Clinical Rheumatology

, Volume 30, Issue 7, pp 887–893

Prevalence of hyperuricemia in Bangkok population

Authors

    • Rheumatology Unit, Department of MedicineBangkok Metropolitan Administration Medical College and Vajira Hospital
  • S. Suraamornkul
    • Endocrine Unit, Department of MedicineBangkok Metropolitan Administration Medical College and Vajira Hospital
  • S. Angkeaw
    • Department of Preventive and Social MedicineBangkok Metropolitan Administration Medical College and Vajira Hospital
  • R. Uaratanawong
    • Department of MedicineBangkok Metropolitan Administration Medical College and Vajira Hospital
Original Article

DOI: 10.1007/s10067-011-1699-0

Cite this article as:
Uaratanawong, S., Suraamornkul, S., Angkeaw, S. et al. Clin Rheumatol (2011) 30: 887. doi:10.1007/s10067-011-1699-0

Abstract

To investigate the prevalence of hyperuricemia in general Thai population and to evaluate its association with metabolic syndrome. A total of 1,945 subjects who sought for routine annual health checkup in our hospital from 1 October 2009 to 31 March 2010 were enrolled into the study. Inclusion criteria were healthy individuals, aged ≥35 years old, and lived in Bangkok for over 10 years. Data of general health status, age, gender, history of alcoholic consumption, body weight, height, and waist circumference were obtained by an interview-structured questionnaire. Fasting blood sample was collected from each subject early in the morning for uric acid, total cholesterol, high density lipoprotein cholesterol, triglycerides, and glucose levels. The prevalence of hyperuricemia in our study population was 24.4%, being significantly more common in men than women (59% vs. 11%, p < 0.001). The condition was also associated with various features of high body mass index or waist circumference, alcohol consumption, dyslipidemia, and high fasting blood glucose. Metabolic syndrome was found in 35% and 23% of men and women with hyperuricemia; direct relationship between level of uric acid and prevalence of metabolic syndrome was observed. Hyperuricemia is common among Bangkok population in our study. This disorder is frequently associated with metabolic syndrome.

Keywords

BangkokHyperuricemiaMetabolic syndromePrevalence

Introduction

Gout is the most common inflammatory arthritis in adult males. There is a trend of increasing incidence of gout worldwide [1]. Recent epidemiological surveys found that the prevalence and incidence of hyperuricemia and gout in the middle aged and older people are rising globally during the last two decades [24]. In the US, approximately 5.1 million of population is estimated to have gout, resulting in 3.9 million ambulatory care visits annually [2].

Hyperuricemia is considered to be the most significant risk factor for gout and is also an important risk factor for cardiovascular diseases [5]. The prevalence of hyperuricemia was reported from 2.6 to 36% in various populations [68] while that of gout ranged from less than 1% to as high as 15.3% [9]. The incidence of gout is directly related to the level of uric acid level; the annual incidence rate of gout is 0.1% for uric level less than 7 mg/dl, 4.9% for value greater than 9 mg/dl, and with 22% cumulative incidence if serum uric value is greater than 9 mg/dl [10].

Many studies found that, aside from gout, hyperuricemia is also commonly seen in association with other several metabolic disorders, such as, obesity, hypertension, and metabolic syndrome [1117]. Direct association of hyperuricemia and obesity was observed; it was found in only 3.4% among those with a relative weight ≤20th percentile, 5.7% in those between the 21st and 79th percentile, and 11.4% in those ≥80th percentile [13]. Many studies demonstrated independent association between serum uric acid and risk for hypertension [1417]. While some of these factors might be independent factors while metabolic syndrome as an entity was influenced or confounded by several factors, leading to variable association [12, 18]. Metabolic syndrome is a cluster of metabolic and hemodynamic disorders characterized by abnormally elevated glucose level, hypertension, and dyslipedemia [11]. The syndrome poses an individual to health hazards of cardiovascular disease and type 2 diabetes mellitus. The influences of several risk factors including increased serum uric levels and the syndrome have been topics of much interest in Asia in recent years [11, 12].

In order to have a strategic plan to prevent hyperuricemia and gout and other metabolic disorders, the objective of this study was to estimate the prevalence of hyperuricemia of the Thai population, particularly in Bangkok, who have had incorporated the Western culture and lifestyle more than the other parts of the country. An association of hyperuricemia with various metabolic syndrome components was also studied.

Patients and method

The study was conducted after an approval by the Bangkok Metropolitan Administration Ethics Committee for Researches involving human subjects. The cross-sectional study was carried out from 1 October 2009 to 31 March 2010. There were 2,298 Bangkok citizens who sought for a general annual health examination and agreed to join the health examination program provided by Bangkok Metropolitan Administration Medical College and Vajira Hospital. Inclusion criteria were healthy volunteers with age ≥35 years old and lived in Bangkok for more than 10 years. An informed consent was signed by each participant before entering into the study.

A detailed medical history including past and current illnesses and social history were taken prior to a complete systemic physical examination. A structured questionnaire which had been developed was used for interviewing participants for his/ her general health status, age, gender, and history of alcoholic consumption. Healthy subject referred to an individual with no known past or current history of medical illnesses. Alcoholic consumption was classified as no drinking and drinking (regular drink ≥1 per week of more than 45 ml of spirit, 240 ml of beer, or 120 ml of wine). Body weight, height, waist circumference (at navel level), and blood pressure were measured by a medical personnel. Blood pressure was taken over the right arm using a sphygmomanometer after a participant being rested in sitting position for more than 5 min. For those with a systolic blood pressure of ≥130 mm/Hg and a diastolic blood pressure of ≥85 mm/Hg, blood pressure measurement was repeated on two occasions after resting, and their average value was obtained [19]. Body mass index (BMI) was calculated as weight in kilograms divided by the square of the height in meters. Overweight was defined according to WHO criteria as BMI >25 kg/m2 [20].

All participants were fasting for at least 12 h and blood samples were collected in the next morning. Serum uric acid, total cholesterol, high density lipoprotein (HDL) cholesterol, low density lipoprotein cholesterol, triglycerides, and fasting plasma glucose level were measured by enzymatic end point, direct detergent, and hexokinase method. Hyperuricemia was defined when serum uric acid was ≥7 mg/dl in men and ≥6 mg/dl in women while diabetes mellitus was defined when fasting plasma glucose level was >126 mg/dl. Metabolic syndrome was defined using International Diabetes Federation criteria as waist circumference >80 cm in women and >90 cm in men, plus two of the following: abnormally elevated glucose level (≥100 mg/dl), hypertension, high triglyceridemia ≥150 mg/dl, and low HDL cholesterol ≤40 mg/dl [21].

Statistical analysis

Statistical analysis was performed using Stata S/E version 7 program (Stata Corp., College Station, Tx, USA). Continuous variables were presented as mean with standard deviation or median with range and categorical variables as number with percentage. Chi-square test was used for categorical variables. Comparisons of continuous data were done by Student’s t test and of categorical variables by chi-square or Fisher’s exact tests as appropriate. Multiple logistic regression was used to examine the risks of having metabolic syndrome. The p value <0.05 was considered statistically significant.

Results

Total of 1,945 participants (542 men and 1,403 women) were included in the study. Mean age of the subjects was 48 (8.4) years. More than 2/3 of the subjects (1,403 or 72.1%) were women with a mean age of 48.2 (8.6) years while 542 (27.9%) were men with mean age of 47.6 (8.0) years. Demographic characteristics of BMI, waist circumference, fasting plasma glucose, cholesterol, triglyceride, HDL cholesterol, serum uric acid, and blood pressure according to gender are shown in Table 1.
Table 1

Baseline demographic characteristics of all participants (n = 1,945)

Variables

Men (n = 542)

Women (n = 1,403)

Mean (SD)

Mean (SD)

Age (years)

47.6 (8.0)

48.2 (8.6)

Weight (kg)

69.9 (11.6)

58.6 (11.1)

Height (cm)

166.5 (6.0)

154 (5.6)

BMI (mg/kg2)

25.2 (3.7)

24.5 (4.3)

Waist circumference (cm)

88.9 (9.8)

80.9 (9.7)

Glucose (mg/dl)

88.9 (23.6)

86.0 (18.2)

Uric acid (mg/dl)

6.4 (1.3)

4.7 (1.1)

Triglyceride (mg/dl)

Median = 143 (IQR = 104.5)

Median = 93 (IQR = 62)

Cholesterol (mg/dl)

228.4 (45.1)

222.8 (39.1)

HDL cholesterol (mg/dl)

42.5 (9.4)

50.6 (11.2)

Systolic blood pressure (mm/Hg)

132.4 (18.4)

124.4 (18.4)

Diastolic blood pressure (mm/Hg)

83.8 (12.5)

77.1 (11.3)

BMI body mass index, IQR interquatile range, HDL high density lipoprotein, SD standard deviation

Using the level of uric acid ≥6 or ≥7 mg/dl as the cutoff value, the prevalence of hyperuricemia in our study population was 24.4% (474/1945). A significantly higher prevalence was found in men than women, 320 or 59% in men compared to 154 or 11% in women (p < 0.001). Incidental hypertension was found in 55.4% of men and 37% in women while diabetes mellitus was demonstrated in 4.1% and 2%, respectively. We studied the association of hyperuricemia and other characteristic features according to the gender of the subjects (Table 2). A significant association between hyperuricemia and alcohol drinking, higher waist circumference, overweight (BMI > 25 kg/m2), hypertriglyceridemia, lower HDL cholesterol, and elevated plasma glucose were evident in men (p < 0.05). In women, the significant associations were found for older age group, higher waist circumference, overweight, hypertension, higher fasting plasma glucose, hypertriglyceridemia, and lower HDL cholesterol.
Table 2

Association between various characteristics and hyperuricemia according to gender (n = 1,945)

  

Men (n = 542)

  

Women (n = 1,403)

 

Hyperuricemia n = 320 (n, %)

Nonhyperuricemia n = 222 (n, %)

p value

Hyperuricemia n = 154 (n, %)

Nonhyperuricemia n = 1,249 (n, %)

p value

Age group (years)

  

0.120

  

0.004

≤44

115 (55.3)

93 (44.7)

 

43 (8.3)

473 (91.7)

 

45–54

145 (63.0)

85 (37.0)

 

64 (10.9)

521 (89.1)

 

55–64

54 (61.4)

34 (38.6)

 

34 (14.0)

209 (86.0)

 

>65

6 (37.5)

10 (62.5)

 

13 (8.4)

46 (3.7)

 

Waist circumference (cm)

  

<0.001

  

<0.001

M ≤90; W ≤80

158 (51.0)

152 (49.0)

 

93 (7.9)

1,078 (92.1)

 

M >90; W >80

162 (69.8)

70 (30.2)

 

61 (26.3)

171 (73.7)

 

Alcohol drinking

  

0.040

  

0.173

No drinking

153 (54.8)

126 (45.2)

 

131 (10.6)

1,109 (89.4)

 

Drinking

167 (63.5)

96 (36.5)

 

23 (14.1)

140 (85.9)

 

BMI (g/m2)

  

<0.001

  

<0.001

≤25

129 (50.0)

129 (50.0)

 

45 (5.1)

834 (94.9)

 

>25

191 (67.3)

93 (32.7)

 

109 (20.8)

415 (79.2)

 

Blood pressure (mm/Hg)

  

0.056

  

<0.001

<130/85

132 (54.5)

110 (45.5)

 

64 (7.3)

810 (92.7)

 

≥130/85

188 (62.7)

112 (37.3)

 

90 (17.0)

439 (83.0)

 

Cholesterol 200 (mg/dl)

  

0.047

  

0.486

<200

71 (51.8)

66 (48.2)

 

45 (11.9)

332 (88.1)

 

≥200

249 (61.5)

156 (38.5)

 

109 (10.6)

917 (89.4)

 

Triglyceride (mg/dl)

  

<0.001

  

<0.001

<150

138 (47.3)

154 (52.7)

 

94 (8.1)

1,067 (91.9)

 

≥150

182 (72.8)

68 (27.2)

 

60 (24.8)

182 (75.2)

 

HDL (mg/dl)

  

<0.001

  

<0.001

>40

154 (51.0)

148 (49.0)

 

97 (8.5)

1,043 (91.5)

 

≤40

166 (69.2)

74 (30.8)

 

57 (21.7)

206 (78.3)

 

Glucose (mg/dl)

  

<0.001

  

<0.001

<100

166 (47.2)

186 (52.8)

 

121 (9.6)

1,137 (90.4)

 

≥100

154 (81.1)

36 (18.9)

 

33 (22.8)

112 (77.2)

 

BMI body mass index, HDL high density lipoprotein cholesterol, M men, W women

Multiple logistic regression models to determine risk of these characteristic factors to hyperuricemia according to their gender are shown in Table 3. Triglycerides and HDL cholesterol were the significant determinants for high serum uric acid levels in both sexes. Other significant factors associated with hyperuricemia in women were older age, higher BMI, hypertension, and high plasma glucose while another significant factor for men was alcoholic drinking. The model using these factors to determine hyperuricemia is also shown in Table 3.
Table 3

Multiple logistic regression model for initial and best fitting model to determine risk of these characteristic factors to hyperuricemia

 

Men (n = 542)

Women (n = 1,403)

Variables

OR (95% CI)

p value

OR (95% CI)

p value

1. Age (years)

    

 45–54

1.4 (−0.088, 0.732)

0.124

1.1 (−0.323, 0.549)

0.610

 55–64

1.5 (−0.142, 0.958)

0.146

1.2 (−0.296, 0.748)

0.397

 ≥65

0.7 (−1.507, 0.735)

0.500

2−7 (0.251, 1.778)

0.009

2. BMI >25

1.4 (−0.025, 0.746)

0.067

2.3 (0.805, 1.592)

<0.001

3. BP ≥130/85 mm/Hg

1.2 (−0.17, .598)

0.274

1.6 (0.121, 0.876)

0.010

4. TG ≥150 mg/dl

2.3 (0.435, 1.214)

<0.001

2.4 (0.494, 1.310)

<0.001

5. Cholesterol ≥200 mg/dl

1.14 (−0.118, 0.735)

0.156

0.7 (−0.755, 0.063)

0.097

6. HDL cholesterol ≤40 mg/dl

1.9 (0.247, 1.035)

0.001

1.7 (0.115, 0.926)

0.012

7. Glucose ≥100 mg/dl

0.8 (−0.777, 0.233)

0.292

1.6 (0.024, 0.958)

0.039

8. Alcohol drinking

1.5 (0.057, 0.809)

0.024

1.3 (−0.271, 0.760)

0.353

The best fitting model

Constant

(−0.767, −0.172)

(0.297, 1.016)

1. BP ≥130/85 mm/Hg

  

1.9 (1.3, 2.7)

<0.001

2. TG ≥ 150 mg/dl

2.5 (1.7, 3.7)

<0.001

2.4 (1.6, 3.5)

<0.001

3. HDL cholesterol ≤40 mg/dl

1.7 (1.1, 2.5)

0.008

1.7 (1.2, 2.6)

0.004

4. Glucose ≥100 mg/dl

  

1.7 (1.0, 2.6)

0.030

5. BMI >25

1.5 (1.0, 2.5)

0.028

2.8 (1.7, 4.4)

<0.001

BP blood pressure, BMI body mass index, HDL high density lipoprotein cholesterol, TG triglyceride, CI confidence interval, OR odds ratio

We found 35% and 23% prevalence of metabolic syndrome in men and women with hyperuricemia, respectively. When we evaluated the prevalence of the syndrome at different levels of hyperuricemia, a direct significant relationship of the syndrome and hyperuricemia was observed. As the level of uric acid was increased, the syndrome was discovered in higher frequency in both men and women (Table 4).
Table 4

Association between metabolic syndrome and different levels of uric acid (n = 1,945)

Level of uric acid (mg/dl)

Metabolic syndrome (n = 248)

Non-metabolic syndrome (n = 1,697)

Total

p value

Men

153 (28.2)

389 (71.8)

542

<0.001

 <6 (n, %)

11 (12.0)

81 (88.0)

92

 

 6.0-6.9 (n, %)

30 (23.1)

100 (76.9)

130

 

 7.0–7.9 (n, %)

79 (31.5)

172 (68.5)

251

 

 8.0–8.9 (n, %)

21 (41.2)

30 (58.8)

51

 

 >9.0 (n, %)

12 (66.7)

6 (33.3)

18

 

Women

95 (6.67)

1,308 (93.24)

1,403

<0.001

 <6 (n, %)

56 (4.5)

1,193 (95.5)

1,249

 

 6.0–6.9(n, %)

22 (20.8)

84 (79.2)

106

 

 7.0–7.9 (n, %)

10 (28.6)

25 (71.4)

35

 

 8.0–8.9(n, %)

3 (50.0)

3 (50.0)

6

 

 >9.0 (n, %)

4 (57.1)

3 (42.9)

7

 

Note: prevalence of metabolic syndrome in men with hyperuricemia (≥ 7 mg/dl) was 35% while in women (≥ 6 mg/dl) was 23%

Discussion

The authors found that the prevalence of hyperuricemia in Bangkok citizens was 24.4% which was similar to 25.3% as reported from a previous study in China [22]. This was much higher than 10.6% as reported in another study in Thai people during the early 1990s [23]. Our finding supported previous epidemiological survey which found increasing prevalence of hyperuricemia and gout during the last two decades [24]. Another study in Asian population from Taiwan found a much higher prevalence of 36% (46% for men and 26% for women) [8] than this study and the China study [22]. The difference might lie on the older age of participants (age ≥65) in the Taiwan study or it may be due to other reasons e.g., genetic or geographical variables.

The higher prevalence of hyperuricemia in Thai people could be the result from several factors. With an economic expansion in Thailand, significant dietary and lifestyle changes of all citizens especially in urban area have been influenced by the Western culture. These changes may consequently lead to common health problems similarly to those found in the West e.g., hyperuricemia, metabolic syndrome, or cardiovascular diseases. The prevalence of these disorders was high in our study, and was found in men more frequently than women: overweight in 52.4% and 37.4%; hypertriglyceridemia in 46.1% and 44.3%, and low HDL cholesterol in 17.6% and 18.7% of men and women, respectively. Our findings were consistent with other studies which found a more common incidence of hyperuricemia in men than women [8, 23, 24]. As alcohol consumption was reported in previous study to be significantly associated with elevated uric acid levels [25], the pattern or amount of alcohol consumption could provide a partial explanation for this finding in our study. Men population in our study had significantly higher rate of alcohol consumption than women, 48.5% vs. 11.6%.

Many risk factors for hyperuricemia have been described e.g., age, gender, diet, etc. In a study of 14,809 participants by the Third National Health and Nutrition Examination Survey, serum uric acid levels were found to be elevated with increasing consumption of meat, seafood, beer, or spirits. Other studies also suggested that consumption of sugar-sweetened soft drinks and fructose also predispose an individual to hyperuricemia and gout [2628].

The authors found an association between overweight, high waist circumference, hypertriglyceridemia, low HDL cholesterol, and high fasting plasma glucose in both men and women and hyperuricemia (p < 0.001). Few exceptions in women were alcoholic consumption and total cholesterol which showed no significant association. No association between age and hyperuricemia in men was observed may be due to low number of participants and younger age [8, 2224]. From multivariable analysis, we found from a multiple logistic regression model that triglycerides, HDL cholesterol, and BMI accounted most regarding the impact on hyperuricemia.

Many previous reports found association between serum uric acid and several components of metabolic syndrome [2932]. However, the association might be confounded by BMI or other individual factor. Various association reported from each study may depend on treatments e.g., diuretics and condition of the individual, insulin resistance, or impaired renal function accompanying hypertension [30, 33].

Aside from a simple association, our study also found a direct relationship between levels of uric acid and metabolic syndrome both in men and women (p < 0.001) similar to previous studies [8, 23, 34]; the prevalence of metabolic syndrome increased according to an increased of uric acid levels.

Recent evidence-based recommendations for the management of hyperuricemia and gout highlight the importance of lifestyle modification, which includes weight reduction, modification of dietary purines, and limitation of alcohol consumption [35, 36]. However, there were some several limitations in this study, such as the possibility that the results could have been influenced by selection bias cannot be completely excluded. Symptomatic participants might have been recruited more than represented in the population. The value of prevalence of hypertension was higher than the one reported in literature. The imbalance of sex distribution also affects the results. The cross-sectional study that we were not able to collect the data required a long term intervention and follow-up.

Conclusion

Hyperuricemia is commonly found among Bangkok population. Additionally, hyperuricemia is associated with metabolic syndrome component in this study. Clinicians should be aware of the presence of metabolic syndrome in patients with hyperuricemia or gout in order to control its component (high blood pressure, obesity, etc.) and hence reduce the risk for cardiovascular disease.

Acknowledgment

The study was supported by a grant from Medical Research Fund, Bangkok Metropolitan Administration Medical College and Vajira Hospital. The authors wish to thank: Dr. Vallop Suwandee and Dr. Siriwan Tangjitgamol for their support in preparing the manuscript; Dr. Sumonmal Manusirivithaya and Miss Busaba Supawattanabodee for their statistical advice.

Disclosures

None

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© Clinical Rheumatology 2011