FRAGILITY FRACTURES IN MALE VETERANS ON THYROID HORMONE THERAPY

Concurrent Use of Thyroid Hormone Therapy and Interfering Medications in Older US Veterans

CONTEXT

Thyroid hormone management in older adults is complicated by comorbidities and polypharmacy.

OBJECTIVE

Determine the prevalence of concurrent use of thyroid hormone and medications that can interfere with thyroid hormone metabolism (amiodarone, prednisone, prednisolone, carbamazepine, phenytoin, phenobarbital, tamoxifen), and patient characteristics associated with this practice.

DESIGN

Retrospective cohort study between 2004 and 2017 (median follow-up, 56 months).

SETTING

Veterans Health Administration Corporate Data Warehouse.

PARTICIPANTS

A total of 538 137 adults ≥ 65 years prescribed thyroid hormone therapy during the study period.

MAIN OUTCOME MEASURE

Concurrent use of thyroid hormone and medications interfering with thyroid hormone metabolism.

RESULTS

Overall, 168 878 (31.4%) patients were on at least 1 interfering medication while on thyroid hormone during the study period. In multivariable analyses, Black/African-American race (odds ratio [OR], 1.25; 95% CI, 1.21-1.28, compared with White), Hispanic ethnicity (OR, 1.12; 95% CI, 1.09-1.15, compared with non-Hispanic), female (OR, 1.11; 95% CI, 1.08-1.15, compared with male), and presence of comorbidities (eg, Charlson/Deyo Comorbidity Score ≥ 2; OR, 2.50; 95% CI, 2.45-2.54, compared with 0) were more likely to be associated with concurrent use of thyroid hormone and interfering medications. Older age (eg, ≥ 85 years; OR, 0.48; 95% CI, 0.47-0.48, compared with age 65-74 years) was less likely to be associated with this practice.

CONCLUSIONS AND RELEVANCE

Almost one-third of older adults on thyroid hormone were on medications known to interfere with thyroid hormone metabolism. Our findings highlight the complexity of thyroid hormone management in older adults, especially in women and minorities.

Evaluating health outcomes in the treatment of hypothyroidism

Clinical hypothyroidism is defined by the inadequate production of thyroid hormone from the thyroid gland to maintain normal organ system functions. For nearly all patients with clinical hypothyroidism, lifelong treatment with thyroid hormone replacement is required. The primary goal of treatment is to provide the appropriate daily dose of thyroid hormone to restore normal thyroid function for each individual patient. In current clinical practice, normalization of thyrotropin (TSH) level is the primary measure of effectiveness of treatment, however the use of a single biomarker to define adequate thyroid hormone replacement is being reevaluated. The assessment of clinical health outcomes and patient-reported outcomes (PROs), often within the context of intensity of treatment as defined by thyroid function tests (i.e., undertreatment, appropriate treatment, or overtreatment), may play a role in evaluating the effectiveness of treatment. The purpose of this narrative review is to summarize the prominent health outcomes literature in patients with treated hypothyroidism. To date, overall mortality, cardiovascular morbidity and mortality, bone health and cognitive function have been evaluated as endpoints in clinical outcomes studies in patients with treated hypothyroidism. More recent investigations have sought to establish the relationships between these end results and thyroid function during the treatment course. In addition to clinical event outcomes, patient-reported quality of life (QoL) has also been considered in the assessment of adequacy of hypothyroidism treatment. From a health care quality perspective, treatment of hypothyroidism should be evaluated not just on its effectiveness for the individual patients but also to the extent to which patients of different sociodemographic groups are treated equally. Ultimately, more research is needed to explore differences in health outcomes between different sociodemographic groups with hypothyroidism. Future prospective studies of treated hypothyroidism that integrate biochemical testing, PROs, and end result clinical outcomes could provide a more complete picture into the effectiveness of treatment of hypothyroidism.