Haemophilia. 2019;00:1–10. wileyonlinelibrary.com/journal/hae | 1 © 2019 John Wiley & Sons Ltd 1 | INTRODUCTION Prophylaxis with regular infusion of clotting factor concentrates (CFCs) has been considered the gold standard treatment for patients with severe haemophilia. 1-3 However, adherence to prophylaxis in haemophilia is very demanding and requires lifelong dedication to prevent bleeding and, consequently, disability. 4 This has been a primary factor underpinning the development of several novel Received: 8 February 2019 | Revised: 20 May 2019 | Accepted: 3 June 2019 DOI: 10.1111/hae.13811 ORIGINAL ARTICLE Comparing objective and self‐reported measures of adherence in haemophilia Vanessa Giroto Guedes 1,2 | José Eduardo Corrente 2 | Albert Farrugia 3 | Sylvia Thomas 4 | Patrick Alexander Wachholz 2 | Edison Iglesias de Oliveira Vidal 2 1 Blood Center of Marília Medical School, FAMEMA, Marília, Brazil 2 Botucatu Medical School, São Paulo State University – UNESP, Botucatu, Brazil 3 School of Surgery, University of Western Australia, Crawley, Western Australia, Australia 4 Radiology Department, Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro ‐ UFRJ, Rio de Janeiro, Brazil Correspondence Vanessa Giroto Guedes, Physiotherapy Service of Blood Center of Marília Medical School ‐ FAMEMA, Rua Lourival Freire, nº 240, Bairro Fragata, Marília/SP – CEP: 17519-050. Email: vanessagiroto@hotmail.com Present address Vanessa Giroto Guedes, Radiology Department, Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro ‐ UFRJ, Rio de Janeiro, Brazil Abstract Aim: To compare subjective and objective measures of adherence to prophylaxis in haemophilia. Methods: In this cross-sectional study, we compared participants’ self-perceived ad- herence and their estimate of the number of clotting factor concentrates (CFCs) that had been missed over the last period of CFC dispensation with an objective measure of adherence based on counts of CFC vials returned by participants. Results: We included 29 out of 31 eligible patients in the study. There was no sig- nificant correlation between self-perceived degree of adherence and the objective classification of adherence (Rho: 0.10, 95% CI: −028 to 0.46, P: 0.61) and between the classification of adherence based on the proportion of missed CFC doses assessed by participants’ self‐report and objectively (Rho: 0.32, 95% CI: −0.01 to 0.59, P: 0.11). Conversely, we found evidence of moderate correlation between the proportion of missed CFC doses as assessed by participants’ self‐report and objectively (Rho: 0.56, 95% CI: 0.24 to 0.77, P: 0.003). Participants’ self-perceived adherence was 3 times more likely to be rated as very good or good than it was for the objective assessment to be classified as adherent or suboptimally adherent. Conclusion: Our results showed significant discrepancies between subjective and objective measures of adherence, which likely reflect the influence of social desir- ability bias in self-reported measures and different concepts of adherence between patients/caregivers and haemophilia experts. Additionally, our results allow us to hy- pothesize that studies on adherence to prophylaxis in haemophilia relying exclusively on information from self-reports and questionnaires may substantially overestimate adherence levels. KEYWORDS Brazil, developing countries, haemophilia, medication adherence, patient compliance