Threshold effect analysis of between SUA/SCr and lung function parameters using the two-piecewise linear regression model
| FVC | FEV1 | |
| β (95% CI) P value | β (95% CI) P value | |
| Model I | ||
| Linear effect | −47.865 (−61.583 to −34.146) <0.0001 | −37.225 (−48.482 to −25.969) <0.0001 |
| Model II | ||
| Inflection point(K) | 4.734 | 4.069 |
| SUA/SCr<K | −62.705 (−85.131 to −40.278) <0.0001 | −57.511 (−84.517 to −30.506) <0.0001 |
| SUA/SCr>K | −28.839 (−55.401 to −2.276) 0.0334 | −27.649 (−43.804 to −11.494) 0.0008 |
| Log likelihood ratio | 0.101 | 0.105 |
The model I and II all adjusted for gender, age, race/ethnicity, education level, poverty income ratio, marital status, physical activity, body mass index, hypertension history, diabetes history, respiratory disease history had at least 12 alcohol drinks/year, smoked at least 100 cigarettes in life, foods of affecting SUA eaten during past 30 days, serum calcium, phosphorus, total bilirubin, total protein, aspartate aminotransferase, alkaline phosphatase, total cholesterol and glycohaemoglobin.
FEV1, forced expiratory volume in one second; FVC, forced vital capacity; SCr, serum creatinine; SUA, serum uric acid.