2.1. Study Population
Eligible subjects of the derivation set were type 2 dia-betic patients aged ≥18 years and without a history of nephropathy and/or renal failure who attended the outpa-tient at diabetes clinic of each hospital between January and December 2009. 225 type 2 diabetic subjects with microalbuminuria were cases group and 225 type 2 dia-betic subjects with normoalbuminuria were controls group diagnosed by radioimmunoassay or Micral test. The sample size was calculated based on ability of the study to determine risk factors of microalbuminuria type 2 diabetes [13]. The authors expected 80% power to de-tect microalbuminuria with 95% confident interval based on logistic regression result of fitting a logistic regres-sion model [14].
The validation set were type 2 diabetic patients aged ≥ 18 years and without a history of nephropathy and/or renal failure who attended the outpatient at diabetes clinic of tertiary hospital between January and December 2008. The subjects who had not laboratory information in the medical record or the database of diabetes clinic were excluded from the study. 116 diabetic subjects with microalbuminuria were cases group and 116 diabetic subjects with normoalbuminuria were controls group.