[Serum potassium levels and long-term mortality in the elderly with hypertension]

There is increasing evidence that small variations within the normal range (3.5-5mEq/L) of potassium are associated with mortality.

To determine whether there is an association between serum potassium level (sK) and mortality in a cohort of elderly hypertensive patients.

A retrospective, observational study was conducted on patients who had sK levels available in a period of clinical stability during their recruitment between January and April 2006 and followed-up for 10 years. The study obtained a total of 62 stable patients, with a mean age of 82.19±6 years (range 69-97), with 74.2% women, 33.9% diabetics, 20.3% with a history of heart failure, Ischaemic heart disease was observed in 19.4% and 44.3% received Angiotensin Converting Enzyme (ACE) inhibitors. An analysis was performed on the mortality rate during the 10 year period. The statistics were performed using the SPSS15.0 package.

There were 49 deaths. The sK had a normal distribution. Baseline mean sK levels and median were 4.45±0.5mEq/L (range 3.1-5.5 mEq/L). Baseline sK levels were significantly higher in diabetic patients and patients on ACE inhibitors. The patients that died had higher sK levels (4.53±0.49mEq/L versus 4.14±0.40mEq/L, P=.011). Survival estimated using Kaplan Meier showed that patients with sK levels higher than the median and P75 had higher mortality.

In our study, sK levels greater than 4.45mEq/L were associated with mortality. When selecting antihypertensive treatment in hypertensive elderly patients,, the use of ACE inhibitors should be assessed individually, with close monitoring at sK levels and try to keep them in the lower limit of the normal range (<4.45 mEq/L).