Patient-reported satisfaction with thyroid hormone replacement therapy for subclinical hypothyroidism in older adults: A pooled analysis of individual participant data from two randomized controlled trials

Background The benefit of levothyroxine treatment of subclinical hypothyroidism (SCH) is subject to debate. This study compared treatment satisfaction between older adults with SCH using levothyroxine or placebo. Methods We analyzed pooled individual participant data from two randomized, double-blind, placebo-controlled trials investigating the effects of levothyroxine treatment in older adults with SCH. Community-dwelling participants aged ≥65 years, with SCH (persistent thyrotropin levels 4.60-19.99 mIU/L for >3 months and normal free thyroxine level) were included. Intervention: dose titration until thyrotropin levels normalized, with a mock dose adjustment of placebo. Treatment satisfaction was determined during the final study visit using the Treatment Satisfaction Questionnaire for Medication (TSQM), encompassing perceived effectiveness, side effects, convenience, and global satisfaction, along with the participants' desire to continue study medication after the trial. Results We included 536 participants. At baseline, the median (IQR) age was 74.9 (69.7-81.4) years, and 292 (55%) were women. The median (IQR) thyrotropin levels were 5.80 (5.10-7.00) mIU/L at baseline in both groups; at final visit 4.97 (3.90-6.35) mIU/L in the placebo and 3.24 (2.49-4.41) mIU/L in the levothyroxine group. After treatment, the groups did not differ significantly in global satisfaction (mean difference [95%CI]: -1.1 [-4.5-2.1], p=0.48), nor in any other domain of treatment satisfaction. These results held true regardless of baseline thyrotropin levels or symptom burden. No major differences were found in the numbers of participants who wished to continue medication after the trial (levothyroxine 35% vs placebo 27%), did not wish to continue (levothyroxine 27% vs placebo 30%), or did not know (levothyroxine 37% vs placebo 42%)(p=0.14). In a subpopulation with high symptom burden from hypothyroid symptoms at baseline, those using levothyroxine more often desired to continue the medication after the trial than those using placebo (mean difference [95% CI] -21.1% [-35.6% to -6.5%]). Conclusion These pooled data from two RCTs, showed no major differences in treatment satisfaction between older adults receiving levothyroxine or placebo. This finding has important implications for decision-making regarding initiating levothyroxine treatment for SCH. Our findings generally support refraining from routinely prescribing levothyroxine in older adults with SCH. Clinical Trial Registration ClinicalTrials.gov: NCT01660126; Netherlands Trial Register: NL3641.