gms | German Medical Science

Background: Most elderly patients suffer from multiple chronic diseases that require long-term drug therapy. Taking many different drugs (polypharmacy, usually defined as taking ≥ 5 medicines/day) increases the risk for adverse drug effects (ADR) [1], [2], [3], [4]. Certain drugs are classified as potentially inadequate medications (PIM) for the elderly, because they have a higher risk of adverse effects in this patient population (PRISCUS list) [5].

The aim of the present analysis is to examine the plausibility of patients self-reported ADR in relation to their medication.

Materials and Methods: In the context of the PRISCUS Research Consortium (http://priscus.net) a standardized survey was conducted in patients following stroke [4]. These interviews included the complete medication of patients, described symptoms, pre-defined potential side effects (insomnia, dizziness, nausea, abdominal pain, constipation and incontinence) and free text information.

Inclusion criterion for the analysis of data was either being 65 years or older or taking at least 5 drugs/day and reporting of complaints.

The patients’ feedbacks to their side effects were checked for plausibility. Therefore the summaries of products characteristics (SmPC) (www.fachinfo.de) of corresponding drugs as well as the Micromedex™-database (www.micromedexsolutions.com) were used. Because of lack of clinical information a formal causality assessment was not possible. Thus self-reported side effects occurring very frequently (> 10 % of patients) or frequently (> 1 % of patients) according to the SmPC were considered as plausible.

Results: Data of 545 patients were available from the Dortmund-Münsteraner stroke cohort (71 ± 11 years; 39 % female) [4]. Patients took 6 ± 3 drugs/day (median), most commonly antithrombotic agents, drugs acting on the renin-angiotensin-aldosterone system and lipid lowering agents. In this cohort 67.5 % of the patients were affected by polypharmacy (taking at least 5 drugs/day); 113 patients (20.7 %) received at least one PIM according to Priscus list, and 23 patients (23.7 %) of patients with side effects took at least one PIM.

In our analysis 178 patients reported about 273 complaints recognized explicitly as side effects. 114 (41.8 %) of these side effects were directly associated with drugs. Only 15 of the 114 reported ADR (12.3 %) were not mentioned in the SmPC or Micromedex™. 58 (50.9 %) of the reported side effects were described in the SmPC as frequent or very frequent side effects of the drug suspected by the patient and were therefore considered as plausible.

28 (24.6 %) of the ADR belong to the group “occasionally” until “very rare”. For 14 (12.3 %) side effects no information on frequency could be found. For 79 complaints patients suspected their drugs but were not able to name the culprit; 10 side effects were related to all medications or to their combination.

Patients’ assignments for the symptoms abdominal pain (83.3 % of denotations), nausea (77.8 %), as well as constipation and incontinence (75 % each) were plausible in many cases. The proportion of plausible answers for dizziness was 61.9 %: Only one patient associated sleep disorders as side effect by a drug correctly: according to the prescribing information, Rotigotine patch can often or very often cause sleep disorders.

Conclusion: PIM-exposed patients suffer more frequently from symptoms which can be attributed to anticholinergic and sedative agents. This correlation can be shown without exploring the plausibility of individual cases.

In the studied cohort of multimorbid patients the detected plausibility of related ADR is > 50 % and therefore strongly supports the validity of information about side effects given by patients. Unfortunately, insufficient clinical information was available to allow for a comprehensive causality assessment of every single case. Therefore, an assessment of plausibility, based on the reported ADR frequency in the literature, was executed.

The results of this analysis demonstrate the chances and limitations of the reporting of side effects by older patients.