Patient health outcomes associated with models of general practice in Aotearoa New Zealand: a national cross-sectional study

Abstract Background Primary care in Aotearoa New Zealand is largely delivered by general practices which are heavily subsidised by government. At least seven models of primary care have evolved: Traditional, Corporate, Health Care Home, Māori practices, Pacific practices, and practices owned by Primary Health Organisations/District Health Boards and Trust/Non-Governmental Organisations. Te Tiriti o Waitangi (1840) guarantees equal outcomes for Māori and non-Māori, but stark differences are longstanding and ongoing. Pacific peoples and those living with material deprivation also have unequal health outcomes. Methods Cross-sectional study (30 September 2018), data from national datasets and practices at patient level. We sought associations between practice characteristics and patient health outcomes, adjusted for patient characteristics. Practice characteristics included: model of care, size, funding model, rurality; number of consultations and time spent with nurses and doctors; practice and doctor continuity. Six primary outcomes measures were chosen: polypharmacy (≥ 65 years), HbA1c testing in adults with diabetes, immunisations (6 months), ambulatory sensitive hospitalisations (0–14, 45–64 years) and emergency department attendances. Results The study included 924 general practices with 4,491,964 enrolled patients. Traditional practices enrolled 73% of the population, but, on average, the proportion of Māori, Pacific and people living with material deprivation was low in any one Traditional practice. Patients with high needs disproportionately clustered into Māori, Pacific and Trust/NGO practices. There were multiple associations between models of care and patient health outcomes in fully-adjusted regressions. Patient health outcomes were most strongly associated with: age, Māori or Pacific ethnicity, deprivation (IMD), multi-morbidity (M3), clinical input, number of first specialist assessments, changing practice, and prescribing (SSRIs, tramadol, antibiotics). Being Māori or Pacific remained associated with poorer outcomes after full adjustment including measures of deprivation. Patients with high health need received more clinical input but this was insufficient to achieve equity of outcomes. Practice-level variance was highest for emergency department attendances. Conclusions Resource models of care with disproportionately high and complex patient health need (Māori, Pacific and Trust/NGO practices). Associations between patient and practice characteristics, and patient health outcomes, should be central to investment decisions.