Polypharmacy in a hospitalized psychiatric population: risk estimation and damage quantification

Abstract

Background: Polypharmacy increases the risk of pharmacological interactions, prevalence of secondary effects and with this the lack of adherence to treatment. It is estimated that between 10 and 40% of patients hospitalized in psychiatric institutions are prescribed more than one antipsychotic. The objective of the present study was to identify the prevalence of polypharmacy, evaluate adverse effects associated to the use of psych drugs and to estimate the risk in specific groups.

Methods: We carried out a longitudinal, retrospective study that included the analysis of all discharged patients (n = 140) in the first trimester of the year in a psychiatric hospital in Mexico. The information was classified into 7 sections: sociodemographic, diagnosis, clinical follow-up information, prescribed drugs, adverse reactions, substance abuse, laboratory and complementary results. Risk estimation was obtained with Odds Ratios, to correlate continuous variables Pearson's correlation was used. Student's T and Mann Whitney's U were used to compare 2 independent samples; multiple and linear regressions were carried out.

Results: The mean number of drugs used during hospitalization was 7.8 drugs per patient. The mean prescribed psych drugs was 4.07. The mean antipsychotic dose was the risperidone equivalent of 5.08 mg. 29.2% of patients had at least one secondary effect associated to the use of drugs, 17.8% presented extrapyramidal symptoms. 81.4% of patients were prescribed 6 or more drugs (polypharmacy) and were 5 times more likely to suffer a secondary effects (OR 6.24). 14.2% had polypharmacy while receiving antipsychotics and had more than twice the risk of presenting extrapyramidal symptoms (OR 3.05). For each added psych drug, hospital stay increased by 6.56 days.

Conclusions: Despite international guideline recommendations where reasoned and conciliatory prescription of psych drugs is advised, there is still a high prevalence of polypharmacy in patients hospitalized in psychiatric institutions. In the present study 4 out of 5 patients received polypharmacy decreasing tolerability, treatment adherence and increasing the risk and costs secondary to an increased hospital stay.

Keywords: Antipsychotic; Antipsychotic prescription duplicity; Drug-drug interaction; Extrapyramidal symptoms; Hospitalized psychiatric population; Pharmacological interactions; Polypharmacy; Secondary effect.

Fig. 1

Linear regression of “Hospital stay length (days)” and “Number of psychodrugs”. The residual distribution is represented by the black histogram. In the superior central white area it is presented the linear regression function, the correlation (r), p value for the significant test of the correlation and the determination coefficient (R²)

Fig. 2

a. “Hospital stay length (days)” versus “Number of psychodrugs” for subgroups patients: “1 diagnostic” and “> 1 diagnostic”. The regression equations, correlations, p values and determination coefficient are presented in the correspondent colour for each subgroup. b, c, and d. Means and standard errors of hospital stay length, psychotropic drugs, and illicit drugs by subgroups. ns means no statistical significance by test Mann Whitney U

Fig. 3

Five subgroups of patients with different treatments. Comparison for the 4 groups with Kruskal Wallis test. Post Hoc test by Nemenyi. Each symbol (cross, square, diamond, triangle or circle) represent one patient. Horizontal black tick lines show the mean group. Superior left bar plot shows mean and standard error for hospital stay length (days) by subgroups: Comb versus Mono (total patients of Atypical + Typical); Null hypothesis significant test was Mann Whitney U. *** represents p value < 0.001, ** p < 0.01 y * p < 0.05