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Patient Reported Outcome Measures (PROMs) in England: Special Topic: Rates of Attrition 2013-14

Publication date: 09:30 May 12, 2016


Patient Reported Outcome Measures (PROMs) have been collected for four conditions since 2009/10; varicose vein procedures, groin hernia procedures and hip and knee replacement operations. Patients undergoing PROMs-eligible procedures are asked to complete a questionnaire before treatment and again three to six months after treatment.

To become a complete PROMs measurement that can be used to compare performance across organisations, a number of different requirements must be met. The patient must have the operation and complete both a pre-operative (Q1) and a post-operative (Q2) questionnaire. The data quality must also be sufficient so that the measures used, such as the Oxford Hip Score are complete and the patient's identifying information must be complete enough to link the questionnaire data with the operation data sourced from their Hospital Episodes Statistics (HES) dataset. Where all of these conditions are met, the record is eligible for casemix adjustment which allows direct comparison to other records. This is referred to as a modelled record.

The reduction in the number of useable records at each stage is known as attrition. This topic shows the numbers at each stage of the process, beginning with number of eligible episodes through to the final number of modelled records, explaining why the number of records reduces at each stage.

This topic is based on 2013/14 data, the latest year of finalised data at the time of publication.

Key Facts

Rate of Attrition: Percentage of participants at each stage during PROMs process 2013/14


• The highest rate of attrition can be seen in varicose vein procedures, with only around 20 per cent of episodes becoming modelled records. The lowest rate of attrition appears in the hip and knee replacements with 53 per cent and 52 per cent of episodes becoming modelled records.


• The single largest impact on attrition is the proportion of patients who elect to participate in PROMs (the participation rate) before their operation. The highest participation is for knee and hip replacements of around 94 per cent and 86 per cent respectively, with groin hernia at 60 per cent and varicose vein trailing at 40 per cent.


• After participation, the post-operative response rate (the proportion of patients who complete and return their post-operative questionnaire) has the largest effect on attrition. The response rate follows a similar pattern to the pre-operative participation rate with hip (around 78.5 per cent) and knee replacement (around 76.5 per cent) patients more likely to return their questionnaire than groin hernia (around 65.5 per cent) and varicose vein at 55 per cent.


• There is significant variation in attrition between providers. Taking hip replacements as an example, the proportion of episodes that can be included in the final analysis ranges from around 85 per cent to as low as 10 per cent.


Date Range: 01 April 2013 to 31 March 2014
Geographical coverage: England
Geographical granularity: NHS Trusts, Hospital Trusts, County, Independent Sector Health Care Providers, Clinical Commissioning Groups

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