Association between newly initiated thiazide diuretics and hospitalization due to hyponatremia

Urea transporter UT-A1 as a novel drug target for hyponatremia

Hyponatremia is the most common disorder of electrolyte imbalances. It is necessary to develop new type of diuretics to treat hyponatremia without losing electrolytes. Urea transporters (UT) play an important role in the urine concentrating process and have been proved as a novel diuretic target. In this study, rat and mouse syndromes of inappropriate antidiuretic hormone secretion (SIADH) models were constructed and analyzed to determine if UTs are a promising drug target for treating hyponatremia. Experimental results showed that 100 mg/kg UT inhibitor 25a significantly increased serum osmolality (from 249.83 ± 5.95 to 294.33 ± 3.90 mOsm/kg) and serum sodium (from 114 ± 2.07 to 136.67 ± 3.82 mmol/L) respectively in hyponatremia rats by diuresis. Serum chemical examination showed that 25a neither caused another electrolyte imbalance nor influenced the lipid metabolism. Using UT-A1 and UT-B knockout mouse SIADH model, it was found that serum osmolality and serum sodium were lowered much less in UT-A1 knockout mice than in UT-B knockout mice, which suggest UT-A1 is a better therapeutic target than UT-B to treat hyponatremia. This study provides a proof of concept that UT-A1 is a diuretic target for SIADH-induced hyponatremia and UT-A1 inhibitors might be developed into new diuretics to treat hyponatremia.

Using Genetics to Inform Interventions Related to Sodium and Potassium in Hypertension

BACKGROUND

Hypertension is a key risk factor for major adverse cardiovascular events but remains difficult to treat in many individuals. Dietary interventions are an effective approach to lower blood pressure (BP) but are not equally effective across all individuals. BP is heritable, and genetics may be a useful tool to overcome treatment response heterogeneity. We investigated whether the genetics of BP could be used to identify individuals with hypertension who may receive a particular benefit from lowering sodium intake and boosting potassium levels.

METHODS

In this observational genetic study, we leveraged cross-sectional data from up to 296 475 genotyped individuals drawn from the UK Biobank cohort for whom BP and urinary electrolytes (sodium and potassium), biomarkers of sodium and potassium intake, were measured. Biologically directed genetic scores for BP were constructed specifically among pathways related to sodium and potassium biology (pharmagenic enrichment scores), as well as unannotated genome-wide scores (conventional polygenic scores). We then tested whether there was a gene-by-environment interaction between urinary electrolytes and these genetic scores on BP.

RESULTS

Genetic risk and urinary electrolytes both independently correlated with BP. However, urinary sodium was associated with a larger BP increase among individuals with higher genetic risk in sodium- and potassium-related pathways than in those with comparatively lower genetic risk. For example, each SD in urinary sodium was associated with a 1.47-mm Hg increase in systolic BP for those in the top 10% of the distribution of genetic risk in sodium and potassium transport pathways versus a 0.97-mm Hg systolic BP increase in the lowest 10% (P=1.95×10-3). This interaction with urinary sodium remained when considering estimated glomerular filtration rate and indexing sodium to urinary creatinine. There was no strong evidence of an interaction between urinary sodium and a standard genome-wide polygenic score of BP.

CONCLUSIONS

The data suggest that genetic risk in sodium and potassium pathways could be used in a precision medicine model to direct interventions more specifically in the management of hypertension. Intervention studies are warranted.

Cumulative Incidence of Thiazide-Induced Hyponatremia : A Population-Based Cohort Study

BACKGROUND

According to drug labels, the frequency of thiazide-induced hyponatremia is unknown or uncommon to very rare (that is, <1 in 10 000 to <1 in 100), but the exact burden remains unclear.

OBJECTIVE

To estimate the increase in the cumulative incidence of hyponatremia using thiazide diuretics compared with nonthiazide antihypertensive drugs in routine clinical practice.

DESIGN

Population and register-based cohort study using target trial emulation.

SETTING

Denmark, 1 January 2014 to 31 October 2018.

PARTICIPANTS

Two target trials were emulated among persons aged 40 years or older who had no recent prescription for any antihypertensive drug, had no previous hyponatremia, and were eligible for the studied antihypertensive treatments. The first target trial emulation compared new use of bendroflumethiazide (BFZ) versus a calcium-channel blocker (CCB). The second target trial emulation compared new use of hydrochlorothiazide plus a renin-angiotensin system inhibitor (HCTZ-RASi; that is, combination pill) versus a RASi alone.

MEASUREMENTS

Two-year cumulative incidences of sodium levels less than 130 mmol/L using stabilized inverse probability of treatment-weighted survival curves.

RESULTS

The study compared 37 786 new users of BFZ with 44 963 of a CCB and 11 943 new users of HCTZ-RASi with 85 784 of a RASi. The 2-year cumulative incidences of hyponatremia were 3.83% for BFZ and 3.51% for HCTZ-RASi. The risk differences were 1.35% (95% CI, 1.04% to 1.66%) between BFZ and CCB and 1.38% (CI, 1.01% to 1.75%) between HCTZ-RASi and RASi; risk differences were higher with older age and higher comorbidity burden. The respective hazard ratios were 3.56 (CI, 2.76 to 4.60) and 4.25 (CI, 3.23 to 5.59) during the first 30 days since treatment initiation and 1.26 (CI, 1.09 to 1.46) and 1.29 (CI, 1.05 to 1.58) after 1 year.

LIMITATION

The study assumed that filled prescriptions equaled drug use, and residual confounding is likely.

CONCLUSION

Treatment initiation with thiazide diuretics suggests a more substantial excess risk for hyponatremia, particularly during the first months of treatment, than indicated by drug labeling.

PRIMARY FUNDING SOURCE

Independent Research Fund Denmark.

Thiazide-associated hyponatremia increases the risk of major adverse cardiovascular events among elderly Taiwanese patients

BACKGROUND

Thiazide-associated hyponatremia (TAH) has been supposed to increase the risk of major adverse cardiovascular events (MACE) in the elderly. Therefore, this study aimed to evaluate the association of TAH with the risk of MACE in elderly Taiwanese patients.

METHODS

Data from the longitudinal generation tracking database (LGTD 2010) of the Health and Welfare Data Science Center (HWDC) were retrospectively assessed. The TAH study group was defined as using > 30 cumulative daily defined doses (CDDDs) thiazide diuretics within one year before diagnosis of hyponatremia. The control group (1:3 propensity score matching) had no diagnosis of hyponatremia but had used > 30 CDDDs thiazide diuretics within one year. Data on MACE were extracted using International Classification of Diseases codes. Outcomes were assessed using a multivariable Cox proportional hazard model and Kaplan-Meier analysis.

RESULTS

A total of 1155 and 3465 individuals were enrolled in the TAH and the control groups, respectively. The rates of MACE (11.1% vs. 7.3%) and death (22.8% vs.12.2%) were significantly higher in the TAH group than the control group. In the TAH group, the adjusted HRs were 1.29 (CI 1.01 ‒ 1.65) for MACE, 1.39 (CI 1.19 ‒ 1.63) for all-cause death, and 1.61 (CI 0.90 ‒ 2.92) for stroke.

CONCLUSION

TAH in patients above 65-years-old is associated with a 29% higher risk of MACE, 39% higher risk of all-cause death, and 61% higher risk of stroke. This work suggests that thiazides prescription in elderly patients should be more careful. However, further research is required to confirm our findings.

Women on diuretics have a higher risk of hospital admission because of hyponatremia than men

PURPOSE

Recent studies suggest that women are more susceptible to diuretic-induced hyponatremia resulting in hospital admission than men. The aim of this study was to confirm whether these sex differences in hyponatremia-related hospital admissions in diuretic users remain after adjusting for several confounding variables such as age, dose, and concurrent medication.

METHODS

In a case-control design nested in diuretic users, cases of hyponatremia associated hospital admissions between 2005 and 2017 were identified from the PHARMO Data Network. Cases were 1:10 matched to diuretic users as controls. Odds ratios (OR) with 95%CIs were calculated for women versus men and adjusted for potential confounders (age, number of diuretics, other hyponatremia-inducing drugs, chronic disease score) using unconditional logistic regression analysis. A subgroup analysis was performed for specific diuretic groups (thiazides, loop diuretics and aldosterone antagonists).

RESULTS

Women had a statistically significantly higher risk of a hospital admission associated with hyponatremia than men while using diuretics (OR 1.86, 95%CI 1.64-2.11). Adjusting for the potential confounders resulted in an increased risk for women compared to men (ORadj 2.65, 95% CI 2.31-3.04). This higher risk in women was also seen in the three subgroup analyses after adjustment.

CONCLUSION

Our findings show a higher risk of hyponatremia-related hospital admission in women than men while using diuretics. Further research is needed to understand the underlying mechanism of this sex difference to be able to provide sex-specific recommendations.

Time-dependent association between omeprazole and esomeprazole and hospitalization due to hyponatremia

PURPOSE

The aim of this study was to explore the time-course of hospitalization due to hyponatremia associated with omeprazole and esomeprazole.

METHODS

In this register-based case-control study, we compared patients hospitalized with a main diagnosis of hyponatremia (n = 11,213) to matched controls (n = 44,801). We used multiple regression to investigate time-related associations between omeprazole and esomeprazole and hospitalization because of hyponatremia.

RESULTS

The overall adjusted OR (aOR) between proton pump inhibitor (PPI) exposure, regardless of treatment duration and hospitalization with a main diagnosis of hyponatremia, was 1.23 (95% confidence interval CI 1.15-1.32). Exposure to PPIs was associated with a prompt increase in risk of hospitalization for hyponatremia from the first week (aOR 6.87; 95% CI 4.83-9.86). The risk then gradually declined, reaching an aOR of 1.64 (0.96-2.75) the fifth week. The aOR of ongoing PPI treatment was 1.10 (1.03-1.18).

CONCLUSION

The present study shows a marked association between omeprazole and esomeprazole and hyponatremia related to recently initiated treatment. Consequently, newly initiated PPIs should be considered a potential culprit in any patient suffering from hyponatremia. However, if the patient has had this treatment for a longer time, the PPI should be considered a less likely cause.

Current and Future Burdens of Heat-Related Hyponatremia: A Nationwide Register-Based Study

CONTEXT

A seasonal variation in hyponatremia, with higher incidence rates during hot summer days, has been demonstrated. Whether this applies to cool temperate regions is currently unknown.

OBJECTIVE

The aim of this study was to investigate the influence of ambient temperature on hyponatremia in the Swedish population under current and future climate scenarios.

METHODS

This nationwide cohort study identified all patients hospitalized with a first-ever principal diagnosis of hyponatremia between October 2005 and December 2014. Incidence rates for hyponatremia were calculated as number of hospitalizations divided by person-days at risk in the adult Swedish population at a given temperature, in increments of 1 °C.

RESULTS

The incidence of hyponatremia was stable at 0.3 per million person-days from -10 to 10 °C, but increased rapidly at 24-hour mean temperatures above 15 °C, with 2.26 hospitalizations per million days at the highest recorded temperature of 25 °C. Women and elderly carried the greatest risk, with an incidence of 35 hospitalizations per million days in individuals ≥ 80 years of age on the hottest days, corresponding to a 15-fold increase in incidence compared with cool days. A future 1 or 2 °C increase in mean temperature is expected to increase the incidence of hyponatremia by 6.3% and 13.9%, respectively.

CONCLUSION

The risk of hospitalization due to hyponatremia increases rapidly at temperatures above 15 °C, indicating a threshold effect. Over the next decades, rising global temperatures are expected to increase the inpatient burden of hyponatremia by approximately 10%. Strategies for protecting vulnerable groups are necessary to reduce this risk.

Non-thiazide diuretics and hospitalization due to hyponatraemia: A population-based case-control study

OBJECTIVE

Diuretics are often implicated in hyponatraemia. While thiazides constitute one of the most common causes of hyponatraemia, data on loop diuretics and potassium-sparing agents are limited and partly conflicting. The objective of this investigation was to study the association between use of different types of non-thiazide diuretics and hospitalization due to hyponatraemia.

DESIGN, PATIENTS AND MEASUREMENTS

This was a register-based case-control study on the adult Swedish population. By linking national registers, patients hospitalized with a principal diagnosis of hyponatraemia (n = 11,213) from 1 October 2005 through 31 December 2014 were compared with matched controls (n = 44,801). Multivariable logistic regression, adjusted for multiple confounders, was used to analyse the association between use of diuretics and hyponatraemia. In addition, newly initiated use (≤90 days) and ongoing use were examined separately.

RESULTS

Adjusted odds ratios (aORs) (95% CI) were 0.61 (0.57-0.66) for the use of furosemide, 1.69 (1.54-1.86) for the use of amiloride and 1.96 (1.78-2.18) for the use of spironolactone and hospitalization due to hyponatraemia. For newly initiated therapy, aORs ranged from 1.23 (1.04-1.47) for furosemide to 3.55 (2.75-4.61) for spironolactone. The aORs for ongoing use were 0.52 (0.47-0.57) for furosemide, 1.62 (1.47-1.79) for amiloride and 1.75 (1.56-1.98) for spironolactone.

CONCLUSIONS

Ongoing use of furosemide was inversely correlated with hospitalization due to hyponatraemia, suggesting a protective effect. Consequently, if treatment with furosemide precedes the development of hyponatraemia by some time, other causes of hyponatraemia should be sought. Spironolactone and amiloride may both contribute to hyponatraemia; this effect is most prominent early in treatment.

Time-dependent association between selective serotonin reuptake inhibitors and hospitalization due to hyponatremia

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) have a wide and increasing use for the treatment of depression and anxiety. Previous studies have indicated an increased risk of hyponatremia during the first months of treatment. We aimed to investigate the detailed time-course of SSRI-associated hyponatremia with a high temporal resolution, using registry data encompassing the total Swedish population.

METHODS

This was a population-based case control study using several national registers. Patients hospitalized with a principal diagnosis of hyponatremia (n = 11,213) were compared with matched controls (n = 44,801). Multivariable regression was applied to explore time-dependent associations between SSRIs and hospitalization due to hyponatremia.

RESULTS

Individuals initiating treatment with SSRIs were exposed to an immediately increased risk for hospitalization at week 1, reaching an adjusted odds ratio (aOR) (95% confidence interval) of 29 (19-46). The associations then gradually declined, reaching an aOR of 2.1 (1.0-4.2) by week 13. The aOR for individuals treated for longer than 13 weeks was 0.78 (0.71-0.85).

CONCLUSIONS

This study revealed a dramatically increased risk of hyponatremia exclusively related to newly initiated treatment. Consequently, even subtle symptoms consistent with hyponatremia during the first weeks of SSRI treatment should prompt analysis of sodium levels. In patients treated with SSRIs for several months or years, other causes should primarily be sought in the event of hyponatremia.