Systematic review were predominantly peer based, but managers provided signiﬁcant functional supports, with rural nurses expecting more guidance from management than urban nurses. Ethnography was employed by Ormrod et al40 in three UK NHS mental health clinics to examine how organ- isational practices were spread within networks of prac- tice. Professional networks within psychiatry were found not to spread particular work practices equally to psychiatrists and their associated multi-disciplinary teams at two new sites. This was largely due to ideological differences in psychiatric practice approaches and differences in founder inﬂuence. Webster et al36 used SNA data on advice and social relations, to examine differences in eight mental health case-management teams in a Californian (USA) county mental health system. Male supervisors were substantially more central for ‘instrumental’ (advice) relations than female supervisors, displaying an autocratic leadership style. Male supervised teams were more centralised than female supervised teams. For the ‘social’ relations, male team supervisors were more central than female super- visors. Teams with female supervisors were more centralised than those with male supervisors, yet the female leaders were not the most central team member, showing a democratic leadership style. Signiﬁcant research on the professional social networks of clinical directors of medicine and directors of nursing in UK hospitals was undertaken by West et al.37 Directors of nursing were more central in their networks than clinical directors of medicine, and their networks were more hierarchical. The networks of directors of nursing had lower density (having advan- tages in terms of access to information) than the clinical directors of medicine who tended to be embedded in much more densely connected networks (cliques). Doctors’ networks were more egalitarian and decentral- ised than nurses’ networks, hence change processes for the doctors need to involve group processes, rather than simply convincing individuals of the need to change. In West and Barron’s subsequent research,27 both directors of nursing and clinical directors of medicine discussed ‘important professional matters’ with others similar to themselves in terms of profession, gender, age, and seniority (homophily), with doctors being more extreme in this regard. Managers (non-clinically qualiﬁed) occupied a powerful brokerage role for both nurses and doctors, whereas nurses and doctors were rarely on each other’s networks. Nursing and medicine had quite different social structures. With few informal ties between the two professions, information was unlikely to be spread between professions by informal sources. 246 Structure of quality collaboratives and healthcare partnerships Four studies show the application of SNA in examining the structure and sustainability of collaboratives and partnerships. Gold et al32 applied SNA to research rela- tionships (structure and processes) among organisations participating in a large-scale, publiceprivate, quality collaboration among major US health plans to reduce racial and ethnic disparities in healthcare. Sponsors and support organisations, along with a few of the health plans, formed the ‘glue’ holding the collaboration together. With limited communication among health plans, if the collaboration ended without greater communication among the non-core organisations, the absence of the core would leave a very sparse network. Gold et al advised collaborative sponsors to consider both short-term and long-term goals and whether they can be pursued if a collaborative ends. Mendel et al34 used SNA to explore the numbers and types of inter-organisational partnerships within the US patient safety domain, the changes over time in these networks, and their potential for disseminating patient safety knowledge and practices. Between 2004 and 2006, partnerships grew in all activity domains, particularly dissemination and tools development, signifying growing strength in the capacity to disseminate and implement patient safety advancements. Fragmentation of the overall partnership network decreased, and potential for information ﬂow increased. However, network central- isation increased, suggesting vulnerability to partnership failure if key participants disengaged. SNA was applied by Lewis et al33 in a longitudinal analysis of network structure, dynamics and sustainability in primary care partnerships in Victoria, Australia at three time points between 2002 and 2005. Although network structures changed over the 3 years, there was the continuing centrality of the independent staff employed to manage the partnerships, with their crucial role in holding partnerships together. These partner- ships required long-term support, not just start-up funding. To study whether collaboration initiatives by a local health authority in Italy between 2001 and 2004 had any effect on individual and district-level general practi- tioner (GP) performance on drug expenditure targets, Fattore et al39 used SNA. In terms of the GP’s ability to meet expenditure targets, the social inﬂuence mecha- nism (the performance of peers to whom the GP was directly connected) was more relevant than the social capital mechanism (the centrality of the GP in the network). While collaborative arrangements induced more homogeneous behaviour among GPs, they did not necessarily improve the ability of GPs to meet local health authority objectives. BMJ Qual Saf 2012;21:239e249. doi:10.1136/bmjqs-2011-000187