Over the last decade, patient-reported outcomes (PROs) have gained importance across healthcare and life sciences:

  • Patient-centred care models are integrating PROs into shared decision-making.
  • Comparative effectiveness research and HTA processes aim to include patients as active stakeholders.
  • Industry increasingly collaborates with patients and advocacy groups during medicine development and safety monitoring.
  • Regulatory frameworks (e.g., EU and US pharmacovigilance legislation) require inclusion of patient-reported information in benefit–risk assessments of pharmaceutical products.

To support these efforts, greater attention has been paid to developing PROs, which capture a patient’s direct perspective on their disease and its treatment.

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According to the European Medicines Agency (EMA), a PRO is:
"Any outcome evaluated directly by the patient and based on the patient’s perception of a disease and its treatment(s)."

The term PRO is used as an umbrella to cover both single- and multi-dimensional measures of:

To collect data on these outcomes, tools known as patient-reported outcome measures (PROMs) are used. The term PROs is becoming increasingly synonymous with "patient reported outcome measures" (PROMs).

 

Why are patient-reported outcomes important?

Patient-reported outcomes (PROs) are important because they provide direct insight into how patients perceive the effects of a disease or treatment—perspectives that may not be captured by traditional clinical measures. These outcomes are essential because they can significantly influence a patient's experience and adherence to treatment, even when clinical indicators appear unchanged.

Clinical Measurements vs. Patient Experience

Consider a patient diagnosed with chronic obstructive pulmonary disease (COPD). A review of clinical studies might conclude:

"Tiotropium reduced the number of participants experiencing one or more exacerbations compared with long-acting beta agonists (OR 0.86; 95% CI 0.79 to 0.93)… There was no statistically significant difference in FEV₁ or symptom score between groups."

What do these findings say about how the patient felt about the new treatment? What about how they were able to perform their daily activities? Further understanding about what these outcomes mean for the patient is needed.

For example: 

❓Is an exacerbation something that leads to hospitalisation? Or is it a coughing spell that can be self-managed at home?

❓Is the laboratory test FEV₁ something that directly measures how patients function in different areas of their daily lives?

❓Does the symptom score capture how the patient felt or is it an ‘objective’ measure of symptoms?

Such questions illustrate the limitations of relying solely on clinical endpoints. 

The Value of PROs

PROs offer insight into:

  • How patients feel and function in daily life
  • Individual perceptions of disease burden, treatment side effects, and overall satisfaction (Patients with identical diagnoses may have very different views of their condition, shaped by their coping capacity, values, and social circumstances.)
  • Well-being-focused outcomes, especially relevant when the goal of care is quality of life—not the prolonging life or reducing disease events (For example, patients diagnosed with a chronic disease that is not immediately life-threatening may be most concerned with their ability to work and live a fulfilling life. A patient with a terminal illness may be more concerned on reducing their pain or on their ability to live longer without major discomfort or suffering.)
When PROs Are Especially Important

PROs are crucial in clinical contexts where:

  • Observable patient-important outcomes are rare or unavailable (PRO assessments can be a primary or a secondary end point in determining treatment efficacy[1]).
  • No clear biomarkers or lab results can capture patient experience (In some cases, a PRO may be the only feasible end point because there are no markers of disease or treatment activity measurable by a clinician, observer, or laboratory.)

    For example, they may provide the only reasonable strategy for evaluating treatment impact of certain conditions such as pain syndromes, fatigue, disorders like irritable bowel syndrome, sexual dysfunction, and emotional function. PRO instruments are also used to measure adverse events[2] such as nausea and anxiety. This is well established in the field of oncology, where PROs have been used for adverse event reporting with a high degree of patient engagement and compliance (source).

  • The primary treatment goal is symptom relief or improved daily functioning (PROs enhance the efficiency and patient-centeredness of clinical documentation and facilitate individualized patient care, a key goal of precision medicine.)

[1] The FDA states that if a PRO is being used as a primary or secondary endpoint, its role and the instrument being used to measure it must be clearly defined in the research protocol, with evidence of the PROM instrument’s usefulness from the target population of patients. The CONSORT PRO extension highlights five checklist items recommended for trials in which PROs are primary or important secondary endpoints. An update to the SPIRIT statement (Standard Protocol Items: Recommendations for Interventional Trials), the SPIRIT-PRO Extension provides 16 PRO-specific items for inclusion in clinical trial protocols.

[2] The Patient-Reported Outcomes Safety Event Reporting (PROSPER) Consortium developed guidance for the use of PROs in safety reporting, which outlines definitions and suitable taxonomies, the range of datasets that could be used, data collection mechanisms, and analytic methods