Adherence to oral hypoglycaemic agents among type-2 diabetes patients of Turkish descent

Scientific attention for medication adherence among people with chronic diseases has grown exponentially during the last decades. Despite the fact that the prevalence of DM is higher in non-White ethnic minorities only few studies on adherence to OHA in these populations were published. In chapter 1 (section 2), we presented the results of our systematic literature review on adherence to OHA in non-White ethnic minorities. Demographic, disease-related, treatment-related, socioeconomic and cultural factors were associated with adherence to OHA in the non-White ethnic minorities under study. However, because the included studies suffered from several methodological difficulties we also proposed methodological improvements for future research. The systematic literature review drew our attention to the multitude of factors, some of which may be culturally shaped, influencing adherence to OHA. As such it lay the foundation for our qualitative research study in which we explored perspectives of T2DM-patients of Turkish descent. Furthermore, the, often limited, insights and methodological shortcomings of the included studies strengthened the argumentation for our research design in which a detailed exploration, using qualitative methods, would precede a quantitative assessment of factors influencing OHA. To explore factors influencing adherence to OHA among T2DM-patients of Turkish descent we first conducted a qualitative study, using in-depth interviews (chapter 3). A theoretical sampling procedure was used, meaning analysis results of earlier conducted interviews led to adjusted or new inclusion criteria for patients to be interviewed in the course of the study. This process stopped when theoretical saturation was reached. This cycle of data collection, data analysis and selection of new cases provided us with a broad overview of factors potentially influencing adherence to OHA and a detailed exploration of how influencing factors are interconnected. Furthermore, this theoretical sampling procedure guaranteed the validity of our results because preliminary insights were confirmed, nuanced or sometimes contradicted by newly collected cases. Results from our qualitative study showed adherence to OHA was influenced by a multitude of barriers and facilitators. Next to beliefs about OHA, polypharmacy, beliefs about the course of diabetes, forgetfulness, the perception of the doctor's medical expertise, feelings of depression and social support; factors which are also found in other ethnic groups; some factors distinctive for T2DM patients of Turkish descent emerged. Respondents' causal beliefs about stress and the Belgian climate often led to nonadherence during less stressful periods, like summer holidays in Turkey. Some respondents adjusted their medication use to food intake or during Ramadan fasting. Concerns about OHA led to the use of herbal medicine, which in turn can lead to nonadherence to OHA. The religious framework used to interpret diabetes led, in combination with feelings of depression, to nonadherence but facilitated medication adherence in other patients. The use of qualitative methods also provided detailed insights into the ways these different factors are interconnected, and thus on how one or more factors can strengthen or counter the effect of another factor on adherence to OHA. The perception of the GP's medical expertise as diabetes care provider appeared to be important: firstly because it was able to counter the negative influence of factors like medication beliefs or illness beliefs on adherence to OHA and, secondly, because it may to be a factor distinguishing adherers from nonadherers. These patterns of interdepedendent factors may also be different from men and women, especially among first-generation migrants. Women seemed to adopt a more passive role towards the pharmacological treatment of T2DM probably because of their low educational level, limited language proficiency and the adoption of culturally shaped traditional gender roles. To further investigate whether Ramadan fasting had an impact on adherence to OHA and/or insulin we conducted a cross-sectional study on participation at Ramadan fasting, the use of OHA and/or insulin during Ramadan fasting and advice received from health care providers on Ramadan and diabetes (chapter 4). About half of the sample had received recommendations from their healthcare provider(s) about Ramadan fasting and diabetes. A low prevalence of Ramadan fasting among Turkish migrants with diabetes living in Belgium was observed. Six out of ten patients who actually fasted received recommendations about the intake of diabetes medication. Self-reported medication adherence during Ramadan, defined as following the (modified) regimen prescribed by the doctor, was very high. This study also showed health care workers could improve the provision of information on Ramadan fasting and diabetes. Furthermore, Ramadan fasting was less common among DM patients of Turkish descent living in Belgium compared to patients in Muslim countries. The impact of Ramadan fasting on adherence to OHA and/or insulin may be of minor importance. However, our results are based on a small convenience sample, and thus need to be validated in future studies using larger, at random samples. Because GPs and PHs play an important role in promoting adherence to OHA we conducted a qualitative study, using focus groups, to explore their perspectives on factors influencing adherence to OHA among T2DM-patients of Turkish descent, and on barriers to promoting adherence to OHA in this population (chapter 5). Both professional groups identified most obstacles to adherence to OHA found in our qualitative study with T2DM patients of Turkish descent. GPs and PHs mentioned the lack of knowledge about diabetes and hypoglycaemic medication, medication beliefs, culturally shaped illness beliefs, depression, social support, fatalism (often contributed to religiosity), religious and cultural habits, the health care provider's authority, financial barriers and policies encouraging generic prescribing as obstacles of medication adherence in this population. However, some of the influences described in our interview study were not recognized by most GPs and PHs: the influence of causal beliefs about stress and the Belgian climate, the use of herbal medicine and the positive impact of religiosity on medication adherence. A multitude of barriers to promoting adherence to OHA, both at the level of the patient and at the level of diabetes care provision, were mentioned. At the level of the patient identified barriers were the low educational level, high rates of illiteracy, language disconcordance, a lack of continuity of care, cultural habits and religious demands, culturally shaped gender roles, the influence of ideas about diabetes treatment present in the Turkish community and expectations about consultations. At the level of diabetes care provision the barriers were: the lack of time in consultations (which hinders the exploration of patients' perspectives), a reluctance to discuss medication adherence (out of fear to damage the patientprovider relationship or to arouse concerns about OHAs) and the lack of a close cooperation between GPs and PHs. GPs and PHs suggested several practical solutions to overcome barriers at the patient level: initiatives to overcome language barriers and the use of reminder systems to tackle unintentional nonadherence. Health care providers might also profit from training in cultural competencies and skills to promote behavioural change. At the level of diabetes care provision initiatives to stimulate cooperation between GPs and PHs could be taken, and patients could be stimulated to visit the same GP and PH. To validate the results from our qualitative study and to provide an estimate of the nonadherence rate to OHA we conducted an exploratory, cross-sectional survey study in a, probably, representative sample of T2DM patients of Turkish descent (chapter 6). We have tried to obtain this representative sample of T2DM patients of Turkish descent living in Belgium using a wide variety of recruitment channels and tens of recruiters. Nonadherence to OHA was measured with the medication possession ratio, based on pharmacy databases. Approximately 40 % of T2DM patients of Turkish descent in this sample were nonadherent (MPR<80%) to OHA, with a mean medication possession ratio of 82%. These figures are comparable to nonadherence rates and mean medication possession ratios found in other ethnic groups. However, nonadherence may be underestimated because we can not be completely sure about the sample's representativeness and because adherence rates based on pharmacy databases do not measure the actual intake of medicines. The finding from our qualitative study that patients reduced or temporarily stopped their intake of OHA during their stays in Turkey was confirmed. Approximately one out of four patients who had stayed in Turkey reported these behaviours. According to the results of our qualitative study, this might be explained by patients' perspectives of the influence of stress on diabetes. In order to identify factors influencing adherence to OHA we included a large pool of potential covariates based on the results from our qualitative study with patients, our systematic literature review and other literature reviews. Employment status, living situation, the type of OHA regimen, forgetfulness and the trust put in the GP as diabetes care provider influenced adherence to OHA in this sample. Medication beliefs, illness beliefs, social support, mental health, polypharmacy and the use of CAM did not influence adherence to OHA when controlling for a multitude of other covariates. Results of the qualitative study were only partly confirmed due to the small sample size in the cross-sectional survey study and, to the fact that the influence of some of the factors identified in the qualitative study may only have an important impact on adherence to OHA in a minority of patients.

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