The concentration of complexity: case mix in New Zealand general practice and the sustainability of primary care

Introduction. New Zealand general practice and primary care is currently facing significant challenges and opportunities following the impact of the coronavirus disease 2019 (COVID-19) pandemic and the introduction of health sector reform. For future sustainability, it is important to understand the workload associated with differing levels of patient case mix seen in general practice. Aim. To assess levels of morbidity and concomitant levels of socio-economic deprivation among primary care practices within a large primary health organisation (PHO) and associated Maori provider network. Methods. Routinely collected practice data from a PHO of 57 practices and a Maori provider (PHO) of five medical practices in the same geographical area were used to compare a number of population health indicators between practices that had a high proportion of high needs patients (HPHN) and practices with a low proportion of high needs patients (Non-HPHN). Results. When practices in these PHOs are grouped in terms of ethnicity distribution and deprivation scores between the HPHN and Non-HPHN groups, there is significantly increased clustering of both long-term conditions and health outcome risk factors in the HPHN practices. Discussion. In this study, population adverse health determinants and established co-morbidities are concentrated into the defined health provider grouping of HPHN practices. This 'concentration of complexity' raises questions about models of care and adequate resourcing for quality primary care in these settings. The findings also highlight the need to develop equitable and appropriate resourcing for all patients in primary care.