Seasonal variation in the onset of acute microcrystalline arthritis

Visits to Sexually Transmitted Infection Clinics in Italy from January 2016 to November 2021: A Multicenter, Retrospective Study

There is no evidence of seasonal variation in visits to clinics dedicated to sexually transmitted infections (STIs) in Italy, nor of changes after the advent of the COVID-19 pandemic. An observational, retrospective, multicentric study was conducted to record and analyze all the visits to the STI clinics of the Dermatology Units of the University Hospitals of Ferrara and Bologna and of the Infectious Disease Unit of Ferrara, Italy, between January 2016 and November 2021. Overall, 11.733 visits were registered over a 70-month study period (63.7% males, mean age 34.5 ± 12.8 yrs). The mean number of monthly visits significantly decreased from the advent of the pandemic (136) compared to before (177). In the pre-pandemic period, visits to STI clinics increased in the autumn/winter months when compared to spring/summer, while the trend was the opposite in the pandemic period. Thus, during the pandemic, both an overall significant reduction in visits to STI clinics and a reversal in their seasonality were observed. These trends affected males and females equally. The marked decrease, mostly found in the pandemic winter months, can be linked to the "lockdown"/self-isolation ordinances and social distancing measures during the colder months, coinciding with the spread of the COVID-19 infection, which limited the opportunities for meeting and socializing.

Environmental factors and risk of gout

Gout is a chronic disease with inflammatory arthritis caused by monosodium urate (MSU) crystals deposition, an elevated serum urate level (hyperuricaemia) is the critical factor leading to MSU crystals deposition and promoting the progression of gout. The onset and development of gout is generally the result of multiple factors, such as diet, heredity and environmental factors. Although genetics and diet are thought to play as major factors, a growing body of research evidence has highlighted that environmental factors also play a significant role in the onset and exacerbation of gout. Recent studies have shown that air pollutants such as particulate matter, sulfur dioxide (SO₂) and carbon monoxide (CO) may increase the risk of hospitalizations for gout, and that the changes in temperature and humidity may affect uric acid (UA) levels. There is also seasonal trend in gout. It has been demonstrated that environmental factors may induce or accelerate the production and release of pro-inflammatory mediators, causing an unbalance oxidative stress and systemic inflammation, and then participating in the overall process or a certain link of gout. Moreover, several environmental factors have shown the ability to induce the production urate and regulate the innate immune pathways, involving in the pathogenesis of gout. Nevertheless, the role of environmental factors in the etiology of gout remains unclear. In this review, we summarized the recent literatures and aimed to discuss the relationship between environmental factors (such as microclimate, season, ambient/indoor air pollution and extreme weather) and gout. We further discussed the inflammatory mechanisms of environmental factors and gout and the comprehensive effects of environmental factors on gout. We also made a prospect of the management and treatment of gout, with special consideration to environmental factors associated with gout.

Wastewater-based prevalence trends of gout in an Australian community over a period of 8 years

Gout is a rheumatic arthritis disease which poses a health burden. Monitoring the prevalence of gout is key to reduce the community burden of gout disease and associated health costs. Allopurinol has been used as a first line gout preventive medication in Australia which is metabolised into oxypurinol and excreted in urine. Wastewater-based epidemiology (WBE) was applied to estimate temporal trends of gout prevalence in an Australian community over eight-years via the quantification of oxypurinol in wastewater. A total of 180 wastewater samples collected between 2012 and 2019 were analysed for oxypurinol to estimate allopurinol consumption in a community in South East Queensland, Australia. Annual gout prevalence was estimated by daily defined doses (DDD) consumed and ranged from 24 to 32 DDD/day/1000, an equivalent gout prevalence of 2.3 to 3.2% over the eight-year period. A statistically significant increase in allopurinol consumption was observed over the period (Slope = 0.094, p = 0.0001), equating to year-on-year increases in gout prevalence of 3.6% per year. To the best of our knowledge, this is the first long-term gout prevalence study using wastewater, adding epidemiological and public health insights in the gout research field.

Seasonal variation in the onset of acute calcific tendinitis of rotator cuff

Background

Calcific tendinitis of the rotator cuff is a disorder that causes acute onset of shoulder pain when spontaneous resorption of the calcification occurs. However, factors that trigger calcium resorption have not been clarified. The present study aimed to investigate the association between the onset of calcium resorption in calcific tendinitis and the season of onset.

Methods

We retrospectively reviewed 195 patients (female, 116; male, 79; mean age, 62.6 ± 14.2 years; median age, 62 [52, 73] years) diagnosed with the postcalcification stage of calcific tendinitis, which was defined as acute calcific tendinitis in this study, between 2006 and 2018. The onset date of acute calcific tendinitis for each patient was collected from clinical notes. We evaluated the incidence of acute calcific tendinitis in each season and month. Furthermore, we investigated the correlation between the incidence of acute calcific tendinitis and the mean monthly temperature or humidity levels for each year.

Results

The most common season of acute calcific tendinitis onset was summer (35.4%), followed by spring (24.6%), autumn (24.1%), and winter (15.9%) (P = 0.002). Monthly analyses showed the highest peak of onset was in July (15.4%) and the lowest peak was in February (3.1%) (P = 0.022). The incidence of acute calcific tendinitis had a weak association with mean monthly temperature (R² = 0.066; P = 0.001) but was not associated with mean monthly humidity levels (R² = 0.018; P = 0.099).

Conclusions

This study provides new information on seasonal variation of acute calcific tendinitis onset. The results of this study indicated that the onset of calcium resorption occurs most frequently in the summer in Japan; however, the reasons for seasonal variation remain unclear, and further studies will be needed.

Level of evidence

Level III.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03773-6.

Seasonal Variations and Associated Factors of Gout Attacks: a Prospective Multicenter Study in Korea

BACKGROUND

We purposed to evaluate the seasonality and associated factors of the incidence of gout attacks in Korea.

METHODS

We prospectively enrolled patients with gout attacks who were treated at nine rheumatology clinics between January 2015 and July 2018 and followed them for 1-year. Demographic data, clinical and laboratory features, and meteorological data including seasonality were collected.

RESULTS

Two hundred-five patients (men, 94.1%) were enrolled. The proportion of patients with initial gout attacks was 46.8% (n = 96). The median age, body mass index, attack duration, and serum uric acid level at enrollment were 50.0 years, 25.4, 5.0 days, and 7.4 mg/dL, respectively. Gout attacks were most common during spring (43.4%, P < 0.001) and in March (23.4%, P < 0.001). A similar pattern of seasonality was observed in the group with initial gout attacks. Alcohol was the most common provoking factor (39.0%), particularly during summer (50.0%). The median diurnal temperature change on the day of the attack was highest in the spring (9.8°C), followed by winter (9.3°C), fall (8.6°C), and summer (7.1°C) (P = 0.027). The median change in humidity between the 2 consecutive days (the day before and the day of the attack) was significantly different among the seasons (3.0%, spring; 0.3%, summer; -0.9%, fall; -1.2%, winter; P = 0.015). One hundred twenty-five (61%) patients completed 1-year follow-up (51% in the initial attack group). During the follow-up period, 64 gout flares developed (21 in the initial attack group). No significant seasonal variation in the follow-up flares was found.

CONCLUSION

In this prospective study, the most common season and month of gout attacks in Korea are spring and March, respectively. Alcohol is the most common provoking factor, particularly during summer. Diurnal temperature changes on the day of the attack and humidity changes from the day before the attack to the day of the attack are associated with gout attack in our cohort.

Association between acute gouty arthritis and meteorological factors: An ecological study using a systematic review and meta-analysis

OBJECTIVES

The aims of this study were as follows: (1) to analyze the literature systematically regarding the seasonal and monthly variation of the occurrence of episodes of acute gouty arthritis, and (2) to investigate the relationship between the occurrence of episodes of acute gouty arthritis and meteorological parameters.

METHODS

The present authors systematically reviewed databases for articles published before November 2015. Studies with quantitative data on episodes of acute gouty arthritis by months and/or seasons were included. Meteorological data such as the highest temperature, lowest temperature, diurnal temperature range, change in mean temperature between neighboring days, relative humidity and wind speed for the geographic place(s), and study period where and when each study took place were obtained from meteorological websites.

RESULTS

Ten studies published between 1920 and 2015 were included. A meta-analysis by season showed that acute gouty arthritis occurred significantly more frequently in spring than in other seasons. Analysis by month showed an increase in episodes of acute gouty arthritis from March to July, being the highest in July. The trend reversed, and episodes of acute gouty arthritis started decreasing from July to September, being the lowest in September. The change in mean temperature between neighboring days was the only meteorological parameter that was significantly correlated with the number of monthly episodes of acute gouty arthritis.

CONCLUSIONS

Acute gouty arthritis seems to develop more frequently during the period in which the temperature increases significantly between neighboring days: spring by season and between March and July by month in the northern hemisphere.

Seasonal Variations of Complete Blood Count and Inflammatory Biomarkers in the US Population - Analysis of NHANES Data

Background

Recent studies reported seasonal differences in gene expression in white blood cells, adipose tissue, and inflammatory biomarkers of the immune system. There is no data on the seasonal variations of these biomarkers in the US general population of both children and adults. Then aim of this study is to explore the seasonal trends in complete blood count (CBC), and C-reactive protein (CRP) in a large non-institutionalized US population.

Methods

Seven cross-sectional data collected in the National Health and Nutrition Examination Survey (NHANES) during 1999–2012 were aggregated; participants reporting recent use of prescribed steroids, chemotherapy, immunomodulators and antibiotics were excluded. Linear regression models were used to compare levels of CBC and CRP between winter-spring (November-April) and summer-fall (May-October), adjusting for demographics, personal behavioral factors, and chronic disease conditions.

Results

A total of 27,478 children and 36,644 adults (≥18 years) were included in the study. Levels of neutrophils, white blood cell count (WBC), and CRP were higher in winter-spring than summer-fall (p≤0.05). Red blood cell components were lower in winter-spring than in summer-fall, while the opposite was seen for platelets.

Conclusions

This large population-based study found notable seasonal variations in blood cell composition and inflammatory biomarkers, with a more pro-inflammatory immune system seen in winter-spring than summer-fall. The red blood cell patterns could have implications for the observed cardio-vascular seasonality.

Seasonal variation in acute gouty arthritis: data from Nationwide Inpatient Sample

INTRODUCTION

Studies describing seasonal variations in acute gouty arthritis note seasonal variation, but disagree on timing, with most showing a peak in spring months while others show peaks later in the year. Various theories on the effect of weather and immune system changes on the chronobiology of monosodium urate crystals' equilibrium and precipitation have been proposed. We aimed to shed light on this question by examining the seasonal variation in the incidence of acute gouty arthritis in the USA using a large inpatient database.

METHODS

We used the Nationwide Inpatient Sample (NIS) database to identify patients aged ≥18 years with primary diagnosis of acute gouty arthritis (International Classification of Diseases, 9th Revision, Clinical Modification code 274.01) from 2009-2011 during hospitalization. We used the Edwards recognition and estimation of cyclic trend method to study the seasonal variation of the incidence of acute gout and z-test to compare the seasonal incidences.

RESULTS

A total of 28,172 hospitalizations with primary diagnosis of acute gouty arthritis were reported in the USA from 2009-2011. The peak incidence of acute gout was seen in November (peak/low ratio 1.34, 95 % CI 1.29-1.38, p < 0.05). The highest number of hospitalizations was observed in autumn months while the lowest incidence was observed in spring (28.12 vs. 23.13 %, p < 0.001).

CONCLUSION

The peak incidence of acute gout seems to be in the fall with its peak in the month of November. This seasonality may shed light into the pathophysiology of acute attacks and better management of patients with gout who are at risk of acute attacks.

Seasonality of gout in Korea: a multicenter study

The object of this study was to evaluate the seasonality of gout in Korea. We retrospectively examined data from 330 patients seen at nine rheumatology clinics, treated with urate lowering therapy (ULT) more than one year after stopping prophylactic medication. Demographic data, clinical and laboratory features, and seasonality of gout onset and flares were collected. Season was classified in three-month intervals. The mean age was 52.2 yr and mean disease duration was 26.8 months. The male to female count was 318:12. The onset of acute gouty attacks was obtained in 256 patients. Gout developed most commonly in summer season (36.7%) (P<0.001) and in June (15.6%, P=0.002). During ULT, there were 147 (male 97.3%) gout flares. Although there was no statistically significant difference, gout flares were more common in summer (30.6%). Aggravating factors were identified in 57 flares: alcohol (72.0%) was most common. In the patients who attained target serum uric acid (<6 mg/dL) at the end of prophylaxis, gout flares were high in fall (35.8%) and September (17.0%). In Korea, the summer is most common season of gout onset and there is a tendency for gout flares to increase during ULT in summer/fall season.

Relation of temperature and humidity to the risk of recurrent gout attacks

Gout attack risk may be affected by weather (e.g., because of volume depletion). We therefore examined the association of temperature and humidity with the risk of recurrent gout attacks by conducting an internet-based case-crossover study in the United States (in 2003-2010) among subjects with a diagnosis of gout who had 1 or more attacks during 1 year of follow-up. We examined the association of temperature and humidity over the prior 48 hours with the risk of gout attacks using a time-stratified approach and conditional logistic regression. Among 632 subjects with gout, there was a significant dose-response relationship between mean temperature in the prior 48 hours and the risk of subsequent gout attack (P = 0.01 for linear trend). Higher temperatures were associated with approximately 40% higher risk of gout attack compared with moderate temperatures. There was a reverse J-shaped relationship between mean relative humidity and the risk of gout attacks (P = 0.03 for quadratic trend). The combination of high temperature and low humidity had the greatest association (odds ratio = 2.04, 95% confidence interval: 1.26, 3.30) compared with moderate temperature and relative humidity. Thus, high ambient temperature and possibly extremes of humidity were associated with an increased risk of gout attack, despite the likelihood that individuals are often in climate-controlled indoor environments.

P2X7R: a potential key regulator of acute gouty arthritis

OBJECTIVES

Acute gouty arthritis is an inflammatory disease resulting from the precipitation of long-term hyperuricemia-induced monosodium urate (MSU) crystals in joints, which stimulates the production of interleukin-1beta (IL-1β) and initiates an inflammatory reaction. However, some patients having MSU crystals in the joints never develop acute gouty arthritis, indicating that other predisposing factors are required for the disease onset. This review described the mechanism of production of IL-1β by MSU crystals and other possible factors during a gout attack.

METHODS

The relevant English literature on IL-1β secretion stimulated by MSU crystals and other possible factors during acute gouty arthritis flares was searched and carefully reviewed.

RESULTS

MSU crystals lead to the onset of acute gouty arthritis mainly through the activation of Toll-like receptors (TLRs) and NACHT-LRR-PYD-containing protein 3 (NALP3) inflammasome signaling and downstream IL-1β production. The predisposing factors of acute gouty arthritis, such as strenuous exercise, cold, alcolholism, and overeating have a common characteristic inducing dramatic changes of adenosine triphosphate (ATP) in the body. The ATP changes can activate the purinergic receptor P2X ligand-gated ion channel 7 (P2X7R) signaling system to regulate IL-1β secretion.

CONCLUSIONS

We hypothesize that acute gouty arthritis is induced by two synergistic effects; one is the stimulation of MSU crystals and the other is the activation of P2X7R signaling pathways by extracellular ATP changes, which together lead to the production of IL-1β and the initiation of acute gouty arthritis. This hypothesis will provide a new avenue for the prevention and treatment of acute gouty arthritis.

A genome-wide association study of seasonal pattern mania identifies NF1A as a possible susceptibility gene for bipolar disorder

OBJECTIVE

The use of subphenotypes may be an effective approach for genetic studies of complex diseases. Manic episodes with a seasonal pattern may distinguish phenotypic subgroups of bipolar subjects that may also differ genetically.

METHOD

We have performed a genome-wide association study using GAIN genotype data from the Bipolar Genome Study (BiGS) and bipolar subjects that were categorized as having either seasonal or non-seasonal patterned manic episodes.

RESULTS

A bipolar case-only analysis identified three genomic regions that differed between seasonal and non-seasonal patterned manic episodes of bipolar subjects. The most significant association was for rs41350144, which lies within an intron of NF1A gene on 1p31 (P=3.08×10(-7), OR=2.27). Haplotype construction using flanking three SNPs (rs41453448, rs1125777, and rs12568010) spanning 7549bp showed a more significant association (P=2.12×10(-7), OR=0.4).

CONCLUSIONS

These data suggest that genetic variants in the NF1A gene region may predispose to seasonal patterned of mania in bipolar disorder.

Female gout: age and duration of the disease determine clinical presentation

OBJECTIVE

This study aimed to compare data and associated diseases between women and men with gout paired for age and duration of the disease.

METHODS

Consecutive patients from outpatient gout clinics of 2 rheumatology departments were included in this case-control study. We identified 37 women with gout diagnosis and paired them by age and duration of the disease with 37 men with gout (American College of Rheumatology criteria). Variables were clinical data, associated diseases, and renal function evaluated by 3 methods: creatinine clearance, modification of diet in renal disease, and Cockcroft-Gault.

RESULTS

Mean (SD) age was 54.47 (15.13) years in women versus 53.52 (15.23) years in males, and mean (SD) age at onset 46.77 (16.63) years versus 45.62 (16.16) years in women and men, respectively. Hypertension was found in 26 (73%) of 37 women and in 27 (70%) of 37 men, previous diuretics was found in only 1 man, and no significant differences were found between women and men in gout or associated metabolic diseases. Females had lower creatinine clearance than males did (49.8 [29.7] vs. 67.1 [35.5] mL/min, P = 0.039). But, when it was calculated by methods considering sex, there were no significant differences (Cockcroft-Gault 66.4 [37.6] vs. 78.8 [43.8] mL/min [P = 0.2] and modification of diet in renal disease 73.8 [64.6] vs. 73.1 [35.0] mL/min [P = 0.9], females vs. males, respectively). Thirteen women (35%) were premenopausal at onset, 2 had familial history of gout, and 2 had history of lithiasis; other variables were not different from postmenopausal women.

CONCLUSIONS

Factors previously associated to female gout seem to be more related to age than to sex or to the disease itself. In our country, patients with gout (males and females) are younger at onset. Gender should be considered to evaluate renal function in females with gout. One third of our female patients with gout were premenopausal and had unexpected higher frequency of lithiasis; no other differences with postmenopausal women were found.

Seasonal variation in the activity of systemic lupus erythematosus

OBJECTIVE

To determine whether there is any seasonal variation in the activity of systemic lupus erythematosus (SLE) overall and by individual organs.

METHODS

The study group comprised 2102 patients with SLE who were followed in a prospective longitudinal cohort study. In this cohort, 92.3% of the patients were women. The mean ± SD age of the patients was 47.9 ± 13.9 years, 56.3% were white, 37.1% were African American, and 3.1% were Asian. Global disease activity was recorded by the Safety of Estrogens in Lupus Erythematosus National Assessment - Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) and the physician's global assessment. Activity of each organ was also recorded using SLEDAI terms and a visual analog scale (VAS; 0 to 3).

RESULTS

There was significant seasonal variation in photosensitive rash (p < 0.0001), which was more frequent in the spring and summer months (p < 0.0001). There was significantly more arthritis activity in spring and summer, as measured by both SELENA-SLEDAI (p = 0.0057) and the joint VAS (p = 0.0047). A decrease in renal activity was found in the summer months compared to the rest of the year (p = 0.0397). Serositis recorded by VAS had higher activity from August to October (p = 0.0392). Anti-dsDNA levels were significantly higher during October and November (p < 0.0001). There was significant seasonal variation in antiphospholipid antibody levels (p < 0.0001) and lupus anticoagulant (p = 0.0003). We found a significant variation in activity through the year in global disease activity as measured by SELENA-SLEDAI (p = 0.048).

CONCLUSION

In the Hopkins Lupus Cohort, skin and joint activity is increased during the spring and summer, but other organs have different patterns. These seasonal variations likely reflect environmental factors that influence disease activity, including ultraviolet light and infections.

"Clinical features of women with gout arthritis." A systematic review

Clinically, gout is generally considered as a preferential male disease. However, it definitely does not occur exclusively in males. Our aim was to assess differences in the clinical features of gout arthritis between female and male patients. Five electronic databases were searched to identify relevant original studies published between 1977 and 2007. The included studies had to focus on adult patients with primary gout arthritis and on sex differences in clinical features. Two reviewers independently assessed eligibility and quality of the studies. Out of 355 articles, 14 were selected. Nine fulfilled the quality and score criteria. We identified the following sex differences in the clinical features of gout in women compared to men: the onset of gout occurs at a higher age, more comorbidity with hypertension or renal insufficiency, more often use of diuretics, less likely to drink alcohol, less often podagra but more often involvement of other joints, less frequent recurrent attacks. We found interesting sex differences regarding the clinical features of patients with gout arthritis. To diagnose gout in women, knowledge of these differences is essential, and more research is needed to understand and explain the differences , especially in the general population.

Circannual variation in the onset and relapse of steroid-sensitive nephrotic syndrome

Idiopathic nephrotic syndrome is the most common form of nephrotic syndrome in children, but little is known about the etiology of the disease. To obtain new insights into the etiology of the disease, we studied circannual patterns of initial episodes and relapses of steroid-sensitive nephrotic syndrome (SSNS). From 1986 to 2003, there were 45 children with SSNS in our hospital, and they experienced 43 relapses during that period. Initial episodes of SSNS were found to show significant circannual variation with an autumn peak both by Roger's test and Freedman's test, and the circannual pattern was more obvious in patients with high serum IgE levels. Chronological evaluation by means of Fourier analysis showed a clear circannual pattern. In contrast, relapses of SSNS showed circannual variation with a spring peak, which was a result of a high frequency of relapses after upper respiratory infections in January. These results suggest that circannual variation in initial episodes of SSNS might be associated with allergic predisposition, whereas circannual variation in relapses might be associated with preceding upper respiratory infections.

Seasonal variation in the onset of acute pancreatitis

AIM: A circannual variation in the onset of several acute diseases, mostly dealing with cardiovascular system, has been reported. The present study was to verify the possible existence of a seasonal variability in the onset of acute pancreatitis.

METHODS: All patients consecutively admitted to the Hospital of Ferrara, Italy, between January 1998 to December 2002, whose discharge diagnosis was acute pancreatitis, were considered. According to the time of admission, cases were categorized into twelve 1-mo intervals and in four periods by season. χ² test for goodness of fit and partial Fourier series were used for statistical analysis.

RESULTS: During the study period, 549 cases of acute pancreatitis were observed. A significant peak of higher incidence was found in March-May, both for total population, males and subgroups with and without cholelithiasis or alcoholism. Fourier analysis showed the existence of a circannual rhythmic pattern with its main peak in March (95%C.L.: February-April, P = 0.005), and a secondary one in September. Death occurred more frequently in December-February, compared to the other periods (P = 0.029), and chronobiologic analysis yielded a seasonal peak in November-December (P < 0.001).

CONCLUSION: This study shows the existence of a circannual variation in the onset of acute pancreatitis, with a significantly higher frequency of events in the spring, especially for patients with cholelithiasis or alcoholism. Moreover, events occurring during the colder months seem to be characterized by a higher mortality rate.

A literature review of the epidemiology and treatment of acute gout

BACKGROUND

Gout is the most common cause of inflammatory arthritis in men aged >40 years and is frequently encountered in clinical practice.

OBJECTIVE

The goal of this article was to review the published literature on the epidemiology, treatment, and estimated burden of illness of acute gout.

METHODS

Articles on gout published in English between 1980 and June 2002 were identified through a MEDLINE search. Relevant clinical studies and review articles were found using the text- and keyword-search term gout alone and in combination with epidemiology, prevalence, incidence, complications, outcome, quality of life, economics, cost, prevention or drug therapy. The reference lists of identified articles, especially review articles, were checked for any additional studies that might have been missed in the original MEDLINE search.

RESULTS

The epidemiology of gout in various geographic regions has been well documented. Data suggest that environmental, racial, and hereditary factors may influence the development of gout, and that the prevalence of gout appears to be on the rise worldwide. Evidence from well-designed clinical studies evaluating drug therapies for gout is limited. Therapies for acute gout include corticotropin, corticosteroids, colchicine or, more often, nonsteroidal anti-inflammatory drugs (NSAIDs), which have shown comparable efficacy. A recent study suggests that etoricoxib, a new cyclooxygenase-2-selective inhibitor, may be as effective as and better tolerated than traditional NSAIDs in the treatment of gout. Urate-lowering therapy, prophylactic colchicine, and low-dose NSAIDs are used for the long-term prophylaxis of gout. However, all acute and prophylactic therapies are associated with adverse events. Using an economic model for gout, the annual direct burden of illness for new cases of acute gout can be estimated at 27,378,494 US dollars in the United States.

CONCLUSIONS

Gout is an increasingly prevalent condition worldwide and creates a heavy economic burden. Available treatments are generally effective; however, they are not devoid of adverse events. Well-designed, long-term, controlled clinical trials evaluating the comparative efficacy and tolerability of treatments for gout are needed.

What is new about crystals other than monosodium urate?

Recently, attention has focused on the effects of weather conditions and seasonal changes on the incidence of acute microcrystalline events. Acute gout attacks are more frequent during the spring, but seasonal variations in the incidence of acute pseudogout attacks are less clearly defined. Genetic analysis of two unrelated families with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease showed linkage to the short arm of chromosome 5p. Several recent reports show CPPD crystal disease occurring in association with Gitelman syndrome, the hypocalciuric-hypomagnesemic variant of Bartter syndrome. Two signaling pathways, protein kinase C and adenyl cyclase, modulate generation of extracellular pyrophosphate by porcine cartilage chrondrocytes. These transduction mechanisms may provide potential targets for the treatment of CPPD crystal deposition disease. A controlled clinical trial showed ultrasound therapy to be beneficial in the treatment of symptomatic chronic calcific tendinitis of the shoulder. There is evidence that apatite crystals may contribute to cartilage damage in osteoarthritis and that therapeutic interventions to prevent the formation and biologic effects of the crystals may potentially retard the progression of the osteoarthritic process.

Gout update: from lab to the clinic and back

Reviews and opinion articles stressing the need for better reproducibility of crystal identification in synovial fluid continue to be published. The possibility of definitive diagnosis of gout by crystal identification during intercritical periods appears now established. The problems associated with the use of allopurinol have also received some attention, as well as the strategies of dealing with allopurinol hypersensitivity. Gout in transplanted patients is reviewed, with special attention to the difficulties related to its treatment; various therapeutic options for this group are reviewed. The use of benzbromarone to reduce uricemia appears to be especially appropriate for this group of patients, in whom allopurinol is problematic. Finally, the pathogenetic mechanisms of the disease, and the relation between urate crystals and inflammation are reviewed.