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Serum potassium, cigarette smoking, and mortality in middle-aged men
S G Wannamethee1, A F Lever, A G Shaper
1Department of Primary Care and Population Sciences, Royal Free Hospital School of Medicine, London, England, United Kingdom.
Insights
Elevated serum potassium levels increase mortality risk, especially in smokers, and may be linked to lung cancer deaths. Further research is needed to understand these associations.
Area of Science:
- Cardiology
- Oncology
- Epidemiology
Background:
- Serum potassium levels are crucial electrolytes influencing cardiovascular health.
- Hypertension treatment is associated with lower serum potassium levels.
- The relationship between serum potassium and mortality requires further investigation, particularly in relation to lifestyle factors like smoking.
Purpose of the Study:
- To examine the association between serum potassium levels and all-cause mortality in middle-aged men.
- To investigate the impact of elevated and low serum potassium on mortality, considering factors like smoking and hypertension treatment.
- To explore the potential link between serum potassium, smoking, and specific causes of death, including cancer.
Main Methods:
- Prospective study involving 7,636 middle-aged British men followed for 11.5 years.
- Serum potassium levels were measured, and mortality data (all-cause, cardiovascular, noncardiovascular) were collected.
- Statistical analyses were performed to assess the relationship between potassium levels and mortality, with adjustments for confounding factors like smoking.
Main Results:
- Elevated serum potassium (≥ 5.2 mmol/liter) was associated with a significant increase in all-cause mortality, particularly noncardiovascular deaths.
- This increased mortality risk in individuals with elevated potassium was primarily observed among current smokers.
- Smokers with elevated potassium showed significantly higher relative risks for all-cause mortality, all cancer deaths, and specifically lung cancer deaths.
- In men receiving antihypertensive treatment, elevated potassium was linked to excess risks for both cardiovascular and noncardiovascular deaths.
Conclusions:
- Elevated serum potassium levels, especially in smokers, may influence the risk of death from noncardiovascular diseases, including lung cancer.
- Raised serum potassium could be a marker for other smoking-related risk factors contributing to mortality.
- Further research is warranted to explore the prognostic and therapeutic implications of these findings.
Abstract:
The relation between serum potassium level and all-cause mortality was examined in a prospective study of 7,636 middle-aged British men followed for 11.5 years (1978-1991). Men being treated for hypertension had a significantly lower mean (+/- standard error) potassium level than men not in treatment (4.24 +/- 0.03 mmol/liter vs. 4.32 +/- 0.01 mmol/liter; p < 0.01). During the follow-up period of 11.5 years, after exclusion of the 374 men under antihypertensive treatment, there were 771 deaths from all causes in the remaining 7,262 men. A low potassium level (< 3.7 mmol/liter) was not associated with increased mortality. Elevated potassium levels > or = 5.2 mmol/liter were associated with a significant increase in mortality, particularly noncardiovascular deaths, even after adjustment for potentially confounding factors. However, serum potassium was strongly related to smoking, and the increased risk of mortality associated with elevated potassium was seen only among current smokers. In current smokers with raised potassium levels (> or = 5.2 mmol/liter) compared with smokers with levels under 5.2 mmol/liter, the relative risks of mortality were 1.7 (95% confidence interval (CI) 1.2-2.5) for deaths from all causes, 1.8 (95% CI 1.0-3.2) for all cancer deaths, and 2.5 (95% CI 1.1-5.6) for lung cancer deaths. In the 374 men receiving regular antihypertensive treatment, a low potassium level was not associated with excess mortality; those with raised potassium levels had excess risks for both cardiovascular and noncardiovascular deaths. The findings suggest that either raised potassium levels in association with smoking have an influence on the risk of death from noncardiovascular disease, particularly lung cancer, or a raised serum potassium level is a marker for some other risk factor associated with smoking. The prognostic and therapeutic implications of these observations warrant further exploration.