Table 4 Selected considerations and challenges of conducting conflict-related health research in and on Syria as described in the literature, January 2011- December 2019

Conflict context and safety and security considerations

• impacting on accessibility [13, 14, 16, 22, 25, 33, 41, 70, 71].

• impacting selection of school study sites [60]

• impacting ground team composition and generating reliance on local staff [21, 47, 61)

• impacting ability to conduct research as planned, including delaying data collection [34]; requiring short data collection periods or terminating fieldwork earlier than planned [9, 68]; postponing fieldwork [85]; requiring timing and setting of interviews that were often not conducive to research [9]; and impacting data collection [17]

Ethical considerations due to the context

• Assuring anonymization of data and / or locations, including for data integrity and participant / facility security [25, 21]

• Not including community representatives and other stakeholders in the study due to ethical concerns regarding security, anonymity and any potential risks of coercion regarding aid and services [85]

• Study design considerations, including not using a control group in a clinical study of PTSD treatment in order to benefit as many as possible during wartime [56], and delivering a psychosocial intervention to the control group after completion of data collection [96]

Researcher identity and relationship to the context

• Wariness of researchers affiliated with western institutions [9, 68]

Participant recruitment, sample size

Conflict context impacting availability of research subjects:

• Conflict context potentially impacting willingness to participate [21, 53, 77, 80] and requiring informal approaches to participants through trusted colleagues [9, 68].

• Participant recruitment challenged by confidentiality and safety considerations, limited electricity / internet access and time constraints [77, 80]

• Limited availability of research participants in studies of /with health workers due to the need for extra emergency service provision during times of conflict [42] or due to facilities being closed or out of service [70]

• Practical and logistic difficulties due to war making it difficult to increase number or age range of participants in a clinical study [55]

• Few witnesses left, may be unwilling or unsafe to report what they have seen, or might not know how to report [16]

Study design

• No appropriate control group who are unexposed to war, preventing examination of associations of disease burden with war [41]

• Challenges evaluating the outcome of interventions in conflict settings [21, 34]

• Sampling frame considerations due to limited population data and ongoing population displacement [33]

Data collection

• Need for data collection to be conducted remotely [17, 80]; conducting interviews remotely may impact rapport, non-verbal cues; generates additional ethical considerations of using third-party software [77]

• Lack of / limited follow-up including due to accessibility and safety [43, 73]

• Disruption / breakdown of health surveillance and data infrastructures [23, 54]

Potential research biases

• Potential for social desirability and cultural familiarity biases when interviewers are diaspora / refugees from same context [80]

• Potential for recall and reporting biases, including possible over-reporting among survey respondents if perceived that responses might influence access to aid and services [79] [94], possible under-reporting or lack of willingness to speak openly including due to fear and security considerations [22, 41, 50, 51, 94]

• Potential reporting biases in studies of attacks on healthcare e.g. attacks on larger facilities may be reported more than those on smaller ones if there is less impact or fewer staff witness it; political agendas of witnesses and those reporting on attacks might influence reporting; restricted access to verify reports [35, 52, 67]

• Potential survival bias in retrospective mortality surveys e.g. if all members of a household were killed, will not be captured in household level surveys where participants asked about household deaths [94]

• Selection and respondent biases impacting representativeness; limited generalizability due to restricted geographic access and because not all governorates impacted by war to the same extent and in the same way [27, 33, 48, 49]

• Potential for data collection and categorization to be biased by motivations of researchers, political or advocacy groups [51]

Data availability and quality

• Missing data and limited data availability [20, 28, 74]

• Impact on data quality and availability due to patient care taking precedence over documentation during crisis [89]

• Difficulties of ascertaining casualty counts in an active conflict [90]

• Extracting additional data on war injuries limited as names were deleted from paper medical records for security reasons [74]

• Difficulties with outcome measurement and follow up data, including inability to return for follow up because of security issues, inability to follow up by phone because of disrupted phone network [19]

• Difficulties ascertaining response rate due to inability to contact participants directly, reliance on third party [24]

• Absence of / difficulties with establishing population denominator [32, 38, 57, 61]

• Inability to validate authenticity of data collected from online video sources [11]

Ethics / Institutional Review Board processes

• Lack of formal local ethics committees and governance processes [59, 61, 80]

• Concerns with obtaining written consent related to anonymity and potential risks associated with participation [61]

Permissions and permits

• Need to secure specific travel permissions for local participants to attend workshops outside Syria [85]

• Permission to conduct assessments sought from community leaders as needed [13, 14, 33, 34, 48]

Local contextual factors

• High turnover of staff including in government departments meant limited engagement and inability to effectively translate research findings into policy and practice [9]

• Conflict impacting availability of research funding [53]