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Patient-reported outcomes are more than just statistical measures

Patient-reported outcome measures (PROMs) estimate the effectiveness of healthcare delivered to patients as perceived by the patients themselves. 

PROMs are typically short, self-completed questionnaires, which measure the patient's health status or health-related quality of life at a single point in time.  The information collected from patients by way of PROMs questionnaires before and after an intervention provides an indication of the outcomes or quality of care delivered to NHS patients. Changes in health status as measured by PROMs, controlling for variation in patient characteristics and the influence of other factors, can be attributed to the healthcare delivered.

From 1 April 2009, all providers of NHS-funded care have been required to collect PROMs for four common surgical procedures: hip and knee replacement, inguinal hernia repair and varicose vein surgery.  The NHS Information Centre has recently released the first analysis of national (England) data for 2009-10 on these pre- and post-operative PROMs.1

The recent Government White Paper, ‘Equity and excellence: Liberating the NHS',2 envisages an increase in the scope and coverage of PROMs in future, starting from April 2011.

'Information generated by patients themselves will be critica,' it reads. 'And will include much wider use of effective tools like PROMs, patient experience data, and real-time feedback.'

'The Department will extend national clinical audit to support clinicians across a much wider range of treatments and conditions, and it will extend PROMs across the NHS wherever practicable'. 

For providers, PROMs will provide important data for quality improvement, in the form of comparative, casemix-adjusted pre- to post-operative changes in scores. But how can they be used for commissioning?

For the national PROMs programme, all patients complete the EQ-5D questionnaire and the EQ-5D Visual Analogue Scale (VAS), which are measures of generic or overall health-related quality of life (HRQoL).3  Questionnaire responses can be converted into a single summary index, the EQ-5D index score. The EQ-VAS involves respondents assigning themselves a score between 0 and 100 to convey how good or bad their own health is on the day that they complete the questionnaire.

The PROMs programme also includes disease-specific measures.  For hip and knee replacements the Oxford Hip Scores and Oxford Knee Scores (joint-specific outcome measure tools) are used.4  Scores for each of the 12 questions are added together to provide a single score, with zero indicating the worst possible and 48 indicating the best possible score.  For varicose veins, the Aberdeen Varicose Veins Questionnaire (AVVQ) has been used. The questionnaire is scored from 0 to 100, where 0 represents a patient with no problems associated with varicose veins, and 100 represents the most severe problems associated with varicose veins.5  There is no disease-specific measure for hernia.

The first year's data

Figure 1 shows the percentage of patients with either no increase (no change or a decrease) in PROMs scores post-operatively from the national data.  Relatively few patients show no improvement in disease specific-scores, while a much greater proportion show no improvement in EQ5D Index or VAS scores, i.e. overall health-related quality of life.  This is to be expected, as global scores such as the EQ5D measure a much wider range of health-related quality of life.

 What type of PROM- generic or disease-specific- is used to measure the impact of surgery is likely to be extensively debated.  Using a global measure such as the EQ5D will result in the cost per quality-adjusted life year (QALY) of an intervention being much higher.  For example, a Scandinavian study showed that the benefit (measured by change in HRQoL) of routine cataract surgery was small and confined mainly to an improvement in seeing only. On the other hand, surgeons argue that there are other good reasons for intervening early.  And whichever disease-specific measure is chosen, a global measure is still needed to compare benefits across procedures.


Using PROMs for commissioning

PROMs might be used to identify procedures with little benefit, or subgroups of patients who do not benefit greatly from surgery.   This could allow more effective targeting of resources to improve health gain.  In future GPs will be at the forefront in commissioning these procedures.  So how could they predict which patients are less likely to benefit?  For some interventions, including hip replacement, postoperative improvement is highly correlated with preoperative PROM diseaseseverity. This is shown by data from the earlier English hip replacement audit in Figure 2.Basic analyses of 2009-10 PROMs data has now been published by NHS Networks, along with a simple spreadsheet tool containing local data.7

Similar analyses of the new national PROMs data are needed. If the audit findings are confirmed, we could state that as preoperative severity decreases the benefits will be smaller, and eventually outweighed by the risks, and the cost-per-quality adjusted life year (QALY) higher. Conversely, at higher levels of preoperative severity, postoperative improvement may reach a plateau. A plot of preoperative severity against cost per QALY would then be U-shaped. Commissioners could agree intervention thresholds in the middle of this range, with a cost per QALY comparable with other NHS funded interventions. The data currently available does not yet include cost-effectiveness information, so is still of limited use.

We know that access to elective care is inequitable.8,9  Using PROMs as part of an intervention threshold in guideline format could improve both equity and efficiency of resource allocation. Needs assessment and commissioning will reduce inequity only if they change clinical care, highlighting the need for commissioners and providers to agree on appropriate thresholds for intervention.


  • National 2009-10 data on four surgical patient-reported outcome measures (PROMs) is now available
  • The White Paper Liberating the NHS envisages a major increase in the scope and coverage of PROMs
  • Post-operative improvement in PROMs scores is greater for disease-specific than overall quality of life measures
  • Commissioners could use pre-operative scores to predict improvement - that is, who is likely to benefit most from surgery

Dr Michael Soljak is a postgraduate researcher at the Department of Primary Care and Public Health, Imperial College London.

Additional author: Professor Azeem Majeed, Professor of Primary Care


1. Health and Social Care Information Centre. Patient Reported Outcomes Measures (PROMs) Summary. Information Centre website 2010  URL:


2. Department of Health. White Paper: Equity and excellence- Liberating the NHS. Department of Health website 2010  URL:


3. EuroQoL Group. EQ-5D: a standardised instrument for use as a measure of health outcome. EuroQoL Group  2009 URL:


4. Murray DW, Fitzpatrick R, Rogers K, Pandit H, Beard DJ, Carr AJ et al. The use of the Oxford hip and knee scores. J Bone Joint Surg Br 2007; 89-B(8):1010-1014.


5. Smith JJ, Garratt AM, Guest M, Greenhalgh RM, Davies AH. Evaluating and improving health-related quality of life in patients with varicose veins. J Vasc Surg 1999; 30(4):710-719.


6. Hajat S,Fitzpatrick R, Morris R, Reeves B, Rigge M, Williams O, Murray D, Gregg P. Does waiting for total hip replacement matter? Prospective cohort study. J Health Serv Res Policy 2002; 7(1), 19-25.


7. Health Investment Network. Patient Reported Outcome Measures (PROMs) for commissioners published NHS Networks, 2011.


8. Judge A, Welton NJ, Sandhu J, Ben-Shlomo Y. Equity in access to total joint replacement of the hip and knee in England: cross sectional study.  BMJ2010; 341: c4092.


9. Soljak M, Browne J, Lewsey J, Black N. Is there an association between deprivation and pre-operative disease severity? A cross-sectional study of patient-reported health status.  Int J Qual Health Care 2009; 21(5):311-315.