Large epidemiologic studies of gout: challenges in diagnosis and diagnostic criteria

Epidemiology of gout and hyperuricemia in New Caledonia

OBJECTIVES

New Caledonia is a Pacific island of 270,000 inhabitants with mixed ethnicities, including Polynesians (10.2%), people from European ancestry (27.2%), and Melanesians (39.1%),. This study aimed at determining the prevalence of gout and hyperuricemia in the general population and the various ethnicities of New Caledonia.

METHODS

A 3-degree random sample of the population aged 18 to 60 years was adjusted according to the 2014 New Caledonia census. Face-to-face planned interviews and physical measurements were performed by trained nurses. All consenting participants underwent capillary measurement of creatinine; all consenting men and only women older than 40 years underwent point-of-care uricemia testing. Gout was defined by a validated algorithm. Two definitions of hyperuricemia were used: capillary level equivalent to plasma uric acid level>360μmol/l (6mg/dl) and>420μmol/l (7mg/dl) and/or urate-lowering drug treatment for both thresholds.

RESULTS

We included 1144 participants (adjusted mean age 37.7±12.0 years; adjusted sex ratio 50.4% men). The adjusted prevalence of gout was 3.3% (95% confidence interval 2.2-4.9). Prevalence was 6.7% (2.5-16.8), 4.1% (1.8-8.9), and 2.6% (1.4-4.7) for Polynesians, Europeans and Melanesians, respectively, and 1.9% (0.5-6.6) for other ethnicities. Prevalence of hyperuricemia, determined in 658 participants, was 67.0% (61.9-71.6) and 37.0% (32.3-42.0) for the 360- and 420-μmol/l thresholds, respectively, and was significantly greater for Polynesians and Melanesians than Europeans for both thresholds.

CONCLUSIONS

The prevalence of gout and hyperuricemia in New Caledonia was high, including in patients of European descent.

Outcomes of Care Among Patients With Gout in Europe: A Cross-sectional Survey

OBJECTIVE

To assess health- and patient-centered outcomes in gout across Europe, and explore patient-, care-, and country-level characteristics associated with these outcomes.

METHODS

Patients with self-reported physician-diagnosed gout from 14 European countries completed an online survey. Multivariable mixed-effect logistic and linear regressions were computed for health outcomes (gout flare recurrence) and patient-centered outcomes (patient satisfaction with current medication, and unaddressed goals), accounting for clustering within countries. The role of patient-, care-, and country-level factors was explored.

RESULTS

Participants included 1029 patients, predominantly diagnosed by a general practitioner (GP). One or more gout flares were reported by 70% of patients and ≥ 3 flares by 32%. Gout patients reported 1.1 ± 1.2 unaddressed goals, and 80% were satisfied with current medication. Patients with ≥ 3 and ≥ 1 flares were less likely to be treated with urate-lowering therapy (ULT) (OR 0.52, 95% CI 0.39-0.70 and OR 0.38, 95% CI 0.28-0.53, respectively), but more likely to have regular physician visits (OR 2.40, 95% CI 1.79-3.22 and OR 1.77, 95% CI 1.30-2.41). Three or more gout flares were also associated with lower satisfaction (OR 0.39, 95% CI 0.28-0.56) and more unaddressed goals (β 0.36, 95% CI 0.19-0.53). Notwithstanding, the predicted probability of being satisfied was still between 57% and 75% among patients with ≥ 3 flares but who were not receiving ULT. Finally, patients from wealthier and Northern European countries more frequently had ≥ 3 gout flares.

CONCLUSION

Across Europe, many patients with gout remain untreated despite frequent reported flares. Remarkably, a substantial proportion of them were still satisfied with gout management. A better understanding of patients' satisfaction and its role in physicians' gout management decisions is warranted to improve quality of care and gout outcomes across Europe.

Trends of venous thromboembolism risk before and after diagnosis of gout: a general population-based study

OBJECTIVE

To estimate the overall risk and the temporal trend of venous thromboembolism (VTE), deep vein thrombosis (DVT), and pulmonary embolism (PE) before and after gout diagnosis in an incident gout cohort compared with the general population.

METHODS

We conducted a matched cohort study using a province-wide population-based administrative health database in Canada. We calculated incidence rates (IRs) and multivariable adjusted hazard ratios (HRs) for the risk of VTE, DVT and PE before and after gout diagnosis.

RESULTS

Among 130 708 incident individuals with gout (64% male, mean age 59 years), 2071 developed VTE, 1377 developed DVT and 1012 developed PE. IRs per 1000 person-years for gout were 2.63, 1.74 and 1.28 compared with 2.03, 1.28 and 1.06 for non-gout, respectively. The fully adjusted HRs (95% CI) for VTE, DVT and PE were 1.22 (1.13, 1.32), 1.28 (1.17, 1.41) and 1.16 (1.05, 1.29). For the pre-gout period, the fully adjusted HRs (95% CI) were 1.51 (1.38, 1.64), 1.55 (1.40, 1.72) and 1.47 (1.31, 1.66) for VTE, DVT and PE. During the third, second and first years preceding gout, the fully adjusted HRs for VTE were 1.44, 1.56 and 1.62. During the first, second, third, fourth and fifth years after gout, the fully adjusted HRs were 1.63, 1.29, 1.33, 1.28 and 1.22. Similar trends were also seen for DVT and PE.

CONCLUSION

Increased risks of VTE, DVT and PE were found both before and after gout diagnosis. The risk increased gradually before gout, peaking in the year prior to diagnosis, and then progressively declined. Gout-associated inflammation may contribute to venous thrombosis risk.

Level of Agreement with the Microscopic Analysis of Joint Aspirate for the Diagnosis of Gout in the Lower Extremity

BACKGROUND

Although clinical findings, laboratory serum markers, and radiographic images are also used, the purported gold standard or standard reference test for the diagnosis of gout is microscopic analysis of aspirated joint fluid. This observational investigation sought to identify the level of agreement with the microscopic analysis of joint fluid aspirate for the diagnosis of gout in the lower extremity between two departments in a single health-care center.

METHODS

A retrospective medical record review identified consecutive patients seen for suspected gout who underwent diagnostic joint aspiration. Patients were included if a lower-extremity joint synovial fluid sample was obtained and were excluded if they were not independently evaluated by both the departments of rheumatology and pathology. We categorized the documented joint fluid findings into four groups: no crystals, sodium urate crystals, calcium pyrophosphate dihydrate crystals, or both sodium urate and calcium pyrophosphate dihydrate crystals. We defined a "clinically significant disagreement" as one department observing any type of crystals and the other department observing no crystals.

RESULTS

We observed a clinically significant disagreement rate of 23.26% (intraclass correlation coefficient = 0.496). The department of rheumatology was more likely to observe the presence of crystals in a sample compared with the department of pathology (88.37% versus 65.12%; P = .02).

CONCLUSIONS

These results provide evidence that microscopic analysis of joint fluid aspirate might lack the accuracy and reliability needed to be considered a gold standard diagnostic test for gout in the lower extremity.

Socio-economic gradients in the presence of musculoskeletal and other chronic diseases: results from a cross-sectional study in the Netherlands

Socio-economic gradients in occurrence of diseases have been reported for many chronic conditions. However, whether the magnitude of socio-economic gradients differs across diseases and the extent to which lifestyle mediates such relationships are not known. Cross-sectional data from The National Monitor on Musculoskeletal System was used. Respondents (> 18 years) completed a questionnaire including gender, education, social status, lifestyle, and physician-diagnosed diseases. Logistic regressions investigated the relationship between education and the major chronic diseases (musculoskeletal diseases (MSKD), diabetes, cardiovascular (CVD), cancer, mental, respiratory, any disease). Next, analyses were repeated in individuals with potential to have paid work (i.e., those < 65 having paid work, being unemployed, or receiving living allowance (minimum income)). The mediating role of smoking and BMI between education and occurrence of diseases was assessed by testing indirect effects. From 8904 individuals (mean age 54 years, 46% male), 4378 (49%) had at least one disease. Gradients in occurrence of disease by education were present for all diseases except cancer and mental disease, with the strongest gradient in diabetes (OR 2.0 [95%CI 1.4;2.8]). Unemployment and especially living on minimum income were associated with increased odds to have MSKD and mental and respiratory disease, after adjusting for education. Smoking and obesity mediated part of the relationship between education and disease, with obesity playing more pronounced role. Association between deprivation and occurrence of all major chronic diseases is of comparable magnitude, with education having most consistent contribution. Our results support the notion of the generic (i.e., non-disease specific) mechanisms underlying socio-economic gradients in health.

Prevalence of Chondrocalcinosis in Patients above 50 Years and the Relationship with Osteoarthritis

BACKGROUND

Some studies showed a relation between chondrocalcinosis and osteoarthritis (OA). Hence, considering the importance of chondrocalcinosis diagnosis andnecessity for its integration with OA, the current study aims at investigating prevalence of chondrocalcinosis in patients above 50 years admitted to Isfahan Al-Zahra Medical Center and its relationship with OA.

MATERIALS AND METHODS

In a cross-sectional study, 600 patients who referred to the radiology units of Al-Zahra Hospital for radiography of different joints were studied during 2013-2014. The patients images were studied for chondrocalcinosis and OA by a radiologist and also examined clinically and results of imaging by an expert rheumatologist. The prevalence of chondrocalcinosis and it relation with OA was determined by Statistical Package for Social Sciences software and using of Chi-square and t-test.

RESULTS

23 patients under study had chondrocalcinosis (3.83%). patients with chondrocalcinosis had higher age average, and they were in age group of 70 years and older, but no significant difference was observed regarding the prevalence of the disease in both genders. Chondrocalcinosis prevalence in terms of body mass index showed significant differences (P = 0.001). All patients with chondrocalcinosis had a history of joint disease and prevalence of chondrocalcinosis in terms of joint disease history showed a significant difference (P < 0.001).

CONCLUSION

Prevalence of chondrocalcinosis is relatively high in the Iranian population of 70 years and older. Hence, more investigation considering to the diagnosis of chondrocalcinosis among patients with OA is very important.

Work outcome in persons with musculoskeletal diseases: comparison with other chronic diseases & the role of musculoskeletal diseases in multimorbidity

Background

Chronic diseases and multimorbidity are increasingly common among persons in working age. This study explores the impact of type, number and combinations of chronic diseases with focus on the role of MSKD on (1) adverse work status (i.e. work disability (WD), economic unemployment (UE) or receiving a living allowance (LA)) and on (2) the occurrence of sick leave.

Methods

Subjects participating in a Dutch household survey, who were ≤65 years and could have paid work, provided data on socio-demographics and nine physician diagnosed chronic diseases. To explore the independent association of each chronic disease, of multimorbidity and of MSKD in context of multimorbidity with 1) work status (employed, WD, LA, UE) and 2) sick leave (SL) in those employed, multinomial logistic regressions and logistic regressions were used, respectively.

Results

Among 5396 subjects, MSKD was the most common morbidity (17%), multimorbidity occurred in 755/5396 (14%), 436/755 (61%) of subjects with multimorbidity had an MSKD. For MSKD the odds of WD, LA and UE were 2.06 [95% CI 1.56;2.71], 2.15[1.18;3.91] and 1.35[0.94;1.96], respectively, compared to being employed and the odds of SL in MSKD were 2.29[1.92;2.73]. Mental diseases had a stronger impact on all these outcomes. The odds for adverse work outcomes increased strongly with an increasing number of diseases. When an MSKD was part of multimorbidity, an additional impact on the association with WD and SL was observed.

Conclusions

Multimorbidity has a stronger impact on all work outcomes compared to single chronic diseases. The presence of the MSKD in the context of multimorbidity amplifies the chance of WD or SL.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1365-4) contains supplementary material, which is available to authorized users.

Prevalence of Hyperuricemia and Gout in Mainland China from 2000 to 2014: A Systematic Review and Meta-Analysis

We systematically identified the prevalence of hyperuricemia and gout in mainland China and provided informative data that can be used to create appropriate local public health policies. Relevant articles from 2000 to 2014 were identified by searching 5 electronic databases: PubMed, Google Scholar, Chinese Wanfang, CNKI, and Chongqing VIP. All of the calculations were performed using the Stata 11.0 and SPSS 20.0 software. The eligible articles (n = 36; 3 in English and 33 in Chinese) included 44 studies (38 regarding hyperuricemia and 6 regarding gout). The pooled prevalence of hyperuricemia and gout was 13.3% (95% CI: 11.9%, 14.6%) and 1.1% (95% CI: 0.7%, 1.5%), respectively. Although publication bias was observed, the results did not change after a trim and fill test, indicating that that impact of this bias was likely insignificant. The prevalence of hyperuricemia and gout was high in mainland China. The subgroup analysis suggested that the geographical region, whether the residents dwell in urban or rural and coastal or inland areas, the economic level, and sex may be associated with prevalence.

Socioeconomic inequities in perceived health among patients with musculoskeletal disorders compared with other chronic disorders: results from a cross-sectional Dutch study

OBJECTIVES

To explore the impact of socioeconomic factors on physical and mental health of patients with musculoskeletal disorders (MSKDs) and compare it across patients with other disorders.

METHODS

A representative sample of the Dutch population (n=8904) completed a survey on sociodemographics, physician-diagnosed (co-) morbidities, and physical (physical component summary, PCS) and mental (mental component summary, MCS) subscales of SF-12 (outcome variables). Regression models were computed first in the total group of patients with MSKDs, with education, age, gender, origin and place of residence as independent variables, and, second, in individuals expected to have paid work, adding a variable on social status. Models were repeated for five other subgroups of chronic disorders (cardiovascular (CVD), diabetes, cancer, mental and respiratory) and for healthy individuals.

RESULTS

MSKDs confirmed by a physician were reported by 1766 (20%) participants (mean age 59 years, 38% male), 547 (6%) respondents reported to have diabetes, 1855 (21%) CVD, 270 (3%) cancer, 526 (6%) mental disorders, 679 (8%) respiratory disorders and 4525 (51%) did not report any disease. In patients with MSKDs, (primary school vs university education (-5.3 (PCS) and -3.3 (MCS)) and having a state subsidy vs paid work (-5.3 (PCS) and -4.7 (MCS)) were consistently associated with worse physical and mental health. Gender was only relevant for PCS (female vs male -2.1). Comparable differences in health by education and social status were observed in the other diseases, except for cancer.

CONCLUSIONS

Education and social status in MSKD have the same strong and independent association with health as in other chronic diseases. These health gradients are unfair and partly avoidable, and require consorted attention and action in and outside healthcare.

Using natural language processing and machine learning to identify gout flares from electronic clinical notes

OBJECTIVE

Gout flares are not well documented by diagnosis codes, making it difficult to conduct accurate database studies. We implemented a computer-based method to automatically identify gout flares using natural language processing (NLP) and machine learning (ML) from electronic clinical notes.

METHODS

Of 16,519 patients, 1,264 and 1,192 clinical notes from 2 separate sets of 100 patients were selected as the training and evaluation data sets, respectively, which were reviewed by rheumatologists. We created separate NLP searches to capture different aspects of gout flares. For each note, the NLP search outputs became the ML system inputs, which provided the final classification decisions. The note-level classifications were grouped into patient-level gout flares. Our NLP+ML results were validated using a gold standard data set and compared with the claims-based method used by prior literatures.

RESULTS

For 16,519 patients with a diagnosis of gout and a prescription for a urate-lowering therapy, we identified 18,869 clinical notes as gout flare positive (sensitivity 82.1%, specificity 91.5%): 1,402 patients with ≥3 flares (sensitivity 93.5%, specificity 84.6%), 5,954 with 1 or 2 flares, and 9,163 with no flare (sensitivity 98.5%, specificity 96.4%). Our method identified more flare cases (18,869 versus 7,861) and patients with ≥3 flares (1,402 versus 516) when compared to the claims-based method.

CONCLUSION

We developed a computer-based method (NLP and ML) to identify gout flares from the clinical notes. Our method was validated as an accurate tool for identifying gout flares with higher sensitivity and specificity compared to previous studies.

Association between gout and all-cause as well as cardiovascular mortality: a systematic review

Gout affects 1% to 2% of the population, and the prevalence is increasing due to changes in diet and the ageing of the population. Its development and risk factors have been explored frequently, and recommendations for the diagnosis and management of gout implemented. Nevertheless, there is a lack of knowledge regarding the long-term impact on gouty patients. This systematic review therefore evaluates the association between gout and all-cause as well as cardiovascular mortality. A systematic literature search was performed, and seven long-term studies were ultimately analyzed. Six of them used multivariate regressions to assess the adjusted mortality ratio in gouty patients with reference to patients without the disorder. Despite differences in study designs, study populations, and definitions of gout, the results were consistent: There was an independent association between gout and all-cause as well as cardiovascular mortality. Knowing that patients with gout are at risk emphasizes the need for adequate care.