Development and validation of a self-assessment tool for albuminuria: results from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Abstract

Background: The prevalence of albuminuria in the general population is high, but awareness of it is low. Therefore, we sought to develop and validate a self-assessment tool that allows individuals to estimate their probability of having albuminuria.

Study design: Cross-sectional study.

Setting & participants: The population-based Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study for model development and the National Health and Nutrition Examination Survey (NHANES) 1999-2004 for model validation. US adults 45 years or older in the REGARDS Study (n = 19,697) and NHANES 1999-2004 (n = 7,168).

Predictor: Candidate items for the self-assessment tool were collected using a combination of interviewer- and self-administered questionnaires.

Outcome: Albuminuria was defined as a urinary albumin to urinary creatinine ratio ≥30 mg/g in spot samples.

Results: 8 items were included in the self-assessment tool (age, race, sex, current smoking, self-rated health, and self-reported history of diabetes, hypertension, and stroke). These items provided a C statistic of 0.709 (95% CI, 0.699-0.720) and good model fit (Hosmer-Lemeshow χ(2)P = 0.49). In the external validation data set, the C statistic for discriminating individuals with and without albuminuria using the self-assessment tool was 0.714. Using a threshold of ≥10% probability of albuminuria from the self-assessment tool, 36% of US adults 45 years or older in NHANES 1999-2004 would test positive and be recommended for screening. Sensitivity, specificity, and positive and negative predictive values for albuminuria associated with a probability ≥10% were 66%, 68%, 23%, and 93%, respectively.

Limitations: Repeated urine samples were not available to assess the persistency of albuminuria.

Conclusions: 8 self-report items provide good discrimination for the probability of having albuminuria. This tool may encourage individuals with a high probability to request albuminuria screening.

Figure 1

Distribution of the REGARDS study population by probability of albuminuria on the self-assessment tool The curve shows the % of the REGARDS study population with a probability of albuminuria higher than the value on the x-axis. For example, 54% of the REGARDS study population has a probability of albuminuria from the self-assessment tool ≥ 10%.

Figure 2

Sensitivity and specificity of the self-assessment tool for albuminuria in the derivation study (REGARDS study) Using a cut-point ≥ 10% from the self-assessment tool, the sensitivity and specificity for albuminuria are 78% and 50%, respectively, in the REGARDS study population.

Figure 3

Predicted and observed probability of albuminuria according to decile of predicted probability assigned by the self-assessment tool in the validation cohort (NHANES 1999-2004)