Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
Wellcome Centre for Cultures & Environments of Health, University of Exeter, Exeter, UK.
BMC Med. 2020 Nov 10;18(1):301. doi: 10.1186/s12916-020-01777-6.
The need for better methods for evaluation in health research has been widely recognised. The 'complexity turn' has drawn attention to the limitations of relying on causal inference from randomised controlled trials alone for understanding whether, and under which conditions, interventions in complex systems improve health services or the public health, and what mechanisms might link interventions and outcomes. We argue that case study research-currently denigrated as poor evidence-is an under-utilised resource for not only providing evidence about context and transferability, but also for helping strengthen causal inferences when pathways between intervention and effects are likely to be non-linear.
Case study research, as an overall approach, is based on in-depth explorations of complex phenomena in their natural, or real-life, settings. Empirical case studies typically enable dynamic understanding of complex challenges and provide evidence about causal mechanisms and the necessary and sufficient conditions (contexts) for intervention implementation and effects. This is essential evidence not just for researchers concerned about internal and external validity, but also research users in policy and practice who need to know what the likely effects of complex programmes or interventions will be in their settings. The health sciences have much to learn from scholarship on case study methodology in the social sciences. However, there are multiple challenges in fully exploiting the potential learning from case study research. First are misconceptions that case study research can only provide exploratory or descriptive evidence. Second, there is little consensus about what a case study is, and considerable diversity in how empirical case studies are conducted and reported. Finally, as case study researchers typically (and appropriately) focus on thick description (that captures contextual detail), it can be challenging to identify the key messages related to intervention evaluation from case study reports.
Whilst the diversity of published case studies in health services and public health research is rich and productive, we recommend further clarity and specific methodological guidance for those reporting case study research for evaluation audiences.
人们广泛认识到，在健康研究中需要更好的评估方法。“复杂性转向”引起了人们的关注，即仅依靠随机对照试验的因果推断来理解干预措施在复杂系统中是否以及在何种条件下改善卫生服务或公共卫生，以及哪些机制可能将干预措施与结果联系起来，存在一定的局限性。我们认为，案例研究——目前被贬低为证据不足——不仅是提供有关背景和可转移性证据的未充分利用的资源，而且对于帮助加强干预措施与效果之间的因果推断也很有价值，因为干预措施与效果之间的途径可能是非线性的。
作为一种整体方法，案例研究是基于对复杂现象在其自然或现实生活环境中的深入探索。实证案例研究通常能够动态地理解复杂的挑战，并提供有关因果机制以及干预实施和效果的必要和充分条件（背景）的证据。这不仅是关心内部和外部有效性的研究人员所需要的重要证据，也是政策和实践中的研究用户所需要的证据，他们需要知道复杂计划或干预措施在其环境中的可能效果。健康科学可以从社会科学中的案例研究方法学术中吸取很多经验。然而，充分利用案例研究的潜在学习还面临着诸多挑战。首先是误解，认为案例研究只能提供探索性或描述性证据。其次，对于什么是案例研究，以及如何进行和报告实证案例研究，缺乏共识，而且存在很大的差异。最后，由于案例研究人员通常（并且适当地）专注于详细描述（即捕捉上下文细节），因此从案例研究报告中识别与干预评估相关的关键信息可能具有挑战性。
尽管在卫生服务和公共卫生研究中发表的案例研究多样性丰富且富有成效，但我们建议为那些为评估受众报告案例研究的人提供进一步的明确性和具体的方法指导。
