similar in cases and controls, except for a significant interaction for losartan which increased the risk of NL only in controls (HR = 1.49 (95% CI: 1.03-2.14). Loop diuretics significantly decreased the risk of NL by 30-34% in both cases and controls. Further significant predictors of NL in gout cases were male sex, diabetes and obesity and in controls male sex and kidney disease.

CONCLUSIONS

The risk (age and sex adjusted) of NL was increased by 60% in cases compared to controls. None of the commonly used medications increased the risk of NL in gout patients.

Factors associated with initiation and persistence of urate-lowering therapy

Background

Gout is the most common inflammatory arthritic disease and is caused by crystal deposition secondary to persistent hyperuricemia. Etiological treatment with urate-lowering therapy (ULT) has been available since the 1950s but previous studies have demonstrated suboptimal degree of treatment. In recent years we have seen recommendations for ULT earlier in the course of the disease, but there are few contemporary reports reflecting the current situation. Therefore we set out to investigate proportion receiving and persisting with ULT after gout diagnosis and predictors thereof.

Method

A population-based cohort study using regional and national population-based registers. Cohort of patients (n = 7709) from western Sweden with incident gout aged 18 years and above from 2011 to 2013. An incident case of gout was defined as having been given a diagnosis of gout (ICD-10 M10, M14.0-14.1) not preceded by a gout diagnosis or a dispensation of ULT during the previous 5 years. Main outcome measures were cumulative incidence and predictors for start of, and persistence with, ULT in gout.

Results

Within the first year after first gout diagnosis, 32% received ULT. Male sex, presence of diabetes or cardiovascular comorbidity, reduced kidney function but not diagnosed “end-stage kidney failure” increased the likelihood of receiving ULT. Of those starting ULT a majority (75%) did not persist with ULT treatment within the first 2 years. Age <50 years, lack of comorbidities, and “normal kidney function” or “end-stage kidney failure” were associated with non-persistence with ULT.

Conclusions

Only a minority of patients received ULT and a majority of these did not persist with treatment over the next 2 years. However, the older patients with renal impairment and comorbidities, possibly suffering from a more severe gout disease, were more likely to receive and persist with treatment. There is thus still room for considerable improvement with regards to management of ULT in gout.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1211-y) contains supplementary material, which is available to authorized users.

Prevalence and incidence of gout in southern Sweden from the socioeconomic perspective

OBJECTIVES

To estimate the prevalence and cumulative incidence of gout in southern Sweden with respect to socioeconomic status.

METHODS

Among residents of Skåne region in the year 2013 (total population 1.3 million), adult persons (age 18 years +) who between 1998 and 2013 received a diagnosis of gout (International Classification of Disease 10th Edition (ICD-10) code M10) by any physician were identified using the Skåne Healthcare Register. We calculated the point prevalence by end of 2013 and annual cumulative incidence in 2013 standardised to the whole Skåne population according to sex, individual information on occupation (white collar/blue collar), income (low/middle/high) and level of education (primary school/high school/university).

RESULTS

The crude 2013 point prevalence of gout and 2013 cumulative incidence (95% CI) were 1.69% (1.66% to 1.71%) and 24 cases per 10 000 persons (23-25), respectively. Compared to women, men had higher point prevalence (2.44% (2.40% to 2.49%) vs 0.96% (0.93% to 0.98%)) and higher annual cumulative incidence (33 cases per 10 000 (32-35)) versus 15 (14-16)). These figures increased with higher age but decreased with higher level of education, being the lowest in individuals with a university degree. Persons with middle income had highest point prevalence and cumulative incidence of gout, while those with white collar occupations had the lowest.

CONCLUSIONS

Gout is the most common inflammatory arthritis in southern Sweden with a prevalence of ∼1.7% in the adult population. There is a socioeconomic gradient with more gout present in the lower level of education and with more manual labour.

Effects of bariatric surgery on gout incidence in the Swedish Obese Subjects study: a non-randomised, prospective, controlled intervention trial

Objectives

To assess the long-term effect of bariatric surgery on the incidence of gout and hyperuricaemia in participants of the Swedish Obese Subjects (SOS) study.

Methods

This report includes 1982 subjects who underwent bariatric surgery and 1999 obese controls from the SOS study, a prospective intervention trial designed to assess the effect of bariatric surgery compared with conventional treatment. None of the subjects had gout at baseline. An endpoint on gout incidence was created based on information on gout diagnosis and use of gout medications through national registers and questionnaires. Median follow-up for the incidence of gout was about 19 years for both groups. Moreover, the incidence of hyperuricaemia over up to 20 years was examined in a subgroup of participants having baseline uric acid levels <6.8 mg/dL.

Results

Bariatric surgery was associated with a reduced incidence of gout compared with usual care (adjusted HR 0.60, 95% CI 0.48 to 0.75, p<0.001). The difference in absolute risk between groups was 3 percentage points at 15 years, and the number of subjects needed to be treated by bariatric surgery to prevent one incident gout event was 32 (95% CI 22 to 59). The effect of bariatric surgery on gout incidence was not influenced by baseline risk factors, including body mass index. During follow-up, the surgery group had a lower incidence of hyperuricaemia (adjusted HR 0.47, 95% CI 0.39 to 0.58, p<0.001). The difference in absolute risk between groups was 12 percentage points at 15 years, and the number of participants needed to be treated by bariatric surgery to prevent hyperuricaemia was 8 (95% CI 6 to 13).

Conclusions

Bariatric surgery prevents gout and hyperuricaemia in obese subjects.

Trial registration number

NCT01479452; Results.

Incidence and prevalence of gout in Western Sweden

BACKGROUND

The aim of the present study was to describe prevalence and trends in the incidence of gout and patterns of urate-lowering treatment (ULT) in the Western Swedish Health Care Region (WSHCR) from 2002 to 2012.

METHODS

We used regional and national healthcare registers to estimate the prevalence and incidence of gout in 2012, and trends in incidence for each calendar year from 2005 to 2012. We also investigated the pattern of ULT for gout using the Swedish Prescribed Drug Register.

RESULTS

In 2012, in the population aged 20 years and above, the prevalence of gout was 1.8 % (95 % confidence interval (CI) 1.77 to 1.82) and the incidence was 190 cases (95 % CI 180 to 200) per 100,000 person-years. Applying more strict definitions for a gout case rendered a prevalence of 1.36 % (95 % CI 1.34 to 1.38) and 0.5 (95 % CI 0.49 to 0.51) per 100,000 person-years, respectively. The incidence of gout increased steadily and significantly from 2005 to 2012, with an almost 50 % increase in the total population. There was no significant difference in the prevalence of gout in rural compared to urban areas. ULT was dispensed to only 42 % of patients with gout in 2012 who had ever been diagnosed with gout during the preceding 10-year period.

CONCLUSIONS

Gout is the most common arthritic disease in WSHCR, Sweden, and has increased substantially over the last decade, with only a minority of prevalent cases in 2012 receiving ULT.