Purpose: The aim of our study was to find drug-associated changes in serum levels of major electrolytes using clinical-event monitoring method.
Methods: During 1-year period, electrolyte disturbances in serum samples from patients of Clinical Center Kragujevac, Serbia, were monitored in central biochemical facility. A sample of 982 patients was randomly selected from total population of 43,120 patients whose electrolyte serum levels were measured in the facility during the study period.
Results: Clinically important drug-associated electrolyte disturbances were detected in 181 patient. There were 25 significant associations between the drugs and electrolyte values outside the reference range. However, only four causal connections were established: use of normal saline infusion with hypernatremia (OR 6.97, 95%CI 2.24-21.67), theophylline with acid-base disturbances (7.75, 1.46-41.02), polygeline infusion with decrease in bicarbonate levels (4.08, 1.42-11.73), and association of risperidone and hypocalcemia (4.10, 1.42-11.81).
Conclusion: Although clinical-event monitoring method is far from optimal, it could quantify the known risks and provide evidence for credible hypothesis of drug adverse reactions, based on both relevant biological pathways and reasonable clinical thinking, as it was the case in our study.
(c) 2009 John Wiley & Sons, Ltd.