Predictors of polypharmacy among elderly Thais with depressive and anxiety disorders: findings from the DAS study

Polypharmacy is a geriatric syndrome defined variously as the use of potentially inappropriate drugs and/or the concurrent use of multiple medications including prescription and over-the-counter drugs. An association has been shown between polypharmacy and physical health, increased morbidity and increased mortality. However, there is little information regarding the association between polypharmacy and physical disease, personality trait and mental health problems in elderly. The aim of this study was to investigate potential predictive psychosocial factors related to polypharmacy in elderly Thai people.

The study analysed the secondary data from the Depressive Disorders, Anxiety Disorders, Suicide Risk and Associated Factors Among Elderly Thai People Program (DAS Study) which was funded by National Research Council of Thailand and conducted between January 2012 and April 2013. Demographic and baseline clinical characteristics including sex, age, education, living alone or with others, access to health care privilege and monthly income were described. The number of medication, physical diseases and mental health problems (i.e. depression, anxiety, and personality trait of neuroticism) were analyzed using descriptive statistics, chi-square and proportional odds logistic regression.

The 803 participants consumed an average of 2.13 prescribed medicines daily (SD 1.46, median = 2). The largest group used 3 medications (18.6%). Predictors found to be associated with polypharmacy in the logistic regression model included hypertension (OR = 1.985, 95% CI = 1.420-2.775), anxiety disorder (OR = 4.402, 95% CI = 2.630-7.367), number of diseases (OR = 2.140, 95% CI = 1.874-2.445), depressive disorder (OR = 1.470, 95% CI = 1.080-2.001), diabetes mellitus (OR = 1.864, 95% CI = 1.122-3.098) and dyslipidemia (OR = 0.511, 95%CI = 0.325-0.803).

The prevalence of polypharmacy among Thai elderly was relatively high compared to other related studies. Several aspects should be taken into consideration before starting an additional medication in elderly patients. In addition to the number of physical disease that leads to polypharmacy, general practitioners should be aware of anxiety, depression, and personality trait of neuroticism that may be related to polypharmacy. Early detection for such condition as well as non-pharmacological intervention could be one way to help reduce polypharmacy in the elderly.