Study of Optimal Replacement of Thyroxine in the ElDerly (SORTED): protocol for a mixed methods feasibility study to assess the clinical utility of lower dose thyroxine in elderly hypothyroid patients: study protocol for a randomized controlled trial

BACKGROUND The population of the UK is ageing. There is compelling evidence that thyroid stimulating hormone distribution levels increase with age. Currently, in UK clinical practice elderly hypothyroid patients are treated with levothyroxine to lower their thyroid stimulating hormone levels to a standard non-age-related range. Evidence suggests that mortality is negatively associated with thyroid stimulating hormone levels. We report the protocol of a feasibility study working towards a full-scale randomized controlled trial to test whether lower dose levothyroxine has beneficial cardiovascular outcomes in the oldest old. METHODS/DESIGN SORTED is a mixed methods study with three components: SORTED A: A feasibility study of a dual-center single-blinded randomized controlled trial of elderly hypothyroid patients currently treated with levothyroxine. SETTING Patients will be recruited from 20 general practices and two hospital trust endocrine units in Northumberland, Tyne and Wear. PARTICIPANTS Target recruitment of 50 elderly hypothyroid patients currently treated with levothyroxine, identified in both primary and secondary care settings. INTERVENTION Reduced dose of levothyroxine to achieve an elevated serum thyroid stimulating hormone (target range 4.1 to 8.0 mU/L) versus standard levothyroxine replacement (target range 0.4 to 4.0 mU/L). RANDOMIZATION Using random permuted blocks, in a ratio of 1:1, randomization will be carried out by Newcastle Clinical Trials Unit. OUTCOMES Study feasibility (recruitment and retention rates and medication compliance), acceptability of the trial design, assessment of mobility and falls risk, and change in cardiovascular risk factors. SORTED B Qualitative study using in-depth interviews to understand patients' willingness to take part in a randomized controlled trial and participants' experience of the intervention. SORTED C Retrospective cohort study of 400 treated hypothyroid patients aged 80 years or over registered in 2008 in primary care practices, studying their 4-year cardiovascular outcomes to inform the power of SORTED II. DISCUSSION This is a study to evaluate the feasibility of conducting a randomized controlled trial in elderly hypothyroid patients in general practice and hospital settings. The results will inform the design of the definitive SORTED II trial to evaluate the effects of lower dose thyroxine in elderly hypothyroid patients. TRIAL REGISTRATION Current Controlled Trials ISRCTN16043724.