Prevalence and Factors Associated with SSRI Use Among Adults with Depressive and Thyroid Disorders in the United States

Background:

Patients with hypothyroidism and hyperthyroidism are at high risk for developing anxiety and depression. Sixty percent of adults in the United States with thyroid disorders have depression. Selective serotonin reuptake inhibitors (SSRIs) are used to treat depression. However, SSRIs reduce thyroid function during treatment suggesting SSRIs may not be used in treating depression among adults with thyroid disorders. Few studies have investigated the prevalence and factors associated with SSRI use in adults with diagnosed depression and thyroid disorders.

Objective:

This study estimated the prevalence of SSRI use in adults with diagnosed thyroid and depressive disorders in the United States and examined the factors associated with SSRI use.

Methods:

The study used a cross-sectional design using pooled data from multiple years (2018-2020) of the Medical Expenditure Panel Survey (MEPS), a nationally representative survey of the civilian non-institutionalized population in the US, to gain an adequate sample size. The study was restricted to adults with diagnosed thyroid and depressive disorders with health insurance. The final sample was (Unweighted N=729; Weighted N= 3,090,551). SSRI use was identified from prescription drug files using Multum drug classifications. Rao-Scott Chi-square tests were used to examine the unadjusted group differences in SSRI use. Multivariable logistic regression was used to analyze factors associated with SSRI use. The logistic regressions adjusted for age, sex, race and ethnicity, education, income, insurance coverage, prescription drug coverage, polypharmacy (>6 drug classes excluding antidepressants and thyroid hormones), perceived physical and mental health rating, pain, and thyroid hormones.

Results:

A majority (61.6%) of adults diagnosed with thyroid and depression used SSRIs. A lower percentage of African Americans (28.5%vs.61.9%; p<.05) used SSRIs compared to NHWs; Only 47.0% of those reporting poor health used SSRI compared to those reporting excellent physical health (73.8%) (p<0.01). A lower percentage of adults with extreme pain (49.5%vs.65.8%) used SSRIs compared to those with mild or no pain (p<.05). A lower percentage of adults with moderate to vigorous physical activity of 5 days/week used SSRIs compared to adults with no exercise. (54.2%vs.65.3%; p<.05). A lower percentage of adults with polypharmacy (53.0%vs.67.5%; p<0.01) used SSRI compared to those without polypharmacy. In multivariable logistic regression, African Americans had lower odds of SSRI use (AOR=0.28; 95% CI=0.09, 0.88) compared to NHWs. Lower ratings of physical health were associated with SSRI use. Adults with polypharmacy had lower odds of SSRI use (AOR=0.65; 95% CI=0.44, 0.96).

Conclusion:

6 in 10 adults with thyroid and depressive disorders used SSRIs. Racial disparities in SSRI use were observed. We speculate that SSRI use rates may be lower in those with polypharmacy and poor health to reduce the risk of drug-drug interactions and drug-disease interactions.

Strengths and Limitations:

Limitations include cross-sectional study design, self-reported data, no distinction between hyperthyroidism and hypothyroidism, and a small sample size despite pooling multiple years. Nevertheless, the study used nationally representative data adjusted for a comprehensive list of clinical, demographic, and psychosocial factors.