Diuretic drug therapy monitoring in the elderly: a cohort study

Background Because the elderly are often treated by multiple-drug regimens, their iatrogenic risks are considerably raised. However, despite the serious side-effects that diuretic agents may have in this population, SPCs (summary of product characteristics) do not specify how often serum chemistry should be monitored. This study of long-term diuretic therapy prescription and monitoring in elderly patients was conducted by the Department of Clinical Pharmacology of the Nantes teaching hospital in collaboration with the medical department of the French national health insurance scheme. Methods Data were extracted from the French national health insurance database. Patients were 75 years old or more and had been receiving a diuretic agent for 1 year or longer. The patients were classified into two groups: one group included those patients whose serum chemistry had been monitored at least once (electrolyte levels and/or urea and creatinine blood levels); the other group included the non-monitored patients. Results Mean patient age was 80 +/- 4.6 (SD) years. The non-monitored patients represented 22.8% of the cohort. The at-risk patients were mainly women suffering from no severe disease, treated by a single practitioner (often a general practitioner) and/or always receiving the same type of diuretic agent. Conclusion Many elderly patients receiving diuretic agents do not benefit from regular serum chemistry monitoring. The prescription of serum chemistry assays is correlated to the presence of various patient-related risk factors. Recommendations should be made to help practitioners to ensure a minimal serum chemistry monitoring in all elderly patients receiving diuretics.