BACKGROUND Previous reviews have suggested that infrastructural interventions can be effective in promoting cycling. Given inherent methodological complexities in the evaluation of such changes, it is important to understand whether study results obtained depend on the study design and methods used, and to describe the implications of the methods used for causality. The aims of this systematic review were to summarize the effects obtained in studies that used a wide range of study designs to assess the effects of infrastructural interventions on cycling and physical activity, and whether the effects varied by study design, data collection methods, or statistical approaches. METHODS Six databases were searched for studies that evaluated infrastructural interventions to promote cycling in adult populations, such as the opening of cycling lanes, or the expansion of a city-wide cycling network. Controlled and uncontrolled studies that presented data before and after the intervention were included. No language or date restrictions were applied. Data was extracted for any outcome presented (e.g. bikes counted on the new infrastructure, making a bike trip, cycling frequency, cycling duration), and for any purpose of cycling (e.g. total cycling, recreational cycling, cycling for commuting). Data for physical activity outcomes and equity effects was extracted, and quality assessment was conducted following previous methodologies and the UK Medical Research Council guidance on natural experiments. The PROGRESS-Plus framework was used to describe the impact on subgroups of the population. Studies were categorized by outcome, i.e. changes in cycling behavior, or usage of the cycling infrastructure. The relative change was calculated to derive a common outcome across various metrics and cycling purposes. The median relative change was presented to evaluate whether effects differed by methodological aspects. RESULTS The review included 31 studies and all were conducted within urban areas in high-income countries. Most of the evaluations found changes in favor of the intervention, showing that the number of cyclists using the facilities increased (median relative change compared to baseline: 62%; range: 4 to 438%), and to a lesser extent that cycling behavior increased (median relative change compared to baseline: 22%; range: - 21 to 262%). Studies that tested for statistical significance and studies that used subjective measurement methods (such as surveys and direct observations of cyclists) found larger changes than those that did not perform statistical tests, and those that used objective measurement methods (such as GPS and accelerometers, and automatic counting stations). Seven studies provided information on changes of physical activity behaviors, and findings were mixed. Three studies tested for equity effects following the opening of cycling infrastructure. CONCLUSIONS Study findings of natural experiments evaluating infrastructural interventions to promote cycling depended on the methods used and the approach to analysis. Studies measuring cycling behavior were more likely to assess actual behavioral change that is most relevant for population health, as compared to studies that measured the use of cycling infrastructure. Triangulation of methods is warranted to overcome potential issues that one may encounter when evaluating environmental changes within the built environment. TRIAL REGISTRATION The protocol of this study was registered at PROSPERO (CRD42018091079).

中文翻译：

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对基础设施干预促进自行车运动的影响的系统评价：加强观察数据的因果推论。

背景 以前的评论表明，基础设施干预可以有效促进自行车运动。鉴于评估此类变化的内在方法学复杂性，重要的是要了解获得的研究结果是否取决于所使用的研究设计和方法，并描述用于因果关系的方法的含义。本系统评价的目的是总结研究中获得的效果，这些研究使用广泛的研究设计来评估基础设施干预对骑自行车和身体活动的影响，以及这些影响是否因研究设计、数据收集方法或统计而异方法。方法 在六个数据库中搜索评估基础设施干预措施以促进成年人骑自行车的研究，例如开放自行车道，或扩大全市自行车网络。包括提供干预前后数据的对照和非对照研究。没有应用语言或日期限制。提取的数据用于呈现的任何结果（例如，新基础设施上的自行车数量、骑自行车旅行、骑自行车的频率、骑自行车的持续时间）和任何骑自行车的目的（例如，总骑自行车、休闲骑自行车、骑自行车通勤）。提取了身体活动结果和公平效应的数据，并按照以前的方法和英国医学研究委员会对自然实验的指导进行了质量评估。PROGRESS-Plus 框架用于描述对人口亚群的影响。研究按结果分类，即骑车行为的变化，或使用自行车基础设施。计算相对变化是为了得出跨各种指标和循环目的的共同结果。提出中位数相对变化以评估效果是否因方法学方面而异。结果 该评价包括 31 项研究，所有研究均在高收入国家的城市地区进行。大多数评估发现有利于干预的变化，表明使用这些设施的骑自行车者的数量增加了（与基线相比的中值相对变化：62%；范围：4 至 438%），并且在较小程度上增加了骑自行车的行为（与基线相比的中值相对变化：22%；范围：- 21 至 262%）。测试统计显着性的研究和使用主观测量方法（例如调查和直接观察骑自行车者）的研究发现比没有进行统计测试的研究和使用客观测量方法（例如 GPS 和加速度计，以及自动计数站）。七项研究提供了有关身体活动行为变化的信息，结果喜忧参半。三项研究测试了自行车基础设施开放后的公平效应。结论 评估基础设施干预以促进自行车运动的自然实验的研究结果取决于所使用的方法和分析方法。测量骑车行为的研究更有可能评估与人口健康最相关的实际行为变化，与测量自行车基础设施使用情况的研究相比。有必要对方法进行三角测量，以克服在评估建筑环境内的环境变化时可能遇到的潜在问题。试用注册 本研究的方案已在 PROSPERO (CRD42018091079) 注册。