Association Between Levothyroxine Treatment and Thyroid-Related Symptoms Among Adults Aged 80 Years and Older With Subclinical Hypothyroidism.

Key PointsQuestionAmong adults aged 80 years and older with subclinical hypothyroidism, what is the association between treatment with levothyroxine and thyroid-related symptoms? FindingsIn this pooled analysis of data from 2 randomized clinical trials that included 251 participants aged 80 years and older, treatment with levothyroxine, compared with placebo, was not significantly associated with improvement in thyroid-related patient-reported quality of life outcome scores (range, 0-100; higher scores indicate worse quality of life; minimal clinically important difference, 9) for hypothyroid symptoms (adjusted between-group difference, 1.3) or tiredness (adjusted between-group difference, 0.1). MeaningThese findings do not support routine treatment with levothyroxine for subclinical hypothyroidism in adults aged 80 years and older. ImportanceIt is unclear whether levothyroxine treatment provides clinically important benefits in adults aged 80 years and older with subclinical hypothyroidism. ObjectiveTo determine the association of levothyroxine treatment for subclinical hypothyroidism with thyroid-related quality of life in adults aged 80 years and older. Design, Setting, and ParticipantsProspectively planned combined analysis of data involving community-dwelling adults aged 80 years and older with subclinical hypothyroidism. Data from a randomized clinical trial were combined with a subgroup of participants aged 80 years and older from a second clinical trial. The trials were conducted between April 2013 and May 2018. Final follow-up was May 4, 2018. ExposuresParticipants were randomly assigned to receive levothyroxine (n=112; 52 participants from the first trial and 60 from the second trial) or placebo (n=139; 53 participants from the first trial and 86 from the second trial). Main Outcomes and MeasuresCo-primary outcomes were Thyroid-Related Quality of Life Patient-Reported Outcome (ThyPRO) questionnaire scores for the domains of hypothyroid symptoms and tiredness at 1 year (range, 0-100; higher scores indicate worse quality of life; minimal clinically important difference, 9). ResultsOf 251 participants (mean age, 85 years; 118 [47%] women), 105 were included from the first clinical trial and 146 were included from the second clinical trial. A total of 212 participants (84%) completed the study. The hypothyroid symptoms score decreased from 21.7 at baseline to 19.3 at 12 months in the levothyroxine group vs from 19.8 at baseline to 17.4 at 12 months in the placebo group (adjusted between-group difference, 1.3 [95% CI, -2.7 to 5.2]; P=.53). The tiredness score increased from 25.5 at baseline to 28.2 at 12 months in the levothyroxine group vs from 25.1 at baseline to 28.7 at 12 months in the placebo group (adjusted between-group difference, -0.1 [95% CI, -4.5 to 4.3]; P=.96). At least 1 adverse event occurred in 33 participants (29.5%) in the levothyroxine group (the most common adverse event was cerebrovascular accident, which occurred in 3 participants [2.2%]) and 40 participants (28.8%) in the placebo group (the most common adverse event was pneumonia, which occurred in 4 [3.6%] participants). Conclusions and RelevanceIn this prospectively planned analysis of data from 2 clinical trials involving adults aged 80 years and older with subclinical hypothyroidism, treatment with levothyroxine, compared with placebo, was not significantly associated with improvement in hypothyroid symptoms or fatigue. These findings do not support routine use of levothyroxine for treatment of subclinical hypothyroidism in adults aged 80 years and older. Trial RegistrationClinicalTrials.gov Identifier: NCT01660126; Netherlands Trial Register: NTR3851 This cohort study combines data from 2 randomized trials to estimate associations between use of levothyroxine to manage subclinical hypothyroidism and hypothyroid symptoms and fatigue at 1 year among community-dwelling adults aged 80 years and older.