What is eCOA and How Does it Improve Clinical Trial Data Quality?

Chris Watson, PhD |

What is eCOA?

Electronic Clinical Outcome Assessment (eCOA) is a method of capturing data electronically in clinical trials. It can substantially increase the quality of study data while meeting regulatory requirements. But before we dig into specifically how it does that, let’s review some terms commonly referred to when discussing eCOA:

  • Patient diary: Tool used to collect subjective data from a patient, including symptoms, condition and other measures; traditionally, this has been paper-based
  • Electronic patient diary (eDiary): Electronically registers patient data and automates data entries on, for example, a handheld mobile device, tablet or computer
  • Clinical outcome assessment (COA): Measurement used to evaluate patient safety and quality of life; COA measures include:
    • Patient-reported outcome (PRO): Health outcome reported directly by the patient
    • Performance outcome (PerfO): Measurement based on task(s) performed by a patient according to instructions administered by a healthcare professional; medical devices can be integrated to collect and record objective measures such as motor, sensory and cognition
    • Clinician-reported outcome (ClinRo): Using their clinical judgement, physicians, nurses or other site staff report patient health outcomes after observing the participant’s health condition
    • Observer- or caregiver-reported outcomes (ObsRo): Health outcomes reported by the patient’s family or other caregiver
  • Electronic clinical outcome assessment (eCOA): Employs technology such as handheld devices, tablets or web to allow patients, clinicians and caregivers to directly report outcomes, resulting in more granular endpoint data. eCOA measures include ePRO, ePerfO, eClinRO and eObsRO.

Read on to learn exactly how eCOA improves data quality – or click here to watch a brief video to see a brief video on the benefits of eCOA data capture in clinical trials.

How Does eCOA Improve Data Quality?

A growing majority of clinical trial stakeholders including sponsors, CROs and regulators consider eCOA as the most effective way to capture high-quality and more reliable data than traditional, paper-based methods. Here’s how eCOA does this:

Patient protocol compliance increases with eCOA

  • eCOA increases patient protocol compliance 

Patients using ePRO demonstrate significantly higher protocol compliance — as high as 94% compared to 11% with paper1 (Figure1). Through the use of electronic reminders/alerts, animated compliance feedback and dynamic, context-sensitive messaging, only ePRO captures data in real-time, delivering accurate, reliable information on patients’ experiences during a trial.

Figure 1: Patient protocol compliance increases with eCOA

  • eCOA prevents inconsistent or conflicting data

Electronic data collection uses branching and logic sequences to guide patients through the appropriate questionnaire in the order established by the study protocol. Patients – or sites/observers ─ are prevented from skipping questions or entering inconsistent or conflicting data, if applicable.

  • eCOA eliminates transcription errors

Paper diary studies require site personnel to manually transcribe data into the trial management system, leaving greater opportunity for errors and other inconsistencies. By capturing eCOA data with eDiaries, those steps are automated, which eliminates transcription errors. Any inconsistencies, missing data and other data quality issues are also detected in real-time at data capture.

  • eCOA meets global regulatory standards

Regulatory bodies recommend that the COA data collection method ensures data are collected and reported according to protocol requirements. Unlike paper diaries, eCOA data meet regulatory quality guidelines, meaning they are Attributable, Legible, Contemporaneous, Original and Accurate (ALCOA). By meeting these fundamental elements of quality, regulators’ queries regarding the capture of eCOA data via are virtually eliminated.

Regardless of their size, sponsors and CROs who continue to rely on outdated, error-prone paper diaries for capturing important patient reported outcomes data may be injecting unnecessary risks into their clinical trials. But, those who turn to eDiaries for eCOA data capture benefit from improved data quality, regulatory compliance and accelerated clinical development.


Click here for part 2 of this series, which presents some of the other ways sponsors and CROs benefit from capturing COA data electronically in clinical trials – some of which you may have never considered!


1 . Stone, A. A., Shiffman, S., Schwartz, J.E., Broderick, J.E., Hufford, M.R. (2002). Patient non-compliance with paper diaries. British Medical Journal, 324, 1193 – 1194.

Chris Watson, PhD, is the Director of Product Strategy, Digital Patient at ERT.