Physician Choice of Hypothyroidism Therapy: Influence of Patient Characteristics.

Available online from MWHC library: August 2000 - present, Available in print through MWHC library: 1999 - 2006

Background Most endocrinologists encounter patients who are dissatisfied with their current hypothyroidism therapy and request combination therapy with either liothyronine or thyroid extract. Methods A survey of American Thyroid Association members was conducted in 2017. Respondents were presented with thirteen scenarios describing patients with hypothyroidism and asked to choose among 6 therapeutic options. The index patient was satisfied taking levothyroxine therapy. Twelve variations introduced parameters that potentially provide reasons for considering combination therapy (presence of symptoms, low serum triiodothyronine concentration, documentation of deiodinase polymorphisms). Therapeutic options included a) continuing levothyroxine, b) increasing levothyroxine, c) adding liothyronine to a reduced levothyroxine dose, d) adding liothyronine to the current levothyroxine dose, e) replacing levothyroxine with thyroid extract, and f) replacing levothyroxine with liothyronine. Repeated measures logistic regression analysis was performed both to examine the prescribing of levothyroxine (options a and b) versus all other therapies, and also to examine the choice of continuing levothyroxine (option a) versus either increasing levothyroxine (option b), adding liothyronine (options c and d), or replacing levothyroxine with thyroid extract or liothyronine (options e and f ). Results Of the 389 survey respondents, 363 physicians prescribed therapy for hypothyroidism. For the index patient, 98% of physicians continued current levothyroxine therapy. However, as the patient scenario incorporated other patient characteristics, physicians opted to increase levothyroxine dose or prescribe other therapies. The tendency to prescribe alternative therapies was powerfully increased by patient symptoms (OR 25.6, 95% 9-73, p value <0.0001). Older age and the presence of a comorbidity reduced the likelihood that an alternative therapy was prescribed (p value 0.0002 and <0.0001 respectively). All other characteristics except athyreotic status, patient sex, and BMI significantly increased the likelihood that alternative therapies would be prescribed in multivariate analyses (p value <0.000, all cases). Conclusions Even with the acknowledged limitations of survey methodology, this analysis appears to show a marked increase in the willingness of physicians to prescribe combination therapy in specific circumstances. If current prescribing patterns do incorporate the use of therapies other than levothyroxine, there is a critical need for more research into the benefits and risks of these therapies.

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