Patient Reported Outcome Measures (PROMs)

There are lots of ‘scores’ used in the medical world, like the well known Glasgow Coma scale (GCS) to assess patient’s level of consciousness. Fundamentally, these provide a numeric value to a complex situation, to ease record keeping and evaluate the progress against a baseline. this also provides a common language that all healthcare providers understand, which makes the transfer of information easier.

There are three types of scores – objective, subjective and mixed.

1. Objective scores are obtained by the healthcare provider based on a set of observations or criteria. GCS ( ), National early warning score, or NEWS ( ) fall in this category and are very useful in emergency situations when the patient is unable to provide much information and therefore one must rely on clinical findings.

2. Subjective: In elective setting, the patient is conscious and able to identify the symptoms that are more troublesome than others. This is the basis of patient reported outcome measures (PROMs –, where patients rate their own condition based on a validated questionnaire, rather than a doctor rating their function on objective, surgeon defined criteria. Various scores like the visual analogue scale (VAS), Oxford Hip and knee scores, and EQ – 5D ( ) fall in this category.

3. Mixed scores are a combination of patient ratings and doctor’s observed clinical findings, like the Harris Hip score, Constant Shoulder score or the Knee society score ( ).

Each system has its pros and cons. Historically, the doctors used to report their outcomes based on clinical findings like the radiological alignment of prosthesis, range of movements in the joint etc. However, for elective procedures like the TKR or THR, it has the disadvantage of observer bias, and therefore it sometimes resulted in a paradox where a result deemed good by the doctor based on findings was not always reflected in the level of patient satisfaction.

Ultimately, a procedure is only as good as the relief in symptoms experienced by the patients. Therefore, now PROMs have come to be accepted as the standard in terms of reporting outcomes of the procedures. It empowers the patients to quantify their own symptoms and provides the healthcare provider with a tool to compare the status of patients before and after any intervention.

However, it is not free of pitfalls either. Pain is a complex sensation that is still not fully understood because it involves both peripheral neurological system and the central nervous system including psychology. How we perceive pain can be determined by a number of factors – the physical problem (for example, arthritis), contributing medical factors (eg neuropathy), family or social circumstances (stress), psychological status, medication etc. It is impossible to standardise these external circumstances that can affect pain perception, and there is always some possibility of reporting bias. However, numerous studies have refined the statistical validation of PROMs, such that it is now considered a more reliable tool compared to all other types of scores. In the UK, National joint registry ( has been collecting PROMs for a number of years, and this information can be used to identify poorly performing implants.

Secondly, there are significant cultural differences across the world, and a system developed in one part cannot be extrapolated to populations in another part. For example, while cross leg sitting is non existent in the western world (where majority of these scores are developed), it is an integral part of Asian culture and will weigh heavily when patients in this part of the world rate their function.

In summary, while the PROMs is not foolproof, it is currently accepted as a standard reporting tool to measure the outcome of a procedure. It is important to customise scores to local needs and culture. It may well determine how surgical procedures are funded by the insurance companies or governments in the future.

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