The influence of gender and psychological distress on adherence to prescribed medication

Background: The lack of adherence to drug therapy is a major problem; it can contribute to significant deterioration of disease and increased health-care costs. Improving medication adherence is a big challenge; there is no simple solution to the problem. It is thus essential to improve our knowledge of non-adherence (NA) and its causes. Aims: The aims of the thesis were to study the influence of gender and psychological distress on self-reported, intentional and unintentional non-adherent behaviour, and to investigate the reasons for NA. Methods: A population-based study that included a postal questionnaire was carried out in a cross-section of the general Swedish population (n=7,985, aged 18-84 years). The response rate was 61.1% (n=4,875) and current prescription drug use was reported by 2,802 participants. The questionnaire covered use of prescription drugs, NA to the drug regimens, reasons for NA, economic status, attitudes to drugs, and the presence of somatic or mental problems, and also included the Hospital Anxiety and Depression Scale questionnaire. Results: The results showed differences in various self-reported non-adherent behaviour patterns and reasons for NA between the genders. In most cases, these remained after controlling for confounders such as socioeconomic factors and attitudes to drugs that are known to differ between women and men. Associations were also found between symptoms of anxiety and/or depression and the presence of intentional or unintentional non-adherent behaviour (with a stronger average association for intentional NA), and between anxiety/depression and some of the reasons given for NA, e.g. adverse drug reactions (ADRs). Conclusions: Although it was not possible to confirm causal relationships, this thesis emphasises the effects of gender and psychological distress on NA. In summary, both gender and anxiety and/or depression influenced non-adherent behaviour and the reasons given for NA. For instance, ADRs seemed to influence the decision not to take the drug as prescribed, especially among women and participants under psychological distress. It is suggested that a deep understanding of the causes of NA and of the impact of gender and psychological distress on the outcomes would help those aiming to improve adherence to prescribed medication