Development of a hyponatremia screening tool (ABCDF-S score) for patients with hypertension using thiazide diuretic agents

WHAT IS KNOWN AND OBJECTIVE: Hyponatremia is a common side effect of thiazide diuretics that can lead to increased mortality and hospitalization. A rapid and accurate screening tool is needed for rapid and appropriate management. In this study, we report on the development of a simple clinical screening tool for hyponatremia using thiazide diuretics.

METHODS: This nested case-control study was performed by collecting data from 1 January 2015 to 30 June 2017. Univariable and multivariable logistic regressions were used to identify potential risk factors. The regression coefficients were converted into item scores by dividing each regression coefficient with the minimum coefficient in the model and rounding to the nearest integer. This value was then summed to the total score. The prediction power of the model was determined by the area under the receiver operating characteristic curve (AuROC).

RESULTS AND DISCUSSION: Six clinical risk factors, namely age ≥65 years, benzodiazepine use, history of a cerebrovascular accident, dose of hydrochlorothiazide ≥25 mg, female sex and statin use, were included in our ABCDF-S score. The model showed good power of prediction (AuROC 81.53%, 95% confidence interval [CI]: 78%-84%) and good calibration (Hosmer-Lemeshow X2  = 23.20; P = .39). The positive likelihood ratios of hyponatremia in patients with low risk (score ≤ 6) and high risk (score ≥ 8) were 0.26 (95% CI: 0.21-0.32) and 3.89 (95% CI: 3.11-4.86), respectively.

WHAT IS NEW AND CONCLUSION: The screening tool with six risk predictors provided a useful prediction index for thiazide-associated hyponatremia. However, further validation of the tool is warranted prior to its utilization in routine clinical practice.