Association of antihypertensive monotherapy with serum sodium and potassium levels in Chinese patients

Incidence of severe hypokalaemia in patients taking indapamide

BACKGROUND

Diuretics are commonly used for the treatment of hypertension. Yet, hypokalaemia is a well-recognised adverse effect. We conducted a retrospective study to evaluate the incidence of severe hypokalaemia, defined as requiring hospitalisation, among patients on indapamide.

METHODS

We searched a territory-wide database, Clinical Data Analysis and Reporting System of the Hong Kong Hospital Authority. We traced all hypertensive patients who had been prescribed indapamide in 2007-2016 and all admissions due to hypokalaemia in 2007-2018. Factors associated with hospitalisation were studied using multivariable logistic regression.

RESULTS

During the period studied, 62,881 patients were started on indapamide and 509 (0.8%) were hospitalised for hypokalaemia. 53% of these hospitalisations occurred within the first year of treatment, and half of those in the first year occurred during the first 16 weeks. Female sex (adjusted OR, 1.75; 95%CI, 1.45-2.12) and immediate-release formulation (adjusted OR, 1.41; 95%CI, 1.14-1.75) were associated with hospitalisation. In the multivariable model, advanced age was not a significant predictor. There were no deaths during hospitalisation and the median length of hospital stay was one day.

CONCLUSIONS

In this large population-based study with 147,319 person-years of follow-up, severe hypokalaemia requiring hospitalisation was uncommon among hypertensive patients on indapamide. The risk is higher in women and in the initial weeks and months after starting therapy. The use of the sustained-release formulation reduces the risk. We conclude that using indapamide to treat hypertension is safe, even in the elderly, especially if the sustained-release formulation is used and electrolytes are monitored periodically.

Fracture risk after thiazide-associated hyponatraemia

BACKGROUND/AIM

Although thiazide-type diuretics can promote a positive calcium balance, thiazide can be associated with hyponatraemia, which is recently linked with heightened fracture risk. We examine the chance of developing fracture in patients with and without hyponatraemia after taking thiazide diuretics.

METHODS

In this single-centre retrospective study, we followed up a previously published cohort of patients with (n= 223) and without (n= 216) thiazide-induced hyponatraemia.

RESULTS

A total of 61 osteoporotic fractures was recorded during a mean follow-up period of 82 months. Using univariate regression analysis, the hazard ratio of thiazide-induced hyponatraemia was 1.78 (95% confidence interval (CI), 1.05-3.03; P= 0.033). Cox proportional hazards regression analysis, however, showed that age, body mass index and diabetes mellitus were the only independent predictors of osteoporotic fractures. No association of a history of thiazide-induced hyponatraemia and risk of fracture was evident in the final model.

CONCLUSION

Since a history of thiazide-induced hyponatraemia is associated with osteoporotic fracture in univariate but not multivariate analyses, an alternative explanation is that confounding factors of older age and low body mass index accounted for the apparently increased risk of osteoporotic fracture in patients with thiazide-induced hyponatraemia.

Factors associated with antihypertensive drug discontinuation among Chinese patients: a cohort study

BACKGROUND

Antihypertensive drug discontinuation imposes a substantial health services burden but few studies have addressed the factors associated with their discontinuation in Chinese patients. This study evaluated the association between age, gender, and drug classes with antihypertensive discontinuation.

METHODS

From clinical databases, we included all adult patients prescribed an antihypertensive medication during January 2004 to June 2007 in one large territory of Hong Kong. We studied the factors associated with drug discontinuation within 180 days after the first prescription date by multivariable regression analysis.

RESULTS

From 93,286 eligible patients, 13.2% discontinued their antihypertensive prescriptions. Younger (<50 years; adjusted odds ratio (aOR) = 0.63 for patients aged 50-59 years; 0.52 for patients aged 60-69 years; 0.70 for those aged >or=70 years; all P < 0.001) and male patients (aOR = 1.05, P = 0.027) were more likely to have drug discontinuation. When compared with thiazide diuretics, patients prescribed beta-blockers were more likely (aOR = 1.67, P < 0.001) and patients prescribed calcium channel blocker (CCB) (aOR = 0.76, P < 0.001) and combination therapy (aOR = 0.73, P < 0.001) were less likely to have drug discontinuation. Stratified analyses in different age and gender groups reported similar results; except that only elderly male patients (aOR = 1.12, P = 0.002) and younger patients (aOR = 2.43 for patients aged <50 years, P < 0.001) prescribed beta-blocker were more likely to have drug discontinuation.

CONCLUSIONS

Discontinuation of antihypertensive drug treatment in ethnic Chinese is more likely to occur in younger, male patients, or those prescribed beta-blockers. These data suggest that more meticulous monitoring of patient adherence is required in patients with these characteristics.

Profiles of mortality among Chinese hypertensive patients in Hong Kong: a cohort study

We studied the profiles of all-cause and cardiovascular (CVS) mortality among users of different antihypertensive classes in a Chinese population. From electronic patient records, a cohort study was conducted among 18,338 patients who ever newly prescribed an alpha-blocker, thiazide diuretic, beta-blocker, calcium channel blocker (CCB) or agents acting on the renin-angiotensin system (RAS) without drug discontinuation or switching in the public primary-care sector in a large Territory of Hong Kong during January 2004-June 2007. The odds ratios of mortality (all-cause and CVS) were evaluated according to the prescribed antihypertensive drug classes by Cox proportional hazards regression analyses. A total of 823 deaths (4.5%) were reported during the study period. The crude proportions of all-cause mortality were highest in alpha-blockers (6.2%) and CCB (5.7%), but lowest in beta-blockers (2.8%). Compared with CCB, patients on thiazide diuretics were shown to have statistically significantly lower all-cause (adjusted hazard ratios (aHRs) 0.75, 95% CI 0.60, 0.93, P=0.010) and CVS mortality (aHR 0.40, 95% CI 0.21, 0.78, P=0.007), but the 95% CI of the odds ratios of the major drug classes overlapped. When each drug class was used as a reference group, or when patients with only uncomplicated hypertension were included, their respective 95% CI similarly overlapped. Antihypertensive drug classes were associated with statistically comparable odds of all-cause and CVS mortality. This finding from real-life clinical practice further supports the position statements from international guidelines, which recommend that the major antihypertensive drug classes are suitable for initiating pharmacotherapy for the management of hypertension.