Adherence to selective serotonin and serotonin-norepinephrine reuptake inhibitor prescriptions affects overall medication adherence in older persons: Evidence from the Italian nationwide osmed health-db database

Objective: This study aimed to evaluate prevalence of prescription of and adherence to selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) and whether adherence to these classes of drugs affects overall medication adherence in older persons. Methods: In a cross-sectional analysis of administrative data comprehensive of all prescribed drugs reimbursed by the Italian national health care system, new prescriptions of SSRIs and SNRIs to persons aged 65 years or older were analyzed (n = 380,400 in 2011; 395,806 in 2012; 409,741 in 2013, from a total sample of 3,762,299 persons aged 65 years or older) as well as prescriptions of antihypertensives, statins, other psychiatric drugs, antidiabetics, antiplatelets, anticoagulants, drugs for chronic obstructive pulmonary disease, and antiosteoporotics. Adherence was estimated by calculating the proportion of days covered by drugs dispensed during a period of 365 days. Adherence was defined as a proportion of days covered of more than 80%. Results: Prevalence of SSRI and SNRI prescriptions varied from 11.4% in 2011 to 12.1% in 2013. Adherence to SSRI and SNRI prescriptions ranged from 31.2% in persons aged ≥ 95 years in 2011 to 41.8% in persons aged 75-84 years in 2013. Persons adherent to SSRI and SNRI prescriptions were more likely to be adherent to the other medications, after adjustment for age, gender, and number of drugs prescribed. The highest association was found for adherence to psychiatric drugs (OR = 1.9; 95% CI, 1.8-2.0). Conclusions: Adherence to SSRI and SNRI prescriptions is poor in older persons. However, people adherent to these classes of antidepressants are more likely to be adherent to the other medications they are prescribed. Studies are needed to evaluate the reasons for and the potential benefits of increasing adherence to antidepressants on overall adherence.