Patient-Reported Outcomes

3. Reasons to Measure PROs

There are several important features of self reported measures in medicine and public health:

  • They are used increasingly to help determine whether treatments are doing more good than harm;
  • These outcomes are assessed and often compared to clinical measurements that remain the primary end-points for most clinical trials and for many clinicians, because they are familiar through long or repeated use; and
  • Epidemiological investigations and population surveys incorporate self-reported outcomes to compare populations and to describe the status of different populations.  Sometimes these are called quality of life indicators, although more frequently the term health status indicators best describes the content of these measures.

Difference Between Clinical Measures and Self-Report Measures

Clinical measures include physiologic measures that require professional knowledge to interpret and clinician judgments that come from interviews and observations of patients.

Self-report measures of health and quality of life often have more meaning to the persons who are affected by disease, are undergoing treatments, or are trying to restore or maintain health.

Because perceptions of health and illness influence what people do about their health (e.g. visit doctors, go to a hospital, or ignore signs and symptoms), policy makers are also increasingly interested in self-reported outcomes.

Self-reported measures diff from clinical measures in three important ways.

  1. Self-report measures often correlate poorly with physiologic measures.
    Example: Exercise capacity in the laboratory is only weakly related to exercise capacity in daily life (Guyatt et al., 1985).
  2. Another common disconnect is the observation that two patients with the same clinical status or physiologic state may have dramatically different responses to the condition.
    Example: It is not uncommon for two patients experiencing back pain with the same range of motion and even similar ratings of back pain to have different abilities to work and different responses to pain. One patient with back pain may stay home from work, while another with the same pain rating goes snow skiing. In patients with major depression, depending on individual and environmental factors, some patients may continue to work and take care of their families, while others quit their jobs and stay at home.
  3. Perhaps most importantly, assumptions by clinicians and investigators that physiologic outcomes predict those outcomes that are important measures of benefit often turns out to be incorrect (Kunz et al., 2008).
Kunz R., Bucher H.C., Cook D., Holbrook A., Guyatt G. (2008) Users' Guide to the Medical Literature.In: G. Guyatt, D. Rennie, M. Meade, D. Cook. (Eds) New York: McGraw-Hill.