Did ABCDF-S Score Reflect Thiazide-Associated Hyponatremia Risk in Iraqi Hypertensive Patients? A Validation Study

Background: Thiazide-associated hyponatremia (TAH) is potentially associated with life-threatening conditions. The “ABCDF-S” scale for predicting severe TAH has not been evaluated among Iraqi hypertensive patients on hydrochlorothiazide (HCTZ) therapy. Objectives: To assess the validity and reliability of the “ABCDF-S” scale in anticipating TAH. Materials and Methods: This cross-sectional study was conducted at a single clinic in Mosul City, Iraq, between July 2022 and June 2024. Demographic and clinical data of hypertensive patients aged > 18 years on HCTZ were recorded using convenience sampling. Patients were classified into the non-hyponatremic and hyponatremic (Na < 135 mEq/L) groups. The “ABCDF-S” scale score was estimated for all patients and tested using diagnostic performance tests. Results: Twelve of the 80 patients had TAH, with a mean (± SD) age of 60 (±10) years. The demographic and clinical data were not significantly associated with hyponatremia. The mean (± SD) score of the “ABCDF-S” scale was 1.84 (± 2), indicating a low hyponatremic risk. This scale had a 95% sensitivity and 81% accuracy in predicting a low risk of hyponatremia in patients without hyponatremia. It had a non-significant result in predicting the moderate-to-severe risk of TAH among hyponatremic patients receiving HCTZ therapy (specificity, 0%; P > 0.05). The area under the receiver operating characteristic curve was 0.34, and the kappa value was −0.05, indicating poor diagnostic performance. Conclusion: The “ABCDF-S” scale was not an independent predictor of severe TAH among hypertensive patients. Further studies with a larger sample size are required to explore this condition.