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Quality and Outcomes Framework

Information for Users of QOF Register and Prevalence Data

NHS National Services Scotland ISD Scotland & NHS National Services Scotland

Information for Users of QOF Register and Prevalence Data

QOF register data and "prevalence" rates are increasingly sought by a variety of people as a source of information on the level of different types of health problems in the population. This page provides further information on register and prevalence information from the QOF, including warnings to bear in mind when using the data.

Overview
Use of QOF prevalence data in QOF payments calculations
Warnings about the use of QOF register and prevalence figures for other purposes
National QOF prevalence estimates for Scotland - Table and commentary
Further information and interpretation on individual QOF registers

Overview

Prevalence is a measure of the frequency of a disease or health condition in a population at a particular point in time (and is different to incidence, which is a measure of the number of newly diagnosed cases within a particular time period).

Prevalence data within the QOF are collected in the form of practice "registers". A QOF register may count patients with one specific disease or condition, or it may include multiple conditions. There may also be other criteria for inclusion on a QOF register, such as age or date of diagnosis.

A QOF-reported prevalence rate for a practice is simply the total number of patients on the register, expressed as a proportion or percentage of the total number of patients registered with the practice. QOF prevalence rates are crude because they are not adjusted to account for patient age distribution or other factors that may differ between general practices. Furthermore, although registers may be restricted (e.g. to only include patients over a specified age) the QOF prevalence rate is based on the total number of persons registered with the practice (the practice list size) at one point in time.

Use of QOF prevalence data in QOF payments calculations

Prevalence data are used within the QOF to calculate practice payments within each of the clinical indicator groups. Specifically:

  • Points can only be awarded to a practice for a given clinical indicator group (for example, asthma) if the practice can produce a register of patients with that condition or group of conditions.
  • The number of pounds per point in each clinical domain area is adjusted up or down according to each practice's prevalence rate for the relevant QOF register, relative to the estimated national prevalence rate from the same register.

What follows is a brief summary on the use of prevalence data in QOF calculations. Further details can be found in the Scottish Government's General Medical Services Statement of Financial Entitlements documents, linked to from our QOF home page (the document is updated each year to reflect updates to the QOF and/or payment rules).

The aim of the prevalence adjustments in each of the clinical indicator groups is to deliver a more equitable distribution of payments in the light of different workloads that practices face in achieving the same number of points. Practices with a high prevalence of a specific condition or group of conditions will receive more pounds per point for the relevant indicator group than practices with a low prevalence of the same condition or group of conditions. However, for years up to and including 2009/10 the calculations were set such that even practices with very low prevalence from a given register still received a minimum payment for providing appropriate services for it. This minimum payment was based on a 5% cut-off being applied at the bottom of the prevalence range and any practice with prevalence below this was treated as having the same prevalence as the cut-off point. From 2010/11 practices are paid on actual prevalence, therefore this adjustment is no longer applied.

During calculation of QOF payments, the baseline number of pounds per point (£135.06 in 2015/16) is adjusted up or down within each clinical domain area according to each practice's prevalence for that disease or condition, relative to the estimated national prevalence (see below). The amount by which the pounds are adjusted up or down is known as the Adjusted Disease Prevalence Factor (ADPF). For example, if a practice has an ADPF of 1.20 then the adjusted pounds per point for asthma = £135.06 x 1.20 = £162.07.

The calculation of the ADPF uses, but is not based purely on, the practice's raw disease prevalence for a given condition. The raw disease prevalence for each practice is calculated by dividing the number of patients on the relevant disease register by the number of patients the practice has on its registered list. The prevalence data published here are shown as rates per 100 patients. For example:

A practice has 104 patients on its asthma disease register
Its total list size at 1st January 2016 was 2000
The raw prevalence estimate (per 100 patients) equals:
(104 / 2000) x 100 = 5.2

From 2004/05 to 2008/09, an adjustment was made to the prevalence of clinical indicators within a practice so that practices with a low prevalence would still receive remuneration associated with the costs of keeping a register and the collection of relevant QOF data. However, since this adjustment narrowed the range of prevalence that payment was made on, it also penalised practices with a high prevalence. Therefore for 2009/10 this adjustment was removed. The removal of this adjustment means that payment is now based on a practice's actual reported prevalence rate rather than a version transformed by taking its square root.

A practice's ADPF for each group of clinical indicators is calculated by comparing that practice's prevalence rate from each register with a national estimate. The national QOF prevalence estimate used in payment calculations is based on prevalence data recorded in the QOF payment calculation system (QMAS or QOF Calculator) on a date referred to in QOF as "National Prevalence Day". For each of the financial years 2004/05 to 2007/08 inclusive, National Prevalence Day was 14th February. From 2008/09 onwards National Prevalence Day was changed to 31st March. The change in date means that prevalence data now relate to the same date as the rest of the QOF data, whereas previously (for payment reasons) they were reported earlier. Practices that could not or did not provide prevalence data for National Prevalence Day (e.g. because their clinical IT systems could not be connected into the QOF payment calculation system at the time) were not included in the National Prevalence Day estimates.

A fuller explanation of the method used to calculate ADPFs can be found in the Scottish Government's General Medical Services Statement of Financial Entitlements documents, linked to from our QOF home page (the document is updated each year to reflect updates to the QOF and/or payment rules).

Warnings about the use of QOF prevalence figures for other purposes

Data on the prevalence of specific diseases or health conditions are an important element of the QOF. They can potentially be used to examine variations in the prevalence of the individual diseases and health conditions covered by the QOF, but they should be interpreted with caution. The main general points to note are listed below. Further notes about individual registers are given in the later section Further information and interpretation on individual QOF registers.

  • QOF prevalence rates are what is known as "raw" or "crude" rates - which means that they take no account of differences between practice populations in terms of their age or gender profiles, or other factors that influence the prevalence of health conditions. A QOF prevalence rate is simply the total number of patients on the register, expressed as a proportion or percentage of the total number of patients registered with the practice at one point in time. This could mean for example that one practice with an older population might appear to have higher prevalence rates for age-related conditions such as cancer or stroke than another practice with a younger population.
  • Some QOF registers are restricted to include only persons over a specific age. However, the QOF prevalence rates use as their denominator the total (all ages) number of patients registered to the practice at one point in time. Diabetes registers are based on patients aged 17 and over; chronic kidney disease and depression registers are based on patients aged 18 and over. This means that for these conditions the QOF-reported prevalence will appear lower than would be the case if the age restriction was also applied to the population denominator.
  • Prevalence figures based on QOF registers may also differ from prevalence figures from other sources because of coding or definitional issues. For example, to be on the QOF diabetes register the type of diabetes (type 1 or type 2) must be specified by the practice. If the type is not specified the patient will not be counted in the register. Information on diabetes as reported elsewhere may not be subject to these restrictions.
  • Whilst some QOF registers count patients with one specific disease or condition, others count patients with one or more of a list of multiple conditions. As well as age, there may be other criteria for inclusion on a QOF register, such as date of diagnosis (this applies to the cancer register, for example).
  • Year-on-year changes in the size of QOF registers are influenced by various factors including: changes in demographic changes (such as an ageing population); improvements in case finding by practices; changes over time in the definition of the registers. This point is addressed in more detail below in the section giving Further information and interpretation on individual QOF registers.

QOF prevalence rates can also be affected by other factors such as:

  • health care seeking behaviour - people differ in the readiness with which they seek health care when they are not well;
  • access to services - people are more likely to consult for a condition if services are readily accessible;
  • diagnostic practice - it is impossible to completely standardise the methods clinicians use to make diagnoses;
  • data recording - there may be variations in the completeness and accuracy of practice records. .

These explanations all need to be considered when examining apparent variations in prevalence rates between practices, geographical areas and/or years.

National QOF prevalence estimates for Scotland - Table and commentary

The tables below present information on the reported national prevalence of the diseases or health conditions covered by the QOF registers for the twelve years financial years 2004/05 to 2015/16. The full list of registers has been grouped according to whether the register definitions have stayed the same over the QOF years to date or whether they have been revised at some point.

This table, and all other tables on these web pages, shows Scotland-level estimates based on all prevalence data available in the QOF payment calculation system (QMAS or QOF Calculator) by the time QOF data were extracted for publication (the date of extraction is noted in each data table). This includes those practices whose register data were amended after National Prevalence Day. These are the prevalence data that are likely to be of greater interest to most people. However, these rates are not necessarily the same as the national prevalence rates used in QOF payment calculations. The rates used in payment calculations, which are calculated differently and may be based on data from fewer practices, are shown in an Excel version of the table, downloadable below.

Further information on register definitions, and changes to them for 2006/07, 2008/09, 2009/10, 2011/12, 2012/13, 2013/14, 2014/15 and 2015/16 can be found in the following documents:

Additional information on the prevalence of long-term conditions in Scotland can be found on the Scottish Public Health Observatory (ScotPHO) website, in the Scottish Health Survey and in the Practice Team Information (PTI) pages on the ISD website.

Commentary on the comparability of QOF and PTI data can be found in the PTI pages of the ISD website.

Download Excel fileQOF National Prevalence rates by Register and Year (April-March), Scotland [0.25Mb].

Further information and interpretation on individual QOF registers

For more information on why specific indicators have been included in QOF, by year, please refer to the links below:

Links to QOF Business Rules for specific indicators, by year are listed below (contains the technical requirements for selecting the appropriate register)

If you require more information for years prior to 2012/13 please contact us at nss.isdGeneralPractice@nhs.net.

Asthma

The prevalence statistics provided here are based on annual registers of practice patients with a diagnosis of asthma. Asthma remains a clinical area under the QOF, having been included in the framework from its first year, 2004/05. The current definition is consistent with previous definitions used since 2004/05. The QOF-reported national prevalence rate for asthma has risen from 5.4% in 2004/05 and 2005/06 to 5.9% for 2009/10 and 2010/11, to 6.0% in 2011/12 and to 6.1% in 2012/13 and 2013/14. Prevalence rose to 6.3% in 2014/15 and rose further to 6.4% in 2015/16. The increase may have been due, at least in part, to improved case ascertainment by practices over time.

Further information on the occurrence of asthma in Scotland (including consultation rates in general practice in 2003/04 to 2011/12) is available on ISD's Practice Team Information (PTI) web pages.

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Atrial Fibrillation

Atrial fibrillation is a heart rhythm disorder. The QOF register definition applies to people with an initial event; paroxysmal (intermittent); persistent and permanent atrial fibrillation. Note that this register was introduced to the QOF in April 2006 so that there are now eleven years of comparable data. National prevalence rates in Scotland remained constant at 1.3 per 100 patients over the first three years before a slight rise to 1.4 per 100 for 2009/10 and 2010/11, and to 1.5 per 100 in 2011/12 and 2012/13. There has been a slight increase to 1.6 per 100 in 2013/14 and 2014/15 and a further increase to 1.7 per 100 in 2015/16.

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Cancer

The QOF prevalence statistics provided are based on all cancers. The current definition is consistent with previous patient selections used since 2004/05. Crude (non age-adjusted) national prevalence reported under the QOF has increased from 0.5% in 2004/05 to 2.4% in 2015/16. Because of the date cut-off in the definition of the register, this rise primarily reflects the cumulative accrual of new cancer cases onto practice registers with each passing year and does not provide information about any true increase in cancer prevalence.

Further information on the occurrence of cancer in Scotland is available on the following websites:

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Coronary Heart Disease

Coronary Heart Disease has remained a clinical area within the QOF, with consistent selection criteria, since QOF implementation in 2004/05. The QOF-reported national prevalence of CHD has remained stable until 2013/14, at around 4.3%, but dropped to 4.1% in 2014/15. It remained at 4.1% in 2015/16.

Further information on the occurrence of CHD in Scotland is available on the following websites:

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Chronic Kidney Disease

The QOF indicators for Chronic Kidney Disease (CKD) are based on a practice register of people aged over 18 with chronic kidney disease from any cause. Inclusion in the register is based on estimated Glomerular Filtration Rate (eGFR), a measure of kidney function. Those whose kidney function is assessed at stage 3-5 based on this test are eligible for inclusion on the register. Note that this register was introduced to the QOF in April 2006 so data are only available for six years.

For 2006/07 the final prevalence rate reported from QOF registers was 1.8%, much lower than the true figure expected to emerge over time. The establishment of CKD registers in Scotland was dependent on the existence of systems to support eGFR testing. Unfortunately, in some areas there were delays in introducing eGFR testing and as a result fewer patients than expected were included on CKD registers. By 2007/08 the rate had risen to 2.7%, an increase that was expected and likely to be due largely to improvements in case ascertainment, supported by the improved availability of eGFR testing in Scotland. Further increases to 3.0% for 2008/09, 3.2% in 2009/10; 3.3% in 2010/11 and 2011/12 are likely to reflect ongoing improvements in formal diagnosis of stage 3-5 Chronic Kidney Disease in Scotland. From 2012/13 to 2015/16, the prevalence for CKD remained constant at 3.2%, the same as in 2009/10.

Further information on the occurrence of chronic kidney disease in Scotland is available on the following website:

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Chronic Obstructive Pulmonary Disease (COPD)

COPD has been a clinical area within the QOF since QOF implementation in 2004/05. For 2011/12 there was a change to the diagnostic threshold used to define those on the register meaning that data for this year isn't directly comparable to data from previous years. From 2004/05 to 2010/11 the prevalence of COPD as reported through general practice QOF registers has remained within a range of 1.8% - 2.0%. In 2011/12 and 2012/13 the prevalence was 2.1% and increased to 2.2% in 2013/14. Prevalence remained at 2.2% in 2014/15 but increased to 2.3% in 2015/16..

For 2004/05 and 2005/06 QOF definitions did not allow patients to be on both asthma and COPD registers thus patients with a degree of reversible airways disease were not included on the COPD register. From 2006/07 the rules were revised to allow patients to be included on both COPD and asthma registers. Because of this any comparisons of COPD prevalence before and after this time, and prior to 2011/12, should be made with caution.

Further information on the prevalence of COPD in Scotland is available at:

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Dementia

The definition of this indicator applies to all people diagnosed with dementia either directly by the GP or through referral to secondary care. This register was introduced in April 2006 and there are no directly comparable statistics available for previous years. The final QOF reported national prevalence rates for 2006/07 to 2009/10 were 0.6% in each year with a slight increase to 0.7% in 2010/11 to 2012/13. In 2013/14 there was another slight increase to 0.8%, which it remained at in 2014/15 and 2015/16.

Further information on the occurrence of dementia in Scotland is available on ISD's Practice Team Information (PTI) web pages.

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Depression

From 2006/07 to 2012/13 there were two different QOF registers and indicators related to depression, each based on different criteria. The first indicator relates to case finding of depression among patients with diabetes and/or Coronary Heart Disease (CHD). The second indicator relates to any patient newly diagnosed with depression since the preceding 1st April (e.g. for the 2010/11 QOF year, this would mean patients newly diagnosed after 1st April 2010). Both of the depression indicators were introduced to the QOF in April 2006 and there are no directly comparable statistics available for previous years in either case. From 2013/14 only the newly diagnosed indicator is collected with QOF

The retired register for the depression 1 indicator counts patients with diabetes and/or CHD. The indicator measures whether patients with either or both of these conditions have been assessed for depression. Nationally, 7.2% of patients registered to general practices at 14th February 2007 had diabetes, CHD, or both. This rose to 7.4% at 31st March 2009, 7.6% for 31st March 2010, 7.7% for 31st March 2011, 7.8% for 31st March 2012 and 8.0% for 31st March 2013. This rise is largely due to a rise in the prevalence figures for diabetes over the same time period (from 3.5% to 4.6%).

The remaining register for depression (previously known as depression 2) counts patients with newly diagnosed depression. The indicator then measures whether the severity of the depression has been assessed using an assessment tool validated for use in primary care. An unusual feature has been noted within the technical business rules that define how clinical IT systems should count the register sizes for this indicator. Although the measurement of achievement against this indicator excludes patients diagnosed prior to the preceding 1st April (e.g. 1st April 2010 in the case of the 2011/12 QOF year), the pre-exclusion register size is used for prevalence purposes. For some practices with a long history of recording depression electronically in the clinical record (and where the depression is not recorded as having been resolved), a larger register size will be reported in comparison to an otherwise equivalent practice that has not been recording depression cases electronically over as long a time period. The figures for 2006/07 indicated that nationally 6.2% of patients registered to general practices at 14th February 2007 had been newly diagnosed with depression at some point. The figures for 2008/09 are 7.7% rising to 8.6% for 2009/10 and to 9.0% in 2010/11 and 2011/12. These increases will, at least in part, be due to the cumulative nature of this register.

In 2012/13, a change was introduced to the technical business rules that exclude all patients identified prior to April 2006, which means that the latest figure is not comparable to previous years. The prevalence figure for 2012/13 was 5.2%. This increased to 5.8% in 2013/14 and increased again to 6.3% in 2014/15. The figure increased again to 6.8% in 2015/16. These increases are due, in part, to the cumulative nature of this register.

Further information on the occurrence of depression in Scotland is available on ISD's Practice Team Information (PTI) web pages.

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Diabetes Mellitus

Although indicators related to Diabetes Mellitus have existed in the QOF since April 2004, there has been a change in the selection criteria for counting patients on QOF diabetes registers. Since April 2006, the definition includes all patients aged 17 years and over with diabetes mellitus defined by clinical (Read) codes specific to Type 1 or Type 2 diabetes. Previously there was a wider range of codes accepted under the definition although the age constraint has remained consistent. The prevalence statistics for 2006/07 onwards are therefore not directly comparable with those for 2004/05 and 2005/06.

It should also be noted that QOF prevalence rates use the whole practice population as their denominator, and in the case of diabetes do not exclude patients aged less than 17, even though the register itself is age limited. This has the effect of artificially lowering the prevalence rate, so that the prevalence rates for diabetes reported through the QOF are an underestimate of the true prevalence. The extent of the underestimate depends on the size of the practice population under 17 years.

The QOF-reported prevalence of Diabetes Mellitus has increased steadily from 3.5% at 14th February 2007 to 5.0% at 31st March 2016. This gradual increase over the past few years may be due, at least in part, to improved case ascertainment by practices, but it is consistent with the increase in the prevalence of type 2 diabetes in Scotland reported elsewhere.

It should be further noted that although the practice must record whether the patient has Type 1 or Type 2 diabetes, this level of detail is not recorded within QMAS or QOF Calculator (the national IT systems that support the calculation of QOF achievements and payments). Therefore the register size or prevalence rate cannot be split by type of diabetes.

Further information on the occurrence of diabetes in Scotland is available on the following websites:

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Heart Failure

Patients with Heart Failure counts all patients coded by general practices as having heart failure. Patients with Heart Failure were previously included on two QOF registers, one of which is a subset of the other. The first of these registers counts all patients coded by general practices as having heart failure. This register, and accompanying indicators, was introduced to the QOF in April 2006. The second register counts the subset of patients who have heart failure and left ventricular dysfunction (LVD). LVD was included as a register on the original QOF (2004/05 and 2005/06), but at that time the register related to patients on the coronary heart disease register who also had LVD. LVD was a subset of CHD in previous years, but all these patients are now counted under heart failure registers. This means that LVD rates for the first two years of the QOF are not directly comparable with LVD rates for 2006/07 to 2012/13. In 2014/15 the LVD register was retired.

National QOF prevalence figures for heart failure between 2006/07 and 2015/16 were consistently around 0.8 to 0.9%.

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Hypertension

Hypertension (high blood pressure) has remained a clinical area within the QOF with consistent selection criteria since QOF implementation in 2004/05. The final national prevalence figure for 2005 was 11.5%, and this has risen since to a figure of 13.9% for 2014, which it remained in 2015 and 2016. This increase may be due, at least in part, to improved case ascertainment by practices over time. However the risk of hypertension rises sharply with age and the figures are likely to reflect a real increase in the numbers of people with hypertension in Scotland, a country with a rising proportion of older people.

Further information on the occurrence of hypertension in Scotland is available on the following websites:

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Mental Health

Although indicators for Mental Health have existed in the QOF since April 2004, there has been a change in the selection criteria used to count patients on QOF mental health registers. Since April 2006, the definition has included only patients with serious mental illness, defined as schizophrenia, bipolar affective disorder or other psychoses. Previously, patient selection was based on more a more generalised set of mental health conditions and on the further condition that the patient required, and had consented to, regular follow-up. The prevalence statistics for 2006/07 onwards, although comparable with each other, are not therefore directly comparable with those for 2004/05 and 2005/06.

The prevalence rates for this selected set of mental health conditions, as derived from QOF registers, remained consistent from 2006/07 to 2010/11 at 0.8%, rising slightly to 0.9% for 2011/12. It has remained at this figure for all years up to 2015/16.

Further information on the occurrence of mental health problems in Scotland is available on the following websites:

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Osteoporosis

Introduced in April 2012 for patients aged 50 and over who have been recorded with fragility fracture after 1st April. An osteoporotic fragility fractures can cause substantial pain and severe disability, and are associated with decreased life expectancy. Osteoporotic fragility fractures occur most commonly in the spine (vertebrae), hip (proximal femur) and wrist (distal radius). They also occur in the arm (humerus), pelvis, ribs and other bones. Fractures of the hands and feet (for example, metacarpal and metatarsal fractures) are not generally regarded as osteoporotic fragility fractures. The 2012/13 QOF-reported prevalence rate for Osteoporosis was 0.1%, which rose to 0.2% in 2013/14 but decreased back to 0.1% in 2014/15. It increased to 0.2% again in 2015/16.

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Palliative Care

The definition of the palliative care register has changed since it was first introduced in April 2006. In 2006/07 and 2007/08 it applied to all practice patients aged 18 and over who were identified as being in need of palliative or supportive care. From April 2008, the age restriction was removed so that the register now includes patients of all ages. This means that the figures for 2008/09 onwards are not directly comparable with those for earlier years. This register is particularly difficult to interpret as by its very nature patients join and leave the list over a short period of time. Therefore, the number of patients included on a practice palliative care register is a snapshot of the situation at the time the register was taken (14th February 2007, 14th February 2008, 31st March 2009, 31st March 2010, 31st March 2011 and 31st March 2012 respectively) and may not be a true reflection of practice prevalence throughout the rest of the year. The 2011/12 to 2013/14 QOF-reported prevalence rate for palliative care was 0.2%. In the 2014/15 and 2015/16 QOF all practices display a nil register at year end so prevalence is noted as 0%; provided a contractor can demonstrate that it established and maintained a denominator during the financial year then they will be eligible for payment for this indicator.

The 2011/12 to 2013/14 QOF-reported prevalence rate for palliative care was 0.2%. In 2014/15 QOF all practices display a nil register at year end so prevalence is noted as 0%; provided a contractor can demonstrate that it established and maintained a denominator during the financial year then they will be eligible for payment for this indicator.

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Peripheral Arterial Disease (PAD)

Introduced in April 2012 this set of indicators for PAD aims to improve the identification and management of PAD and ensure all patients, including those without established risk factors already covered in QOF, are managed for their cardiovascular risk. The 2012/13 QOF-reported prevalence rate for PAD was 0.9%, which it has remained since up to 2015/16.

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Rheumatoid Arthritis

A new indicator introduced in April 2014 which maintains a register of patients with rheumatoid arthritis. As this register is new then the results should be interpreted with caution. The 2013/14 QOF-reported prevalence rate was 0.6% and remained the same in 2014/15 and 2015/16.

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Stroke and Transient Ischaemic Attack (TIA)

Stroke and TIA has remained a clinical area within the QOF, with consistent selection criteria for including patients on the register, since the QOF was introduced in 2004/05. Reported national prevalence rose from 1.8% for 2004/05 to 2.0% in 2006/07, 2007/08 and 2008/09. For 2009/10, 2010/11, 2011/12 and 2012/13, a prevalence of 2.1% has been recorded. The figure increased to 2.2% in 2013/14 and was the same in 2014/15 and 2015/16. The increase in the initial years of the QOF may have been due, at least in part, to improved case ascertainment by practices over time and an ageing population in Scotland.

Further information on the occurrence of stroke in Scotland is available on the following websites:

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