Objective To explore the predictive value of serum uric acid on new-onset cholelithiasis. Methods The retrospective cohort study was conducted. The data of 97 469 subjects who participated health examination at the Kailuan General Hospital Affiliated to the North China University of Science and Technology, Kailuan Linxi Hospital, Kailuan Zhaogezhuang Hospital, Kailuan Tangjiazhuang Hospital, Kailuan Fan′gezhuang Hospital, Kailuan Lyujiatuo Hospital, Kailuan Jinggezhuang Hospital, Kailuan Linnancang Hospital, Kailuan Qianjiaying Hospital, Kailuan Majiagou Hospital and Kailuan Branch Hospital from June 2006 to December 2015 were collected. Epidemiological investigation, anthropometric parameters and biochemical indicators were collected. All the subjects were allocated into 4 groups according to squartiles of serum uric acid: 24 140 with serum uric acid <232 μmol/L in the Q1 group, 24 473 with 232 μmol/L≤ serum uric acid <282 μmol/L in the Q2 group, 24 382 with 282 μmol/L≤ serum uric acid <338 μmol/L in the Q3 group and 24 474 with serum uric acid ≥338 μmol/L in the Q4 group. Observation indicators: (1) comparisons of clinical characteristics among the 4 groups; (2) incidence of cholelithiasis in the 4 groups; (3) effects of serum uric acid on the new-onset cholelithiasis: ① the dose-response relationship between serum uric acid and the risk of cholelithiasis, ② comparisons of the fitting degree of serum uric acid on the cholelithiasis model, ③ effects of different serum uric acid levels on incidence of cholelithiasis after stratification by sex, ④ serum uric acid of different gender on the boxplots, ⑤ effects of different serum uric acid levels on the incidence of cholelithiasis after stratification by age. Measurement data with normal distribution were expressed as ±s, and comparisons among groups were analyzed using the one-way ANOVA. Measurement data with skewed distribution is expressed by M (Q), and comparisons among groups were analyzed using the nonparametric Krustal-willis test. Count data were represented by percentage, and comparisons among groups were analyzed using chi-square test. The incidences of cholethiasis in 4 groups of different serum uric acid were calculated by person-year incidence. Restrictive cubic spline regression was used to calculate the dose-response relation between the continuous variable and the risks of new-onset cholelithiasis and 95% confidence interval (CI). COX regression model was used to analyze the hazard ratio (HR) and 95%CI of different serum uric acid levels on new-onset cholelithiasis. Likelihood ratio test and akaike information criterion (AIC) were used to calculate the fitting degree of serum uric acid on new-onset cholelithiasis model. Boxplots were used to describe serum uric acid in different genders. Results (1) comparisons of clinical characteristics among the 4 groups: sex (male), age, body mass index (BMI), systolic pressure, diastolic pressure, fasting plasma glucose (FPG), total cholesterol (TC), triglyceride (TG), high sensitive C-reactive protein, diabetes, hypertension, smoking, drinking and physical exercise were 15 162, (50±11)years, (24±3)kg/m2, (123±21)mmHg (1 mmHg=0.133 kPa), (82±12)mmHg, (5.6±2.0)mmol/L, (4.8±1.2)mmol/L, 1.14 mmol/L (range, 0.81-1.63 mmol/L), 0.70 mmol/L (range, 0.23-2.23 mmol/L), 2 537, 9 415, 4 575, 2 380, 2 649 in the Q1 group, 19 079, (51±12)years, (25±3)kg/m2, (130±21)mmHg, (83±12)mmHg, (5.5±1.7)mmol/L, (4.9±1.2)mmol/L, 1.20 mmol/L (range, 0.86-1.76 mmol/L), 0.71 mmol/L (range, 0.28-1.98 mmol/L), 2 287, 10 124, 6 918, 3 649, 3 288 in the Q2 group, 21 132, (52±13)years, (25±3)kg/m2, (132±21)mmHg, (84±12)mmHg, (5.5±1.6)mmol/L, (5.0±1.2)mmol/L, 1.29 mmol/L (range, 0.91-1.94 mmol/L), 0.80 mmol/L (range, 0.30-2.06 mmol/L), 2 027, 10 755, 8 259, 4 730, 3 958 in the Q3 group, 22 651, (53±14)years, (26±3)kg/m2, (134±21)mmHg, (85±12)mmHg, (5.4±1.5)mmol/L, (5.1±1.2)mmol/L, 1.54 mmol/L (range, 1.05-2.35 mmol/L), 1.02 mmol/L (range, 0.43-2.50 mmol/L), 1 981, 12 082, 9 562, 6 209, 4 758 in the Q4 group, respectively, with statistically significant differences among the 4 groups (χ2=7 624.63, F=279.93, 961.91, 330.84, 271.40, 38.25, 353.18, H=3 406.30, 912.23, χ2=108.15, 590.49, 2567.07, 2 209.21, 760.15, P 0.05). In male participants, adjusted for age, BMI, TC, TG, diabetes, hypertension, smoking, drinking and physical exercise, risks of new-onset cholelithiasis in Q2, Q3 and Q4 groups were increased compared with Q1 group (HR=1.17, 1.24, 1.30, 95%CI: 1.06-1.30, 1.12-1.37, 1.18-1.44, P 0.05), however, risk of new-onset cholelithiasis was increased in the Q4 group (HR=1.15, 95%CI: 1.02-1.28, P 60 years old, adjusted for sex, BMI, TC, TG, diabetes, hypertension, smoking, drinking and physical exercise, risk of new-onset cholelithiasis in the Q2 groups was not increased compared with Q1 group (HR=1.16, 95%CI: 0.99-1.36, P>0.05), however, risks of new-onset cholelithiasis were increased in the Q3 and Q4 groups (HR=1.19, 1.21, 95%CI: 1.02-1.40, 1.04-1.41, P<0.05). Conclusion Elevated serum uric acid is an independent risk factor for the new-onset cholelithiasis. Key words: Cholelithiasis; Serum uric acid; Incidence; Risk factor
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