OBJECTIVES: To determine the prevalence, potential causes and management of hyponatraemia and to identify factors associated with severity of hyponatraemia among older persons in a primary care setting.
METHODS: Electronic records were searched to identify all cases aged ≥60 years with a serum sodium <135mmol/l, attending outpatient clinic in 2014. Patients' medical records with the available blood test results of glucose, potassium, urea and creatinine were reviewed.
RESULTS: Of the 21,544 elderly, 5873 patients (27.3%) had electrolyte profile tests. 403 (6.9%) had hyponatraemia in at least one blood test. Medical records were available for 253, mean age 72.9±7.3 years, 178 (70.4%) had mild hyponatraemia, 75 (29.6%) had moderate to severe hyponatraemia. Potential causes were documented in 101 (40%). Patients with moderate to severe hyponatraemia were five times more likely to have a cause of hyponatraemia documented (p<0.01). Medications were the commonest documented cause of hyponatraemia (31.7%). Hydrochlorothiazide use was attributed in 25 (78.1%) of 32 with medication-associated hyponatraemia. Repeat renal profile (89%) was the commonest management of hypotonic hyponatraemia.
CONCLUSION: Whilst hyponatraemia was common in the clinic setting, many cases were not acknowledged and had no clear management strategies. In view of mild hyponatraemia has deleterious consequences, future studies should determine whether appropriate management of mild hyponatraemia will lead to clinical improvement.
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.