<p>Supplmentary Text A–D and Tables A–F.</p>

<p><b>Text A.</b> Multimorbidity Treatment Burden Questionnaire (MTBQ), self-administered Spanish version. <b>Text B.</b> Multimorbidity Treatment Burden Questionnaire (MTBQ), Spanish version administered by the interviewer. <b>Text C.</b> Stata script used in the analysis. <b>Text D.</b> Summary of study findings alongside models, theories and contextual factors in the Peruvian setting. <b>Table A.</b> Evidence of validation of the Multimorbidity Treatment Burden Questionnaire (MTBQ). <b>Table B.</b> Definition and details of social, health and healthcare-related measures. <b>Table C.</b> Observed power estimations to assess the difference of the Multimorbidity Treatment Burden (MTBQ) score by geographical area and healthcare provider. <b>Table D.</b> Comparison of included and excluded participants. <b>Table E.</b> Description of chronic conditions of the study sample. <b>Table F.</b> Distribution of scores by item of the Multimorbidity Treatment Burden Questionnaire (MTBQ).</p> <p>(DOCX)</p>