Characteristics of the participants

A total of 6558 patients were included, including 4240 males and 2318 females, with a sex ratio of 1.83:1.The average age was 49.0 ± 14.8 years, ranging from 20 to 94 years. In 1396 patients with NAFLD, the prevalence rate was 21.3%, which was defined as the NAFLD group, among which 1056 (24.9%, 1056/4240) males and 340 (14.7%, 340/2318) females had NAFLD. The prevalence of NAFLD was much greater in males compared to females, (χ2 = 93.748, P < 0.001). 5162 non-NAFLD patients were defined as the control group.

A comparison of medical and laboratory tests in NAFLD and control groups

In Table 1, the NAFLD group had higher values for age, waist circumference, BMI, systolic and diastolic blood pressure, total cholesterol, LDL cholesterol, liver enzymes, fasting glucose, uric acid, glycated hemoglobin, and hs-CRP compared to the control group, with statistically significant differences. The high-density lipoprotein cholesterol was reduced in comparison to the control group.

Table 1 A comparison of clinical and laboratory indicators between subjects in the control and NAFLD groupsCorrelation between hs-CRP levels and the development of NAFLD

To investigate the relationship between hs-CRP levels and NAFLD prevalence rates, the level of hs-CRP was stratified by the quartile. And then grouped according to it, the values of different groups were Q1 ≤ 0.3 mg/L, Q2 > 0.4 mg/L- ≤ 0.5 mg/L, Q3 > 0.5 mg/L- ≤ 1.0 mg/L, and Q4 > 1.1 mg/L. According to Table 2, the prevalence of NAFLD gradually increased with the increase of hs-CRP level in both men, women and the general population, showing statistical significance (P < 0.001).

Table 2 Relationship between hs-CRP levels and incidence of NAFLD [n (%)]Clinical characteristics of indicators related to hs-CRP levels

6558 subjects were stratified and compared according to hs-CRP levels. Levels of age, waist circumference (WC), body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), triglycerides (TG), LDL cholesterol (LDL-C), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), fasting plasma glucose (FPG), uric acid (UC), and hemoglobin A1c (HbA1c) all rose as hs-CRP levels increased (P < 0.001).As hs-CRP level increased, HDL cholesterol (HDL-C) levels decreased significantly (P < 0.001), Table 3.

Table 3 Clinical characteristics of elderly people after hs-CRP stratificationElevated hs-CRP levels are associated with a higher risk of developing NAFLD in non-obese people

We employed the risk factors associated with NAFLD. Multivariate analysis revealed that being male, age, WC, BMI, DBP, TC, TG, LDL-C, AST, ALT, GGT, FPG, UC, HbA1c, and hs-CRP levels were associated with an increased risk of NAFLD (Fig. 1).

Fig. 1

Univariate and multivariate logistic regression analysis of risk factors for NAFLD

To investigate the relationship between hs-CRP and NAFLD, the hs-CRP level was divided into quartiles, with NAFLD (1 = present, 0 = absent) as the outcome variable. The risk of NAFLD increases when considering hs-CRP concentration (Q1, Q2, Q3, Q4), age, sex, WC, BMI, SBP, DBP, FPG, TC, TG, HDL-C, AST, ALT, GGT, UC, and HbA1c as predictors. This trend remained statistically significant after adjusting for related factors (P < 0.01, Fig. 2).

Fig. 2

Risk was determined by the quartile of baseline serum hs-CRP in unadjusted and adjusted models. Model1 accounted for age and gender adjustments; Model2 included adjustments for Model1 as well as waist circumference and BMI; Model3 further adjusted for systolic and diastolic blood pressure, fasting blood sugar, total cholesterol, triglycerides, HDL cholesterol, ALT, AST, GGT, uric acid, and HbA1c