Limited evidence to assess the impact of primary health care system or service level attributes on health outcomes of Indigenous people with type 2 diabetes: a systematic review

BACKGROUND: To describe reported studies of the impact on HbA1C levels, diabetes-related hospitalisations, and other primary care health endpoints of initiatives aimed at improving the management of diabetes in Indigenous adult populations of Australia, Canada, New Zealand and the United States. METHOD: Systematic literature review using data sources of MEDLINE, Embase, the Cochrane Library, CINHAL and PsycInfo from January 1985 to March 2012. Inclusion criteria were a clearly described primary care intervention, model of care or service, delivered to Indigenous adults with type 2 diabetes reporting a program impact on at least one quantitative diabetes-related health outcome, and where results were reported separately for Indigenous persons. Joanna Briggs Institute critical appraisal tools were used to assess the study quality. PRISMA guidelines were used for reporting. RESULTS: The search strategy retrieved 2714 articles. Of these, 13 studies met the review inclusion criteria. Three levels of primary care initiatives were identified: 1) addition of a single service component to the existing service, 2) system-level improvement processes to enhance the quality of diabetes care, 3) change in primary health funding to support better access to care. Initiatives included in the review were diverse and included comprehensive multi-disciplinary diabetes care, specific workforce development, systematic foot care and intensive individual hypertension management. Twelve studies reported HbA1C, of those one also reported hospitalisations and one reported the incidence of lower limb amputation. The methodological quality of the four comparable cohort and seven observational studies was good, and moderate for the two randomised control trials. CONCLUSIONS: The current literature provides an inadequate evidence base for making important policy and practice decisions in relation to primary care initiatives for Indigenous persons with type 2 diabetes. This reflects a very small number of published studies, the general reliance on intermediate health outcomes and the predominance of observational studies. Additional studies of the impacts of primary care need to consider carefully research design and the reporting of hospital outcomes or other primary end points. This is an important question for policy makers and further high quality research is needed to contribute to an evidence-base to inform decision making.