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Table 1 Common limitations of randomized controlled trials and whether they can be amended by routinely collected health data

From: Routinely collected data for randomized trials: promises, barriers, and implications

Limitations of RCTs [10] What using RCD for RCTs can offer Challenges Potential of RCD to improve RCTs
Generalizability and real-world relevance No specific data collection processes (follow-up visits, measurements) outside routine care, avoiding artificial situations Random allocation of interventions may still require some deviation from routine care processes (e.g., obtaining informed consent). Very high
Costs and resources No costs to the trial for data collection processes and related activities (study site setup, study staff salary, monitoring and auditing activities, training costs) Potential costs for obtaining the RCD (if the collecting entity does not provide it for free; e.g., data brokers); additional costs for data management, processing, merging, cleaning, and so forth Very high
Specific conditions/subgroup effects Larger sample sizes that are less influenced by resource constraints and feasibility issues may provide sufficient power for evaluating subgroups. More opportunities for exploratory analyses with spurious findings High
Late outcomes RCD can provide long-term outcome data without actively following patients and often reducing the number of patients lost to follow-up Patients moving away from RCD infrastructure will be lost and may still require active contact, highly dependent on RCD infrastructure High
Speed No cumbersome outcome ascertainment (follow-up contacts, data recording and collection) and no need for setting up the data collection infrastructure, thus results can be obtained faster Management, processing, merging, and “cleaning” of large datasets may be time-consuming. Reporting of specific adverse events may be delayed. High to moderate
Conflicts of interest/sponsorship bias Collection of RCD is more objective and less easily manipulated to obtain a desired result. Data may still be analyzed and reported nonobjectively to convey preferred conclusions. Moderate
Understudied healthcare questions Providing information on routine care allows researchers to address understudied healthcare questions because more resources are spared or different outcomes are collected. Not all desired endpoints might be available; funding may not be the sole barrier Moderate
Regulations Obtaining approval for intervention imposes several bureaucratic loopholes; RCD are already available and might require different ethical clearance. RCD still require approval in terms of data protection and confidentiality. Moderate
Rare or uncommon conditions Recruiting an appropriate sample size may be hard with rare diseases; larger samples with RCD and easier EHR or registry recruitment can reduce these difficulties. Only possible if RCD resources are extensive, highly dependent on RCD infrastructure Moderate
  1. Abbreviations: EHR Electronic health record, RCD Routinely collected health data, RCT Randomized controlled trial