A Mixed Methods Study of Adherence to Prophylactic Treatment Among Young People With Haemophilia

Abstract

Introduction Haemophilia is an inherited bleeding disorder caused by a deficiency in one of the coagulation or blood clotting factors in the blood. When injured someone with haemophilia does not bleed more intensely than a person without haemophilia, but they tend to bleed for a much longer time. For people affected by severe haemophilia, the deficiency in coagulation factor can cause spontaneous internal bleeding in joints and muscles, as well as intracranial bleeding, and bleeding in soft tissues (e.g. nosebleeds or bleeding gums). The most common form is Haemophilia A which is caused by a deficiency in factor VIII. Haemophilia B is caused by a deficiency of factor IX and tends to be less severe than haemophilia A. Haemophilia is treated by replacing the deficient coagulation factor in the blood through intravenous injections of factor concentrate. Treatment can be on-demand, where medication is used to treat a bleeding episode; or preventative, where factor replacement treatment is used to increase the concentration of coagulation factor in the blood to prevent bleeding. Most young people with severe haemophilia in the UK follow a preventative treatment regimen (prophylactic treatment or prophylaxis). Patients with severe haemophilia A usually take 3 or 4 injections per week on alternate days, whereas patients with severe haemophilia B usually take 2 or 3 injections per week. There is good evidence that prophylaxis reduces bleeds and joint damage, whilst also improving quality of life. Therefore it is imperative for future health and functioning that young people with haemophilia (YPH) follow the prophylactic regimen they agreed with their haemophilia team. However, reported adherence levels among YPH vary widely (17 - 93%). Additionally, drivers of (non)adherence among YPH specifically have not been evidenced. Aims The overall aim of the research described in this thesis was to gain a better understanding of the extent to which YPH adhere to their prophylactic treatment, and better understand what drives their (non-)adherence. The aims of the quantitative questionnaire study were to measure levels of adherence among YPH, and to assess whether psychosocial factors that have been shown to be associated with adherence among young people with other chronic illnesses, such as self-efficacy and social support, are also associated with adherence among YPH.

Based on previous research on adherence and social cognitive models of illness, it was hypothesised that: - there would be differences between adolescents and young adults in relation to psychosocial correlates of adherence. - higher perceptions of pain and impact of pain would be associated with better adherence (De Moerloose, Urbancik, Van Den Berg, & Richards, 2008; Treil, Rice, & Leissinger, 2007). - higher perceptions of chronicity, consequences and treatment control would be predictive of higher adherence (Chilcot et al., 2010; Horne & Weinman, 2002). - greater perception of necessity of prophylaxis would be predictive of higher adherence whereas concerns about prophylaxis would not be predictive (de Thurah, Nørgaard, Harder, & Stengaard-Pedersen, 2010; Horne et al., 2013; Horne & Weinman, 1999; Llewellyn, Miners, Lee, Harrington, & Weinman, 2003; Wileman et al., 2014). - greater negative mood would be associated with lower adherence scores (Cox & Hunt, 2015; Helgeson, Siminerio, Escobar, & Becker, 2009; Snell, Fernandes, Bujoreanu, & Garcia, 2014). In addition, based on evidence that lower adherence results in worse disease outcomes (Berntorp, 2009; M. J. Manco-Johnson et al., 2007), it was anticipated that non-adherence to prophylaxis would be associated with higher numbers of bleeds and hospital visits. The aims of the qualitative interview studies with YPH, parents of YPH, and haemophilia healthcare professionals were to examine perceptions and experiences in relation to prophylaxis and how they make sense of these experiences. It was anticipated that this would provide evidence to gain a better understanding of the complexities surrounding prophylaxis and of the barriers and facilitators to adherence among YPH.